FIELD OF THE INVENTION
The present invention generally relates to deposition techniques in which material
is deposited onto a substrate surface.
BACKGROUND OF THE INVENTION
This section illustrates useful background information without admission of any
technique described herein representative of the state of the art.
Atomic Layer Deposition (ALD) is a special chemical deposition method based on
sequential introduction of at least two reactive precursor species to at least one
substrate in a reaction space. The growth mechanism of ALD relies on the bond
strength differences between chemical adsorption (chemisorption) and physical
adsorption (physisorption). ALD utilizes chemisorption and eliminates
physisorption during the deposition process. During chemisorption a strong
chemical bond is formed between atom(s) of a solid phase surface and a molecule
that is arriving from the gas phase.
An ALD deposition cycle consists of four sequential steps: pulse A, purge A, pulse
B, and purge B. Pulse A consists of metal precursor vapor and pulse B of nonmetal
precursor vapor. Inactive gas, such as nitrogen or argon, and a vacuum
pump are used for purging gaseous reaction by-products and the residual reactant
molecules from the reaction space during purge A and purge B. A deposition
sequence comprises at least one deposition cycle. Deposition cycles are repeated
until the deposition sequence has produced a thin film of desired thickness.
Precursor species form through chemisorption a chemical bond to reactive sites of
substrate surface. No more than a molecular monolayer of a solid material forms
on the surface during one precursor pulse. The growth process is thus selfterminating
or saturative. For example, the first precursor can include ligands that
remain attached to the adsorbed species and saturate the surface, which prevents
further chemisorption. Reaction space temperature is maintained above
condensation temperatures and below thermal decomposition temperatures of the
utilized precursors such that the precursor molecule species chemisorb on the
substrate(s) essentially intact. Essentially intact means that volatile ligands may
come off the precursor molecule when the precursor molecules species chemisorb
on the surface. The surface becomes essentially saturated with the first type of
reactive sites, i.e. adsorbed species of the first precursor molecules. This
chemisorption step is followed by a first purge step (purge A) wherein the excess
first precursor and possible reaction by-products are removed from the reaction
space. Second precursor vapor is then introduced into the reaction space. Second
precursor molecules react with the adsorbed species of the first precursor
molecules, thereby forming the desired thin film material. This growth terminates
once the entire amount of the adsorbed first precursor has been consumed and
the surface has essentially been saturated with the second type of reactive sites.
The excess of second precursor vapor and possible reaction by-product vapors
are then removed by a second purge step (purge B). The cycle is then repeated
until the film has grown to a desired thickness.
Thin films grown by ALD are dense, pinhole free and have uniform thickness. For
example, in an experiment aluminum oxide has been grown by ALD from
trimethylaluminum (CH3)3AI, also referred to as TMA, and water resulting in only
about 1% non-uniformity over a substrate wafer.
One problem of the ALD technology is the rather slow growth rate.
SUMMARY
It is an object of the present invention to provide a deposition method with a
relatively fast growth rate.
According to a first example aspect of the invention there is provided a deposition
method, comprising:
providing a channel through a deposition apparatus,
feeding precursor vapor into the channel;
depositing material from the precursor vapor onto a substrate on its way through
the deposition apparatus by exposing the substrate to the precursor vapor and to
alternating photon exposure and shade periods within the channel.
In certain example embodiments, the channel restricts movement of the precursor
vapor in a vertical direction. In certain example embodiments, a reaction space is
defined by a channel top part and the substrate. In certain example embodiments,
the reaction space has a limited height limiting the vertical movement of precursor
vapor. In certain example embodiments the vertical dimension of the reaction
space is less than 2 mm, in certain other example embodiments less than 5 mm,
in certain other example embodiments less than 10 mm, in certain other example
embodiments less than 5 cm, and in certain other example embodiments less than
10 cm.
In certain example embodiments, the precursor vapor comprises a first precursor
species and a second precursor source gas, the second precursor source gas
functioning as carrier gas for the first precursor species. In certain example
embodiments, a second precursor species is activated from the second precursor
source gas by photon exposure. In certain example embodiments, the first
precursor species and the second precursor source gas/second precursor species
are present in a same volume (mixed with each other). In certain example
embodiments, the first precursor species is a metal precursor species and the
second precursor species a non-metal precursor species. In certain other
embodiments, both precursor species are non-metal precursor species. Examples
of coating materials are, for example, metals, oxides, and nitrides.
