DESCRIPTION
SEMICONDUCTOR DEVICE, METHOD FOR MANUFACTURING THE SAME, AND
RINSING LIQUID
Technical Field
[0001] The present invention relates to a semiconductor device, a method for manufacturing
the same, and a rinsing liquid.
Baclcground Art
[0002] In the field of semiconductor devices, in which scaling is proceeding, various
investigations have been made on materials having a low dielectric constant (hereinafter also
referred to as "low-k materials") and having a porous structure, as interlayer insulating layers
for semiconductors.
In such porous interlayer insulating layers, increasing the porosity thereof with a
view to further lowering the dielectric constant results in facilitation of entry of a metal
component that is to be embedded as a wiring material such as copper, a plasma component
(at least one of a radical or an ion; the same shall apply hereinafter) generated through a
plasma treatment, or the like into minute openings of the semiconductor interlayer insulating
layers, and thus results in an increase in the dielectric constant or occurrence of a current
leakage in some cases.
Penetration of the metal component, the plasma component, or the like also occurs in
non-porous interlayer insulating layers in some cases, which results in an increase in the
dielectric constant or occurrence of a current leakage in some cases, similar to the case of
porous interlayer insulating layers.
[0003] In order to deal with the above issue, a technique has been studied in which an
interlayer insulating layer (in a case in which the interlayer insulating layer is a porous
interlayer insulating layer, minute openings (pores) that are present in the porous interlayer
insulating layer) is covered (sealed) using a polymer having a cationic functional group.
For example, a sealing composition for a semiconductor that contains a polymer
having two or more cationic functional groups and a weight average molecular weight of from
2,000 to 100,000 is known as a sealing composition for a semiconductor that has an excellent
pore-covering property (sealing property) with respect to porous interlayer insulating layers
(see, for example, International Publication WO 2010113771 1 pamphlet).
[0004] Furthermore, a semiconductor substrate is known which has a configuration having:
an interlayer insulating layer having a recess portion (a trench or a via); and a wiring, at least
a part of the surface of the wiring being exposed on at least a part of the bottom face of the
trench or via. In the semiconductor substrate having the configuration described above,
another wiring or the like is embedded in the trench or via in a subsequent step, whereby the
wiring embedded in the trench or via and the wiring of which a part was exposed on the
bottom face of the trench or via are electrically connected to each other (see, for example,
International Publication,WO 20091153834 pamphlet).
DISCLOSURE OF INVENTION
Technical Problem
[0005] In the sen~iconductors ubstrate having an interlayer insulating layer which has a
recess portion (such as a trench or a via) and a wiring which contains copper and of which at
least a part of the surface thereof is exposed on at least a part of the bottom face of the recess
portion, sealing the wall faces of the recess portion using a sealing layer for a semiconductor
that includes a cationic functional group-containing polymer causes the following problems in
some cases.
Specifically, the sealing layer for a semiconductor is formed not only on the side face
but also on the bottom face, from among the wall faces (the side face and the bottom face) of
the recess portion; namely, the sealing layer for a semiconductor is also formed on the wiring
exposed on the bottom face. When another wiring is formed on the recess portion in a
subsequent process with the sealing layer for a semiconductor left on the wiring, there are
cases in which the sealing layer for a semiconductor is sandwiched between the wiring
formed on the recess portion and the wiring of which a part is exposed on the botiom face of
the recess portion, thereby blocking electric signals between these wirings (increasing the
interconnection resistancc bctween the wirings).
Meanwhile, with a view to addressing the above problem, an attempt may be made to
remove the sealing layer for a semiconductor located on the bottom face of the recess portion
(particularly, on the wiring exposed on the bottom face) using a rinsing liquid or the like
before a wiring is formed on the recess portion; however, there are cases in which the attempt
results in removal of the sealing layer for a semiconductor located on the side face of the
recess portion as well as the sealing layer for a semiconductor located on the bottom face of
the recess portion, thereby deteriorating the capacity to seal the side face of the recess portion.
Forming a wiring on the recess portion under these conditions results in penetration of the
material of the formed wiring (metal components) into the interlayer insulating layer in some
cases, which leads to a decrease of the insulating properties of the interlayer insulating layer.
[0006] For the reasons discussed above, in the case of forming a sealing layer for a
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semiconductor on at least a side face of a recess portion of a seiniconductor substrate that is
provided with an interlayer insulating layer having the recess portion and a copper-containing
wiring of which at least a part of the surface thereof is exposed on at least a part of the bottoin
face of the recess portion, a technique whereby provision of a sealing layer for a
semiconductor on the wiring exposed on the bottom face of the recess portion can be avoided
as far as possible is required.
[0007] Further, in semiconductor device manufacturing processes, there are cases in which
the semiconductor device is cleaned with plasma in a state in which the sealing layer for a
semiconductor is exposed, and there are also cases in which a layer is formed on the sealing
layer for a semiconductor using a plasma CVD method or the like. Therefore, there are
cases in which the sealing layer for a senliconductor is requested to have plasma resistance.
[0008] The inventions (the first invention to the fifth invention) have been made in view of
the above problems, and aim to accomplish the following objects.
Specifically, an object of the first invention is to provide a method for manufacturing
a semiconductor device whereby formation of a sealing layer for a semiconductor on a wiring
that is exposed on the bottom face of a recess portion provided in an interlayer insulating
layer is suppressed, but whereby a sealing layer for a semiconductor can be formed on at least
a side face of the recess portion.
An object of the second invention is to provide a rinsing liquid with which a sealing
layer for a semiconductor present on the exposed face of the wiring can effectively be
removed.
An object of the third invention is to provide a rinsing liquid which can improve the
plasma resistance of a sealing layer for a semiconductor.
An object of the fourth invention is to provide a semiconductor device in which
diffusion of wiring materials (for example, copper) into an interlayer insulating layer is
suppressed, and in which an increase in interconnection resistance of the connection portion
between the wirings is suppressed.
Further, an object of the fifth invention is to provide a semiconductor device in which
the plasma resistance of a sealing layer for a semiconductor is improved.
Solution to Problem
[0009] Specific means for solving the above problems include those described below.
A method for manufacturing a semiconductor device, the method including:
a sealing composition application process of applying a sealing composition for a
semiconductor to at least a bottom face and a side face of a recess portion of a semiconductor
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substrate, to form a sealing layer for a seiniconductor on at least the bottom face and the side
face of the recess portion, the sealing co~npositionf or a semiconductor including a polymer
having a cationic functional group and a weight average molecular weight of from 2,000 to
1,000,000, each of the content of sodium and the content of potassium in the sealing
coinposition for a seiniconductor being 10 ppb by mass or less on an elerneiltal basis, and the
semiconductor substrate being provided with an interlayer insulating layer having the recess
portioil and a copper-containing wiring of which at least a part of the surface thereof is
exposed on at least a part of the bottom face of the recess portion; and
a removal process of subjecting a surface of the semiconductor substrate at a side at
which the sealing layer for a semiconductor has been formed to heat treatment under a
temperature condition of from 200°C to 425'C, to remove at least a part of the sealing layer
for a semiconductor that has been formed on an exposed face of the wiring.
In the present specification, the method for manufacturing a semiconductor device
according to above is also referred to as the "method for manufacturing a semiconductor
device according to the first invention".
According to the method for manufacturing a semiconductor device according to the
first invention, a sealing layer for a semiconductor can be formed on at least a side face of the
recess portion although formation of a sealing layer for a semiconductor on a wiring exposed
on the bottom face of the recess portion formed in the interlayer insulating layer is
suppressed.
[0010] <2> The method for manufacturing a semiconductor device according to ,
wherein the polymer has a cationic functional group equivalent weight of from 27 to 430.
1 3 2 The method for manufacturing a semiconductor device according to or <2>,
wherein the polymer is polyethyleneimine or a polyethyleneimine derivative.
<4> The method for manufacturing a semiconductor device according to any one of
to <3>, the method including a washing process of washing at least the side face and the
bottom face of the recess portion with a rinsing liquid having a temperature of from 15°C to
10O0C, after the sealing composition application process but before the removal process.
