DESCRIPTION
Title of Invention
METHOD FOR MNUFACTURING SUBSTRATE HAVING TEXTURED
STRUCTURE AND METHOD FOR MANUFACTURING ORGANIC EL
ELEMENTS USING SAME
Technical Field
[0001] The present invention relates to a method for producing a substrate having
irregular concavities and convexities used for production of an organic
electro-luminescent element and the like and a method for producing an organic EL
using the same.
Background Art
[0002] As a self-luminescent display element, there has been known an organic
electro-luminescent element (also referred to as an organic light-emitting diode.
Hereinbelow, referred to as an "organic EL element"). As compared with a liquid
crystal element, the organic EL element has high visibility and does not need a backlight,
and thus it is possible to reduce the weight thereof. For this reason, research and
development of the organic EL element as the display element for the next generation
has been actively carried out.
[0003] In the organic EL element, a hole injected from a hole injecting layer and
electron injected from an electron injecting layer are carried to a light emitting layer
respectively, then the hole and the electron are recombined on an organic molecule in
the light emitting layer to excite the organic molecule, and thereby light emission
occurs. Therefore, in a case that the organic EL element is used as a display device,
the light from the light emitting layer is required to be efficiently extracted from the
surface of the organic EL element. In order to meet this demand, PATENT
LITERATURE 1 and the like disclose that a diffraction-grating substrate is provided on
a light extraction surface of the organic EL element.
Citation List
Patent Literature
[0004] PATENT LITERATURE 1: Japanese Patent Application Laid-open No.
2006-236748
PATENT LITERATURE 2: PCT International Publication No.
WO2011/007878A1
Summary of Invention
Technical Problem
[0005] The applicant of the present invention discloses the following method in
PATENT LITERATURE 2. That is, a solution obtained by dissolving a block
copolymer satisfying a predetermined condition into a solvent is applied on a base
member, and drying is performed to form a micro phase separation structure of the
block copolymer, thereby obtaining a master block (metal substrate) in which a minute
or fine and irregular concavity and convexity pattern is formed. According to this
method, it is possible to obtain the master block used for the nanoimprint and the like by
using a self-organizing phenomenon of the block copolymer. A mixture of a
silicone-based polymer and a curing agent is dripped onto the obtained master block and
then cured to obtain a transferred pattern. Then, a glass substrate to which a curable
resin has been applied is pressed against the transferred pattern and the curable resin is
cured by irradiation with ultraviolet rays. In this way, a diffraction grating in which
the transferred pattern is duplicated is manufactured. It has been confirmed that an
organic EL element obtained by stacking a transparent electrode, an organic layer, and a
metal electrode on the diffraction grating has sufficiently high light emission efficiency,
sufficiently high level of external extraction efficiency, sufficiently low
wavelength-dependence of light emission, sufficiently low directivity of light emission,
and sufficiently high power efficiency.
[0006] It is desired that even the organic EL element in which the diffraction grating
produced in PATENT LITERATURE 2 as described above is used emits light at a
uniform luminance from the entire display surface(s) in a case that the organic EL
element is used as the display device and/or the illumination device of a cellular or
mobile phone, a television screen, and the like. Thus, it is necessary to confirm
whether or not the irradiation or emission from the organic EL element is uniform, that
is, whether unevenness of luminance is within an acceptable range, after completion of
the organic EL element. In a case that the unevenness of luminance of the completed
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organic EL element is judged to be beyond the acceptable range, the organic EL
element is determined to be a unsatisfactory or defective product, and a step for
stacking many layers on the diffraction grating as described above goes to waste.
Especially, stacking of the transparent electrode, the organic layer, the metal electrode,
and the like is a complex or time-consuming process requiring a high production cost.
Therefore, it is strongly desired that the number of such the unsatisfactory or defective
products is reduced to improve the yield rate, and thereby reducing the waste of the
material and the production cost.
[0007] In view of the above, an object of the present invention is to provide a method
for producing an organic EL element which includes a diffraction-grating substrate
having an irregular concave and convex surface with a high throughput. Further,
another object of the present invention is to provide a method for producing a substrate
having an irregular concave and convex surface which is used as an optical component,
the method including a step for evaluating unevenness of luminance of the substrate.
Solution to the Problem
[0008] According to the present invention, there is provided a method for producing a
substrate having an irregular concave and convex surface for scattering light, including:
manufacturing the substrate having the irregular concave and convex surface;
irradiating the concave and convex surface of the manufactured substrate with
inspection light from a direction oblique to a normal direction of the concave and
convex surface, and detecting returning light of the inspection light returned from the
concave and convex surface by a light-receiving element provided in the normal
direction of the concave and convex surface; and
judging unevenness of luminance of the concave and convex surface based on
light intensity of the received returning light.
[0009] In the method for producing the substrate of the present invention, any method
in which phase separation of the block copolymer is utilized can be adopted as the
method for manufacturing the substrate having the irregular concave and convex surface.
The method for manufacturing the substrate having the irregular concave and convex
surface is exemplified by a method in which the phase separation of the block
copolymer is promoted by heat or solvent vapor. In a case of the phase separation due
to heat, the method may include: a step of applying a block copolymer solution of a
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block copolymer made of at least a first polymer and a second polymer on a surface of a
base member to form a coating film; a step of drying the coating film on the base
member; a first heating step for heating the coating film after the drying at a
temperature higher than a glass transition temperature of the block copolymer of the
block copolymer solution (step of performing the phase separation of the block
copolymer); and an etching step for etching the coating film after the first heating step
to remove the second polymer so that a concavity and convexity structure is formed on
the base member. Further, the method may include a second heating step of heating
the concavity and convexity structure, for which the etching has been performed in the
etching step, at a temperature higher than a glass transition temperature of the first
polymer. Furthermore, the method may include: a step of forming a seed layer on the
concavity and convexity structure after the second heating step; a step of stacking a
metal layer on the seed layer by electroforming; and a step of peeling off the base
member having the concavity and convexity structure from the metal layer and the seed
layer to obtain a metal substrate. By performing the second heating step, each convex
portion in the concavity and convexity structure develops into a chevron shape. Thus,
even in a case that the metal layer as a mold is stacked on the concavity and convexity
structure by the electroforming, the metal layer can be peeled off from the concavity and
convexity structure easily. The obtained metal substrate may be a substrate having the
irregular concave and convex surface. Alternatively, the substrate having the irregular
concave and convex surface may be obtained as follows. That is, the obtained metal
substrate is pressed to a transparent substrate to which a curable resin has been applied;
the curable resin is cured; and the metal substrate is detached. Or, the substrate having
the irregular concave and convex surface made of a sol-gel material may be obtained as
follows. That is, the obtained metal substrate is pressed to a substrate to which a
curable resin has been applied; the curable resin is cured; the metal substrate is detached
to form a substrate having a concavity and convexity structure on the substrate; the
substrate having the concavity and convexity structure is pressed onto a transparent
substrate to which the sol-gel material has been applied; the so-gel material is cured;
and the substrate is detached.
[0010] A micro phase separation structure of the block copolymer may be generated in
the drying step or the first heating step, and the micro phase separation structure
preferably has a lamellar form.
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[0011] In the method for producing the substrate of the present invention, the
manufacturing the substrate having the irregular concave and convex surface may
include: a step of forming a vapor-deposited film on a surface of a polymer film, which
is made of a polymer of which volume changes by heat, under a temperature condition
of 70 degrees Celsius or above, and then cooling the polymer film and the
vapor-deposited film to form concavities and convexities of wrinkles in a surface of the
vapor-deposited film; a step of attaching a master block material on the vapor-deposited
film; a step of curing the master block material; and a step of detaching the master
block material after the curing from the vapor-deposited film to obtain a master block.
The irregular concave and convex surface can be manufactured effectively in such a
method as well. In this case, the polymer of which volume changes by heat may be a
silicone-based polymer.
[0012] In the method for producing the substrate of the present invention, irregular
concavities and convexities of the irregular concave and convex surface have a pseudo
periodic structure, and in a case that an average period of the concavities and
convexities is denoted by d, and that central wavelength of the inspection light is
denoted by X, the average period d and the central wavelength X preferably satisfy 0.5d
< X < 2.0d. Further, the inspection light is desirably a light of a blue band.
Furthermore, the concave and convex surface is preferably irradiated with the inspection
light so that an incident angle a, which is oblique to the normal direction of the concave
and convex surface, is 30° < a < 90°.
[0013] In the method for producing the substrate of the present invention, the
light-receiving element may be an imaging device, and a maximum value and a
minimum value of the returning light intensity may be obtained from output of each
pixel of the imaging device to judge whether or not maximum value/minimum value is
less than 1.5. In accordance with this reference or criterion, it is possible to judge the
unevenness of luminance of the substrate effectively.
[0014] In the method for producing the substrate of the present invention, the substrate
having the irregular concave and convex surface may be a film-shaped substrate (for
example, a film-shaped substrate made of resin) or a glass substrate. The film-shaped
substrate or the glass substrate may be irradiated with the inspection light while being
moved continuously relative to the inspection light. Accordingly, it is possible to
continuously and efficiently produce the substrate by using a line facility.
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[0015] In the method for producing the substrate of the present invention, the irregular
concave and convex surface may be formed of metal, resin, or a sol-gel material.
[0016] According to the second aspect of the present invention, there is provided a
method for producing an organic EL element, including: manufacturing a
diffraction-grating substrate having a concave and convex surface by using the method
for producing the substrate of the present invention; and stacking a transparent electrode,
an organic layer, and a metal electrode on the concave and convex surface of the
diffraction-grating substrate sequentially to produce the organic EL element. In the
method for producing the organic EL element, only in a case that it is judged that
unevenness of luminance of the manufactured diffraction-grating substrate is within a
predetermined range, the transparent electrode, the organic layer, and the metal
electrode can be stacked sequentially on the concave and convex surface of the
diffraction-grating substrate having the unevenness of luminance within the
predetermined range to produce the organic EL element. Accordingly, the
diffraction-grating substrate having a high degree of unevenness of luminance can be
excluded in advance, and the organic EL element generating a uniform illumination
intensity can be produced with a high throughput. Whether or not the unevenness of
luminance of the manufactured diffraction-grating substrate is within the predetermined
range can be judged as follows. That is, a maximum value and a minimum value of
the returning light intensity are obtained from output of each pixel of an imaging device
used as a light-receiving element, and it is judged whether or not maximum
value/minimum value is less than 1.5.
Advantageous Effects of Invention
[0017] According to a method for producing a substrate of the present invention, a
substrate having an irregular concavity and convexity structure which is used for an
element such as an organic EL element can be produced efficiently, while unevenness of
luminance of the substrate having the irregular concavity and convexity structure is
measured effectively. According to a method for producing the organic EL element of
the present invention, the organic EL element can be produced with a high throughput
by associating property of the unevenness of luminance of the organic EL element with
property of the unevenness of luminance of the substrate having the irregular concave
and convex surface which is used for the organic EL element. Especially, since
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prediction of occurrence of the unevenness of luminance of the completed organic EL
element and evaluation of the completed organic EL element can be performed in the
production step of the substrate, it is possible to further reliably produce the organic EL
element having a uniform illumination intensity by using a substrate which passed the
judgment of the unevenness of luminance or which was judged to have a satisfactory or
acceptable unevenness of luminance. Further, even in a case that the uniformity of the
illumination intensity (unevenness of luminance) of the organic EL element is
unsatisfactory, since it can be determined whether the defect occurred at a substrate
formation stage or a formation stage of the element itself, it is possible to respond such
a situation rapidly.
Brief Description of Drawings
[0018]
Fig. 1 is a flowchart showing a method for producing a substrate of the present
invention.
Fig. 2 schematically shows a process for manufacturing the substrate in
accordance with BCP method.
Fig. 3 schematically shows a process for manufacturing the substrate after
electroforming.
Fig. 4 is a flowchart showing the process for manufacturing the substrate in
accordance with the BCP method.
Fig. 5 schematically shows a method for producing the substrate in accordance
with BKL method.
Fig. 6 schematically shows an inspection step of the substrate according to the
method of the present invention.
Fig. 7 schematically shows a diffraction condition of a substrate having a
concave and convex surface.
Fig. 8 shows a cross-section structure of an organic EL element.
Fig. 9 shows a concavity and convexity analysis image, which was obtained by
use of an atomic force microscope, of a surface of a resin of a diffraction-grating
substrate manufactured in Example 1.
Fig. 10 shows a Fourier-transformed image obtained from the concavity and
convexity analysis image, which was obtained by use of the atomic force microscope, of
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the surface of the resin of the diffraction-grating substrate manufactured in Example 1.
Fig. 11(A) is a photograph showing an image from a surface of the substrate
observed in Example 1.
Fig. 11(B) is a graph showing profile of pixel positions on the line LI in the
photograph of Fig. 11(A) and pixel values at the pixel positions.
Fig. 12(A) is a photograph showing an image from the surface of the substrate
observed in Example 1.
Fig. 12(B) is a graph showing profile of pixel positions on the line LI in the
photograph of Fig. 12(A) and pixel values at the pixel positions.
Fig. 13 shows a concavity and convexity analysis image, which was obtained
by use of the atomic force microscope, of a surface of a resin of a diffraction-grating
substrate manufactured in Example 2.
Fig. 14 shows a Fourier-transformed image obtained from the concavity and
convexity analysis image, which was obtained by use of the atomic force microscope, of
the surface of the resin of the diffraction-grating substrate manufactured in Example 2.
Fig. 15(A) is a photograph showing an image from a surface of the substrate
observed in Example 2.
Fig. 15(B) is a graph showing profile of pixel positions on the line L2 in the
photograph of Fig. 15(A) and pixel values at the pixel positions.
Fig. 16(A) is a photograph showing an image from the surface of the substrate
observed in Example 2.
Fig. 16(B) is a graph showing profile of pixel positions on the line L2 in the
photograph of Fig. 16(A) and pixel values at the pixel positions.
Fig. 17 illustrates an outline of continuous molding and inspection line of a
film-shaped substrate.
Fig. 18 illustrates another outline of the continuous molding and inspection line
of the film-shaped substrate.
Fig. 19 shows photographs of images of the concave and convex surface of the
substrate obtained by using LED bar illuminations having blue LED, white LED, and
red LED, respectively.
Fig. 20(A) is a photograph showing an image from the surface of the substrate
observed in Example 1.
Fig. 20(B) is a graph showing profile of pixel positions on the line L3 in the
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photograph of Fig. 20(A) and pixel values at the pixel positions.
Description of Embodiments
[0019] In the following, preferred embodiments of a method for producing a substrate
and a method for producing an organic EL according to the present invention will be
described in detail with reference to the drawings.
[0020] The outline of the method for producing the substrate and the method for
producing the organic EL according to the present invention is shown in the flowchart
of Fig. 1. At first, a substrate having an irregular concavity and convexity structure is
produced in accordance with a substrate manufacturing step exemplified below (SI).
Next, luminance of the surface of the obtained substrate is inspected in accordance with
an inspection step as will be described later on (S2). The inspection result is subjected
to a judgment in which it is judged whether or not the substrate has a uniform luminance
distribution in accordance with a predetermined judgment step which will be described
later (S3). In a case that it is judged that the substrate has the uniform luminance
distribution, the organic EL is produced using the substrate (S4). In a case that it is not
judged that the substrate has the uniform luminance distribution, an aftertreatment as
will be described later on is performed (S5). In the following, an explanation will be
made about each of the steps with reference to drawings.
[0021]
1. Step of manufacturing substrate
According to the method for producing the substrate of the present invention, a
substrate having an irregular concave and convex surface is manufactured. The
"substrate having an irregular concave and convex surface" refers to a substrate in
which a concavity and convexity pattern formed therein has no regularity, in particular,
a substrate in which pitches of concavities and convexities are ununiform and
orientations of the concavities and convexities have no directivity. The light scattered
and/or diffracted on such a substrate is not light having single wavelength or wavelength
having a narrow band. The light scattered and/or diffracted on such a substrate has a
range of wavelength relatively broad, has no directivity, and is directed in various
directions. However, the "substrate having an irregular concave and convex surface"
includes a pseudo periodic structure such as that in which a Fourier-transformed image,
which is obtained by performing a two-dimensional fast Fourier-transform processing
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on an concavity and convexity analysis image obtained by analyzing a concavity and
convexity shape on the surface, shows a circular or annular pattern, that is, such as that
in which, although the orientations of the concavities and convexities have no directivity,
the pitches of the concavities and convexities vary. Therefore, the substrate having
such a pseudo periodic structure is suitable for a diffraction substrate used in a
surface-emitting element and the like such as an organic EL element, provided that the
substrate which has the distribution or variability in the pitch of the concavities and
convexities diffracts visible light. On the other hand, a substrate, which is formed so
that all of the recording tracks (groups) are aligned in the same direction at the same
pitch, such as an optical recording medium and magnetic recording medium, is not
included in an object of production according to the present invention.
[0022] In order to produce the substrate having the irregular concave and convex
surface as described above, it is preferable to use a method of utilizing self-organization
or assembly (micro phase separation) of a block copolymer described in Japanese Patent
Application Laid-open No. 2011-006487 of the inventors of the present invention to be
described below (hereinafter referred to as "BCP (Block Copolymer) method" as
appropriate) or a method of heating and cooling a polymer film on a vapor-deposited
film to form concavities and convexities of wrinkles on a surface of polymer disclosed
in International Application No. PCT/JP2010/062110 (WO2011/007878A1) of the
inventors of the present invention (hereinafter referred to as "BKL (Buckling) method"
as appropriate). Each of the methods will be described below.
[0023]
A. Production of substrate by BCP method
An explanation will be made about the production of the substrate by the BCP
method with reference to Figs. 2 to 4.
[0024]