In certain example embodiments, a first precursor species reacts with reactive
sites on the substrate surface on the shade period and, on the following photon
exposure period, a second precursor species reacts with chemisorbed first
precursor species.
In certain example embodiments, the method comprises:
causing the reaction on the photon exposure period by received photon energy.
In certain example embodiments, the method comprises:
defining photon exposure and shade periods by shading the substrate surface so
that an area of shade has the shade period and a non-shaded area the photon
exposure period.
In certain example embodiments, reactions during the shade period are selfsaturative
surface reactions. In certain example embodiments, the shade period
terminates material growth until the following photon exposure. In certain example
embodiments, deposition is based on self-saturative growth in which material
growth terminates on the shade period when all reactive sites for the first
precursor have been consumed on the substrate surface.
In certain example embodiments, deposition cycles are performed without
performing purge periods.
A deposition cycle may be considered to begin with the shade period or with the
photon exposure period. The first deposition cycle may begin with a shade period
during which the first precursor reacts with the substrate surface. The photon
exposure period then immediately follows the shade period. The photon exposure
period produces half a monolayer of deposited material. And, the shade period
produces half a monolayer of deposited material. The photon exposure and shade
period altogether produce a monolayer of deposited material (coating material).
The first and second precursor species may be selected so that they are inert with
respect to each other in gas phase in normal process conditions, i.e., in the
processing temperature without activation (excitation). In certain example
embodiments, the second precursor species is inert towards the adsorbed first
precursor species without activation whereas the first precursor species is
reactive, also without activation, with the second precursor species adsorbed to
the surface.
In certain example embodiments, the periods of photon exposure and shade
alternate, wherein photon exposure occurs only during the photon exposure
period. The photon exposure may be implemented by photons emitted by a photon
source, such as an UV lamp, a LED lamp, a xenon lamp, an X-ray source, a laser
source, or an infrared source.
In certain example embodiments, the number of precursor species is more than
two. In these embodiments, one of the precursors may be reactive with the surface
without excitation the other precursors being inert towards surface reactions
without excitation.
The method in accordance with the first example aspect and its embodiment can
be used for a plurality of different applications, for example, for coating any
applicable moving substrate. The substrate may be, for example, a plate-like
object, such as silicon wafer, a glass plate, a metal foil. The substrate may be a
substrate web, a strand or a strip. The substrate may be a thin flexible glass
substrate. It may be a polymer. It may be a fibrous web of paper, board or
nanocellulose. It may be a solar cell, an OLED display, a printed circuit board
component or generally a component of electronics. The method can be used for
low temperature passivation of heat sensitive applications.
According to a second example aspect of the invention there is provided a
deposition apparatus, comprising:
a channel through the deposition apparatus;
at least one in-feed line for feeding precursor vapor into the channel, the
deposition apparatus being further configured to
deposit material from the precursor vapor onto a substrate on its way through the
deposition apparatus by exposing the substrate to the precursor vapor and to
alternating photon exposure and shade periods within the channel.
In certain example embodiments, the channel is configured to restrict movement of
the precursor vapor in a vertical direction.
In certain example embodiments, the deposition apparatus comprises an input slit
for inputting the substrate into the channel and an output slit for outputting the
substrate from the channel.
In certain example embodiments, the precursor vapor comprises a first precursor
species and a second precursor source gas, and the apparatus is configured to
use the second precursor source gas as carrier gas for the first precursor species.
In certain example embodiments, the apparatus is configured to cause:
a first precursor species to react with reactive sites on the substrate surface on the
shade period and, on the following photon exposure period, a second precursor
species to react with chemisorbed first precursor species.
In certain example embodiments, the apparatus comprises:
a photon source configured to emit photon energy to cause the reaction on the
photon exposure period.