<5> The method for manufacturing a semiconductor device according to <4>,
wherein the temperature of the rinsing liquid is from 30°C to 100°C.
<6> The method for manufacturing a semiconductor device according to any one of
<1> to <5>, the method including a washing process of washing at least the side face and the
bottom face of the recess portion with a rinsing liquid having a pH at 25'C of 6 or lower, after
the sealing composition application process but before the removal process.
<7> The method for manufacturing a semiconductor device according to <6>,
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wherein the rinsing liquid includes a coinpound having, in one molecule thereof, at least one
of a moiety A that blocks an active species or a moiety E that forms a bond with the polymer
when heated.
[0011] <8> A rinsing liquid for use in reilloval of at least a part of the sealing layer for a
semiconductor that is formed in the sealing composition application process in the method for
manufacturing a semiconductor device according to any one of <1> to <7>, the rinsing liquid
having a pH at 25'C of 6 or lower.
In the present specification, the rinsing liquid according to <8> above is also referred
to as the "rinsing liquid according to the second invention".
According to the rinsing liquid according to the second invention, the sealing layer
for a semiconductor located on the exposed face of a wiring can effectively be removed.
The rinsing liquid according to the second invention is a rinsing liquid that is used to
remove at least a part of the sealing layer for a semiconductor mentioned in the iirst
invention.
[0012] <9> A rinsing liquid for a sealing layer for a semiconductor, the sealing layer being
formed on a surface of an interlayer insulating layer of a semiconductor substrate that is
provided with the interlayer insulating layer, and being derived from a polymer having a
cationic functional group and a weight average molecular weight of from 2,000 to 1,000,000,
the rinsing liquid including a compound having, in one molecule thereof, at least one
of a moiety A that blocks an active species or a moiety B that forms a bond with the polyn~er
when heated.
In the present specification, the rinsing liquid according to <9> above is also referred
to as the "rinsing liquid according to the third invention".
According to the rinsing liquid according to the third invention, the plasma resistance
of the sealing layer for a semiconductor can be improved.
[0013] The rinsing liquid according to <9>, wherein the compound has, in one
molecule thereof, two or more carboxyl groups as the moiety B, and
wherein the compound has, in one molecule thereof, at least one of a structure in
which each of two neighboring carbon atoms bonds to a carboxyl group or a structure in
which each of two non-central carbon atoms from among three consecutive carbon atoms
bonds to a carboxyl group.
11 1> The rinsing liquid according to <9>, wherein the compound has the moiety A
and the moiety B, the moiety A is at least one selected from the group consisting of an
aromatic ring structure, an alicyclic structure, a manganese atom, and a silicon atom, and the
moiety B is a carboxyl group.
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[0014] <12> A semiconductor device including, on a semiconductor substrate:
an interlayer insulating layer having a recess portion;
a first wiring that includes copper, and that is formed on the recess portion;
a sealing layer for a semiconductor that is present at least between a side face of the
recess portion of the interlayer insulating layer and the first wiring, and that includes a
polymer having a cationic fuilctional group and a weight average molecular weight of from
2,000 to 1,000,000; and
a second wiring that contains copper, that has an upper face constituting at least a
part ofa bottoin face of the recess portion, and that is electrically connected to the first wiring
via the upper face,
wherein the thickness of the sealing layer for a semiconductor in a connection
portion between the first wiring and the second wiring is 5 nm or less.
In the present specification, the semiconductor device according to 4 2 1 above is
also referred to as the "semiconductor device according to the fourth invention".
According to the semiconductor device according to the fourth invention, diffusion
of a wiring material (for example, copper) into the interlayer insulating layer is suppressed,
and an increase in the interconnection resistance of the connection portion between the
wirings is suppressed.
The semiconductor device according to the fourth invention cannot be manufactured
by known methods for manufacturing semiconductor devices. The semiconductor device
according to the fourth invention is manufactured, for the first time, by the method for
manufacturing a semiconductor device according to the first invention.
[0015] <13> A semiconductor device including, on a semiconductor substrate:
an interlayer insulating layer;
a first wiring that includes copper; and
a sealing layer for a semiconductor that is present between the interlayer insulating
layer and the first wiring, and that includes a polymer having a cationic functional group and
a weight average molecular weight of from 2,000 to 1,000,000,
wherein the sealing layer for a semiconductor includes at least one selected from the
group consisting of an imide bond and an arnide bond, and also includes at least one selected
from the group consisting of an aromatic ring structure, a manganese atom, and a silicon
atom.
In the present specification, the semiconductor device according to <13> above is
also referred to as the "semiconductor device according to the fifth invention".
According to the semiconductor device according to the fifth invention, the plasma
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resistance of the sealing layer for a semiconductor is improved.
The semiconductor device according to the fifth invention cannot be produced by
lcnown methods for manufacturing se~niconductord evices. The semiconductor device
according to the fifth invention is produced, for the first time, using the rinsing liquid
according to the third invention.
[0016] <14> The semiconductor device according to <12> or <13>, wherein the polymer
has a cationic functional group equivalent weight of from 27 to 430.
<15> The semiconductor device according to any one of <12> to <14>, wherein the
polymer is polyethyleneimine or a polyethyleneimine derivative.
<16> The semiconductor device according to any one of <12> to <15>, wherein the
interlayer insulating layer is a porous interlayer insulating layer having an average pore radius
of from 0.5 nm to 3.0 nm.
Advantageous Effects of Invention
[0017] According to the first invention, a method for manufacturing a semiconductor device
whereby a sealing layer for a semiconductor can be formed on at least the side face of the
recess portion although formation of the sealing layer for a semiconductor on a wiring
exposed on the bottom face of a recess portion formed in an interlayer insulating layer is
suppressed can be provided.
According to the second invention, a rinsing liquid with which the sealing layer for a
semiconductor located on the exposed face of the wiring can effectively be removed can be
provided.
According to the third invention, a rinsing liquid which can improve the plasma
resistance of the sealing layer for a semiconductor can be provided.
According to the fourth invention, a semiconductor device can be provided in which
diffusion of a wiring material (for example, copper) into the interlayer insulating layer is
suppressed and an increase in the interconnection resistance of the connection portion
between the wirings is suppressed.
According to the fifth invention, a semiconductor device can be provided in which
the plasma resistance of the sealing layer for a semiconductor is improved.
BRIEF DESCRPTION OF DRAWINGS
[0018] Fig. 1 is a schematic cross-sectional diagram schematically illustrating a cross
section of a semiconductor substrate before the sealing composition application process, in
one example of the method for manufacturing a semiconductor device according to the first
invention.
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Fig. 2 is a schematic cross-sectional diagram schematically illustrating a cross
section of a semiconductor substrate after the sealing ccmposition application process, in one
example of the method for 1::anufacturing a semiconductor device according to the first
invention.
Fig. 3 is a schematic cross-sectional diagram schematically illustrating a cross
section of a semicoi:ductor substrate after the removal process, in one example of the method
for manufacturing a semiconductor device according to the first invention.
Fig. 4 is a schematic cross-sectional diagram schematically illustrating a cross
section of a semiconductor device, in one example of the semiconductor device according to
the fourth invention.
MODES FOR CARRYING OUT THE INVENTION
[0019] Hereinafter, the inventions (the first invention to the fifth invention) are described in
detail.
[0020] <>
The method for manufacturing a semiconductor device according to the first
invention (hereinafter also referred to as the "manufacturing method according to the first
invention") includes:
a sealing composition application process of applying a sealing composition for a
semiconductor to at least a bottom face and a side face of a recess portion of a semiconductor
substrate, to form a sealing layer for a semiconductor on at least the bottom face and the side
face of the recess portion, the sealing composition for a semiconductor including a polymer
having a cationic functional group and a weight average molecular weight of from 2,000 to
1,000,000, each of the content of sodium and the content of potassium in the sealing
composition for a semiconductor being 10 ppb by mass or less on an elemental basis, and the
sen~iconductor substrate provided with an interlayer insulating layer having the recess portion
and a copper-containing wiring of which at least a part of the surface thereof is exposed on at
least a part of the bottom face of the recess portion; and
a removal process of subjecting a surface of the semiconductor substrate at a side at
which the sealing layer for a semiconductor has been formed to heat treatment under a
temperature condition of from 200°C to 42S°C, to remove at least a part of the sealing layer
for a semiconductor that has been formed on an exposed face of the wiring.