The block copolymer used for the BCP method includes at least a first polymer
segment made of a first homopolymer and a second polymer segment made of a second
homopolymer different from the fist homopolymer. The second homopolymer
desirably has a solubility parameter which is higher than a solubility parameter of the
first homopolymer by 0.1 to 10 (cal/cm3)'/2. In a case that the difference between the
solubility parameters of the first and second homopolymers is less than 0.1 (cal/cm3)"2,
11
it is difficult to form a regular micro phase separation structure of the block copolymer.
In a case that the difference exceeds 10 (cal/cm3)1/2, it is difficult to prepare a uniform
solution of the block copolymer.
[0025] Examples of monomers serving as raw materials of homopolymers usable as
the first homopolymer and second homopolymer include styrene, methylstyrene,
propylstyrene, butylstyrene, hexylstyrene, octylstyrene, methoxystyrene, ethylene,
propylene, butene, hexene, acrylonitrile, acrylamide, methyl methacrylate, ethyl
methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl
methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl
acrylate, octyl acrylate, methacrylic acid, acrylic acid, hydroxyethyl methacrylate,
hydroxyethyl acrylate, ethylene oxide, propylene oxide, dimethylsiloxane, lactic acid,
vinylpyridine, hydroxystyrene, styrenesulfonate, isoprene, butadiene, e-caprolactone,
isopropylacrylamide, vinyl chloride, ethylene terephthalate, tetrafluoroethylene, and
vinyl alcohol. Of these monomers, styrene, methyl methacrylate, ethylene oxide,
butadiene, isoprene, vinylpyridine, and lactic acid are preferably used from the
viewpoints that the formation of phase separation easily occurs, and that the concavities
and convexities are easily formed by an etching.
[0026] In addition, examples of a combination of the first homopolymer and the
second homopolymer include combinations of two selected from the group consisting of
a styrene-based polymer (more preferably polystyrene), polyalkyl methacrylate (more
preferably polymethyl methacrylate), polyethylene oxide, polybutadiene, polyisoprene,
polyvinylpyridine, and polylactic acid. Of these combinations, a combination of the
styrene-based polymer and polyalkyl methacrylate, a combination of the styrene-based
polymer and polyethylene oxide, a combination of the styrene-based polymer and
polyisoprene, a combination of the styrene-based polymer and polybutadiene are more
preferable, and the combination of the styrene-based polymer and polymemyl
methacrylate, the combination of the styrene-based polymer and polyisoprene, the
combination of the styrene-based polymer and polybutadiene are particularly preferable,
from the viewpoint that the depths of the concavities and convexities formed in the
block copolymer can be further increased by preferentially removing one of the
homopolymers by the etching process. A combination of polystyrene (PS) and
polymethyl methacrylate (PMMA) is further preferable.
[0027J The number average molecular weight (Mn) of the block copolymer is
preferably 500,000 or more, and is more preferably 1,000,000 or more, and particularly
preferably 1,000,000 to 5,000,000. In a case that the number average molecular
weight is less than 500,000, the average pitch of the concavities and convexities formed
by the micro phase separation structure of the block copolymer is so small that the
average pitch of the concavities and convexities of the obtained diffraction grating
becomes insufficient. Especially, in a case of the diffraction grating used for the
organic EL, since the diffraction grating needs to diffract illumination light over a range
of wavelength of a visible region, the average pitch is desirably 100 to 600 nm, and thus
the number average molecular weight (Mn) of the block copolymer is preferably
500,000 or more. Further, according to experiments conducted by the applicant, it has
been appreciated that, in a case that the number average molecular weight (Mn) of the
block copolymer is 500,000 or more, it is difficult to obtain a desired concavity and
convexity pattern by an electroforming, unless the second heating step is performed
after the etching step, as it will be described later.
[0028] The molecular weight distribution (Mw/Mn) of the block copolymer is
preferably 1.5 or less, and is more preferably 1.0 to 1.35. In a case that the molecular
weight distribution exceeds 1.5, it is not easy to form the regular micro phase separation
structure of the block copolymer.
[0029] Note that the number average molecular weight (Mn) and the weight average
molecular weight (Mw) of the block copolymer are values measured by gel permeation
chromatography (GPC) and converted to molecular weights of standard polystyrene.
[0030] In the block copolymer, a volume ratio between the first polymer segment and
the second polymer segment (the first polymer segment: the second polymer segment) is
desirably 3:7 to 7:3 in order to create a lamellar structure by self-organization or
assembly, and is more preferably 4:6 to 6:4. In a case that the volume ratio is out of
the above-described range, a concavity and convexity pattern owing to the lamellar
structure is difficult to form.
[0031] The block copolymer solution used in the BCP method is prepared by
dissolving the block copolymer in a solvent. Examples of the solvent include aliphatic
hydrocarbons such as hexane, heptane, octane, decane, and cyclohexane; aromatic
hydrocarbons such as benzene, toluene, xylene, and mesitylene; ethers such as diethyl
ether, tetrahydrofuran, and dioxane; ketones such as acetone, methyl ethyl ketone,
isophorone, and cyclohexanone; ether alcohols such as butoxyethyl ether, hexyloxyethyl
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alcohol, methoxy-2-propanol, and benzyloxyethanol; glycol ethers such as ethylene
glycol dimethyl ether, diethylene glycol dimethyl ether, triglyme, propylene glycol
monomethyl ether, and propylene glycol monomethyl ether acetate; esters such as ethyl
acetate, ethyl lactate, and y-butyrolactone; phenols such as phenol and chlorophenol;
amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and
N-methylpyrrolidone; halogen-containing solvents such as chloroform, methylene
chloride, tetrachloroethane, monochlorobenzene, and dichlorobenzene; hetero-element
containing compounds such as carbon disulfide; and mixture solvents thereof. A
percentage content of the block copolymer in the block copolymer solution is preferably
0.1 to 15% by mass, and more preferably 0.3 to 5% by mass, relative to 100% by mass
of the block copolymer solution.
[0032] In addition, the block copolymer solution may further include a different
homopolymer (a homopolymer other than the first homopolymer and the second
homopolymer in the block copolymer contained in the solution: for example, when the
combination of the first homopolymer and the second homopolymer in the block
copolymer is the combination of polystyrene and polymethyl methacrylate, the different
homopolymer may be any kind of homopolymer other than polystyrene and polymethyl
methacrylate), a surfactant, an ionic compound, an anti-foaming agent, a leveling agent,
and the like.
[0033] By containing the different homopolymer, the micro phase separation structure
of the block copolymer can be improved. For example, polyalkylene oxide can be
used to increase the depths of the concavities and convexities formed by the micro
phase separation structure. As the polyalkylene oxide, polyethylene oxide or
polypropylene oxide is more preferable, and polyethylene oxide is particularly
preferable. In addition, as the polyethylene oxide, one represented by the following
formula is preferable:
HO-(CH2-CH2-0)n-H
[in the formula, "n" represents an integer of 10 to 5000 (more preferably an integer of
50 to 1000, and further preferably an integer of 50 to 500)]. In a case that the value of
n is less than the lower limit, the molecular weight is so low that the effect obtained by
containing the different homopolymer becomes insufficient, because the polyethylene
14
#
oxide is lost due to volatilization, vaporization, or the like during a heating process at a
high-temperature. In a case that the value exceeds the upper limit, the molecular
weight is so high that the molecular mobility is low. Hence, the speed of the phase
separation is lowered, and the formation of the micro phase separation structure is
adversely affected.
[0034] In addition, the number average molecular weight (Mn) of the different
homopolymer is preferably 460 to 220,000, and is more preferably 2,200 to 46,000. In
a case that the number average molecular weight is less than the lower limit, the
molecular weight is so low that the effect obtained by containing the different
homopolymer becomes insufficient, because the different homopolymer is lost due to
volatilization, vaporization, or the like during the heating process at the
high-temperature. In a case that the number average molecular weight exceeds the
upper limit, the molecular weight is so high that the molecular mobility is low. Hence,
the speed of the phase separation is lowered, and the formation of the micro phase
separation structure is adversely affected.
[0035] The molecular weight distribution (Mw/Mn) of the different homopolymer is
preferably 1.5 or less, and more preferably 1.0 to 1.3. In a case that the molecular
weight distribution exceeds the upper limit, uniformity of the shape of the micro phase
separation is less likely to be maintained. Note that the number average molecular
weight (Mn) and the weight average molecular weight (Mw) are values measured by gel
permeation chromatography (GPC) and converted to molecular weights of standard
polystyrene.
[0036] In addition, in a case that the different homopolymer is used in the BCP method,
it is preferable that the combination of the first homopolymer and the second
homopolymer in the block copolymer be the combination of polystyrene and
polymethyl methacrylate (polystyrene-polymethyl methacrylate), and that the different
homopolymer be a polyalkylene oxide. By using a polystyrene-polymethyl
methacrylate block copolymer and polyalkylene oxide in combination as described
above, the orientation in the vertical direction is further improved, thereby making it
possible to further increase the depths of the concavities and convexities on the surface,
and to shorten the heating process time during the manufacture.
[0037] In a case that the different homopolymer is used, the content thereof is
preferably 100 parts by mass or less, and more preferably 5 parts by mass to 100 parts
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by mass, relative to 100 parts by mass of the block copolymer. In a case that the
content of the different homopolymer is less than the lower limit, the effect obtained by
containing the different homopolymer becomes insufficient.
[0038] In a case that the surfactant is used, the content thereof is preferably 10 parts by
mass or less relative to 100 parts by mass of the block copolymer. Moreover, in a case
that the ionic compound is used, the content thereof is preferably 10 parts by mass or
less relative to 100 parts by mass of the block copolymer.
[0039] In a case that the block copolymer solution contains the different homopolymer,
the total percentage content of the block copolymer and the different homopolymer is
preferably 0.1 to 15% by mass, and more preferably 0.3 to 5% by mass, in the block
copolymer solution. In a case that the total percentage content is less than the lower
limit, it is difficult to uniformly apply the solution to attain a film thickness sufficient to
obtain a necessary film thickness. In a case that the total percentage content exceeds
the upper limit, it is relatively difficult to prepare a solution in which the block
copolymer and the different homopolymer are uniformly dissolved in the solvent.
[0040]

According to the method for producing the substrate using the BCP method, as
shown in Fig. 2(A), the block copolymer solution prepared as described above is
applied on a base member 10 to form a thin film 30. The base member 10 is not
especially limited, and is exemplified, for example, by substrates of resins such as
polyimide, polyphenylene sulfide (PPS), polyphenylene oxide, polyether ketone,
polyethylene naphthalate, polyethylene terephthalate, polyarylate, triacetyl cellulose,
and polycycloolefin; inorganic substrates such as glass, octadecyldimethyl chlorosilane
(ODS) treated glass, octadecyl trichlorosilane (OTS) treated glass, organo silicate
treated glass, and silicon substrates; and substrates of metals such as aluminum, iron,
and copper. In addition, the base member 10 may be subjected to a surface treatment
such as an orientation treatment, etc. By performing treatment on the surface of the
substrate such as the glass with ODS, organo silicate, or the like, the micro phase
separation structure such as the lamellar structure, a cylinder structure, and a globular or
spherical structure is more likely to be arranged perpendicular to the surface in a heating
step as will be described later on. The reason thereof is that domain of each block
forming the block copolymer is more likely to be perpendicularly-oriented by
16
decreasing the difference in interface energy between each block copolymer component
and the surface of the substrate.
[0041] The method for applying the block copolymer solution is not particularly
limited, and, for example, a spin coating method, a spray coating method, a dip coating
method, a dropping method, a gravure printing method, a screen printing method, a
relief printing method, a die coating method, a curtain coating method, or an ink-jet
method can be employed as the method.
[0042] The thickness of the thin film 30 of the block copolymer is preferably within a
range which allows the thickness of a dried coating film, as will be described later, to be
10 to 3000 run, and more preferably within a range which allows the thickness of the
dried coating film to be 50 to 500 nm.
[0043]

After the block copolymer solution is applied on the base member 10 to form
the thin film 30, the thin film 30 on the base member 10 is dried. The drying can be
performed in the ambient atmosphere. The temperature for drying the thin film 30 is
not particularly limited, provided that the solvent can be removed from the thin film 30.
For example, the temperature is preferably 30 degrees Celsius to 200 degrees Celsius,
and more preferably 40 degrees Celsius to 100 degrees Celsius. It is noted that
concavities and convexities are found, in some cases, on the surface of the thin film 30
when the formation of the micro phase separation structure of the block copolymer is
started during the drying step.
[0044]

After the drying step, the thin film 30 is heated at a temperature of not less than
a glass transition temperature (Tg) of the block copolymer (first heating step or
annealing process). The heating step (an example of a step of generating the micro
phase separation structure) promotes the self-organization or assembly of the block
copolymer, and the micro phase separation of the block copolymer into portions of a
first polymer segment 32 and second polymer segment 34 occurs as shown in Fig. 2(B).
In a case that the heating temperature is less than the glass transition temperature of the
block copolymer, the molecular mobility of the polymer is so low that the
self-organization or assembly of the block copolymer does not make progress
17
adequately and thus the micro phase separation structure can not be formed enough or
the heating time required for sufficiently generating the micro phase separation structure
is long. In addition, the upper limit of the heating temperature is not particularly
limited, unless the block copolymer is pyrolyzed at the temperature. The first heating
step can be performed in the ambient atmosphere using an oven or the like. The
drying step and the heating step can be performed continuously by gradually increasing
the heating temperature. Accordingly, the drying step is included in the heating step.
[0045]

After the first heating step, the etching process of the thin film 30 is performed.
Since the molecular structure of the first polymer segment 32 is different from the
molecular structure of the second polymer segment 34, etchability of the first polymer
segment 32 is also different from that of the second polymer segment 34. Therefore,
by performing the etching process depending on each type of the polymer segments,
that is, depending on each type of homopolymer, it is possible to selectively remove one
of the polymer segments (second polymer segment 34) forming the block copolymer.
A remarkable concavity and convexity structure appears on the coating film by
removing each second polymer segment 34 from the micro phase separation structure in
the etching process. As the etching process, an etching method using a reactive ion
etching method, an ozone oxidation method, a hydrolysis method, a metal ion staining
method, an ultraviolet-ray etching method, or the like can be employed. Moreover, as
the etching process, a method may be employed in which covalent bonds in the block
copolymer are cleaved by treating the covalent bonds with at least one selected from the
group consisting of acids, bases, and reducing agents, and then the coating film in which
the micro phase separation structure is formed is cleaned with a solvent which dissolves
only one of the polymer segments, or the like, thereby removing only the one of the
polymer segments, while keeping the micro phase separation structure. In the
embodiments which will be described later, the ultraviolet-ray etching is used in view of
operability and the like.
[0046]