In certain example embodiments, the apparatus comprises:
a shader in between the substrate and a photon source having photon permeable
areas and photon impermeable areas to define photon exposure and shade
periods by shading the substrate surface so that an area of shade has the shade
period and a non-shaded area the photon exposure period.
In certain example embodiments, a roof of the channel is formed by a plane-like
shader where at least the lower surface of the shader is planar.
Different non-binding example aspects and embodiments of the present invention
have been illustrated in the foregoing. The above embodiments are used merely to
explain selected aspects or steps that may be utilized in implementations of the
present invention. Some embodiments may be presented only with reference to
certain example aspects of the invention. It should be appreciated that
corresponding embodiments may apply to other example aspects as well. Any
appropriate combinations of the embodiments may be formed.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example only, with reference to the
accompanying drawings, in which:
Fig. 1 shows an example timing diagram of a method in accordance
with an example embodiment;
Fig. 2 shows an example construction for implementing the method in
accordance with an example embodiment;
Fig. 3 shows a side view of an example apparatus in accordance with
an example embodiment;
Fig. 4 shows a top view of an apparatus in accordance with an example
embodiment;
Fig. 5 shows process gas in-feed in accordance with an example
embodiment;
Fig. 6 shows an example shader in accordance with an example
embodiment; and
Fig. 7 shows a rough block diagram of a deposition apparatus control
system in accordance with an example embodiment.
DETAILED DESCRIPTION
Fig. 1 shows an example timing diagram of a method in accordance with an
example embodiment. A deposition sequence comprising a plurality of deposition
cycles is performed where each cycle produces a monolayer of deposited
material. The deposition cycle comprises introducing a first precursor species and
a second precursor species to a substrate surface in a reaction space.
A method is implemented, comprising providing a channel through a deposition
apparatus, feeding precursor vapor into the channel, and depositing material from
the precursor vapor onto a substrate on its way through the deposition apparatus
by exposing the substrate to the precursor vapor and to alternating photon
exposure and shade periods within the channel. The method can be denoted as a
photon assisted surface coating application (PASCA) method.
In the example shown in Fig. 1, an activation period (from time instant ti to t.2)
during which photon exposure is on and a regeneration period (from time instant t.2
to t.3) during which photon exposure is off are alternated. The activation period in
Fig. 1 therefore forms the photon exposure period of the method and the
regeneration period the shade period of the method.
During the regeneration period, the precursor species of a first processing gas
(first precursor species) reacts with reactive sites on the substrate surface by
chemisorption. In the end of the regeneration period the substrate surface is
covered by the first precursor species adhered to the substrate surface. The
second processing gas (second precursor source gas) is inert towards the surface
without photon exposure. Accordingly, the material growth terminates in the end of
the regeneration period when all reactive sites for the first precursor species are
consumed. The growth mechanism is self-saturative.
During the activation period, the precursor species of the second processing gas
(second precursor species) reacts, by chemisorption, with the first precursor
species adhered to the substrate surface leading to the situation in which the
substrate surface becomes covered by the second precursor species adhered to
the substrate surface.
The activation period reaction occurs on the substrate area which is exposed to
photon energy. The photon exposure gives either the second processing gas or
the adhered first precursor species the additional energy required for a surface
reaction to occur.
In a first alternative, the second processing gas is excited by photon energy to
form radicals. These radicals (i.e., the second precursor species) react with the
reactive sites of the adhered first precursor species on the substrate surface. The
substrate surface becomes saturated by the second precursor species.
In a second alternative, the adhered first precursor species is excited by photon
energy. This gives the additional energy required to the reaction between the first
precursor species adsorbed to the substrate surface and the gaseous second
precursor species. As a result, the substrate surface becomes saturated by the
second precursor species.
The desired alternative may be selected by adjusting the wavelength of the
photons (i.e., light/radiation).
The deposition cycle formed by the activation period and the immediately following
regeneration period (or by the regeneration period and the immediately following
activation period in certain embodiments) is repeated to obtain a coating of a
desired thickness. The deposition cycle is performed without a purge period
therefore achieving a faster growth rate compared to self-saturative growth
methods in which purge periods are used.