71ne manufacturing method according to the first invention may further include other
processes, if necessary.
8
According to the manufacturing method according to the first invention, a sealing
layer for a seiniconductor can be fonned on the side facz of the recess portion although
formation of a sealing layer for a semiconductor on a wiring exposed on the bottom face of a
recess portion formed in the interlayer insulating layer is suppressed.
The reason why such an effect can be obtained is presumed as follows; however, the
first invention is not limited by the following reason.
[0021] Specifically, in the manufacturing method according to the first invention, through
the sealing composition application process, cationic functional groups of the polymer having
a cationic functional group and a weight average molecular weight of from 2,000 to 1,000,000
undergo ~nultiplep oint adsorption on at least the bottom face and the side face of the recess
portion of the interlayer insulating layer, whereby the side face and the bottom face of the
recess portion (in a case in which the interlayer insulating layer is a porous interlayer
insulating layer, minute openings (pores) present on the side face and the bottom face of the
recess portion of the porous interlayer insulating layer) are covered by a sealing layer for a
semiconductor (hereinafter also referred to as the "sealing layer" or the "polymer layer") that
includes the polymer.
This sealing layer exhibits excellent sealing property with respect to the interlayer
insulating layer. For example, in a case in which a wiring is formed on the recess portion in
a subsequent process, diffusion of components (metal components or the like) of the wiring
into the interlayer insulating layer is suppressed by the sealing layer formed on the side face
of the recess portion. Further, the sealing layer formed of the polymer is a thin layer (for
example, 5 nrn or less); therefore, in a case in which a wiring is formed on the recess portion,
the sealing layer provides excellent adhesion between the wiring formed on the recess portion
and the interlayer insulating layer, and suppresses a change in relative dielectric constant.
[0022] Further, in the manufacturing method according to the first invention, the removal
process results in preferential (preferably selective) removal of the sealing layer formed on the
exposed face of the copper-containing wiring in the bottom face of the recess portion, as
compared to the sealing layer formed at portions other than the exposed face (for example, the
side face of the recess portion). The reason therefor is not clear, hut it is surmised that the
reason may he that a catalytic activity of copper contained in the wiring is exerted due to the
heat treatment under the condition described above, and that the polymer contained in the
sealing layer formed on the wiring is decomposed due to the catalytic activity.
Since the sealing layer sufficiently remains at portions other than the exposed face
(for example, the side face of the recess portion) even after the removal process, the excellent
sealing property with respect to the interlayer insulating layer is maintained by the residual
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sealing layer.
[0023] Next, an example of the manufacturing methoc! according to the first invention is
described with reference to the drawings; however, the first invention is by no means limited
to the one example described below. In the figures (Fig. 1 to Fig. 4), illustration of elements
(for example, an etching stopper layer or the like) not essential in the first invention is omitted.
In the following, the same member is designated by the same reference character, and
overlapping explanations thereof may be omitted.
[0024] Fig. 1 is a schematic cross-sectional diagram schematically illustrating a cross
section of a semiconductor substrate before the sealing composition application process.
As illustrated in Fig. 1, a first interlayer insulating layer 14, a second interlayer
insulating layer 12 that is disposed on the lower layer side of the first interlayer insulating
layer 14 (the side nearer to the semiconductor substrate lo), and a wiring 20 that is embedded
in the second interlayer insulating layer 12 are formed on a semiconductor substrate 10. The
wiring 20 includes at least copper,
In the first interlayer insulating layer 14, a recess portion 16 is formed in advance
through etching such as dry etching, and the wiring 20 is exposed at at least a part of the
bottom face of the recess portion 16. Namely, at least a part of the bottom face of the recess
portion 16 is constituted by an exposed face 20a of the wiring 20.
[0025] However, the semiconductor substrate before the sealing composition application
process in the first invention is not limited to this example.
For example, a barrier layer or the like may be formed on at least a part of the side
face of the recess portion 16.
Further, another layer, such as an etching stopper layer or the like, may be present
between the first interlayer insulating layer 14 and the second interlayer insulati~~lagy er 12.
Alternatively, the first interlayer insulating layer 14 and the second interlayer insulating layer
12 may be integrated to form one interlayer insulating layer.
The cross-sectional shape of the recess portion 16 illustrated in Fig. 1 is a
cross-sectional shape having two different depths (in the stepped shape); however the
cross-sectional shape of the recess portion in the first invention is not limited to this example.
The cross-sectional shape of the recess porlion may be a cross-sectional shape having only
one depth (namely, having a constant depth), or a cross-sectional shape having three or more
different depths. Further, in addition to the recess portion 16, another recess portion of
which the depth of the deepest portion thereof is different from that of the recess portion 16
may also be provided in the interlayer insulating layer, .
If necessary, a semiconductor circuit or the like, such as a transistor, may be formed
10
between the sen~iconductors ubstratelo, and the wiring 20 and the second interlayer insulating
layer 12.
[0026] Fig. 2 is a schematic cross-sectional diagram schematically illustrating a cross
section of a semiconductor substrate after the sealing composition application process.
As illustrated in Fig. 2, in the sealing composition application process, a sealing
composition for a semiconductor is applied at a side of the semiconductor substrate 10
illustrated in Fig. 1 at which the first interlayer insulating layer 14 and the lilce are formed, to
form a sealing layer 30 as a sealing layer for a semiconductor on at least the bottom face and
the side face of the recess portion 16. In this process, the sealing layer 30 is also formed on
the exposed face 20a of the wiring 20.
[0027] Fig. 3 is a schematic cross-sectional diagram schematically illustrating a cross
section of a semiconductor substrate after the removal process.
In the removal process, a face of the semiconductor substrate after the sealing
composition application process illustrated in Fig. 2 at a side at which the sealing layer 30 has
been formed is subjected to heat treatment under the temperature condition of from 200°C to
42S°C, to remove the sealing layer for a semiconductor located on the exposed face 20a of the
wiring 20. Here, it is not essential that the sealing layer for a semiconductor located on the
exposed face 20a be entirely removed; it is sufficient that the sealing layer for a
semiconductor located on the exposed face 20a be removed to such an extent that the
interconnection resistance between the wiring (for example, the first wiring 40 in Fig. 4
described below) that will be embedded in the recess portion 16 in a subsequent process and
the wiring 20 is not increased.
As described above, the removal process enables removal of at least a part of the
sealing layer located on the wiring 20 while leaving the sealing layer 30 on the side face of
the recess portion 16,
In this way, a semiconductor device 100 which has the sealing layer 30 on at least the
side face of the recess portion 16, and in which the formation of the sealing layer for a
semiconductor on the wiring 20 is suppressed, can be produced.
[0028] In the above description, an example of the manufacturing method according to the
first invention is illustrated; however, the first invention is by no means limited to this
example.
For example, as described below, it is preferable that a washing process of washing at
least the side face and the bottom face of the recess portion 16 with a rinsing liquid is
provided between the sealing composition application process and the removal process. The
washing process further improves the removability of the sealing layer located on the wiring.
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Further, the manufacturing method according to the first invention may include
another process, such as a wiring forination process of embedding a wiring in the recess
portion performed after the removal process.
[0029] Next, the respective processes of the manufacturing method according to the first
invention are described in detail.
[0030]
The sealing composition application process in the first invention is a process of
applying a sealing composition for a semicoilductor to at least the bottom face and the side
face of a recess portion of a semiconductor substrate, the sealing composition for a
semiconductor including a polymer having a cationic functional group and a weight average
molecular weight of from 2,000 to 1,000,000, each of the content of sodium and the content
of potassium in the sealing composition for a semiconductor being 10 ppb by mass or less on
an elemental basis, the semiconductor substrate being provided with an interlayer insulating
layer that has the recess portion and a wiring that includes copper, and at least a part of the
surface of the wiring being exposed on at least a part of the bottom face of the recess portion;
through the sealing composition application process, a sealing layer for a semiconductor is
formed on at least the bottom face and the side face of the recess portion.