The second heating process or the annealing process is performed to a
concavity and convexity structure 36 of the thin film 30 obtained by the etching step.
18
The heating temperature in the second heating process is desirably not less than the
glass transition temperature of the first polymer segment 32 remaining after the etching,
that is, not less than the glass transition temperature of the first homopolymer. For
example, the heating temperature in the second heating process is desirably not less than
the glass transition temperature of the first homopolymer and not more than a
temperature higher than the glass transition temperature of the first homopolymer by 70
degrees Celsius. In a case that the heating temperature is less than the glass
transition temperature of the first homopolymer, it is not possible to obtain a desired
concavity and convexity structure (that is, a smooth chevron structure) after the
electroforming, or a long time is required to perform the heating. In a case that the
heating temperature is much higher than the glass transition temperature of the first
homopolymer, the first polymer segment 32 is melted and/or the shape of the first
polymer segment 32 is collapsed severely. Thus, it is not preferable. In view of the
above, the heating is desirably performed within a range from the glass transition
temperature to the temperature higher than the glass transition temperature by about 70
degrees Celsius. Similar to the first heating process, the second heating process can be
performed in the ambient atmosphere using the oven or the like.
[0047] According to experiments conducted by the inventors of the present invention,
it has been found out that a desired transfer pattern is hardly obtained in case that the
concavity and convexity structure 36 of the coating film obtained by the etching step is
used as a master (master block) to transfer the concavity and convexity structure to a
metallic mold by the electroforming which will be described later. Especially, this
problem becomes conspicuous as the molecular weight of the block copolymer is higher.
As described above, the molecular weight of the block copolymer is deeply linked with
the micro phase separation structure, and thus the pitch of the diffraction grating
obtained therefrom. Therefore, in a case that the diffraction grating is used for a
purpose such as the organic EL element, a distribution of the pitch is required to be such
that diffraction occurs in a wavelength region such as the visible region including a
wavelength range which is wide and includes relatively long wavelength. In order to
realize this, even in a case that a block copolymer having a relatively high molecular
weight is used, it is necessary to reliably obtain, by the electroforming, a concavity and
convexity structure having the desired pitch distribution. In the present invention, by
performing the heating process for the concavity and convexity structure obtained by
19
the etching, a metal substrate (mold), in which the concavity and convexity structure is
also reflected enough, is successfully obtained in the subsequent electroforming step.
[0048] The reason thereof is considered by the inventors as follows. The concavity
and convexity structure 36 after the etching is considered to have a complicated
cross-section structure, in which the side surfaces of grooves defined by the concavity
and convexity structure are coarse and the concavities and convexities (including the
overhang) are generated in a direction perpendicular to a thickness direction. The
following three problems are arisen by the complicated cross-section structure.
i) In the complicated cross-section structure, a portion at which a seed layer for the
electroforming is not attached is generated, and thereby making it difficult to uniformly
accumulate the metal layer by the electroforming. As a result, it is considered that the
obtained metal substrate has low mechanical strength and that defects such as
deformation of the metal substrate and pattern defect are caused.
ii) In the electroforming (electroplating), a thickness of plating varies depending on
shapes of respective parts of an object to be subjected to the plating. In particular, a
plated metal is more likely to be attracted to convex portions and projecting or
prominent corners of the object, and is less likely to be attracted to concave portions and
hollow portions of the object. Also for these reasons, it is difficult to obtain an
electroformed film having a uniform film thickness on the complicated concave and
convex cross-section structure after the etching.
iii) Even when the complicated cross-section structure as described above can be
transferred to the metal substrate by the electroforming, in a case that an attempt is
made to transfer the concavity and convexity shape by pressing the metal substrate
against a curable resin, the curable resin enters into gaps in the complicated
cross-section structure of the metal substrate. Hence, the metal substrate can not be
released from the cured resin, or the pattern defect occurs by fracture of the portion of
the metal substrate having the low strength. Conventionally, the transfer has been
repeated using polydimethylsiloxane (PDMS) to prevent the above problem.
[0049J In the BCP method, the first polymer segment 32 constructing the side surfaces
of the grooves is subjected to the annealing process by heating the concavity and
convexity structure after the etching. Thereby, as shown in Fig. 2(D) conceptually,
each cross-section shape defined by the first polymer segment 32 is formed of a
relatively smooth and sloped surface to have a shape of chevron narrowing upward from
20
the base member (referred to as "chevron-shaped structure" in this invention). The
overhang does not appear in such a chevron-shaped structure, and the chevron-shaped
structure is duplicated into the inverted pattern in a metal layer accumulated on the first
polymer segment 32, thereby the metal layer can be released easily. It has become
clear that the three problems can be solved by the effects of the second heating step as
described above. According to the applicant of the present invention, it has been found
out that the concavities and convexities are smooth, each convex portion has the smooth
chevron shape, and no overhang is observed in a micrograph, taken by a scanning
electron microscope (SEM), showing the cross-section structure of the metal substrate,
which is formed by Ni-electroforming using the concavity and convexity structure
obtained by the heating process after the- etching process of the block copolymer. On
the other hand, it has confirmed that Ni portions form grooves each having a
complicated shape including an overhang structure and the resins are penetrated or
entered into the grooves in a SEM micrograph showing the cross-section structure of the
metal substrate, which is formed by the Ni-electroforming (nickel electroforming) using
the concavity and convexity structure obtained without the second heating process after
the etching process of the block copolymer.
[0050] The base member 10, which has a chevron-shaped structure 38 obtained in the
second heating step, is used as a master for transfer in subsequent steps. The average
pitch of the concavities and convexities representing the chevron-shaped structure 38 is
preferably within a range from 100 to 600 nm, and more preferably 200 to 600 nm. In
a case that the average pitch of the concavities and convexities is less than the lower
limit, the pitches are so small relative to wavelengths of the visible light that required
diffraction of the visible light is less likely to occur by using the diffraction grating
obtained by use of such a master. In a case that the average pitch exceeds the upper
limit, the diffraction angle of the diffraction grating obtained by use of such a master is
so small that functions as the diffraction grating can not be fulfilled sufficiently. Note
that for the average pitch of the concavities and convexities, a concavity and convexity
analysis image is obtained by performing a measurement with an atomic force
microscope in a randomly selected measuring region of 3 urn square (length: 3 um,
width: 3 um) in the diffraction grating (details will be described later). The obtained
concavity and convexity analysis image is subjected to a flattening process including
primary inclination correction, and then subjected to two-dimensional fast Fourier
transform processing. Thus, a Fourier-transformed image is obtained. For each of
the points of Fourier-transformed image, intensity and distance (unit: urn"1) from the
origin of Fourier-transformed image are obtained. Then, the average value of the
intensity is obtained for the points each having the same distance from the origin. As
described above, a relation between the distance from the origin of the
Fourier-transformed image and the average value of the intensity is plotted, a fitting
with a spline function is carried out, and the wavenumber of peak intensity is regarded
as the average wavenumber (urn-1). For the average pitch, it is allowable to make a
calculation by another method, for example, a method for obtaining the average pitch of
the concavities and convexities as follows. That is, a concavity and convexity analysis
image is obtained by performing a measurement in a randomly selected measuring
region of 3 urn square (length: 3 urn, width: 3 urn) in the diffraction grating, then the
distances between randomly selected adjacent convex portions or between randomly
selected adjacent concave portions are measured at 100 points or more in the concavity
and convexity analysis image, and then an average of these distances is determined.
[0051] In addition, the average height of the concavities and convexities representing
the chevron-shaped structure 38 is preferably within a range from 5 to 200 nm, more
preferably within a range from 20 to 200 nm, and further preferably within a range from
50 to 150 nm. In a case that the average height of the concavities and convexities is
less than the lower limit, the height is so small relative to the wavelengths of the visible
light that the diffraction is insufficient. In a case that the average height exceeds the
upper limit, the following tendency is found. When the obtained diffraction grating is
used as an optical element on the light extraction port side of the organic EL element,
the element tends to be easily destructed and the life thereof tends to be shortened
because of heat generation which occurs when the electric field distribution in the EL
layer becomes non-uniform, and hence electric fields concentrate on a certain position
or area. Note that the average height of the concavities and convexities refers to an
average value of the heights of the concavities and convexities obtained when heights of
the concavities and convexities (the distances between concave portions and convex
portions in the depth direction) on the surface of the cured resin layer are measured. In
addition, a value calculated as follows is employed as the average value of the heights
of the concavities and convexities. That is, a concavity and convexity analysis image
is obtained by measuring the shape of the concavities and convexities on the surface by
22
use of the scanning probe microscope (for example, one manufactured by SII
NanoTechnology Inc., under the product name of "E-sweep", or the like), then the
distances between randomly selected concave portions and convex portions in the depth
direction are measured at 100 points or more in the concavity and convexity analysis
image, and then the average of the distances is determined as the average value of
heights of concavities and convexities.
[0052]

As shown in Fig. 2(E), a seed layer 40 functioning as an electroconductive
layer for a subsequent electroforming process is formed on the surface of the
chevron-shaped structure 38 of the master obtained as described above. The seed layer
40 can be formed by non-electrolytic plating, sputtering, or vapor deposition. The
thickness of the seed layer 40 is preferably not less than 10 nm and more preferably not
less than 100 nm to uniformalize current density during the subsequent electroforming
process, and thereby making the thickness of the metal layer accumulated by the
subsequent electroforming process to be constant. As a material of the seed layer, it is
possible to use, for example, nickel, copper, gold, silver, platinum, titanium, cobalt, tin,
zinc, chrome, gold-cobalt alloy, gold-nickel alloy, boron-nickel alloy, solder,
copper-nickel-chromium alloy, tin-nickel alloy, nickel-palladium alloy,
nickel-cobalt-phosphorus alloy, or alloy thereof. It is considered that the relatively
smooth chevron-shaped structure as shown in Fig. 2(D) is more likely to be attached to
the seed layer completely and with a uniform thickness, compared with the complicated
cross-section structure as shown in Fig, 2(C).
[0053] Subsequently, the metal layer is accumulated on the seed layer 40 by the
electroforming (electroplating) shown in Fig. 2(F). The entire thickness of a metal
layer 50 including the thickness of the seed layer 40 can be, for example, 10 to 3000 um.
As a material of the metal layer 50 accumulated by the electroforming, it is possible to
use any of metal species as described above which can be used as the seed layer 40. In
view of wear resistance and peeling property of the metal substrate as the mold, nickel
is preferable. In this case, nickel is also preferably used for the seed layer 40. The
current density during the electroforming may be, for example, 0.03 to 10 A/cm2 for
suppressing bridge to form a uniform metal layer and in view of shortening of an
electroforming time. Considering ease of the subsequent processes such as pressing to
23
the resin layer, peeling, and cleaning, the formed metal layer 50 desirably has
appropriate hardness and thickness. A diamond like carbon (DLC) process or a Cr
plating processing treatment can be performed on the surface of the metal layer in order
to improve the hardness of the metal layer formed by the electroforming. Alternatively,
the hardness of the surface may be improved by further performing the heating process
of the metal layer.
[0054]

The metal layer 50 including the seed layer obtained as described above is
peeled off from the base member having the concavity and convexity structure to obtain
a metal substrate as a father die. As a peeling method, the metal layer 50 may be
peeled off physically, or the first homopolymer and the remained block copolymer may
be dissolved to be removed by using an organic solvent dissolving them, such as toluene,
tetrahydrofuran (THF), and chloroform.
[00551

In a case that the metal substrate is peeled off from the base member 10 having
the chevron-shaped structure 38 as described above, a part of the polymer 60, like the
first polymer segment, remains in the metal substrate in some cases as shown in Fig.
2(G). In such a case, each part 60 remained in the metal substrate can be removed by a
cleaning. As a cleaning method, a wet cleaning or a dry cleaning can be used. As the
wet cleaning, the remained parts can be removed by performing the cleaning with the
organic solvent such as toluene and tetrahydrofuran, the surfactant, or an alkaline
solution. In a case that the organic solvent is used, an ultrasonic cleaning may be
carried out. Alternatively, the remained parts may be removed by performing an
electrolytic cleaning. As the dry cleaning, the remained parts can be removed by an
ashing using ultraviolet rays and/or plasma. The wet cleaning and the dry cleaning
may be used in combination. After the cleaning as described above, a rinse process
with pure water or purified water may be performed, and then ozone irradiation may be
carried out after a drying. Accordingly, a metal substrate (mold) 70 having a desired
concavity and convexity structure is obtained (Fig. 2(H)).
[0056] Next, an explanation will be made about a method for producing the diffraction
grating used for the organic EL element and the like using the obtained metal substrate
24
70 with reference to Fig. 3(A) to Fig. 3(E).
[0057]
< Mold-release treatment step of metal substrate>
In a case that the concavity and convexity structure is transferred to the resin
using the metal substrate 70 as the mold, a mold-release treatment of the metal substrate
70 may be performed to improve the mold releasability from the resin. As the
mold-release treatment, a manner to decrease surface energy is commonly used, and the
mold-release treatment is not particularly limited and includes, for example, a method in
which a concave and convex surface 70a of the metal substrate 70 is coated with a
mold-release agent such as a fluorine-based material and a silicon resin as shown in Fig.
3(A), a method in which the surface is subjected to a treatment using a fluorine-based
silane coupling agent, and a method in which a film of a diamond like carbon is formed
on the surface.
[0058]