The first processing gas and second processing gas flow to the reaction space is
maintained during the whole deposition cycle. In certain example embodiments,
the second processing gas is used as carrier gas for the first processing gas (first
precursor species). In those embodiments, the first precursor and the second
precursor may be present in the reaction space simultaneously.
The first precursor may be a metal precursor and the second precursor a nonmetal
precursor. In certain other embodiments, both precursor species are nonmetal
precursor species. Examples of coating materials are, for example, metals,
oxides, and nitrides. The precursors may be selected so that they are inert
towards each other in gas phase. In an example embodiment, trimethylaluminium
(TMA, (CH3)3AI) is used as a metal precursor and oxygen (O2) as the second
processing gas. Then during the photon exposure period, oxygen is excited to
oxygen radicals O* , surface reaction takes place between O* radicals and
adsorbed TMA to form the desired coating material, aluminium oxide (AI2O3).
Fig. 2 shows an example construction for implementing the disclosed method in
accordance with an example embodiment. The construction comprises in a
deposition apparatus (for example, a reactor module) a channel through the
deposition apparatus. In the example shown in Fig. 2, the channel is formed by a
bottom part 255 and a top part 250 that form the channel therebetween. The
channel is a horizontal channel with a limited height. An in-feed line conveys
precursor vapor into the channel through a gas distribution nozzle 2 11 or similar.
The top and bottom parts 250, 255 are plates or plane-like parts, or at least the
channel side of the top part 250 is planar. The channel side of the bottom part may
also be planar. The channel may be open on the sides.
A planar substrate 201 is moved along the channel. In an alternative embodiment,
the planar substrate 201 is a support web supporting at least one substrate or a
set of substrates (not shown) travelling on it.
A photon source 240 is placed on the top of the top part 250. The photon source
240 can be an UV lamp, a xenon lamp, LED lamp or, for example, an X-ray
source, a laser source, or an infrared source. It provides photon exposure by
emitting photons 241 .
The top part 250 may be a shader comprising photon impermeable areas 251 and
photon permeable areas (or windows) 252 to define photon exposure and shade
periods by shading the surface of the substrate 201 beneath the shader. The
photon permeable areas may be formed of glass or other material through which
the precursor vapor cannot penetrate. While the substrate propagates beneath the
shader, an area of shade has the shade period and a non-shaded area 262 the
photon exposure period. In an example embodiment, half a monolayer of desired
coating material grows when the substrate is on the shade and half of a monolayer
grows when the substrate is on the non-shaded area. In such an embodiment, the
number of photon impermeable areas and permeable areas define the number of
cycles and thus the obtained thickness of the desired coating.
The reaction space is defined by the top part 250 and the substrate 201 . The
reaction space has a limited height limiting the vertical movement of precursor
vapor so that the main direction of movement of the vapor is a horizontal direction.
In certain example embodiments the vertical dimension of the reaction space (and
of the channel) is less than 2 mm, in certain other example embodiments less than
5 mm, in certain other example embodiments less than 10 mm, in certain other
example embodiments less than 5 cm, and in certain other example embodiments
less than 10 cm.
The in-feed line conveys precursor vapor into the reaction space so that the
reaction space is populated by the first and second precursor species. The in-feed
may be from one or more nozzles on the side or, as described later in this
description, from the top of the substrate through a shader nozzle. A vacuum
pump in an evacuation line (not shown in Fig. 2) maintains an outgoing flow from
the reaction chamber.
The precursor vapor comprises the first precursor species and the second
precursor source gas, the second precursor source gas functioning as carrier gas
for the first precursor species. In certain other embodiments, however, the first
precursor species in-feed into the reaction space can occur via separate in-feed
line with respect to the in-feed of the second precursor species (which may have
its own in-feed line).
Fig. 3 shows a side view of an example apparatus in accordance with an example
embodiment. The apparatus can be a reactor or a reactor module suitable for
continuous deposition as a part of a processing line. The apparatus comprises a
reaction chamber 2 10 which is surrounded by an outer chamber 220. An
intermediate space between the outer chamber 220 and the reaction chamber 2 10
is pressurized by conveying inactive shield gas to the space so that there is a
slight overpressure compared to the interior of the reaction chamber 2 10.