[0031] As the semiconductor substrate, ordinarily-employed senliconductor substrates may
be used without limitations. Specifically, a silicon wafer, or a silicon wafer having a circuit,
such as a transistor, formed thereon, may be used as the semiconductor substrate.
On the semiconductor substrate, at least an interlayer insulating layer that is provided
with a recess portion and a wiring that includes copper and of which at least a part of the
surface thereof is exposed on at least a part of the bottom face of the recess portion are
provided.
[0032] It is preferable that at least a part of the interlayer insulating layer is a porous
interlayer insulating layer.
With this configuration, the pores of the porous interlayer insulating layer can be
covered by the sealing composition for a semiconductor, and, therefore, an Increase in the
dielectric constant or occurrence of current leakage, which may be caused by penetration of
metal components (copper or the like) into the pores, can further be suppressed.
[0033] Further, it is preferable that the porous interlayer insulating layer includes porous
silica and has silanol residues derived from the porous silica on the surface thereof (preferably,
the face to which the sealing composition for a semiconductor is to be applied, for example,
the side face of the recess portion). By the interaction between this silanol residue and the
cationic functional group contained in the polymer, the pore-covering property of the polymer
12
is further enhanced.
The pore radius in the porous interlayer insulating layer is not particularly limited.
From the viewpoint of more effectively exerting the effect in terms of sealing property due to
the sealing layer for a semiconductor, the pore radius is preferably from 0.5 nm to 3.0 mn, and
more preferably from 1.0 nm to 2.0 nm.
[0034] As the porous silica, porous silicas ordinarily-employed in interlayer insulating
layers of semiconductor devices may be used without particular limitations. Examples
thereof include an oxide having uniform mesopores obtained by hydrothermal synthesis using
silica gel, a surfactant, and the like in a sealed heat-resistant container through utilization of
self-organization of an organic compound and an inorganic compound, as described in
International Publication WO 9111 1390 pamphlet, and porous silica manufactured from a
condensate of an alkoxysilane and a surfactant, as described in Nature, 1996, vol. 379 (page
703) or Supramolecular Science, 1998, vol. 5 (page 247 and the like).
As the porous silica, it is also preferable to use porous silica (for example, porous
silica formed using a composition that includes a specific siloxane compound) described in
International Publication WO 20091123 104 pamphlet and International Publication WO
20101137711 pamphlet.
The porous interlayer insulating layer can be formed, for example, by applying the
composition for forming porous silica described above to a semiconductor substrate, and then
carrying out heat treatment or the like in accordance with necessity.
[0035] The recess portion formed in the interlayer insulating layer is a recess portion (void)
that is formed in the interlayer insulating layer by etching or the like. The recess portion is
formed in order to embed, for example, a wiring material in a subsequent process. Specific
examples of the recess portion include a trench and a via.
The width of the recess portion can be set to be, for example, from 10 nm to 32 nm.
[0036] The term "bottom face of the recess portion" refers to a face from among the wall
faces of the recess portion that is positioned at the deepest portion of the recess portion
(namely, a face of which the distance from the surface of the semiconductor substrate is the
smallest), and that is substantially parallel to the surface of the semiconductor substrate.
Further, the term "side face of the recess portion" refers to the other face(s) than the bottom
face from among the wall faces of the recess portion.
[0037] As described below, the application of the sealing composition for a semiconductor
to the bottom face and side face of the recess portion is useful since it enables effective
suppression of diffusion of components constituting the wiring material into the pores of the
porous interlayer insulating layer when a wiring material is embedded in the recess portion in
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a subsequent process.
[0038] The process of foiming a recess portion in the interlayer insulating layer may be
carried out in accordance with ordinarily-employed process conditions for manufacturing
semiconductor devices. For example, a recess portion having a desired pattern can be
formed by forming a hard mask and a photoresist on the interlayer insulating layer, and
carrying out etching in accordance with the pattern of the photoresist. In a case in which the
porous interlayer insulating layer includes porous silica as described above, the surface of the
porous silica is abraded when the recess portion is formed, as a result of which the density of
silanol groups on the surface tends to increase.
[0039] The semiconductor substrate is provided with a wiring that includes copper, and at
least a part of the surface of this wiring is exposed on at least a part of the bottom face of the
recess portion. Namely, at least a part of the bottom face of the recess portion is an exposed
face of the copper-containing wiring. At the exposed face, the wiring having the exposed
face and the wiring that is to be embedded in the recess portion in a subsequent process are
electrically connected.
[0040] It is preferable that wirings that include copper in the first invention (including, for
example, the first wiring and the second wiring described below) include copper as the main
component.
Here, the "main component" refers to the component of which the content ratio
(atom%) is the highest.
The content ratio is preferably 50 atom% or higher, preferably 80 atom% or higher,
and preferably 90 atom% or higher.
The wiring may include another element (for example, Ta, Ti, Mn, Co, W, Ru, or N),
if necessary.
[0041] The copper-containing wiring of which at least a part of the surface thereof is
exposed on at least a part of the bottom face of the recess portion (for example, the second
wiring described below) and the wiring that is to be embedded in the recess portion in a
subsequent process (for example, the first wiring described below) can be formed in
accordance with known process conditions. For example, a copper wiring may be formed
directly on the silicon wafer or on the interlayer insulating layer on which a recess portion has
been formed, using a metal CVD method, a sputtering method, or an electroplating method,
and the film may be smoothed using chemical mechanical polishing (CMP). If necessary, on
the surface of the film, a cap film may be formed, and, subsequently, a hard mask may be
formed, and formation of an interlayer insulating layer and the wiring formation process may
be repeated, to obtain a multilayer structure.
14
[0042] With regard to the configuration of the semiconductor substrate (semiconductor
device) described above, the configuration of a se~niconductord evice described, for example,
in International Publication WO 20091153834 pamphlet (especially, paragraphs 0040 to 0041,
and Fig. 2E) can be referenced.
[0043] (Sealing Composition for Semiconductor)
The sealing composition for a semiconductor includes a polymer having a cationic
functional group and a weight average molecular weight of from 2,000 to 1,000,000, and each
of the contei~ot f sodium and the content of potassium in the sealing composition for a
semiconductor is 10 ppb by mass or less on an elemental basis.
[0044] The polymer has at least one type of cationic functional group. The polymer may
further have an anionic functional group and/or a nonionic functional group, if necessary.
Further, the polymer may be a polymer having a repetitive unit structure having a cationic
functional group, or a polymer that does not have a specific repetitive unit struclure but has a
random structure formed by branched polymerization of a monomer constituting the polymer
In the first invention, the polymer is preferably a polymer that does not have a specific
repetitive unit structure hut has a random structure formed by branched polymerization of a
monomer constituting the polymer, from the viewpoint of suppressing the diffusion of metal
components.
[0045] The cationic functional group may be any functional group that can be positively
charged, without particular limitations. Examples thereof include an amino group and a
quaternary ammonium group. From the viewpoint of suppressing the diffusion of metal
components, the cationic functional group is preferably at least one selected from the group
consisting of a primary amino group and a secondary amino group.
The nonionic funclional group may be a hydrogen bond-accepting group or a
hydrogen bond-donating group. Examples thereof include a hydroxyl group, a carbonyl
group, and an ether bond.
The anionic functional group may be any functional group that can be negatively
charged, without particular limitations. Examples thereof include a carboxylic acid group, a
sulfonic acid group, and a sulfuric acid group.
[0046] Since the polymer has a cationic functional group in one molecule thereof, the
polymer is capable of suppressing the diffusion of metal components. Further, from the
viewpoint of suppressing the diffusion of metal components, the polymer preferably has a
high cation density. Specifically, the cationic functional group equivalent weight is
preferably from 27 to 430, more preferably from 43 to 430, and particularly preferably from
200 to 400.