By using the obtained metal substrate 70, a mother die is produced by
transferring the concavity and convexity structure (pattern) of the metal substrate to a
resin layer 80. As the method of the transfer process, for example, a curable resin is
applied on a transparent supporting substrate 90, and then the resin layer 80 is cured
while pressing the concavity and convexity structure of the metal substrate 70 against
the resin layer 80, as shown in Fig. 3(B). The transparent supporting substrate 90 is
exemplified, for example, by base members made of a transparent inorganic substance
such as glass; base members made of a resin such as polyethylene terephthalate (PET),
polyethylene terenaphthalate (PEN), polycarbonate (PC), cycloolefin polymer (COP),
polymethyl methacrylate (PMMA), or polystyrene (PS); stacked base members each
having a gas barrier layer made of an inorganic substance such as SiN, SiC>2, SiC,
SiOxNy, TiO?, or AI2O3 formed on the surface of the base member made of any one of
the above-described resins; and stacked base members each having base members made
of any one of the above-described resins and gas barrier layers made of any one of the
above-described inorganic substances stacked alternately on each other. In addition,
the thickness of the transparent supporting substrate may be within a range from 1 to
500 urn.
[0059] Examples of the curable resin include epoxy resin, acrylic resin, urethane resin,
25
melamine resin, urea resin, polyester resin, phenol resin, and cross-linking type liquid
crystal resin. The thickness of the cured resin is preferably within a range from 0.5 to
500 um. In a case that the thickness is less than the lower limit, heights of the
concavities and convexities formed on the surface of the cured resin layer are more
likely to be insufficient. In a case that the thickness exceeds the upper limit, an effect
of volume change of the resin which occurs upon curing is likely to be so large that the
formation of the shape of the concavities and convexities tends to be insufficient.
[0060] As a method for applying the curable resin, it is possible to adopt various
coating methods such as a spin coating method, a spray coating method, a dip coating
method, a dropping method, a gravure printing method, a screen printing method, a
relief printing method, a die coating method, a curtain coating method, an ink-jet
method, and a sputtering method. Moreover, the condition for curing the curable resin
varies depending on the kind of the resin used. For example, a curing temperature is
preferably within a range from room temperature to 250 degrees Celsius, and a curing
time is preferably within a range from 0.5 minutes to 3 hours. Alternatively, a method
may be employed in which the curable resin is cured by irradiation with energy rays
such as ultraviolet rays or electron beams. In such a case, the amount of the irradiation
is preferably within a range from 20 mJ/cm2 to 5 J/cm2.
[0061] Subsequently, the metal substrate 70 is detached from the cured rein layer 80 in
a cured state. A method for detaching the metal substrate 70 is not limited to a
mechanical peeling method, and can adopt any known method. Then, as shown in Fig.
3(C), it is possible to obtain a resin film structure 100 in which the cured rein layer 80
having the concavities and convexities is formed on the transparent supporting substrate
90. The resin film structure 100 may be used, as it is, as the diffraction grating.
[0062] The method for producing the substrate according to the BCP method can be
used not only in production of the diffraction grating provided on the light extraction
port side of the organic EL element but also in production of an optical component
having a minute or fine pattern used for various devices. For example, the method for
producing the substrate according to the BCP method can be used to produce a wire grid
polarizer, an antireflection film, or an optical element for providing a light confinement
effect in a solar cell by being placed on the photoelectric conversion surface side of the
solar cell.
[0063] As described above, the resin film structure 100 having a desired pattern can be
26
obtained. In a case that the inverted pattern of the resin film structure 100 is used as
the diffraction grating, the resin film structure 100 obtained through the transfer process
of the metal substrate as described above is used as the mother die; a curable resin layer
82 is applied on another transparent supporting substrate 92 as shown in Fig. 3(D); and
the curable resin layer 82 is cured while pressing the resin film structure 100 against the
curable resin layer 82, similar to a case in which the resin film structure 100 is formed.
Subsequently, the resin film structure 100 is peeled off from the curable resin layer 82 in
a cured state. Accordingly, a replica 110 as another resin film structure as shown in
Fig. 3(E) can be obtained. Further, it is allowable to produce a replica having the
inverted pattern of the replica 110 by performing the above transfer step using the
replica 110 as a master and/or to produce a sub-replica by repeating the above transfer
step again using the replica having the inverted pattern as the master.
[0064] Next, an explanation will be made about a method for manufacturing a
structure having concavities and convexities made of the sol-gel material (hereinafter
referred to as "sol-gel structure" or "sol-gel material substrate" as appropriate) by
further using the obtained resin film structure 100 as the master. A method for forming
a substrate having a concavity and convexity pattern using the sol-gel material mainly
includes: a solution preparation step for preparing a sol solution; an application step for
applying the prepared sol solution on the substrate; a drying step for drying the coating
film of the sol solution applied on the substrate; a pressing step for pressing a mold with
a transfer pattern; a pre-sintering step during which the coating film to which the mold
is pressed is subjected to the pre-sintering; a peeling step for peeling off the mold from
the coating film; and a main sintering step during which the coating film is subjected to
the main sintering. Hereinbelow, an explanation will be made about each of the steps
sequentially.
[0065] At first, a sol-gel solution is prepared to form a coating film to which a pattern
is transferred by a sol-gel method (solution preparation step). For example, in a case
that silica is synthesized by the sol-gel method on the substrate, the sol solution of metal
alkoxide (silica precursor) is prepared. The silica precursor is exemplified by metal
alkoxides including, for example, tetraalkoxide monomers such as tetramethoxysilane
(MTES), tetraethoxysilane (TEOS), tetra-i-propoxysilane, tetra-n-propoxysilane,
tetra-i-butoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, and
tetra-t-butoxysilane; trialkoxide monomers such as methyl trimethoxysilane, ethyl
27
trimethoxysilane, propyl trimethoxysilane, isopropyl trimethoxysilane, phenyl
trimethoxysilane, methyl triethoxysilane, ethyl triethoxysilane, propyl triethoxysilane,
isopropyl triethoxysilane, phenyl triethoxysilane, methyl tripropoxysilane, ethyl
tripropoxysilane, propyl tripropoxysilane, isopropyl tripropoxysilane, phenyl
tripropoxysilane, methyl triisopropoxysilane, ethyl triisopropoxysilane, propyl
triisopropoxysilane, isopropyl triisopropoxysilane, phenyl triisopropoxysilane; a
polymer obtained by polymerizing the above monomers in small amounts; and a
composite material characterized in that functional group and/or polymer is introduced
into a part of the material. Further, the silica precursor is exemplified, for example, by
metal acetylacetonate, metal carboxylate, oxychloride, chloride, and mixtures thereof.
The silica precursor, however, is not limited thereto. Examples of metal species
include, in addition to Si, Ti, Sn, Al, Zn, Zr, In, and mixtures thereof, but are not limited
thereto. It is also possible to use any appropriate mixture of precursors of the above
oxidized metals.
[0066] In a case that a mixture of TEOS and MTES is used, the mixture ratio thereof
can be 1:1, for example, in a molar ratio. The sol solution produces amorphous silica
by performing hydrolysis and polycondensation reaction. An acid such as
hydrochloric acid or an alkali such as ammonia is added in order to adjust pH of the
solution as a synthesis condition. The pH is preferably not more than 4 or not less than
10. Water may be added to perform the hydrolysis. An amount of water to be added
can be 1.5 times or more with respect to metal alkoxide species in the molar ratio.
[0067] Examples of the solvent include alcohols such as methanol, ethanol, isopropyl
alcohol (IPA), and butanol; aliphatic hydrocarbons such as hexane, heptane, octane,
decane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and
mesitylene; ethers such as diethyl ether, tetrahydrofuran, and dioxane; ketones such as
acetone, methyl ethyl ketone, isophorone, and cyclohexanone; ether alcohols such as
butoxyethyl ether, hexyloxyethyl alcohol, methoxy-2-propanol, and benzyloxyethanol;
glycols such as ethylene glycol and propylene glycol; glycol ethers such as ethylene
glycol dimethyl ether, diethylene glycol dimethyl ether, and propylene glycol
monomethyl ether acetate; esters such as ethyl acetate, ethyl lactate, and
y-butyrolactone; phenols such as phenol and chlorophenol; amides such as
N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone;
halogen-containing solvents such as chloroform, methylene chloride, tetrachloroethane,
28
monochlorobenzene, and dichlorobenzene; hetero-element containing compounds such
as carbon disulfide; water; and mixture solvents thereof. Especially, ethanol and
isopropyl alcohol are preferable. Further, a mixture of water and ethanol and a mixture
of water and isopropyl alcohol are also preferable.
[0068] As an additive, it is possible to use, for example, polyethylene glycol,
polyethylene oxide, hydroxypropylcellulose, and polyvinyl alcohol for viscosity
adjustment; alkanolamine such as triethanolamine as a solution stabilizer; P-diketone
such as acetylacetone; P-ketoester; formamid; dimetylformamide; and dioxane.
[0069] The sol solution prepared as described above is applied on the substrate
(application step). As the substrate, substrates made of inorganic materials such as
glass, silica glass, and silicon substrates or substrates of resins such as polyethylene
terephthalate (PET), polyethylene terenaphthalate (PEN), polycarbonate (PC),
cycloolefin polymer (COP), polymethyl methacrylate (PMMA), polystyrene (PS),
polyimide (PI), and polyarylate may be used. The substrate may be transparent or
opaque. In a case that a substrate having a concavity and convexity pattern obtained
from the substrate is used for production of the organic EL element as will be described
later, the substrate desirably has resistance to heat and ultraviolet (UV) light etc. In
view of this, the substrates made of the inorganic materials such as the glass, the silica
glass, and the silicon substrates are more preferable. It is allowable to perform a
surface treatment or provide an easy-adhesion layer on the substrate in order to improve
adhesion property and to provide a gas barrier layer in order to keep out moisture and/or
gas such as oxygen. As a method for applying the sol solution, it is possible to use any
application method such as a bar coating method, a spin coating method, a spray coating
method, a dip coating method, a die coating method, and an ink-jet method. Among
the methods as described above, the bar coating method, the die coating method, and the
spin coating method are preferable, because the sol solution can be uniformly applied on
the substrate having a relatively large area and the application can be quickly completed
prior to gelation of the sol solution. It is noted that, since a desired concavity and
convexity pattern by a sol-gel material layer is formed in subsequent steps, the surface
of the substrate (including the surface treatment or the easy-adhesion layer in case that
the surface treatment or the easy-adhesion layer is present) may be flat, and the
substrate itself does not have the desired concavity and convexity pattern.
[0070] After the application step, the substrate is kept in the atmosphere or under
29
reduced pressure to evaporate the solution in the applied coating film (hereinafter
referred to also as "sol-gel material layer" as appropriate) (drying step). Subsequently,
the resin film structure 100 (mold) is pressed against the coating film (pressing step).
In this situation, the resin film structure 100 may be pressed by using a pressing roll.
A period of time during which the mold and the coating film are brought in contact with
each other in a roll process is shorter than that in a pressing system, and thus there are
advantages such that it is possible to prevent deformation of pattern due to difference
among coefficients of thermal expansion of the mold, the substrate, a stage on which the
substrate is provided, and the like; it is possible to prevent generation of bubbles of gas
in the pattern due to bumping of the solvent in the gel solution or to prevent trace or
mark of gas from being left; it is possible to reduce transfer pressure and peeling force
due to line contact with the substrate (coating film), and thereby making it possible to
deal with a larger substrate readily; no bubble is included during the pressing; and the
like. Further, the heating may be performed while pressing the resin film structure
100.
[0071] After the resin film structure 100 as the mold is pressed against the coating film
(sol-gel material layer), the coating film may be subjected to the pre-sintering
(pre-sintering step). The pre-sintering promotes gelation of the coating film to solidify
the pattern, and thereby the pattern is less likely to be collapsed during the peeling. In
a case that the pre-sintering is performed, the heating is preferably performed at a
temperature from 40 degrees Celsius to 150 degrees Celsius in the atmosphere. It is
not indispensable to perform the pre-sintering.
[0072] The resin film structure 100 is peeled off from the coating film (sol-gel material
layer) after the pressing step or the pre-sintering step. In a case that the roll is used
during the pressing, the peeling force may be smaller than that in a case that a
plate-shaped mold is used, and it is possible to easily peel off the mold from the coating
film without remaining the coating film in the mold.
[0073] After the resin film structure 100 is peeled off from the coating film (sol-gel
material layer) on the substrate, the coating film is subjected to the main sintering (main
sintering step). Hydroxyl group and the like contained in silica (amorphous silica)
forming the coating film is desorbed or eliminated by the main sintering to further
strengthen the coating film. The main sintering may be performed at a temperature
from 200 degrees Celsius to 1200 degrees Celsius for about 5 minutes to 6 hours.
30
Accordingly, the coating film is cured, and thereby obtaining a sol-gel structure
(diffraction grating) with a concavity and convexity pattern film which corresponds to
the concavity and convexity pattern of the resin film structure 100, that is, a sol-gel
structure (diffraction grating) in which the sol-gel material layer having an irregular
concavity and convexity pattern is directly formed on the flat substrate. In this
situation, depending on a sintering temperature and a sintering time, the silica as the
sol-gel material layer is amorphous, crystalline, or in a mixture state of the amorphous
and the crystalline.
[0074] In a case that the replica 110 (or sol-gel structure) is duplicated using the resin
film structure 100, or in a case that another replica is duplicated using the obtained
replica 110 (or sol-gel structure), a film may be laminated or stacked, on the surface of
the resin film structure 100 or the replica 110 having the concavity and convexity
pattern, by a gas phase method such as a vapor deposition or a sputtering method. By
stacking the film as described above, in a case that transfer etc. is performed with, for
example, applying the resin onto the surface of the film, the adhesion between the
substrate and the resin (for example, a UV curable resin) can be lowered, so that the
master block is more likely to be easily peeled. Examples of the vapor-deposited film
include metals such as aluminum, gold, silver, platinum, and nickel; and metal oxides
such as aluminum oxide. In addition, the thickness of the vapor-deposited film is
preferably 5 to 500 nm. In a case that the thickness is less than the lower limit, a
uniform film is difficult to obtain, so that sufficient effect of lowering the adhesion is
decreased. In a case that the thickness exceeds the upper limit, the shape of the master
block is more likely to be dull. In a case that the cured resin layer of the resin film
structure 100 or the replica 110 is made of a UV curable resin, postcure may be
conducted as appropriate by, for example, ultraviolet light irradiation, after curing of the
resin.
[0075] In the steps shown in Figs. 3(B) and 3(D), the curable resins 80, 82 are applied
on the transparent supporting substrates 90, 92, respectively. In addition, it is
allowable to use one obtained as follows as the master block. The curable resin is
applied directly on the surface of the metal substrate 70 which is the master block or the
surface of the cured resin layer 80, and then the cured resin is detached. Alternatively,
instead of applying the resin onto the surface of the master block, it is allowable to
employ, as the master block, a concavity and convexity film of the cured resin obtained
31
as follows. That is, the master block is pressed onto the coating film of the resin, and
the resin is cured. *
[0076]
B. Method for producing substrate by BKL method
As described in detail in PCT International Publication No.
WO2011/007878A1, the BKL method includes a step in which a vapor-deposited film is
formed, under a temperature condition of 70 degrees Celsius or above, on the surface of
a polymer film made of a polymer of which volume changes by heat, and then the
polymer film and the vapor-deposited film are cooled, thereby forming concavities and
convexities of wrinkles in the surface of the vapor-deposited film (a concavity and
convexity shape formation step), and a step in which a master block material is attached
on the vapor-deposited film and then the master block is cured, and thereafter the cured
master block material is detached from the vapor-deposited film to obtain a master
block (a master block formation step).
[0077] Figs. 5(A) to 5(D) are schematic views for explaining a preferred embodiment
of a method for producing the master block in a method for producing the diffraction
grating in accordance with the BKL method. Fig. 5(A) is a schematic cross-sectional
view showing a state in which the vapor-deposited film is formed on the surface of the
polymer film in the method for producing the master block; Fig. 5(B) is a schematic
cross-sectional view showing a state in which the concavities and convexities of
wrinkles are formed in the surface of the vapor-deposited film by cooling the polymer
film and the vapor-deposited film; Fig. 5(C) is a schematic cross-sectional view
showing a state in which the master block material is attached on the vapor-deposited
film with the concavities and convexities and then cured; and Fig. 5(D) is a schematic
cross-sectional view showing a state in which the cured master block is detached from
the vapor-deposited film.
[0078] In the concavity and convexity shape formation step, first, the polymer film
made of the polymer of which volume changes by heat is prepared. As the polymer of
which volume changes by heat, one of which volume changes by heating or cooling (for
example, one having a coefficient of thermal expansion of 50 ppm/K or more) can be
used as appropriate. As the polymer, a silicone-based polymer is more preferable, and
a silicone-based polymer containing polydimethylsiloxane is particularly preferable,
from the viewpoint that the concavities and convexities of wrinkles are easily formed on
32
the surface of the vapor-deposited film, because the difference between the coefficient
of thermal expansion of the polymer and the coefficient of thermal expansion of the
vapor-deposited film is large, and because the polymer has a high flexibility. As a
method for forming the polymer film as described above, for example, a spin coating
method, a dip coating method, a dropping method, a gravure printing method, a screen
printing method, a relief printing method, a die coating method, a curtain coating
method, an ink-jet method, a spray coating method, a sputtering method, a vacuum
vapor deposition method, or the like can be employed. Further, the thickness of the
polymer film is preferably within a range from 10 to 5000 urn, and is more preferably
within a range from 10 to 2000 um.
[0079] In the concavity and convexity shape formation step, next, a vapor-deposited
film 28 is formed on a surface of a polymer film 27 under a temperature condition of 70
degrees Celsius or above (see Fig. 5(A)). The temperature at which the
vapor-deposited film 28 is formed needs to be 70 degrees Celsius or above, and is more
preferably 90 degrees Celsius or above. In a case that the temperature is lower than 70
degrees Celsius, the concavities and convexities of wrinkles can not be formed
sufficiently on the surface of the vapor-deposited film. As the method for forming the
vapor-deposited film 28, any known method such as a vapor deposition metiiod or a
sputtering method can be employed as appropriate. Of these methods, the vapor
deposition method is preferably employed, from the viewpoint of maintaining the shape
of the concavities and convexities formed on the surface of the polymer film.
Meanwhile, a material of the vapor-deposited film 28 is not particularly limited, and
examples thereof include metals such as aluminum, gold, silver, platinum, and nickel;
and metal oxides such as aluminum oxide.
[0080] In the concavity and convexity shape formation step, subsequently, concavities
and convexities of wrinkles are formed on the surface of the vapor-deposited film 28 by
cooling the polymer film 27 and the vapor-deposited film 28 (see Fig. 5(B)). Since
there is the difference between the coefficient of thermal expansion of the polymer film
27 and the coefficient of thermal expansion of the vapor-deposited film 28, the
concavities and convexities (the so-called bucking pattern, or the so-called turing
pattern) of wrinkles can be formed on the surface of the vapor-deposited film 28 as
shown in Fig. 5(B), when the volume of each of the polymer film 27 and the
vapor-deposited film 28 as shown in Fig, 5(A) changes by heat. Further, the
33
temperatures of the polymer film 27 and the vapor-deposited film 28 after the cooling
are preferably 40 degrees Celsius or below. In a case that the temperatures of the
polymer film 27 and the vapor-deposited film 28 after the cooling exceed the upper
limit, it tends to be difficult to form the concavities and convexities of wrinkles on the
surface of the vapor-deposited film. Furthermore, the rate of temperature drop in
cooling the polymer film 27 and the vapor-deposited film 28 is preferably within a
range from 1 to 80 degrees Celsius/minute. In a case that the rate of temperature drop
is less than the lower limit, the concavities and convexities tend to be relaxed. On the
other hand, in a case that the rate of temperature drop exceeds the upper limit, scars
such as cracks tend to be easily formed on the surfaces of the polymer film and the
vapor-deposited film.
[0081] In the master block formation step, first, a master block material 29 is attached
onto the vapor-deposited film 28 and cured as shown in Fig. 5(C). The master block
material 29 is not particularly limited, and examples thereof include inorganic
substances such as nickel, silicon, silicon carbide, tantalum, glassy carbon, silica glass,
and silica; and resin compositions such as silicone-based polymers (silicone rubbers),
urethane rubbers, norbornene resins, polycarbonate, polyethylene terephthalate,
polystyrene, polymethyl methacrylate, acrylic, and liquid crystal polymers. Of these
master block materials 29, silicone-based polymers, nickel, silicon, silicon carbide,
tantalum, glassy carbon, silica glass, and silica are more preferable, silicone-based
polymers are further more preferable, and silicone-based polymers containing
polydimethyl siloxane are particularly preferable, from the viewpoint of moldability,
followability to a fine pattern, and mold releasability. Further, a method for attaching
the master block material 29 as described above is not particularly limited, and,
examples of employable method include a vacuum vapor deposition method; and
various coating methods such as a spin coating method, a spray coating method, a dip
coating method, a dropping method, a gravure printing method, a screen printing
method, a relief printing method, a die coating method, a curtain coating method, an
ink-jet method, and a sputtering method. Although conditions for curing the master
block material 29 vary depending on what kind of the master block material is used, it is
preferable to set a curing temperature within a range from room temperature to 250
degrees Celsius, and a curing time within a range from 0.5 minutes to 3 hours, for
example. Further, a method may be employed in which the master block material 29 is
34
cured by irradiation with energy rays such as ultraviolet rays and electron beams. In
such a case, the amount of the irradiation is preferably within a range from 20 mJ/cm2 to
10 J/cm2.
[0082] In the master block formation step, subsequently, the master block 29 is
obtained by detaching the cured master block material 29 from the vapor-deposited film
28 as shown in Fig. 5 (D). A method for detaching the master block 29 from the
vapor-deposited film 28 as described above is not particularly limited, and any known
method can be employed as appropriate.
[0083] In the BKL method, the concavity and convexity shape formation step and the
master block formation step may be repeated by use of the master block 29 obtained as
the polymer film. Accordingly, it is possible to deepen the wrinkles formed on the
surface of the master block and to increase the average height of the concavities and
convexities formed on the surface of the master block.
[0084] Further, it is also possible to employ, as the master block, one obtained in such
a manner that a resin (a material used as the master block material) is applied on the
surface of the obtained master block 29, then cured, and thereafter detached.
Furthermore, it is also possible to employ, as the master block, a concavity and
convexity film of a cured resin obtained by pressing the master block 29 onto a coating
film of a resin and curing the resin, instead of applying the resin onto the surface of the
obtained master block 29. A resin film in which the concavities and convexities are
inverted as described above can also be used as the master block.
[0085] A final master block may be manufactured from the master block 29 by
repeating inversion and/or transfer of the concavities and convexities through one or
more intermediate master blocks. As the intermediate master blocks, those obtained
by appropriately inverting and/or transferring the concavity and convexity structure as
described above can be used. Further, in a case that the master block is manufactured
by repeating the inversion and/or the transfer of the concavities and convexities as
described above, it is possible to conduct temporal transfer to a flexible material (for
example, a plastic film or a silicone rubber) during the transfer of the concavity and
convexity structure of the master block, in order to facilitate the transfer of the
concavity and convexity structure even in a case in which a non-flexible substrate (for
example, glass) for which the resin film or the like is difficult to peel is used. Hence,
the same concavity and convexity structure (the same even-odd property of the
35
concavity and convexity structure) as that of the master block used tends to be easily
obtained. In addition, it is also possible to further repeat the concavity and convexity
shape formation step and the master block formation step by use of, as the master block
29, polymer films obtained by applying the polymer of which volume changes by heat
onto the intermediate master blocks and curing the polymer. In addition, in a case that
the intermediate master block is made of an UV curable resin, the intermediate master
block may be obtained by irradiation with ultraviolet light during the manufacturing
thereof, and then postcure may be conducted by irradiation again with ultraviolet light.
The postcure conducted by irradiating again the master block made of the UV curable
resin with ultraviolet light as described above leads to a tendency that the degree of the
cross-linking in the master block is raised or improved and the mechanical strength and
the chemical resistance are improved.
[0086] Further, the master blocks (including the intermediate master blocks) may be
converted to metal master blocks by performing a plating treatment by use of any
known method. The formation of metal master block by plating as described above
leads to a tendency that master blocks which are excellent in mechanical strength and
which can be used repeatedly can be obtained. The use of the master block obtained
by performing the plating treatment as the mold of nanoimprint and the like enables
repeated transfers to cured resin substrates, and thereby enabling mass production of a
resin substrate having a predetermined concavity and convexity pattern. Examples of
materials usable for the plating include nickel, copper, iron, nickel-cobalt alloys,
nickel-iron alloys, and the like. Note that the thickness of the plating layer is
preferably 50 urn to 1 mm, from the viewpoints of mechanical strength, time required
for the formation of the metal master block, and the like.
[0087] Then, in the present invention, a master block obtained by conducting the BKL
method as described above (a master block 29, or the master block obtained by
repeating the concavity and convexity shape formation step and the master block
formation step by use of the master block 29 obtained as a polymer film, or the like) can
be used as the master block for forming the diffraction grating. Further, a sol-gel
structure having concavities and convexities made of the sol-gel material may be
manufactured by use of the resin substrate obtained by conducting the BKL method as
the master block in the similar manner as the manufacture of the sol-gel structure having
concavities and convexities made of the sol-gel material by use of the resin film
36
structure obtained by conducting the BCP method as the master block.
[0088] Further, a master block, which is obtained by heating the master block obtained
by the BKL method under the atmospheric pressure under a temperature condition of
about 80 to 200 degrees Celsius for about 1 to 48 hours, may be used as the master
block used for manufacturing the diffraction grating. By heating the master block as
described above, it is possible to obtain, as the diffraction grating, a diffraction grating
having an excellent concavity and convexity structure for the organic EL element.
[0089]
2. Step of Inspecting substrate
The substrate obtained by the BCP method or BKL method (including the
substrate having the concavity and convexity structure made of the sol-gel material) has
the irregular concave and convex surface, and an explanation will be made about a step
of inspecting the optical characteristics, in particular, the unevenness of luminance, of
such a substrate (step S2 in Fig. 1). It is considered that the unevenness of luminance
is generated by local distribution of a specific pitch of the concavities and convexities of
the substrate, local distribution of orientation of the concavities and convexities in a
specific direction, unevenness of depth of the concavities and convexities, and the like.
The scattered light from the concave and convex surface of a substrate 100 having the
irregular concave and convex surface is observed by using an apparatus 200 as shown in
Fig. 6. The apparatus 200 includes a stage 104 which is formed of a pair of black
blocks 102 arranged on a floor surface at a predetermined distance; a pair of light
sources 122 which is arranged obliquely above the stage 104 at positions symmetrical
with the center of the stage 104; an imaging element 124 which is arranged above the
center of the stage 104 at a predetermined distance from the stage 104; and an image
processing device 126 connected to the imaging element 124. The pair of light sources
122 may be any light source which is capable of emitting light 122a having high
directivity and with which a predetermined width (area) is illuminated. For example, it
is possible to use a LED bar light in which a plurality of LEDs are embedded in an array
form in one direction. The imaging element 124 may be any imaging element
provided that the element has pixels which are capable of two-dimensionally receiving
the scattered light from the entire substrate 100, and a digital camera, a two-dimensional
luminance colorimeter, and the like are suitably used. The imaging element 124
preferably has the number of pixels of at least 30 or more. The image processing
37
device 126 is a computer which processes image data detected by the imaging element
124. The scattered light from the concave and convex surface 100a of the substrate
100 is observed in the following manner using the apparatus 200. The luminance
distribution is obtained from the observed scattered light.
[0090] The substrate 100 is arranged on the stage 104 so that the concave and convex
surface 100a faces upward. The concave and convex surface 100a of the substrate 100
is irradiated obliquely from above with the light from the pair of light sources 122, for
example, at an incident angle of about 80° to a normal direction of the concave and
convex surface 100a of the substrate 100. The light is scattered in various directions
from the concave and convex surface 100a of the substrate 100 which is irradiated with
the light. The scattered light includes diffracted light from the concave and convex
surface. The imaging element 124 is arranged relative to the substrate 100 such that
end portions of the concave and convex surface 100a of the substrate 100 are included
in field of view of the imaging element 124, so that the light, of the scattered light,
which is directed from the entire area of the concave and convex surface 100a of the
substrate 100 to an approximately normal direction of the concave and convex surface
100a of the substrate 100, is allowed to be received by the imaging element 124.. The
image data detected by each pixel is subjected to image processing by the image
processing device 126, and light intensity corresponding to the two-dimensional
position of the concave and convex surface 100a of the substrate 100 is obtained.
Although the drawing in which the substrate 100 is disposed parallel to the floor surface
is exemplified in this description, the substrate may be in a state of standing upright by a
support and the like or in a state of inclining at a certain angle.
[0091] Here, in a case that the concavities and convexities of the concave and convex
surface 100a of the substrate 100 have a rectangular concavity and convexity pattern as
shown in Fig. 7, diffraction occurs in accordance with Bragg diffraction condition.
The following relational expression holds, on the assumption that an angle between the
incident light and the normal of the diffraction-grating surface (incident angle) is
defined as a and that an angle between the diffracted light and the normal of the
diffraction grating (diffraction angle) is defined as (3.
d (sina ± sin|3)= mX
or
sina ± sinp = NmX,
38
Here, d represents a period (pitch) of the diffraction grating, N represents the number of
grooves per 1 mm, m represents diffraction order (m= 0, ±1, ±2 ...), and X represents
wavelength.
[0092] In accordance with the relational expression described above, the diffracted
light of m= 0 (zero-order light) is regularly reflected irrespective of the wavelength X.
Thus, the zero-order light of the incident light obliquely coming into the surface is not
directed to the direction of the imaging element 124 and does not come into the imaging
element 124. Further, in a case of m^ 0, the diffraction angle P which satisfies the
relational expression varies by wavelength X, and changes depending on the period d of
the diffraction grating and the incident angle a. Thus, the diffracted light can not be
observed in some cases depending on the wavelength X, the incident angle a, and the
number of grooves N (or the period d). For example, in a case that +1 -order diffracted
light (m= +1) from the diffraction grating (incident angle a= 80°, the number of grooves
N= 3000/mm (d= 333 nm)) is assumed, sin p is 1.12 when the wavelength X is 700 nm,
thus, it is appreciated that the diffracted light can not be obtained. Therefore, it is
found out that, in order to obtain the first-order diffracted light directed to the front
direction in a case that the light enters obliquely at a relatively a shallow angle (that is, a
great incident angle) in the construction of the apparatus 200 shown in Fig. 6 ,the ratio
of the incident angle a to the period d of the diffraction angle is restricted based on the
relational expression. Especially, it is preferable to use light having the wavelength
which is substantially the same as the period of the diffraction grating, in particular,
light having the wavelength X which is 0.5 to 2.0 times as long as the period d of the
diffraction grating (0.5d < X < 2.0d), more preferably light having the wavelength X
which is 0.5 to 1.5 times as long as the period d of the diffraction grating (0.5d < X <
1.5d), in order that the first-order diffracted light having a high diffraction efficiency is
introduced into the imaging element provided in the normal direction of the substrate
without causing diffraction of higher-order (±2, ±3...) than the first-order. In a case
that the inspection light has a wavelength band other than single wavelength, X
represents the central wavelength.
[0093] Regarding the incident angle, for example, it is considered a case in which the
substrate having the irregular concave and convex surface, which is an object of the
present invention, is applied to the organic EL element. It has been found out by
39
experiments conducted by the inventors of the present invention that, in a case that the
substrate having the irregular concavity and convexity structure is used for the organic
EL, the pitch of concavities and convexities on the irregular concave and convex surface
is desirably 100 nm to 600 nm, more desirably 150 nm to 600 nm (for example, see PCT
International Publication No. WO2011/007878A1). It has been found out by
experiments conducted by the inventors of the present invention that the incident angle
a is preferably 30° < a < 90°, and more preferably 60° < a < 85° in a case that, for
example, the light having the wavelength of 470 nm is used as each of a pair of
light-sources with respect to the substrate having the irregular concave and convex
surface, the pitch of which is within a range of 150 nm to 600 nm,. In a case that the
incident angle a is less than 30°, the diffraction efficiency is low and the luminance is
lowered. Thus, the unevenness of luminance is not observed clearly. Further, the
following problems arise. That is, since an area which can be irradiated with the light
uniformly is small, the area subjected to the evaluation is small; there is fear that a
regular reflection light enters into the imaging element, etc. The lower limit of the
incident angle a is further preferably 60° in terms of the diffraction efficiency and the
unevenness of luminance. On the other hand, in a case that the incident angle a
exceeds 90°, the back surface of the substrate is irradiated with the light and the amount
of reflected light is decreased. In a case that an opaque object such as a metal plate is
used as the substrate, the observation itself can not be performed. In a case that the
incident angle a exceeds 85°, the surface of the sample can not be irradiated with the
light efficiently even in a case of using a highly directional light source. Thus, the
amount of light entering the imaging element is insufficient.
[0094]
3. Judgment step
Subsequently, whether or not the substrate has a uniform luminance
distribution is evaluated and judged based on the result obtained by the above inspection
step (step S3 of Fig. 1). In the following, an explanation will be made about an
evaluation/judgment method in a case of using a digital camera as the imaging element.
A pixel value is read from output of each pixel of the imaging element obtained in the
above inspection step. The pixel value corresponds to the intensity or luminance of the
scattered (diffracted) light of each pixel. The maximum value, the minimum value,
and the average value of the pixel values of the entire concave and convex surface of the
40
substrate are obtained. Then, it is judged whether the maximum value, the minimum
value, and the average value are within desired acceptable ranges, respectively.
Further, it is judged whether the intensity distribution of the scattered (diffracted) light
is within a desired range. For example, the ratio of the maximum value to the
minimum value is obtained, and the unevenness of luminance can be judged depending
on the magnitude of maximum value/minimum value. It has been found out by the
inventors of the present invention that, in a case that the maximum value/minimum
value of the pixel values is 1.5 or more in the substrate of the present invention and the
organic EL element of the present invention in which an electrode and an organic layer
are stacked on the substrate to maintain concavities and convexities, the uniformity of
light emission of the organic EL element is obviously deteriorated, that is, the
unevenness of luminance exceeds the acceptable range. Illumination, a display, and
the like using such an organic EL element are not suitable as products. However, it is
possible to set the maximum value/minimum value of the pixel values as a threshold
value depending on the acceptability limit of the unevenness of luminance, that is,
depending on desired uniformity of the luminance and the way of use of the organic EL
element. Alternatively, difference of scattered intensity (fluctuation in scattered
intensity) may be expressed as the following expression to perform judgment by
comparing with a predetermined value.
Difference of scattered intensity = (maximum value - minimum value) / (maximum
value + minimum value) x 100
[0095] Regarding the average pixel value, evaluation can be performed by the
following method. That is, it is performed a process in which the measured pixel
values are converted into a gray scale. By converting the pixel value of each pixel on
the line in a predetermined direction (X or Y direction) on the taken image into the gray
scale, (cross-section) profile of intensity of the scattered light on the line can be
obtained. Denoting the maximum pixel value which can be recorded in the imaging
element (255 in a case of using a general digital camera) by "MAX", in order to make
the evaluation of the unevenness of luminance easier,the average value of the pixel
values (pixel average value) (after converting into the gray scale) on the line is
preferably 0.2 MAX to 0.8 MAX.
[0096] In a case that it is judged that the ratio of the maximum value to the minimum
value, the difference of scattered intensity, or the average pixel value is within a desired
41
range in the evaluation/judgment step, an organic EL element is produced by using this
substrate in accordance with a process which will be described later. In a case that it is
judged that the ratio of the maximum value to the minimum value, the difference of
scattered intensity or the average pixel value is beyond the desired range, an
aftertreatment is performed (step S5 in Fig. 1). As the aftertreatment, whether the
defect (unevenness of luminance) of the substrate is caused by dust, scratch, periodic
error, or random error is analyzed. In a case that the defect is caused by adhering
matter such as the dust, it is possible to perform repair by applying pressurized air on
the surface of the substrate to blow off the adhering matter. Thereafter, the substrate is
again subjected to the above inspection . In a case that the inspection is performed for
a plurality of substrates in a continuous-type manner or batch-type manner, it is possible
to provide a step of separating a substrate in which the ratio of the maximum value to
the minimum value, the difference of scattered intensity, or the average pixel value is
within the desired range from a substrate in which the ratio of the maximum value to the
minimum value, the difference of scattered intensity, or the average pixel value is
beyond the desired range based on the inspection result. The substrate in which the
ratio of the maximum value to the minimum value, the difference of scattered intensity,
or the average pixel value is within the desired range can be supplied to a production
line of the organic EL element and the like to produce the organic EL element and the
like sequentially. The substrate in which the ratio of the maximum value to the
minimum value, the difference of scattered intensity, or the average pixel value is
beyond the desired range can be subjected to a defect analysis or can be discarded.
[0097]