A first transfer chamber 230 is attached to a side of the outer chamber 220, and a
second transfer chamber 230' is attached to an opposite side of the outer chamber
220. The reaction chamber 2 10 positioned within the outer chamber comprises an
input port 261 on its first side and an output port 261 ' on an opposite side. The
input port 261 and the output port 261 ' may be formed as a slit in a respective
reaction chamber wall.
A substrate web 201 to be coated is driven continuously through the first transfer
chamber 230 into the outer chamber 220, therefrom through the input port 261 into
the reaction chamber 2 10 for deposition, and therefrom through the output port
261 ' into an opposite part of the outer chamber 220, and through the second
transfer chamber 230' to a subsequent phase of the processing line. In an
alternative embodiment, the substrate web 201 is a web supporting a set of
substrates 201 ' (to be coated) travelling on it. In yet an alternative embodiment,
the substrate is a strand or a strip.
The apparatus comprises the construction shown in Fig. 2 . Accordingly, the
apparatus comprises the channel formed by the top and bottom parts 250, 255
extending through the reaction chamber 2 10, the photon source 240 on the top of
the top part 250. Furthermore, the apparatus comprises the in-feed line which
conveys precursor vapor (via nozzle 2 11 or similar) into the reaction space defined
in between the top part 250 and the substrate 201 .
The apparatus further comprises an evacuation line 2 12 and a vacuum pump 2 13
in the evacuation line to maintain vacuum pressure in the reaction chamber, if
desired, and to maintain an outgoing flow from the reaction chamber.
The apparatus operates similarly as described with reference to Figs. 1 and 2.
Accordingly, when the substrate 201 or 201 ' moves forward different areas of the
substrate see the photon source 240. An area of shade has the shade period
(regeneration period) and a non-shaded area the photon exposure period
(activation period). Deposition cycles described in the foregoing with reference to
Figs. 1 and 2 are performed.
During the shade period, the first precursor species reacts with reactive sites
produced by the adhered second precursor species on the substrate surface. And,
during the photon exposure period, the second precursor species reacts with the
first precursor species adhered to the substrate surface. Accurate thickness
control of material growth is achieved by maintaining the propagation speed of the
substrate with respect to the width of the non-shaded area on a level that half a
monolayer of desired coating material grows when the substrate is on the shaded
area and the remaining half of a monolayer grows when the substrate is on the
non-shaded area.
Certain example embodiments are implemented without including any transfer
chamber(s) for loading and/or unloading. Furthermore, certain example
embodiments are implemented without including an outer chamber around the
reaction chamber. Furthermore, the reaction chamber form can deviate from the
example form presented in the Figures. In certain example embodiments, the
channel through the apparatus forms the reaction chamber. Accordingly, there is
no separate reaction chamber in excess to the channel. In certain example
embodiments, the substrate propagates through the channel continuously at a
constant speed. In certain other embodiments, the substrate is periodically moved
(e.g., in a stop and go fashion) through the channel.
Fig. 4 shows a top view of an apparatus in accordance with an example
embodiment. Same reference signs as in Figs. 2 and 3 have been used for similar
features. The in-feed of precursor vapor can be arranged from one side and the
evacuation of gases from the opposite side. In the embodiment of Fig. 4, a row of
in-feed nozzles 2 11 of precursor vapor in-feed line is on a first side of the
substrate 201 and an evacuation line mouth 421 on the opposite side.
Fig. 5 shows process gas in-feed in accordance with an example embodiment in
which the second processing gas is used as carrier gas for the first processing
gas. The apparatus may be of the type shown in Figs. 3 and 4 . The apparatus
comprises a first processing gas source 4 1 and a second processing gas source
40.