15
In a case in which the surface of the porous interlayer insulating layer is subjected to
hydrophobication treatment using a ltnown method, for example, the methods described in
International Publicatioin WO 041026765 pamphlet, International Publication WO 061025501
pamphlet, and the like, the density of polar groups at the surface is decreased; therefore, a
cationic functional group equivalent weight of from 200 to 400 is also preferable.
Here, the term "cationic functional group equivalent weight" means a weight average
inolecular weight per cationic functional group, and is a value (Mwln) obtained by dividing
the weight average molecular weight (Mw) of the polymer by the number (n) of the cationic
functional groups included in one molecule of the polymer. The greater the cationic
functional group equivalent weight is, the smaller the density of cationic functional groups is.
The smaller the cationic functional group equivalent weight is, the greater the density of
cationic functional groups is.
[0047] In a case in which the polymer in the first invention has a repetitive mil structure
having a cationic functional group (hereinafter also referred to as "specific unit structure"), in
the specific unit structure, the cationic functional group may be included as at least a part of
the main chain, or included as at least a part of a side chain, or included as at least a part of
the main chain and at least a part of a side chain.
Further, in a case in which the specific unit structure includes two or more cationic
functional groups, the two or more cationic functional groups may be the same as or different
from each other.
The cationic functional group is preferably contained such that the ratio (hereinafter
also referred to as the "relative distance between cationic functional groups) of the main chain
length of a specific unit structure to the average distance between the adsorption points (for
example, silanol residues) Sor cationic functional groups that are present on the surface of the
porous interlayer insulating layer is from 0.08 to 1.2, and more preferably from 0.08 to 0.6.
This embodiment enables the polymer to undergo multiple point adsorption on the surface of
the porous interlayer insulating layer with higher efficiency.
[0048] In the first invention, the specific unit structure preferably has a molecular weight of
from 30 to 500, and more preferably from 40 to 200, from the viewpoint of adsorbability to
the interlayer insulating layer. Here, the molecular weight of the specific unit structure
means the molecular weight of the monomer constituting the specific unit structure.
The specific unit structure in the first invention is preferably such that the relative
distance between cationic functional groups is from 0.08 to 1.2 and the molecular weight of
the specific unit structure is from 30 to 500, and more preferably such that the relative
distance between cationic functional groups is from 0.08 to 0.6 and the molecular weight of
16
the specific unit structure is from 40 to 200, from the viewpoint of adsorbability to the
interlayer insulating layer.
[0049] In the first invention, specific exa~npleso f the specific unit structure that includes a
cationic functional group include a unit structure derived from ethyleneimine, a unit structure
derived from allylamine, a unit structure derived from diallyl dimethyl ammonium salt, a unit
structure derived from viuylpyridine, a unit structure derived from lysine, a unit structure
derived from ~nethylvinylpyridinea, nd a unit structure derived from p-vinylpyridine.
Among them, at least one of a unit structure derived from ethyleneimine or a unit structure
derived from allylamine is preferable from the viewpoint of adsorbability to the interlayer
insulating layer.
[0050] The polymer may further include at least one of a unit structure that includes a
nonionic functional group or a unit structure that includes an anionic functional group.
Specific examples of the unit structure that includes a nonionic functional group
include a unit structure derived from vinyl alcohol, a unit structure derived from alkylene
oxide, and a wiit structure derived from vinyl pyrrolidone.
[0051] Specific examples of the unit structure that includes an anionic functional group
include a unit structure derived from styrenesulfonic acid, a unit structure derived from
vinylsulfuric acid, a unit structure derived from acrylic acid, a unit structure derived from
methacrylic acid, a unit structure derived from maleic acid, and a unit structure derived from
fumaric acid.
[0052] In the first invention, in a case in which the polymer includes two or more kinds of
specific unit structures, the specific unit structures may differ in any of the kind or number of
polar group(s) contained therein, the molecular weight, or the like. Further, the two or more
kids of specific unit struclures may be included in the form of a block copolylncr or included
in the form of a random copolymer.
[0053] The polymer lnay further include at least one kind of repetitive unit structure
(hereinafter also referred to as "second unit structure") other than the specific unit structure
described above. In a case in which ihe polymer includes the second unit structure, the
specific unit structure and the second unit structure may be included in the form of a block
copolymer or included in the form of a random copolymer.
The second unit structure may be any unit structure derived from a monomer that can
polymerize with a monomer constituting the specific unit structure, without particular
limitations. Examples of the second unit structure include a unit structure derived from
olefin.
[0054] In a case in which the polymer in the first invention is a polymer that does not have a
17
specific repetitive unit st~uctureb ut has a random structure formed by branched
polymerization of a monomer for constituting the polymer, the cationic functional group may
be included as at least a part of the main chain, or included as at least a part of a side chain, or
included as at least a part of the main chain and at least a part of the side chain.
Examples of monomers capable of forming the polymer include ethyleneimine and
derivatives thereof.
[0055] Specific exanlples of the polymer that includes a cationic functional group in the first
invention include polyethyleneimine (PEI), polyallylamine (PAA),
polydiallyldimethylammoniu~n(P DDA), polyvinylpyridine (PVP), polylysine,
polymethylpyridylvinyl (PMPyV), protonated poly(p-pyridyl vinylene) (R-PHPyV), and
derivatives thereof. Among them, polyethyleneimine (PEI) or a derivative thereof,
polyallylamine (PAA), and the like are preferable, and the polymer is more preferably
polyethyleneirnine (PEI) or a derivative thereof.
[0056] In general, polyethyleneimine (PEI) can be manufactured by polymerizing
ethyleneimine using ordinarily-employed methods. Polymerization catalysts,
polymerization conditions, and the like may also be selected, as appropriate, from those
generally employed in the polymerization of ethyleneimine. Specifically, for example, the
reaction can be conducted in the presence of an effective amount of acid catalyst, such as
hydrochloric acid, at a temperature of from 0°C to 200°C. Further, ethyleneimine may be
addition-polymerized to polyethyleneirnine as the basis. The polyethyleneimine in the first
invention may be a homopolymer of ethyleneimine, or a copolymer of ethyleneimine and a
compound that can copolymerize with ethyleneimine, for example, an amine. With regard to
such methods for manufacturing polyethyleneimine, for example, Japanese Patent Publication
(JP-B) No. S43-8828 and JP-B No. S49-33120 may be referenced.
The polyethyleneimine in the first invention may be obtained using crude
ethyleneimine obtained from monoethanol amine. Specifically, for example, JP-ANo.
2001-2123958 or the like may be referenced.
[0057] The polyethyleneimine manufactured in the manner as described above has a
complicated skeleton having a partial structure in which ethyleneimine is ring-opened to be
bonded in the form of a straight chain, as well as a partial structure in which ethyleneimine is
ring-opened to be bonded in the form of a branched chain, a partial structure in which straight
chain partial structures are cross-linked to each other, and the like. Use of a polymer that has
a cationic functional group and that has such a structure enables the polymer to undergo
multiple point adsorption with higher efficiently. Further, a covering layer (a sealing layer)
is formed more effectively due to the interaction between polymers.
18
[0058] It is also preferable that the polyiller is a polyethyleneimiile derivative. The
polyethyleneimine derivative may be any compound that can be manufactured using the
polyethyleneirnine, without particular limitations. Specific examples of the
I i polyethyleneimine derivative include a polyethyleneimine derivative obtained by introducing
an alkyl group (preferably having from 1 to 10 carbon atoms) or an aryl group into
polyethyleneimine, and a polyethyleneimine derivative obtained by introducing a crosslinking
group, such as a hydroxyl group, into polyeihyleneimine.
These polyethyleneinline derivatives can be manufactured using polyethyleneimine
according to ordinarily-employed methods. Specifically, for example, these
polyethyleneimine derivatives can be manufactured according to the method described in
JP-ANo. H6-016809 and the like.