Subsequently, an organic EL element is produced by using a substrate which
passed the above judgment step among the resin film substrates (or glass substrates or
substrates in which concavities and convexities made of the sol-gel material are formed)
obtained by using methods exemplified by the BCP method and BKL method. An
explanation will be made about a method for producing the organic EL element using a
diffraction grating made of the resin film substrate with reference to Fig. 8. At first, as
shown in Fig. 8, a transparent electrode denoted by a reference numeral 3 is stacked on
a resin layer 80 (see Fig. 3(C)) of the resin film (substrate) 100 to maintain a concavity
and convexity structure formed on the surface of the resin 80. As a material for the
42
#
transparent electrode 3, for example, indium oxide, zinc oxide, tin oxide, indium-tin
oxide (ITO), which is a composite material thereof, gold, platinum, silver, or copper is
used. Of these materials, ITO is preferable from the viewpoint of the transparency and
the electrical conductivity. The thickness of the transparent electrode 3 is preferably
within a range from 20 to 500 nm. In a case that the thickness is less than the lower
limit, the electrical conductivity is more likely to be insufficient. In a case that the
thickness exceeds the upper limit, there is possibility that the transparency is so
insufficient that the emitted EL light cannot be extracted to the outside sufficiently. As
a method for stacking the transparent electrode 3, any known method such as a vapor
deposition method or a sputtering method can be employed as appropriate. Of these
methods, the sputtering method is preferably employed from the viewpoint of
improving adhesion property. It is allowable to put a glass substrate on a side opposite
to the resin layer 80 of the resin film 100 before the transparent electrode 3 is provided
on the resin layer 80.
[0098] Next, an organic layer denoted by a reference numeral 4 as shown in Fig. 8 is
stacked on the transparent electrode 3 to maintain the shape of the concavities and
convexities formed on the surface of the resin 80. The organic layer 4 is not
particularly limited, provided that the organic layer 4 is one usable as an organic layer
of the organic EL element. As the organic layer 4, any known organic layer can be
used as appropriate. The organic layer 4 may be a stacked body of various organic thin
films, and, for example, may be a stacked body of an anode buffer layer 11, a hole
transporting layer 12, and an electron transporting layer 13 as shown in Fig. 8. Here,
examples of materials for the anode buffer layer 11 include copper phthalocyanine,
PEDOT, and the like. Examples of materials for the hole transporting layer 12 include
derivatives of triphenylamine, triphenyldiamine derivatives (TPD), benzidine,
pyrazoline, styrylamine, hydrazone, triphenylmethane, carbazole, and the like.
Examples of materials for the electron transporting layer 13 include
aluminum-quinolinol complex (Alq), phenanthroline derivatives, oxadiazole derivatives,
triazole derivatives, phenylquinoxaline derivatives, silole derivatives, and the like.
The organic layer 4 may be, for example, a stacked body of a hole injecting layer made
of a triphenylamine derivative or the like, and a light emitting layer made of a
fluorescent organic solid such as anthracene, a stacked body of the light emitting layer
and an electron injecting layer made of a perylene derivative or the like, or a stacked
43
body of these hole injecting layer, light emitting layer, and electron injecting layer.
[0099] The organic layer 4 may be a stacked body of the hole transporting layer, the
light emitting layer, and the electron transporting layer. In this case, examples of
materials of the hole transporting layer include aromatic diamine compounds such as
phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives,
N,N'-bis(3-methylphenyl)-(l,l'-biphenyl)-4,4'-diamine (TPD), and
4,4'-bis[N-(naphthyl)-N-phenyl-amino]biphenyl(a-NPD); oxazole; oxadiazole; triazole;
imidazole; imidazolone; stilbene derivatives; pyrazoline derivatives;
tetrahydroimidazole; polyarylalkane; butadiene; and
4,4' ,4 " -tris(N-(3 -methylphenyl)N-phenylamino)triphenylamine (m-MTDATA). The
materials of the hole transporting layer, however, are not limited thereto.
[0100] By providing the light emitting layer, a hole injected from the transparent
electrode and electron injected from a metal electrode are recombined to occur light
emission. Examples of materials of the light emitting layer include metallo-organic
complex such as anthracene, naphthalene, pyrene, tetracene, coronene, perylene,
phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin,
oxadiazole, bisbenzoxazoline, bisstyryl, cyclopentadiene, and aluminum-quinolinol
complex (Alq3); tri-(p-terphenyl-4-yl)amine; l-aryl-2,5-di(2-thienyl) pyrrole
derivatives; pyran; quinacridone; rubren; distyrylbenzene derivatives; distyryl arylene
derivatives; distyryl amine derivatives; and various fluorescent pigments or dyes.
Further, it is preferable that light-emitting materials selected from the above compounds
are mixed as appropriate and then are used. Furthermore, it is possible to preferably
use a material system generating emission of light from a spin multiplet, such as a
phosphorescence emitting material generating emission of phosphorescence and a
compound including, in a part of the molecules, a constituent portion formed by the
above materials. The phosphorescence emitting material preferably includes heavy
metal such as iridium.
[0101] A host material having high carrier mobility may be doped with each of the
light-emitting materials as a guest material to generate the light emission using
dipole-dipole interaction (Forster mechanism), electron exchange interaction (Dexer
mechanism). Examples of materials of the electron transporting layer include
heterocyclic tetracarboxylic anhydrides such as nitro-substituted fluorene derivatives,
diphenylquinone derivatives, thiopyran dioxide derivatives, and naphthaleneperylene;
44
#
and metallo-organic complex such as carbodiimide, fluorenylidene methane derivatives,
anthraquino dimethane and anthrone derivarives, oxadiazole derivatives, and
aluminum-quinolinol complex (Alq3). Further, in the oxadiazole derivatives
mentioned above, it is also possible to use, as an electron transporting material,
thiadiazole derivatives in which oxygen atoms of oxadiazole rings are substituted by
sulfur atoms and quinoxaline derivatives having quinoxaline rings known as electron
attractive group. Furthermore, it is also possible to use a polymeric material in which
the above materials are introduced into a macromolecular chain or the above materials
are made to be a main chain of the macromolecular chain. It is noted that the hole
transporting layer or the electron transporting layer may also function as the
light-emitting layer. In this case, there are two organic layers between the transparent
electrode and the metal electrode which will be described later.
[0102] From the viewpoint of facilitating charge injection or hole injection into such a
organic layer 4, a layer made of a metal fluoride such as lithium fluoride (LiF) or L12O3,
a highly active alkaline earth metal such as Ca, Ba, or Cs, an organic insulating material,
or the like may be provided on the transparent electrode 3 or the organic layer 4.
[0103] In a case that the organic layer 4 is a stacked body formed of the anode buffer
layer 11, the hole transporting layer 12, and the electron transporting layer 13, the
thicknesses of the anode buffer layer 11, the hole transporting layer 12, and the electron
transporting layer 13 are preferably within a range from 1 to 50 nm, a range from 5 to
200 nm, and a range from 5 to 200 nm, respectively, from the viewpoint of maintaining
the shape of the concavities and convexities formed on the surface of the cured resin
layer. In a case that the organic layer 4 is a stacked body formed of the hole
transporting layer, the light-emitting layer, and the electron transporting layer, the
thicknesses of the hole transporting layer, the light-emitting layer, and the electron
transporting layer are preferably within a range from 1 to 200 nm, a range from 5 to 100
nm, and a range from 5 to 200 nm, respectively. As a method for stacking the organic
layer 4, any known method such as a vapor deposition method, a sputtering method, and
a die coating method can be employed as appropriate. Of these methods, the vapor
deposition method is preferably employed from the viewpoint of maintaining the shape
of the concavities and convexities formed on the surface of the resin 80.
[0104] Subsequently, as shown in Fig. 8, a metal electrode denoted by a reference
numeral 5 is stacked on the organic layer 4 so as to maintain the shape of the concavities
45
#
and convexities formed on the surface of the resin 80 in the step for forming the organic
EL element. Materials of the metal electrode 5 are not particularly limited, and a
substance having a small work function can be used as appropriate. Examples of the
materials include aluminum, MgAg, Mgln, and AlLi. The thickness of the metal
electrode 5 is preferably within a range from 50 to 500 nm. In a case that the thickness
is less than the lower limit, the electrical conductivity is more likely to be decreased.
In a case that the thickness exceeds the upper limit, there is possibility that the shape of
the concavities and convexities is difficult to maintain. Any known method such as a
vapor deposition method and a sputtering method can be adopted to stack the metal
electrode 5. Of these methods, the vapor deposition method is preferably employed
from the viewpoint of maintaining the concavity and convexity structure formed on the
surface of the resin 80. Accordingly, an organic EL element 400 having a structure as
shown in Fig. 8 can be obtained.
[0105] The resin 80 on the base member 100 manufactured by the BCP method, has
the chevron-shaped structure. Thus, each of the transparent electrode 3, the organic
layer 4, and the metal electrode 5 is readily stacked to maintain the chevron-shaped
structure of the resin 80. Hence, it is possible to sufficiently suppress repetition of
multiple reflection of light generated in the organic layer 4 in the element due to total
reflection at each interface. Further, it is also possible to re-emit light which has been
totally reflected at an interface between the transparent supporting substrate and the air
by diffraction effect. Furthermore, since each of the transparent electrode 3, the
organic layer 4, and the metal electrode 5 is more likely to have the same structure as
the chevron-shaped structure formed on the surface of the resin layer 80, an
inter-electrode distance between the transparent electrode 3 and the metal electrode 5 is
partially short. For this reason, in comparison with those in which the inter-electrode
distance between the transparent electrode 3 and the metal electrode 5 is uniform, an
increase in electric field intensity can be expected in application of voltage, and also
light emission efficiency of the organic EL element can be improved.
[0106] In the diffraction grating (substrate) produced according to the method for
producing the substrate of the present invention and the organic EL element including
the diffraction grating, the average height of the concavities and convexities formed on
the surface (the cured surface of curable resin) of the diffraction grating is preferably
within the range from 5 to 200 nm, more preferably within the range from 20 to 200 nm,
46
and further preferably within the range from 50 to 150 nm as described above.
[0107] In the diffraction grating (substrate) produced according to the present
invention and the organic EL element including the diffraction grating, the average pitch
of the concavities and convexities formed on the surface (the cured surface of curable
resin) of the diffraction grating is preferably within the range from 100 to 600 nm, and
more preferably within the range from 200 to 600 nm as described above.
[0108] In the following, the present invention will be described in detail by Examples.
However, the present invention is not limited to the examples below.
EXAMPLES
[0109]