The second processing gas source 40 is in fluid communication with the input of a
carrier and shield gas line valve 50. A first output of valve 50 leads as a shield gas
line 5 12 into an intermediate space between an outer chamber 220 and a reaction
chamber 2 10 of the apparatus. The second processing gas in the property of
inactive shield gas is released to the intermediate space via a gas release point
2 12 . A second output of valve 50 is in fluid communication with the input of a
carrier gas input valve 54. A first output of valve 54 is in fluid communication with a
carrier gas input of the first processing gas source 4 1. A second output of valve 54
is in fluid communication with a second input of a precursor vapor in-feed line
valve 5 1. The first processing gas source 4 1 is in fluid communication with a first
input of valve 5 1. The output of valve 5 1 continues as a precursor vapor in-feed
line 5 11 towards the reaction chamber 2 10 . The gas/vapor flowing in the in-feed
line 5 11 is released to the said channel in the reaction chamber 2 11 via a gas
release point or nozzle 2 11. The routes from the second processing gas source 40
to the first processing gas source 4 1 and therefrom to the in-feed line 5 11 are kept
open during processing.
The shield gas line 512 is kept open or closed depending on implementation. In
certain example embodiments, the shield gas line 512 is kept open during the
whole deposition cycle/sequence allowing second processing gas in the property
of inactive shield gas to enter the intermediate space via the gas release point
2 12 .
Fig. 6 shows an example shader in accordance with an example embodiment. The
shader (or shader nozzle) 850 can be used both as a shader and as a precursor
in-feed nozzle. It can be used as the top part 250. The shader 850 comprises a
shader frame 851 with solid portions through which the emitted photons cannot
penetrate and rectangular windows 852 made of glass, for example, through which
the emitted photons can penetrate (but through which the precursor vapor cannot
penetrate). The form of the windows 852 depends on the implementation. A
precursor in-feed line 8 11 is attached to the shader 850. The in-feed line 8 11
branches to individual lateral flow channels 871 which extend throughout the
shader frame 851 along the solid portions. The flow channels 871 have a plurality
of apertures (not shown) on their lower surface to guide precursor vapor
downwards towards the substrate surface.
On the right side of Fig. 6 is a partial cross-section of the shader 850. The black
portions show photon impermeable areas and the white portions photon
permeable areas. The flow channels 871 have been embedded into the frame 851
of the shader.
In certain example embodiment, in which the shader 850 is used to distribute
precursor vapor on the substrate surface from the top side of the substrate, the
evacuation of gases into an evacuation line can occur from both sides of the
substrate.
In accordance with certain example embodiments, the precursor vapor in-feed
line(s) of the apparatuses described in the preceding are implemented by the
required pipings and their controlling elements.
The in-feed line controlling elements comprise flow and timing controlling
elements. In an example embodiment, a precursor vapor in-feed line valve and
mass (or volume) flow controller in a precursor vapor in-feed line control the timing
and flow of precursor vapor into the reaction chamber. Correspondingly, a carrier
and shield gas line valve and mass (or volume) flow controller in fluid
communication with a second processing gas source control the timing and flow of
the carrier and shield gas.
In an example embodiment, the in-feed line controlling elements form part of a
computer controlled system. A computer program stored into a memory of the
system comprises instructions, which upon execution by at least one processor of
the system cause the coating apparatus, or deposition reactor, to operate as
instructed. The instructions may be in the form of computer-readable program
code. Fig. 7 shows a rough block diagram of a deposition apparatus control
system 700 in accordance with an example embodiment. In a basic system setup
process parameters are programmed with the aid of software and instructions are
executed with a human machine interface (HMI) terminal 706 and downloaded via
a communication bus 704, such as Ethernet bus or similar, to a control box 702
(control unit). In an embodiment, the control box 702 comprises a general purpose
programmable logic control (PLC) unit. The control box 702 comprises at least one
microprocessor for executing control box software comprising program code
stored in a memory, dynamic and static memories, I/O modules, A D and D/A
converters and power relays. The control box 702 sends electrical power to
pneumatic controllers of appropriate valves, and controls mass flow controllers of
the apparatus. The control box controls the operation of the photon source, and
the vacuum pump. The control box further controls any motion devices needed to
move the substrate(s). The control box 702 receives information from appropriate
sensors, and generally controls the overall operation of the apparatus. The control
box 702 may measure and relay probe readings from the apparatus to the HMI
terminal 706. A dotted line 7 6 indicates an interface line between reactor parts of
the apparatus and the control box 702.