[0059] The polyethyleneimine and derivatives thereof may be commercially available
products. For example, products may be selected from polyethyleneimine and derivatives
thereof available from NIPPON SHOKUBAI CO., LTD., BASF and the like, as appropriate,
and used.
[0060] The weight average molecular weight of the polymer in the first invention is from
2,000 to 1,000,000, preferably from 2,000 to 600,000, more preferably from 2,000 to 300,000,
still more preferably from 2,000 to 100,000, yet more preferably from 10,000 to 80,000, and
particularly preferably from 20,000 to 60,000. When the weight average molecular weight
of the polymer is from 2,000 to 1,000,000, an excellent covering property (sealing property)
with respect to the recess portion of the interlayer insulating layer is obtained, and a decrease
in dielectric constant during the formation of the polymer layer (the sealing layer) is
suppressed.
For example, whcn the weight average molecular weight of the polymer is more than
1,000,000, the size of the polymer molecule would be greater than the size of the recess
portion, and there are cases in which the polymer cannot enter the recess portion and the
covering property with respect to the recess portion is lowered.
When the weight average molecular weight of the polymer is less than 2,000, there
are cases in which the molecule of the polymer does not undergo multiple point adsorption on
the interlayer insulating layer. In addition, the size of the polymer molecule would be
smaller than the diameters of pores of the interlayer insulating layer, and there are cases in
which the resin molecule enters the pores of the interlayer insulating layer and the dielectric
constant of the interlayer insulating layer increases.
The weight average molecular weight and molecular weight distribution in the first
invention refers to a polyethylene glycol-equivalent weight average molecular weight and a
19
polyethylene glycol-equivalent n~olecularw eight distribution as measured by GPC (Gel
Permeation Chromatography) method.
Specifically, the weight average molecular weight and the molecular weight
distribution in the first invention are measured using an aqueous solution having an acetic
acid concentration of 0.5 moliL and a sodium nitrate concentration of 0.1 lnoliL as an eluent
and using an analyzer SWODEX GPC-101 and a column ASAHIPAK GF-7M HQ, and are
calculated using polyethylene glycol as a reference standard.
[0061] It is also preferable that the polymer has a critical micelle concentration in an
aqueous solvent of 1% by mass or more, or is a polymer that does not substantially form a
lnicelle structure. The expression "does not substantially form a micelle structure" as used
herein means that a micelle is not formed under ordinary conditions, such as in an aqueous
solvent at an ordinary temperature, namely, the critical micelle concentration cannot be
measured. By using such a polymer, a thin polymer layer having a thickness at a molecular
level (for example, 5 nm or less) can be formed, and an increase in the dielectric constant of
the interlayer insulating layer can effectively be suppressed. In addition, adhesion between
the interlayer insulating layer and the wiring material is enhanced more effectively.
[0062] Further, the polymer in the first invention is preferably a polyethyleneimine having a
weight average molecular weight of from 2,000 to 600,000 and a cationic functional group
equivalent weight of from 43 to 430, and more preferably a polyethyleneimine having a
weight average molecular weight of from 10,000 to 80,000 and a cationic functional group
equivalent weight of from 200 to 400. With this configuration, diffusion of metal
components into the interlayer insulating layer is suppressed more effectively, and the
tightness of adhesion between the interlayer insulating layer and the wiring material is further
enhanced.
[0063] The content of the polymer in the sealing composition for a semiconductor is not
particularly limited. The content of the polymer may be set to be, for example, from 0.01%
by mass to 1.0% by mass, and is preferably from 0.02% by mass to 0.3% by mass. Further,
the content of the polymer in the composition may be adjusted also in view of the area and
pore density of the surface on which the polymer layer is to be formed using the sealing
composition for a semiconductor.
[0064] In the sealing composition for a semiconductor, each of the content of sodium and
the content of potassium is 10 ppb or less on an elemental basis. The content, 10 ppb or less,
indicates that sodium and potassium are not positively contained. When the content of
sodium or the content of potassium exceeds 10 ppb on an elemental basis, a current leakage is
generated in some cases.
20
[0065] The sealing composition for a selniconductor may include a solvent in addition to the
polymer, if necessary. The sealing cornposition for a semiconductor i~lcludesa solvent at
least in the sealing composition application process. The solvent may be any solvent in
which the polymer uniformly dissolves and does not easily form a micelle, without particular
limitations. Examples thereof include water (preferably, ultrapure water) and water-soluble
organic solvents (for example, alcohols). In the first invention, it is preferable to use water
or a mixture of water and a water-soluble organic solvent, as the solvent, from the viewpoint
of inicelle forming properties.
[0066] The boiling point of the solvent is not particularly limited. The boiling point of the
solvent is preferably 210°C or lower, and more preferably 160°C or lower. With a boiling
point of the solvent within the above range, for example, performing a washing process or a
drying process after the sealing composition application process enables removal of the
solvent and formation of the sealing layer for a semiconductor at a low temperature that does
not significantly impair the insulating properties of the interlayer insulating layer and that
does not cause separation of the sealing composition from the interlayer insulating layer.
The term "sealing composition for a semiconductor" is also used for a sealing composition
that has formed such a sealing layer for a semiconductor.
[0067] Further, the sealing composition for a semiconductor may further include a cation
such as a cesium ion, if necessary, as long as the effects of the first invention are not impaired.
When the sealing composition includes a cation of cesium or the like, it becomes easier for
the resin in the sealing composition for a semiconductor to more uniformly spread over the
surface of the interlayer insulating layer.
[0068] Moreover, it is preferable that a compound that erodes or dissolves the interlayer
insulating layer is not added to the sealing composition for a semiconductor. Specifically,
for example, there are cases in which inclusion of a fluorine compound or the like in the
composition according to the first invention causes dissolution of the interlayer insulating
layer and impairment of the insulating properties thereof, thereby increasing the relative
dielectric constant, especially in a case in which the main material of the interlayer insulating
layer is an inorganic compound such as silica.
[0069] It is preferable that the sealing composition for a semiconductor includes only a
compound having a boiling point of 210°C or lower, preferably 160°C or lower, or a
compound that does not exhibit degradability even under heat treatment up to 250°C.
The expression "compound that does not exhibit degradability even under heat
treatment up to 250°C" refers to a compound of which a change in mass after the compound
has been maintained at 250°C under nitrogen for one hour relative to the mass thereof
21
measured at 25'C is sinaller than 50%.
[0070] The pH of the sealing composition for a semiconductor is not particularly limited.
The pH is preferably equal to or higher than the isoelectric point of the interlayer insulating
layer, froill the viewpoint of the adsorbability of the polymer to the interlayer insulating layer.
Further, in a case in which the polymer has a cationic functional group as a polar group, the
pH of the sealing composition for a semiconductor is preferably within a pH range in which
the cationic functional group is in the cationic state. When the sealing composition for a
senliconductor has a pH as specified above, the polymer more efficiently adsorbs on the
surface of the interlayer insulating layer due to an electrostatic interaction between the
interlayer insulating layer and the polymer.
[0071] The isoelectric point of the interlayer insulating layer is the isoelectric point
exhibited by the compound constituting the interlayer insulating layer. For example, in a
case in which the compound constituting the interlayer insulating layer is porous silica, the
isoelectric point is around pH 2 (at 25OC).
The expression "pH range in which the cationic functional group is in the cationic
state" refers to a pH of the sealing composition for a semiconductor that is equal to or lower
than the pKb of the resin that includes a cationic functional group. For example, in a case in
which the resin that includes a cationic functional group is polyallylamine, the pKb is from 8
to 9, and in a case in which the resin that includes a cationic functional group is
polyethyleneimine, the pKb is from 7 to 11.
Namely, in the first invention, the pH of the sealing composition for a semiconductor
may be selected, as appropriate, in accordance with the kind of the compound constituting the
interlayer insulating layer and the kind of the resin. For example, the pH is preferably from
2 to 11, and more preferably from 7 to 11. Here, the pH (at 25OC) is measured using an
ordinarily-employed pH measuring instrument.
[0072] As the sealing composition for a semiconductor, it is also preferable to use a sealing
composition for a semiconductor described in, for example, International Publication WO
201011 3771 1 pamphlet or International Publication WO 20121033 172 pamphlet.