In this Example, a substrate having a concave and convex surface was
produced by using the BCP method, and then an organic EL element was produced
using the produced substrate. At first, it was prepared a block copolymer produced by
Polymer Source Inc. which was made of polystyrene (hereinafter referred to as "PS" in
an abbreviated manner as appropriate) and polymethyl methacrylate (hereinafter
referred to as "PMMA" in an abbreviated manner as appropriate) as described below.
Mn of PS segment= 868,000
Mn of PMMA segment= 857,000
Mn of block copolymer = 1,725,000
Volume ratio between PS segment and PMMA segment (PS:PMMA)= 53:47
Molecular weight distribution (Mw/Mn)= 1.30
Tg of PS segment= 96 degrees Celsius
Tg of PMMA segment= 110 degrees Celsius
[0110] The volume ratio of the first polymer segment and second polymer segment
(the first polymer segment: the second polymer segment) in the block copolymer was
calculated on the assumption that the density of polystyrene was 1.05 g/cm3, the density
of polymethyl methacrylate was 1.19 g/ cm3. The number average molecular weights
(Mn) and the weight average molecular weights (Mw) of polymer segments or polymers
were measured by using gel permeation chromatography (Model No: "GPC-8020"
manufactured by Tosoh Corporation, in which TSK-GEL SuperHlOOO, SuperH2000,
SuperH3000, and SuperH4000 were connected in series). The glass transition
47
temperatures (Tg) of polymer segments were measured by use of a differential scanning
calorimeter (manufactured by Perkin-Elmer under the product name of "DSC7"), while
the temperature was raised at a rate of temperature rise of 20 degrees Celsius/min over a
temperature range from 0 to 200 degrees Celsius. The solubility parameters of
polystyrene and polymethyl methacrylate were 9.0 and 9.3, respectively (see Kagaku
Binran Ouyou Hen (Handbook of Chemistry, Applied Chemistry), 2nd edition).
[0111] Toluene was added to 150 mg of the block copolymer and 38 mg of
Polyethylene Glycol 4000 manufactured by Tokyo Chemical Industry Co., Ltd. (Mw=
3000, Mw/Mn= 1.10) as polyethylene oxide so that the total amount thereof was lOg,
followed by dissolving them. Then, the solution was filtrated or filtered through a
membrane filter having a pore diameter of 0.5 um to obtain a block copolymer solution.
The obtained block copolymer solution was applied, on a polyphenylene sulfide film
(TORELINA manufactured by TORAYINDUSTPJRES, INC.) as a base member, in a
film thickness of 200 to 250 nm, by a spin coating. The spin coating was performed at
a spin speed of 500 rpm for 10 seconds, and then performed at a spin speed of 800 rpm
for 30 seconds. The thin film applied by the spin coating was left at a room
temperature for 10 minutes until the thin film was dried.
[0112 J Subsequently, the base member on which the thin film was formed was heated
for 5 hours in an oven of 170 degrees Celsius (first annealing process). Concavities
and convexities were observed on the surface of the heated thin film, and it was found
out that micro phase separation of the block copolymer forming the thin film was
caused (see Fig. 2(B)).
[0113] The heated thin film as described above was subjected to an etching process as
described below to selectively decompose and remove PMMA on the base member.
The thin film was irradiated with ultraviolet rays at an irradiation intensity of 30J/cm2
by use of a high pressure mercury lamp. Then, the thin film was immersed in acetic
acid, and was subjected to cleaning with ion-exchanged water, followed by being dried.
As a result, there was formed, on the base member, a concavity and convexity pattern
clearly deeper than the concavities and convexities which appeared on the surface of the
thin film by the heating process (see Fig. 2(C)).
[0114] Next, the base member was subjected to a heating process (second annealing
process) for 1 hour in an oven of 140 degrees Celsius so that the concavity and
convexity pattern formed by the etching process was deformed to have a
48
chevron-shaped structure (process for forming a shape of chevrons) (see Fig. 2(D)).
[0115] About 10 tun of a thin nickel layer was formed as a current seed layer by a
sputtering on the surface of the thin film, for which the process for forming the shape of
chevrons had been performed (see Fig. 2(E)). Subsequently, the base member with the
thin film was subjected to an electroforming process (maximum current density:
0.05A/cm~) in a nickel sulfamate bath at a temperature of 50 degrees Celsius to
precipitate nickel until the thickness of nickel became 250 um (see Fig. 2(F)). The
base member with the thin film was mechanically peeled off from the nickel
electroforming body obtained as described above (see Fig. 2(G)). Subsequently, the
nickel electroforming body was immersed in Chemisol 2303 manufactured by The
Japan Cee-Bee Chemical Co., Ltd., followed by being cleaned while being stirred for 2
hours at 50 degrees Celsius. Thereafter, polymer component(s) adhered to a part of the
surface of the electroforming body was(were) removed by repeating the following
process three times. That is, an acrylic-based UV curable resin was applied on the
nickel electroforming body; and the applied acrylic-based UV curable resin was cured;
and then the cured resin was peeled off (see Fig. 2(H)).
[0116] Subsequently, the nickel electroforming body was immersed in HD-2101TH
manufactured by Daikin Chemicals Sales, Co., Ltd. for about 1 minute and was dried,
and then stationarily placed overnight. The next day, the nickel electroforming body
was immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd. to perform
an ultrasonic cleaning process for about 1 minute. Accordingly, a nickel mold (nickel
substrate) for which a mold-release treatment had been performed was obtained (see Fig.
3(A)).
[0117] Subsequently, a fluorine-based UV curable resin was applied on a PET
substrate (COSMOSHINE A-4100 manufactured by Toyobo Co., Ltd.). Then, the
fluorine-based UV curable resin was cured by irradiation with ultraviolet rays at 600
mJ/cm2, with the obtained nickel mold being pressed to the PET substrate (see Fig.
3(B)). After curing of the resin, the nickel mold was peeled off from the cured resin
(see Fig. 3(C)). Accordingly, a diffraction grating made of the PET substrate with the
resin film to which the surface profile of the nickel mold was transferred was obtained.
[0118] An analysis image of the concavity and convexity shape on the surface of the
resin in the diffraction grating was obtained by using an atomic force microscope (a
scanning probe microscope equipped with an environment control unit "Nanonavi II
49
Station/E-sweep" manufactured by SII NanoTechnology Inc.). Analysis conditions of
the atomic force microscope were as follows. Measurement mode: dynamic force
mode
Cantilever: SI-DF40 (material: Si, lever width: 40 urn, diameter of tip of chip: 10 nm)
Measurement atmosphere: in air
Measurement temperature: 25 degrees Celsius
[0119] Fig. 9 shows a concavity and convexity analysis image of the surface of the
resin of the obtained diffraction grating.
[0120]

A concavity and convexity analysis image was obtained as described above by
performing a measurement in a randomly selected measuring region of 3 urn square
(length: 3 urn, width: 3 um) in the diffraction grating. Distances between randomly
selected concave portions and convex portions in the depth direction were measured at
100 points or more in the concavity and convexity analysis image, and the average of
the distances was calculated as the average height (depth) of the concavities and
convexities. The average height of the concavity and convexity pattern obtained by
the analysis image in this example was 62 nm.
[0121]