Without limiting the scope and interpretation of the patent claims, certain technical
effects of one or more of the example embodiments disclosed herein are listed in
the following: A technical effect is a method based on self-saturative growth with a
faster deposition rate. Another technical effect is lower required processing
temperature due to photon exposure. Another technical effect is simplified
chemical usage by using a second processing gas as both a precursor and carrier
gas. Another technical effect is self-saturative growth although both precursors are
present in the reaction space simultaneously.
It should be noted the some of the functions or method steps discussed in the
preceding may be performed in a different order and/or concurrently with each
other. Furthermore, one or more of the above-described functions or method steps
may be optional or may be combined.
The foregoing description has provided by way of non-limiting examples of
particular implementations and embodiments of the invention a full and informative
description of the best mode presently contemplated by the inventors for carrying
out the invention. It is however clear to a person skilled in the art that the invention
is not restricted to details of the embodiments presented above, but that it can be
implemented in other embodiments using equivalent means without deviating from
the characteristics of the invention. It is to be noted that a metal precursor species
has been used as an example for the first precursor species, and a non-metal
precursor species as an example for the second precursor species in certain
example embodiments. However, this must not be considered limiting. The first
precursor can alternatively be a non-metal precursor. Both precursors can be, for
example, non-metal precursors, etc.. The choice of precursors is only dependent
on the particular implementation and/or the desired coating material.
Furthermore, some of the features of the above-disclosed embodiments of this
invention may be used to advantage without the corresponding use of other
features. As such, the foregoing description should be considered as merely
illustrative of the principles of the present invention, and not in limitation thereof.
Hence, the scope of the invention is only restricted by the appended patent claims.

Claims
. A deposition method, comprising:
providing a channel through a deposition apparatus,
feeding precursor vapor into the channel;
depositing material from the precursor vapor onto a substrate on its way
through the deposition apparatus by exposing the substrate to the precursor
vapor and to alternating photon exposure and shade periods within the
channel.
2 . The method of claim 1, wherein the channel restricts movement of the
precursor vapor in a vertical direction.
3 . The method of claim 1 or 2, wherein the precursor vapor comprises a first
precursor species and a second precursor source gas, the second precursor
source gas functioning as carrier gas for the first precursor species.
4 . The method of any preceding claim, wherein a first precursor species reacts
with reactive sites on the substrate surface on the shade period and, on the
following photon exposure period, a second precursor species reacts with
chemisorbed first precursor species.
5 . The method of claim 4, comprising:
causing the reaction on the photon exposure period by received photon
energy.
6 . The method of any preceding claim, comprising:
defining photon exposure and shade periods by shading the substrate
surface so that an area of shade has the shade period and a non-shaded area
the photon exposure period.
7 . The method of any preceding claim, wherein reactions during the shade period
are self-saturative surface reactions.
8 . A deposition apparatus, comprising:
a channel through the deposition apparatus;
at least one in-feed line for feeding precursor vapor into the channel, the
deposition apparatus being further configured to
deposit material from the precursor vapor onto a substrate on its way
through the deposition apparatus by exposing the substrate to the precursor
vapor and to alternating photon exposure and shade periods within the
channel.
9 . The apparatus of claim 8, the channel being configured to restrict movement
of the precursor vapor in a vertical direction.
10 . The apparatus of claim 8 or 9, wherein the precursor vapor comprises a first
precursor species and a second precursor source gas, and the apparatus is
configured to use the second precursor source gas as carrier gas for the first
precursor species.
11. The apparatus of any preceding claim 8-1 0, wherein the apparatus is
configured to cause:
a first precursor species to react with reactive sites on the substrate surface
on the shade period and, on the following photon exposure period, a second
precursor species to react with chemisorbed first precursor species.
12 . The apparatus of claim 11, comprising:
a photon source configured to emit photon energy to cause the reaction on
the photon exposure period.
13 . The apparatus of any preceding claim 8-1 2, comprising:
a shader in between the substrate and a photon source having photon
permeable areas and photon impermeable areas to define photon exposure
and shade periods by shading the substrate surface so that an area of shade
has the shade period and a non-shaded area the photon exposure period.