[0073] (Method of Applying Sealing Composition for Semiconductor)
In the sealing composition application process, the method employed for applying
the sealing composition for a semiconductor is not particularly limited, and
ordinarily-employed methods may be used.
For example, a method of contacting the sealing composition for a semiconductor
with at least the bottom face and the side face of the recess portion of the interlayer insulating
layer may be used which employs a dipping method (see, for example, US Patent No.
22
5208111), a spraying method (see, for example, Schlenoff et al., Langmuir, 16(26), 9968,
2000 or Izuquierdo et al., Langmuir, 21(16), 7558,2005), a spin coating method (see, for
example, Lee et al., Langmuir, 19(18), 7592,2003 or J. Polymer Science, part B, polymer
physics, 42, 3654,2004), or the like.
[0074] The method employed for applying the sealing composition for a semiconductor
using a spin coating method is not particularly limited. For exa~nplea, method may be
employed which includes: dropping the sealing composition for a semiconductor onto an
interlayer insulating layer while a substrate having the interlayer insulating layer formed
thereon is rotated using a spin coater; then dropping a rinsing liquid such as water and
perfonning rinsing treatment; and then increasing the rotation speed of the substrate to
perform drying. In this process, the drying may be carried out after the dropping of the
sealing composition for a semiconductor and the dropping of water are repeated plural times.
Alternatively, a method may be used which includes, after dropping the sealing composition
for a semiconductor; increasing the rotation speed of the substrate to perform drying; placing
the substrate in heat treatment instrument, such as a hot plate, to perform heat treatment after
the drying; and re-placing the substrate in the spin coater after the heat treatment, and
performing rinsing treatment and drying. These procedures may be repeated plural times.
In the above method of applying the sealing composition for a semiconductor using a
spin coating method, there is no limitations on various conditions such as the rotation speed of
the substrate, the amount of the sealing composition for a semiconductor to be dropped, the
duration of the dropping of the sealing composition for a semiconductor, the rotation speed of
the substrate at drying, the amount of the rinsing liquid to be dropped, and the duration of the
dropping of the rinsing liquid; these conditions may be adjusted, as appropriate, in
consideration of, for example, the thiclcness of the polymer layer (sealing layer) lo be formed.
[0075] In the sealing composition application process, the sealing composition for a
semiconductor is applied to at least the bottom face and the side face of the recess portion of
the semiconductor substrate (and, further, drying is performed according to an
ordinarily-employed method, as necessary, in accordance with the necessity), whereby a
sealing layer is formed on at least the bottom face and the side face of the recess portion.
After the application of the sealing composition for a semiconductor, the polymer may be
polymerized via crosslinking.
The thickness of the sealing layer for a semiconductor is not particularly limited.
The thickness is, for example, from 0.3 nm to 5 nm, and preferably from 0.5 nm to 2 nm.
In a case in which the interlayer insulating layer is a porous interlayer insulating layer.
the scope of the sealing layer includes not only a configuration in which the sealing layer is a
23
layer composed only of the polymer, but also a configuration of a layer (a so-called
impregnated layer) having a configuration in which the pores of the porous interlayer
insulatiilg layer is impregnated with the polymer.
[0076] Further, the concentration of the polymer contained in the sealing con~positionf or a
semiconductor for use in the sealing composition application process is preferably lower than
the critical micelle concentration of the polymer. The polymer concentration as specified
above enables the polymer to be applied, in the form of a thin layer (for example, 5 nm or less,
and preferably 2 nm or less), to the interlayer insulating layer, and an increase in the dielectric
constant can be suppressed.
[0077]
The removal process in the first invention is a process that is performed after the
process of applying the sealing composition for a semiconductor described above, and that
includes thermally treating a surface of the semiconductor substrate at a side at which the
sealing layer for a semiconductor has been formed, under a temperature condition of from
200°C to 425'C, thereby removing at least a part of the sealing layer for a semiconductor
formed on the exposed face of the wiring.
In the present process, through the heat treatment under the condition described
above, the sealing layer formed on the exposed face of the copper-containing wiring is
removed in preference to the sealing layer formed on portions (for example, the side face of
the recess portion) other than the exposed face, (preferably, selectively over the sealing layer
formed on portions other than the exposed face).
Here, the temperature is the temperature of a face of the semiconductor substrate at a
side at which the sealing layer for a semiconductor has been formed.
[0078] When the temperature is lower than 200°C, the effect with respect to the removal of
the sealing layer formed on the exposed face of the wiring would be insufficient.
When the temperature is higher than 425"C, migration of copper would occur easily.
The temperature is preferably from 250°C to 400°C, and more preferably from
300°C to 400°C.
[0079] The pressure at which the heat treatment is carried out (the pressure of the
atmosphere to which the sealing layer for a semiconductor is exposed during the heat
treatment) is not particularly limited, and is preferably higher than 17 Pa but not higher than
the atmospheric pressure in terms of absolute pressure.
When the absolute pressure is higher than 17 Pa, the removal speed when the sealing
layer on the exposed face of the wiring is removed further increases.
When the absolute pressure is not higher than the atmospheric pressure, the removal
24
speed when the sealing layer on the exposed face of the wiring is removed is easier to adjust.
The absolute pressure is more preferably 1,000 Pa or higher but not higher than the
atmospheric pressure, still more prelerably 5,000 Pa or higher but not higher thail the
atmospheric pressure, and particularly preferably 10,000 Pa or higher but not higher than the
atmospheric pressure.
[0080] Heating @eat treatment) in the present process may be carried out according to
ordinary methods using an oven or a hot plate. As the oven, for example, a SPX-1120
manufactured by APEX Co., Ltd., or a VF-IOOOLP manufactured by ICoyo Thermo Systems
Co., Ltd., may be used.
Further, the heating (heat treatment) in the present process may be carried out under
atmospheric air; however, from the viewpoints of, for example, suppressing oxidation of
copper, which is the wiring material, heating (heat treatment) is more preferably carried out
under an inert gas (for exatnple, nitrogen gas, argon gas, or helium gas) atmosphere, and is
particularly preferably carried out under a nitrogen gas atmosphere.
[0081] The duration of the heating (heat treatment) is not particularly limited, and the
duration is, for example, 1 hour or less, preferably 30 minutes or less, more preferably 10
minutes or less, and particularly preferably 5 minutes or less. The lower limit of the duratjon
of the heating (heat treatment) is not particularly limited, and may be set to, for example, 0.1
minutes.
When the duration of the heating (heat treatment) is 1 hour or less, the sealing
property of the sealing layer with respect to the interlayer insulating layer are maintained at a
higher level.
[0082]
The method for maliufacturing a semiconductor device according to thc first
invention preferably includes a washing process of washing at least the side face and the
bottom face of the recess portion with a rinsing liquid, after the sealing composition
application process but before the removal process.
By including the washing process, the removability of the sealing layer located on
the exposed face of the wiring is further improved.
[0083] The rinsing liquid is not particularly limited. From the viewpoint of improvement
in washing efficiency, the rinsing liquid preferably includes a solvent having high polarity.
Since the sealing composition for a semiconductor (hereinafter also referred to as
"sealing composition") includes a polymer having a cationic functional group and has high
polarity, the sealing composition easily dissolves in a high-polarity solvent. Thus, use of a
rinsing liquid that contains a high-polarity solvent further improves the removability of the
25
sealing layer located on the exposed face of the wiring.
Specifically, the rinsing liquid preferably includes a polar solvent such as water,
methanol, ethanol, propanol, butanol, or propylene glycol monomethyl ether acetate.
Such polar solvents do not significantly impair the interaction between the interlayer
insulating layer and the sealing composition for a semiconductor. Therefore, washing using
a rinsing liquid that includes such a polar solvent is unlikely to cause removal of the sealing
layer located on the interlayer insulating layer (the sealing layer that functions effectively),
and thus such washing is preferable.
The rinsing liquid may include only one kind of polar solvent, or may include two or
more kinds of polar solvents.