A concavity and convexity analysis image was obtained as described above by
performing a measurement in a randomly selected measuring region of 3 um square
(length: 3 um, width: 3 um) in the diffraction grating. The obtained concavity and
convexity analysis image was subjected to a flattening process including primary
inclination correction, and then to two-dimensional fast Fourier transform processing.
Thus, a Fourier-transformed image was obtained. Fig. 10 shows the obtained
Fourier-transformed image. As is clear from the result shown in Fig. 10, it was
confirmed that the Fourier-transformed image showed a circular pattern substantially
centered at an origin at which an absolute value of wavenumber was 0 urn"1, and that the
circular pattern was present within a region where the absolute value of wavenumber
was within a range of 10 um"1 or less.
[0122] The circular pattern of the Fourier-transformed image is a pattern observed due
to gathering of bright spots in the Fourier-transformed image. The term "circular"
50
#
herein means that the pattern of the gathering of the bright spots looks like a
substantially circular shape, and is a concept further including a case where a part of a
contour looks like a convex shape or a concave shape. The gathering of the bright
spots may look like a substantially annular shape, and this case is expressed as the term
"annular". It is noted that the term "annular" is a concept further including a case
where a shape of an outer circle or inner circle of the ring looks like a substantially
circular shape and further including a case where a part of the contours of the outer
circle and/or the inner circle of the ring looks like a convex shape or a concave shape.
Further, the phrase "the circular or annular pattern is present within a region where an
absolute value of wavenumber is within a range of 10 urn" or less (more preferably
from 1.25 to 10 um"1, further preferably from 1.25 to 5 um"1)" means that 30% or more
(more preferably 50% or more, further more preferably 80% or more, and particularly
preferably 90% or more) of bright spots forming the Fourier-transformed image are
present within a region where the absolute value of wavenumber is within a range of 10
um"1 or less (more preferably from 1.25 to 10 urn1, and further preferably from 1.25 to
5 um"1). Regarding a relation between the pattern of the concavity and convexity
structure and the Fourier-transformed image, the followings have been appreciated.
That is, in a case that the concavity and convexity structure itself has neither the pitch
distribution nor the directivity, the Fourier-transformed image appears to have a random
pattern (no pattern). In a case that the concavity and convexity structure is entirely
isotropic in an XY direction and has the pitch distribution, a circular or annular
Fourier-transformed image appears. In a case that the concavity and convexity
structure has a single pitch, the annular shape appeared in the Fourier-transformed
image tends to be sharp.
[0123] The two-dimensional fast Fourier transform processing on the concavity and
convexity analysis image can be easily performed by electronic image processing using
a computer equipped with software for two-dimensional fast Fouriertransform
processing.
[0124] As a result of the image analysis of the obtained Fourier-transformed image,
the wavenumber 2.38 um"1 was the most intensive. That is, the average pitch was 420
nm. The average pitch could be obtained as follows. For each of the points of
Fourier-transformed image, intensity and distance (unit: um"1) from the origin of
Fourier-transformed image were obtained. Then, the average value of the intensity
51
was obtained for the points each having the same distance from the origin. As
described above, a relation between the distance from the origin of the
Fourier-transformed image and the average value of the intensity was plotted, a fitting
with a spline function was carried out, and the wavenumber of peak intensity was
regarded as the average wavenumber (um"1). For the average pitch, it is allowable to
make a calculation by another method, for example, a method for obtaining the average
pitch of the concavities and convexities as follows. That is, a concavity and convexity
analysis image is obtained by performing a measurement in a randomly selected
measuring region of 3 um square (length: 3 um, width: 3 um) in the diffraction grating,
then the distances between randomly selected adjacent convex portions or between
randomly selected adjacent concave portions are measured at 100 points or more in the
concavity and convexity analysis image, and then an average of these distances is
determined.
[0125] The apparatus shown in Fig. 6 was provided in a dark room to observe the
intensity distribution of scattered light of the substrate obtained as described above
under the following conditions. The height of the pair of black blocks in a rectangular
parallelepiped shape of the stage device 104 was 40 mm; the distance between the pair
of black blocks was 27 mm; a square substrate of 30 mm x 30 mm was provided as the
substrate; a pair of highly directional LED bar illuminations (produced by CCS Inc.,
LDL2-119 x 16BL) having a light-emission central wavelength of 470 nm and an area
of light-emitting section of 119 mm x 160 mm was provided at a position having a
height of 160 mm from the floor surface; the pair of LED bar illuminations was
provided to be inclined toward the floor surface at 10° from a horizontal state, and to set
the distance between the two LED bar illuminations to 307 mm; a digital camera was
used as the imaging element 124 and arranged at a position having a distance of 770
mm from the surface of the substrate; and light emission of the pair of LED bar
illuminations was performed at a maximum output (each 5.7 W) and an image of the
substrate was obtained. The type of the digital camera and the imaging conditions
were as follows:
Camera: Canon EOS Kiss X3
Lens: EF-S18-55 mm F3. 5-5. 6 IS
Shutter speed: 1/100 seconds
ISO sensitivity: 3200
52
Aperture value: F5.6
White balance: Standard
Picture style: Standard
Pixel value: 0 to 255
[0126] Blue pixel values were sampled or extracted from the image obtained by the
digital camera, and the blue pixel values were displayed as a gray scale. Further, as
shown in Fig. 11(A), only the pixel values on a line LI, which extended in an X
direction at a substantially central position of the image in a Y direction, were sampled
to be outputted as profile of the pixel values with respect to pixel positions in the X
direction. Only the pixel values in the portion to be made into the organic EL element
(within the frame depicted by broken lines in Fig. 11(A)) as will be described later was
outputted as the cross-section profile. Fig. 11 (B) shows profile of the obtained pixel
values with respect to the pixel positions in the X direction. The average pixel value
was 113; the maximum pixel value was 128; and the minimum pixel value was 100.
From these values, it was appreciated that the maximum pixel value / minimum pixel
value was 1.28, which was less than 1.5 as a judgment reference value.
[0127] Subsequently, on the resin layer of the obtained diffraction grating, a
transparent electrode (ITO, thickness: 120 nm) was stacked by a sputtering method, and
a hole transporting layer (N,N'-diphenyl-N,N'-bis(3-methylphenyl)-l,r-diphenyl-4,4'
-diamine, thickness: 40 nm), an electron transporting layer (8-hydroxyquinoline
aluminum, thickness: 30 nm), a lithium fluoride layer (thickness: 1.5 nm), and a metal
electrode (aluminum, thickness: 150 nm) were each stacked by a vapor deposition
method so that the shape of the concavities and convexities formed on the surface of the
cured resin layer is maintained. Accordingly, the organic EL element was obtained.
A direct-current power supply was connected to the obtained organic EL element such
that negative voltage was applied on the metal electrode side and positive voltage was
applied on the transparent electrode side. Then, the voltage of 3 V was applied and the
image of the light emission state of the organic EL element was obtained by the digital
camera. The central wavelength of the light emission of the organic EL element was
520 nm. The imaging conditions of the digital camera were similar to the imaging
conditions of the digital camera used for the substrate imaging, except that the shutter
speed was changed to 1/1600 seconds.
[0128] Green pixel values were sampled or extracted from the image obtained by the
53
digital camera, and the green pixel values were displayed as a gray scale. As shown in
Fig. 12(A), only the pixel values on a line LI (position which is the same as the line LI
on the substrate), which extended in an X direction at a substantially central position of
the image in a Y direction, were sampled to be outputted as profile of the pixel values
with respect to pixel positions in the X direction. Fig. 12(B) shows profile of the
obtained pixel values with respect to the pixel positions in the X direction. The
average pixel value was 99; the maximum pixel value was 105; and the minimum pixel
value was 89. From these values, it was appreciated that the maximum pixel value /
minimum pixel value was 1.18, which was less than 1.5 as the judgment reference value.
Further, it was appreciated that the profile shown in Fig. 12(B) had a tendency which
was approximately consistent with that of the profile shown in Fig. 11(B) and that the
distribution of scattered light on the substrate reflected the distribution of scattered light
on the organic EL element. Accordingly, it is found out that light-emitting property
(unevenness of luminance) of the organic EL element can be known in advance by
performing the inspection and evaluation of the scattered light on the diffraction-grating
substrate before inspecting the unevenness of luminance of the completed organic EL
element in the manufacturing process of the organic EL element. As described above,
it is possible to produce the organic EL element with a high throughput by associating
property of the unevenness of luminance of the organic EL element with property of the
unevenness of luminance of the substrate having the irregular concave and convex
surface which is used in the organic EL element. Especially, since prediction of
occurrence of the unevenness of luminance of the completed organic EL element and
evaluation of the completed organic EL element can be performed in the production step
of the substrate, it is possible to further reliably produce the organic EL element having
a uniform illumination intensity by excluding a substrate which was determined to be
unsatisfactory or defective in the judgment of the unevenness of luminance and using
only a substrate which passed or was determined to be satisfactory or acceptable in the
judgment of the unevenness of luminance.
[0129]

In this Example, a substrate having a concave and convex surface is produced
by BKL method, and then an organic EL element is produced by using the produced
substrate. First, a silicone-based polymer (a resin composition of a mixture of 90% by
54
mass of a silicone rubber (manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601") and 10% by mass of a curing agent) was applied onto a base
member (material: glass, size: 20 mm x 12 mm) by a spin coating method, and cured by
being heated at 100 degrees Celsius for 1 hour. Accordingly, a silicone-based polymer
film was formed.
[0130] Next, an aluminum vapor-deposited film (thickness: 10 nm) was formed on the
silicone-based polymer film by a vapor deposition method under conditions of a
temperature of 100 degrees Celsius and a pressure of 1 x 10° Pa. Then, after cooling
to room temperature (25 degrees Celsius) over a period of 30 minutes, the pressure was
returned to the atmospheric pressure (1.013 x 105Pa). Consequently, concavities and
convexities were formed on the surface of the aluminum vapor-deposited film formed
on the silicone-based polymer film. Subsequently, a silicone-based polymer (a resin
composition of a mixture of 90% by mass of a silicone rubber (manufactured by Wacker
Chemie AG under the product name of "Elastosil RT601") and 10% by mass of a curing
agent) was applied onto the aluminum vapor-deposited film by a dropping method, then
cured by being heated at 100 degrees Celsius for 1 hour, and thereafter detached from
the aluminum vapor-deposited film. Thus, Master Block (M-1B) was obtained.
[0131] Then, an aluminum vapor-deposited film (thickness: 10 nm) was formed on the
obtained Master Block (M-1B) by a vapor deposition method under conditions of a
temperature of 100 degrees Celsius and a pressure of 1 x 10~3 Pa. After cooling to
room temperature (25 degrees Celsius) over a period of 30 minutes, the pressure was
returned to the atmospheric pressure (1.013 x 105Pa). Consequently, concavities and
convexities were formed on the surface of the aluminum vapor-deposited film formed
on the Master Block (M-1B). Subsequently, a silicone-based polymer (a resin
composition of a mixture of 90% by mass of a silicone rubber (manufactured by Wacker
Chemie AG under the product name of "Elastosil RT601") and 10% by mass of a curing
agent) was applied onto the aluminum vapor-deposited film by a dropping method, then
cured by being heated at 100 degrees Celsius for 1 hour, and thereafter detached from
the aluminum vapor-deposited film. Thus, Master Block (M-2B) was obtained.
Further, an aluminum vapor-deposited film (thickness: 10 nm) was formed on the
Master Block (M-2B) having concavities and convexities formed on the surface thereof
by a vapor deposition method under conditions of a temperature of 100 degrees Celsius
and a pressure of 1 x 10"3 Pa. Then, after cooling to room temperature (25 degrees
55
Celsius) over a period of 30 minutes, the pressure was returned to the atmospheric
pressure (1.013 x 105Pa). Consequently, concavities and convexities were formed on
the surface of the aluminum vapor-deposited film formed on the Master Block (M-2B).
Subsequently, a silicone-based polymer (a resin composition of a mixture of 90% by
mass of a silicone rubber (manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601") and 10% by mass of a curing agent) was applied onto the
aluminum vapor-deposited film by a dropping method, then cured by being heated at
100 degrees Celsius for 1 hour, and thereafter detached from the aluminum
vapor-deposited film. Thus, Master Block (M-3B) was obtained.
[0132]
(i) Manufacture of diffraction grating
A glass substrate of 50 mm x 50 mm (produced by Matsunami glass Ind. Ltd.,
product name "Micro slide glass") and a curable resin (Produced by Norland Products
Inc., product name "NOA 61") were prepared and the curable resin was applied onto the
glass substrate. Then, the curable resin was cured by irradiation with ultraviolet rays
for 1 hour while the Master Block (M-3B) was pressed against the curable resin in a
step-and-repeat-manner twice in each of the horizontal direction and vertical direction
so as to obtain a diffraction grating having a cured resin layer in which concavities and
convexities were formed in an area of 40 mm x 24 mm positioned at the substantially
central portion of a glass substrate. Reference can be made, for example, to Jun
TANIGUCHI "Hajimete no nano-imprint gijutsu (Introduction to nano-imprint
technology)" Beginner's book 38, p 51, published by Kogyo Chosakai Publishing Inc.,
about details of this process. A concavity and convexity analysis image of the surface
of the resin of the obtained diffraction grating is obtained by use of the atomic force
microscope used in Example 1, and the concavity and convexity analysis image is
shown in Fig. 13. The observation and analysis conditions by the atomic force
microscope are similar to those in Example 1.
[0133]

A concavity and convexity analysis image was obtained as described above by
performing a measurement in a randomly selected measuring region of 3 urn square
(length: 3 urn, width: 3 urn) in the diffraction grating. Distances between randomly
selected concave portions and convex portions in the depth direction were measured at
56
100 points or more in the concavity and convexity analysis image, and the average of
the distances was calculated as the average height (depth) of the concavities and
convexities. The average height of the concavity and convexity pattern obtained by
the analysis image in this example was 35 nm.
[0134]

A concavity and convexity analysis image was obtained as described above by
performing a measurement in a randomly selected measuring region of 3 um square
(length: 3 um, width: 3 um) in the diffraction grating. The obtained concavity and
convexity analysis image was subjected to a flattening process including primary
inclination correction, and then to two-dimensional fast Fourier transform processing.
Thus, a Fourier-transformed image was obtained. Fig. 14 shows the obtained
Fourier-transformed image. As is clear from the result shown in Fig. 14, it was
confirmed that the Fourier-transformed image showed a circular pattern substantially
centered at an origin at which an absolute value of wavenumber was 0 um"1, and that the
circular pattern was present within a region where the absolute value of wavenumber
was within a range of 10 um"1 or less.
[0135] As a result of the image analysis of the obtained Fourier-transformed image,
the wavenumber 2.67 um"1 was the most intensive. That is, the average pitch was 375
nm.
[0136] The intensity distribution of the scattered light on the substrate obtained as
described above was observed using the apparatus shown in Fig. 6 under the same
conditions as Example 1, except that the size of a glass substrate used in this Example
was different from that used in Example 1. The glass was arranged so that the center
of the area in which the concavities and convexities were formed was coincident with
the center of an area of which image is to be taken. The digital camera used in
Example 1 was used in this Example, and imaging conditions in this Example were
same as those in Example 1.
[0137] Blue pixel values were sampled or extracted from the image obtained by the
digital camera, and the blue pixel values were displayed as a gray scale. Further, as
shown in Fig. 15(A), only the pixel values on a line L2, which extended in an X
direction at a substantially central position of the image in a Y direction, were sampled
to be outputted as profile of the pixel values with respect to pixel positions in the X
57
direction. Noted that, Fig. 15(A) shows an image of only the portion to be made into
the organic EL element as will be described later. Fig. 15(B) shows profile of the
obtained pixel values with respect to the pixel positions in the X direction. The
average pixel value was 118; the maximum pixel value was 149; and the minimum pixel
value was 69. From these values, it was appreciated that the maximum pixel value /
minimum pixel value was 2.16, which exceeded 1.5 as the acceptable range.
[0138]
(ii) Manufacture of organic EL element
The difference of scattered intensity of the diffraction-grating substrate
obtained as described above exceeded the acceptable value. However, on the cured
resin layer of the substrate, a transparent electrode (ITO, thickness: 120 nm) was
stacked by a sputtering method and a hole transporting layer
(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-l,r-diphenyl-4,4' -diamine, thickness: 40
nm), an electron transporting layer (8-hydroxyquinoline aluminum, thickness: 30 nm), a
lithium fluoride layer (thickness: 1.5 nm), and a metal electrode (aluminum, thickness:
150 nm) were each stacked by a vapor deposition method, so that the shape of the
concavities and convexities formed on the surface of the cured resin layer is maintained.
Accordingly, the organic EL element was obtained (see Fig. 8). A direct-current power
supply was connected to the obtained organic EL element such that negative voltage
was applied on the metal electrode side and positive voltage was applied on the
transparent electrode side. Then, the voltage of 3 V was applied and the image of the
light emission state of the organic EL element was obtained by the digital camera. The
central wavelength of the light emission of the organic EL element was 520 nm. The
imaging conditions of the digital camera were similar to the imaging conditions of the
digital camera used for the substrate imaging, except that the shutter speed was changed
to 1/1600 seconds.
[0139] Green pixel values were sampled or extracted from the image obtained by the
digital camera, and the green pixel values were displayed as a gray scale. As shown in
Fig. 16(A), only the pixel values on a line L2 (position which is the same as the line L2
on the substrate), which extended in an X direction at a substantially central position of
the image in a Y direction, were sampled to be outputted as profile of the pixel values
with respect to pixel positions in the X direction. Fig. 16(B) shows profile of the
obtained pixel values with respect to the pixel positions in the X direction. The
58
average pixel value was 151; the maximum pixel value was 183; and the minimum pixel
value was 114. From these values, it was appreciated that the maximum pixel value /
minimum pixel value was 1.61, which exceeded 1.5 as the judgment reference value.
Further, it was appreciated that the profile shown in Fig. 16(B) had a tendency which
was approximately consistent with that of the profile shown in Fig. 15(B) and that the
distribution of scattered light on the substrate reflected the distribution of scattered light
on the organic EL element. Accordingly it is possible to further reliably produce the
organic EL element having a uniform illumination intensity by inspecting and
evaluating the scattered light on the diffraction-grating substrate before inspecting the
unevenness of luminance of the completed organic EL element in the manufacturing
process of the organic EL element, then excluding a substrate which does not meet a
criterion for the unevenness of luminance, and using only a substrate which meets the
criterion for the unevenness of luminance.
[0140]

In Examples 1 and 2, a blue light source having the light-emission central
wavelength of 470 nm was used as a light source in the inspection step. In this
Example, a white LED and a red LED were used to evaluate visibility of the scattered
light on the resin substrate obtained in Example 1. Fig. 19 shows photographs of the
images of the concave and convex surface of the substrate obtained by using LED bar
illuminations having the blue LED (Example 1), the white LED, and the red LED
respectively. In each of the photographs, in a case of using the red LED, the
unevenness of pattern (unevenness of luminance) was hardly observed and foreign
substances on the resin substrate were emphasized; and in a case of using the while
LED an image having an intermediate property or appearance between the property or
appearance of the image obtained by using the blue LED and the property or appearance
of the image obtained by the red LED, that is, an image in which both the unevenness of
pattern and the foreign substances on the resin substrate were emphasized was obtained.
As is understood from Examples 1 and 2, since the unevenness of luminance is caused
by the unevenness of pattern, the blue light source (for example, the light-emission
central wavelength is 430 nm to 485 nm) is preferable as a light source of an inspection
system which inspects the unevenness of luminance of the diffraction-grating substrate
for the organic EL element which has concavities and convexities of which pitch is, for
59
example, 100 nm to 600 nm.
[0141]

In this example, a nickel mold (nickel substrate), for which a mold-release
treatment was performed, was obtained by using the BCP method similar to Example 1.
Subsequently, a fluorine-based UV curable resin was applied on a PET substrate
(easily-adhesion PET film manufactured by Toyobo Co., Ltd., product name:
COSMOSHINE A-4100). Then, the fluorine-based UV curable resin was cured by
irradiation with ultraviolet rays at 600 mJ/cm2, with the nickel mold being pressed to the
PET substrate. After curing of the resin, the nickel mold was peeled off from the cured
resin. Accordingly, a diffraction grating mold made of the PET substrate with the resin
film to which the surface profile of the nickel mold was transferred was obtained.
Next, 2.5 g of tetraethoxysilane (TEOS) and 2.1 g of methyltriethoxysilane (MTES)
were added by drops to a mixture of 24.3 g of ethanol, 2.16 g of water, and 0.0094 g of
concentrated hydrochloric acid, followed by being stirred for 2 hours at a temperature of
23 degrees Celsius and humidity of 45 % to obtain a sol solution. The sol solution was
applied on a soda-lime glass plate of 15 x 15x0.11 cm by a bar coating. Doctor Blade
(manufactured by Yoshimitsu Seiki Co., Ltd.) was used as a bar coater. The doctor
blade was designed so that the film thickness of the coating film was 5 urn. However,
the doctor blade was adjusted so that the film thickness of the coating film was 40 urn
by sticking an imide tape having the thickness of 35um to the doctor blade. When 60
seconds have elapsed after the application of the sol solution, the diffraction grating
mold, made of the PET substrate with the resin film to which the surface profile of the
nickel mold was transferred, which was prepared similar to Example 1, was pressed
against the coating film on the glass plate by a pressing roll using a method described
below.
[0142] At first, the surface on which the pattern of the mold has been formed was
pressed against the coating film on the glass substrate while rotating the pressing roll of
which temperature was 23 degrees Celsius from one end to the other end of the glass
substrate. Immediately after completion of the pressing, the substrate was moved on a
hot plate and then heated at a temperature of 100 degrees Celsius (pre-sintering). After
continuing the heating for 5 minutes, the substrate was removed from the hot plate and
the mold was manually peeled off from the substrate from the edge. The mold was
60
peeled off such that an angle (peel angle) of the mold with respect to the substrate was
about 30°.
[0143] Subsequently, a main sintering was performed by heating the substrate for 60
minutes in an oven of 300 degrees Celsius to obtain a diffraction-grating substrate.
Thereafter, the pattern transferred to the coating film was evaluated.
[0144] For the diffraction grating, the analysis image of the concavity and convexity
shape on the surface was obtained by using the atomic force microscope used in
Example 1. Analysis conditions of the atomic force microscope were the same as
those in Example 1. A concavity and convexity analysis image was obtained in the
similar manner as Example 1 by performing a measurement in a randomly selected
measuring region of 3 urn square (length: 3 urn, width: 3 urn) in the diffraction grating.
The average height of the concavity and convexity pattern obtained by the analysis
image in this example was 56 nm. It was confirmed that the Fourier-transformed
image showed a circular pattern substantially centered at an origin at which an absolute
value of wavenumber was 0 urn1, and that the circular pattern was present within a
region where the absolute value of wavenumber was within a range of 10 um"1 or less.
As a result of the image analysis of the obtained Fourier-transformed image, the
wavenumber 2.38 um"1 was the most intensive. That is, the average pitch was 420 nm.
The intensity distribution of the scattered light on the substrate obtained as described
above was observed by using the apparatus shown in Fig. 6 and the same digital camera
as Example 1 under the same imaging conditions as Example 1. Blue pixel values
were sampled or extracted from the image obtained by the digital camera, and the blue
pixel values were displayed as a gray scale. As shown in Fig. 20(A), only the pixel
values on a line L3, which extended in an X direction at a substantially central position
of the image in a Y direction, were sampled to be outputted as profile of the pixel values
with respect to pixel positions in the X direction. Fig. 20(B) shows profile of the
obtained pixel values with respect to the pixel positions in the X direction. According
to calculations of the average pixel value, the maximum pixel value, and the minimum
pixel value depending on the cross-section profile, which is outputted from the image of
the digital camera in the similar manner as Example 1, the average pixel value was
205.6; the maximum pixel value was 221.0; and the minimum pixel value was 181.0.
From these values, it was appreciated that the maximum pixel value/minimum pixel
value was 1.22, which was less than 1.5 as the judgment reference value.
61
[0145] In the above description, the methods of the present invention were explained
by Examples. The present invention, however, is not limited thereto, and can be
realized in various aspects. Although the substrates were produced by the BCP
method and BKL method in the Examples, another method may be used provided that
the substrate having the irregular concave and convex surface can be produced.
Further, although the substrate for electroforming, the metal substrate (mold) formed by
the electroforming, and the resin substrate formed from the metal substrate each has a
flat plate shape in the Examples, each of the substrates may have a curved shape. For
example, the metal substrate may be formed as a drum having a concavity and
convexity pattern by forming the metal substrate to have a drum shape by the
electroforming. Further, in the Examples, the intensity of the scattered light on each of
the produced substrate and the produced organic EL element using the produced
substrate was measured and evaluated by using the apparatus shown in Fig. 6. The
present invention, however, is also applicable to a large-size glass substrate or a film on
a roll in which a long film is wound on a core, by providing a line sensor camera at the
upper portion of a film transport system and monitoring the intensity of the scattered
light.
[0146] Further, the substrate for which the inspection step and evaluation/judgment
step were performed was the resin substrate molded by using the metal substrate formed
by the electroforming in the BCP method in each of the Examples. However, it is
possible to inspect a substrate obtained at any stage (any process step), provided that the
substrate has the irregular concave and convex surface which is formed in order to
produce the resin substrate. For example, the substrate before the second heating step
in the BCP method (see Fig. 2(C)), the substrate having a concave and convex surface in
a shape of chevrons obtained in the second heating step (see Fig. 2(D) and Fig. 2(E)),
and the metal substrate having a concave and convex surface obtained in the
electroforming step (see Fig. 2(H)) can be also subjected to the inspection step and
subsequent steps. Further, the resin substrate molded by using the metal substrate; the
resin substrate which is directly obtained by performing a transfer in which the resin
substrate molded by using the metal substrate is used as the master block or the resin
substrate which is indirectly obtained by repeating the transfer in which the resin
substrate molded by using the metal substrate is used as the master block; and the
substrate including a sol-gel material can be also subjected to the inspection step and
62
subsequent steps. Also for the BKL method, the substrate having the concave and
convex surface obtained at any stage at which the concavities and convexities have been
formed (see, for example, Fig. 5(B)) can be subjected to the inspection step and
subsequent steps. Further, the substrate which is directly or indirectly obtained by
performing the transfer by use of the master block of the polymer film obtained by the
BKL method and the substrate including the sol-gel material can be also subjected to the
inspection step and subsequent steps.
[0147] In a case that the substrate and the organic EL element are continuously
produced by using the drum (roll) having the concavities and convexities formed by the
electroforming as described above in order to enable mass production, it is possible to
perform an in-line evaluation as follows. For example, in a substrate production line
facility 250 shown in Fig. 17, a film 131 to which a UV curable resin has been applied
is fed to a Ni (nickel) roll for transfer 136 via an intermediate roller 142, the UV curable
resin is cured by a UV light irradiated from a UV radiation device 133 provided in the
vicinity of the Ni (nickel) roll for transfer 136 while a concavity and convexity pattern
is transferred to the UV curable resin by the Ni (nickel) roll for transfer 136, and thereby
molding a transferred film 141 continuously. The molded portion of the transferred
film 141 is fed to a downstream side via an intermediate roller 144, the molded portion
is illuminated with an incident light 146 from an illumination for inspection 132
provided on the downstream of a transport line in order to observe the unevenness of the
concavity and convexity shape, and the intensity of the diffracted light/scattered light is
measured by a line sensor camera 134 provided to face the transferred film 141. The
transferred film 141 is fed by being wound on a winder 138. Accordingly, in the
substrate production line facility 250, a predetermined portion of the transferred film
141 is continuously inspected while the concavity and convexity pattern is transferred
continuously, and thereby making it possible to judge quality of the transferred film
141.
[0148] Fig. 18 shows a substrate production line facility 300 which is a modification
of the substrate production line facility 250 shown in Fig. 17. In a transferring section
150, a UV curable resin applied on a film 131 is cured by a UV light irradiated from a
UV radiation device 133, which is provided to face a Ni (nickel) roll for transfer 136
with the film 131 intervening therebetween, while a concavity and convexity shape is
transferred to the UV curable resin by the Ni (nickel) roll for transfer 136, and thereby
63
molding a transferred film 141 continuously. In an inspection section 170 on the
downstream side in a transport direction, a pair of illuminations for inspection 132 and
an area camera (or a two-dimensional luminance colorimeter) 134 which measures
intensity distribution of the diffracted light/scattered light of incident lights 146 emitted
from the pair of illuminations for inspection 132 are provided. Although the film 141
is transported continuously in the transferring section 150, a film accumulation
mechanism 160 is provided between the transferring section 150 and the inspection
section 170 so as to transport the film 141 intermittently in the inspection section 170.
The film accumulation mechanism 160 includes, for example, upper up-and-down rolls
166, 168, a lower up-and-down roll 164, and intermediate rollers 162, 172. By moving
the upper up-and-down rolls 166, 168 and the lower up-and-down roll 164 in an
up-down direction appropriately, the film 141 to be fed from the film accumulation
mechanism 160 can be stopped intermittently.
[0149] In the Examples, the intensity of scattered light was measured and the
unevenness of luminance was observed in the inspection step. However, it is possible
to evaluate uniformity of chromaticity of the organic EL element based on the
evaluation of the uniformity of the concavity and convexity pattern of the substrate. In
this case, it is possible to use the two-dimensional luminance colorimeter as an imaging
element.
[0150] In the Examples, the production of the substrate for the organic EL element was
explained. The present invention, however, is not limited thereto, and is applicable to
production of a substrate having a concave and convex surface used in a solar cell. It
is considered that the substrate having the concavity and convexity structure has a
function to change a travelling direction of sunlight, which is from the front of a solar
panel, to a lateral direction. Thus, it is possible to perform prediction and evaluation of
in-plane distribution of conversion efficiency of the solar cell in the inspection step and
evaluation/judgment step.
Industrial Applicability
[0151] According to the present invention, it is possible to efficiently produce a
substrate having an irregular concave and convex surface used for a device such as an
organic EL element while performing an inspection of unevenness of luminance. In a
case that an organic EL element which includes a diffraction-grating substrate having
64
the irregular concave and convex surface is produced, prediction of occurrence of
unevenness of luminance of a completed organic EL element and evaluation of the
completed organic EL element can be performed at a manufacturing stage of the
substrate by associating property of the unevenness of luminance of the organic EL
element with property of the unevenness of luminance of the substrate having the
irregular concave and convex surface which is used in the organic EL element. Thus,
it is possible to further reliably produce the organic EL element having a uniform
illumination intensity with a high throughput by excluding a substrate which was
determined to be unsatisfactory or defective in the judgment of the unevenness of
luminance and using only a substrate which passed the judgment of the unevenness of
luminance. Further, even when the uniformity of the illumination intensity of the
organic EL element is judged as unsatisfactory, since it can be determined whether the
defect occurred at a substrate formation stage or a formation stage of the element itself,
it is possible to cope with such a situation rapidly.
65

We claim:
[Claim 1]
A method for producing a substrate having an irregular concave and convex
surface for scattering light, comprising:
manufacturing the substrate having the irregular concave and convex surface;
irradiating the concave and convex surface of the manufactured substrate with
inspection light from a direction oblique to a normal direction of the concave and
convex surface, and detecting a returning light of the inspection light returned from
the concave and convex surface by a light-receiving element provided in the normal
direction of the concave and convex surface; and
judging unevenness of luminance of the concave and convex surface based on
light intensity of the received returning light.
[Claim 2]
The method for producing the substrate according to claim 1, wherein an
average pitch of concavities and convexities of the irregular concave and convex surface
on the substrate is within a range from 100 nm to 600 nm, and an average height of the
concavities and convexities of the irregular concave and convex surface on the substrate
is within a range from 5 nm to 200 nm.
[Claim 3]
The method for producing the substrate according to claim 1 or 2, wherein the
manufacturing the substrate having the irregular concave and convex surface includes:
a step of applying a block copolymer solution of a block copolymer made of at
least a first polymer and a second polymer on a surface of a base member to form a
coating film;
a step of drying the coating film on the base member; and
a step of generating a micro phase separation structure of the coating film of
the block copolymer solution after the drying.
[Claim 4]
The method for producing the substrate according to claim 3, wherein the step
of generating the micro phase separation structure includes a first heating step for
66
heating the coating film after the drying at a temperature higher than a glass transition
temperature of the block copolymer; and
the method for producing the substrate further includes an etching step for
etching the coating film after the first heating step to remove the second polymer so that
a concavity and convexity structure is formed on the base member.
[Claim 5]
The method for producing the substrate according to claim 4, further
comprising a second heating step of heating the concavity and convexity structure, for
which the etching has been performed in the etching step, at a temperature higher than a
glass transition temperature of the first polymer.
[Claim 6]
The method for producing the substrate according to claim 4 or 5, further
comprising:
a step of forming a seed layer on the concavity and convexity structure after the
etching step;
a step of stacking a metal layer on the seed layer by electroforming; and
a step of peeling off the base member having the concavity and convexity
structure from the metal layer and the seed layer to obtain a metal substrate.
[Claim 7]
The method for producing the substrate according to claim 6, further
comprising a second heating step of heating the concavity and convexity structure for
which the etching has been performed before the step of forming the seed layer at a
temperature higher than a glass transition temperature of the first polymer.
[Claim 8]
The method for producing the substrate according to claim 6 or 7, further
comprising:
pressing the obtained metal substrate to a transparent substrate to which a
curable resin has been applied;
curing the curable resin; and
67
detaching the metal substrate to obtain the substrate having the irregular
concave and convex surface.
[Claim 9]
The method for producing the substrate according to claim 6 or 7, further
comprising:
pressing the metal substrate obtained to a substrate to which a curable resin has
been applied;
curing the curable resin;
detaching the metal substrate to form a substrate having a concavity and
convexity structure on the substrate;
pressing the substrate having the concavity and convexity structure to a
transparent substrate to which a sol-gel material has been applied;
curing the sol-gel material; and
detaching the substrate having the concavity and convexity structure to obtain
the substrate having the irregular concave and convex surface made of the sol-gel
material.
[Claim 10]
The method for producing the substrate according to claim 6 or 7, wherein the
substrate having the irregular concave and convex surface is made of metal.
[Claim 11]
The method for producing the substrate according to any one of claims 3 to 10,
wherein the micro phase separation structure has a lamellar form.
[Claim 12]
The method for producing the substrate according to claim 1 or 2, wherein the
manufacturing the substrate having the irregular concave and convex surface includes:
a step of forming a vapor-deposited film on a surface of a polymer film, which
is made of a polymer of which volume changes by heat, under a temperature condition
of 70 degrees Celsius or above, and then cooling the polymer film and the
vapor-deposited film to form concavities and convexities of wrinkles in a surface of the
68
vapor-deposited film;
a step of attaching a master block material on the vapor-deposited film;
a step of curing the master block material; and
a step of detaching the master block material after the curing from the
vapor-deposited film to obtain a master block.
[Claim 13]
The method for producing the substrate according to claim 12, wherein the
polymer of which volume changes by heat is a silicone-based polymer.
[Claim 14]
The method for producing the substrate according to any one of claims 1 to 13,
wherein irregular concavities and convexities of the irregular concave and convex
surface have a pseudo periodic structure, and in a case that an average period of the
concavities and convexities is denoted by d, and that central wavelength of the
inspection light is denoted by X, the average period d and the central wavelength X,
satisfy 0.5d