[0084] The temperature of the rinsing liquid in the present process is preferably from 15°C
to 100°C, more preferably from 30°C to 100°C, still more preferably from 40°C to 100°C,
and particularly preferably from 50°C to 100°C.
When the temperature of the rinsing liquid is 15°C or higher (more preferably 30°C
or higher), the removability of the sealing layer located on the exposed face of the wiring is
further improved.
When the temperature of the rinsing liquid is 100°C or lower, evaporation of the
rinsing liquid can be further suppressed.
[0085] The washing in the present process may be carried out while ultrasonic waves are
applied to the rinsing liquid.
[0086] From the viewpoint of suppressing oxidization of a wiring material that includes
copper, the rinsing liquid preferably includes a reducing agent or a compound having a
reductive activity. An example of the reducing agent or the compound having a reductive
activity is formalin.
[0087] Further, the rinsing liquid preferably has a content of oxidative compounds (for
example, hydrogen peroxide, nitric acid) of 10% by mass or lower, and it is more preferable
that the rinsing liquid does not include any oxidative compound, from the viewpoints of
preventing cleavage of carbon-carbon bonds or the like in the polymer of the sealing
composition and suppressing the detachment of the sealing layer (the sealing layer that
functions effectively) formed on the surface of the interlayer insulating layer.
[0088] The rinsing liquid preferably has an ionic strength of 0.003 or higher, and preferably
0.01 or higher.
An ionic strength of 0.003 or higher is preferable from the viewpoint that such an
ionic strength facilitates dissolution of the sealing layer (the polymer) but does not
significantly impair the interaction between the interlayer insulating layer and the sealing
layer.
The upper limit of the ionic strength is not particularly limited, and may be an ionic
strength corresponding to a concentration at which the ionic conlpound can dissolve.
The ionic strength is a value represented by the following equation.
Ionic strength = 112 x C(c x z2)
In the equation, c represents the inolar concentration of the ionic compound
contained in the rinsing liquid, and Z represents the ionic valence of the ionic compound
contained in the rinsing liquid.)
[0089] In order to adjust the ionic strength, ionic compounds such as the acid described
below or an organic base (such as ammonia, pyridine, or ethylamine) may be added, if
necessary.
Further, a polymer (for example, polyethyleneimine) that haps copper ions after
copper is detached may be added.
[0090] It is also preferable that the rinsing liquid is a rinsing liquid having a pH at 2SoC of 6
or lower (preferably, 5 or lower). Use of such a rinsing liquid further improves the
removability of the sealing layer located on the exposed face of the wiring, and enables
dissolution and removal of copper oxide formed on the exposed face of the wiring.
The lower limit of the pH of such a rinsing liquid is not particularly limited, and the
pH value thereof is preferably 1 or higher, and more preferably 2 or higher.
A pH value of 1 or higher enables dissolution of the interlayer insulating layer to be
more suppressed, and, therefore, enables the sealing layer formed on the surface of the
interlayer insulating layer to be more favorably maintained.
From the viewpoint of more effective realization of both the removability of the
sealing layer located on thc exposed face of the wiring and the maintenance of the sealing
layer provided on the surface of the interlayer insulating layer, the pH of the rinsing liquid is
preferably from 1 to 6, more preferably from 2 to 5, and particularly preferably from 2 to 4.
[0091] The rinsing liquid (especially, the rinsing liquid having a pH at 25°C of 6 or lower)
preferably includes at least one acid.
The acid is not particularly limited. The acid is preferably an acid that has a low
tendency to contaminate or destroy the interlayer insulating layer and a low tendency to
remain on the semiconductor substrate is preferable.
Specific examples of the acid include monocarboxylic acids such as formic acid and
acetic acid; dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid,
adipic acid, pimelic acid, maleic acid, fumaric acid, and phthalic acid; tricarboxylic acids such
as trimellitic acid and tricarballylic acid; oxymonocarboxylic acids such as hydroxybutyric
27
acid, lactic acid, and salicylic acid; oxydicarboxylic acids such as nlalic acid and tartaric acid;
oxytricarboxylic acids such as citric acid; an~inocarbox;ilica cids such as aspartic acid and
glutan~ica cid; organic acids such as para-toluenesulfonic acid and methanesulfonic acid; and
inorganic acids such as hydrochloric acid, nitric acid, and phosphoric acid.
Further, examples of the acid also include specific compounds that are acids, among
the specific compounds described below.
[0092] In the process of manufacturing a semiconductor device, there are cases in which a
semiconductor device is cleaned with a plasma in a state in which a sealing layer is exposed,
or cases in which a layer is formed on a sealing layer using, for example, a plasma CVD
method.
Therefore, there are cases in which the sealing layer is required to have resistance to
plasma.
From the viewpoint of improving the plasma resistance of the sealing layer, the
rinsing liquid preferably includes at least one compound (hereinafter also referred to as the
"specific compound") having, in one molecule thereof, at least one (preferably both) selected
from the group consisting of a moiety A that blocks active species (for example, plasma active
species such as radicals, ions, and electrons) and a moiety B (preferably a functional group;
the same shall apply hereinafter) that forms a bond, under heating, with the polymer having a
cationic functional group and a weight average molecular weight of from 2,000 to 1,000,000
(the polymer used for forming the sealing layer for a semiconductor).
In the following, the rinsing liquid that inclndes the specific compound is sometimes
referred to as the "rinsing liquid according to the third invention". The rinsing liquid
according to the third invention is favorable as a rinsing liquid for improving the plasma
resistance of the sealing layer.
[0093] The specific compound is preferably an acid.
In a case in which the rinsing liquid according to the third invention includes an acid
that is the specific compound, the effect with respect to the improvement of ihe plasma
resistance of the sealing layer as well as the effect with respect to the improvement of the
removability when the sealing layer located on the exposed face of the wiring is removed can
be expected to be exerted.
Further, the rinsing liquid according to the third invention may include both an acid
and the specific compound that is not an acid.
Moreover, from the viewpoint of more effectively exerting the effect with respect to
the improvement of the removability, the rinsing liquid according to the third invention
preferably has a pH at 25°C of 6 or lower.
28
[0094] The illoiety A is not particularly limited. For example, a functional group having a
conjugated system, an alicyclic structure, and a metal atom are preferable as the moiety A.
Specific examples thereof include an aromatic ring structure, an alicyclic structure, a
manganese atom, and a silicon atom.
Regarding the form of the specific compound, the specific compound preferably has,
in one molecule thereof, at least one selected from the group consisting of a benzene ring, a
biphenyl slteleton, a naphthalene skeleton, a benzophenone skeleton, a diphenyl ether skeleton,
and a bicyclo skeleton, as the moiety A.
The bicyclo skeleton may he either a saturated bicyclo slceletoil or an unsaturated
bicyclo skeleton.
[0095] The specific compound having a manganese atom as the illoiety A is, for example,
manganese(I1) diacetate.
Examples of the specific compound having a silicon atom as the moiety A include an
alkoxysilane compound (for example, bis(triethoxysily1)ethane or dimethyldiethoxysilane, or
the like) and a disilyl compound (for example, hexamethyldisiloxane or the like). In regard
to the alkoxysilane compound and disilyl compound, the alkoxysilane compounds and the
disilyl compounds described in International Publication WO 20091123 104 pamphlet and
International Publication WO 20101137711 pamphlet may also be used.
[0096] The moiety B is, for example, a carboxyl group. For example, in a case in which
the sealing layer includes a polymer (for example, polyethyleneimine) that includes at least
one of a primary amino group or a secondary amino group (an imino group), the carboxyl
group reacts with the at least one of a primary amino group or a secondary amino group (an
imino group) contained in the polymer, to form an amide hond or an imide hond.
This further improves the plasma resistance of the sealing layer.
The number of moieties B in one molecule of the specific compound is preferably 1
or greater, more preferahly 2 or greater, still more preferably 3 or greater, and particularly
preferably 4 or greater.
The upper limit of this number isnot particularly limited. Ths number may be set
to he, for example, 6 or smaller.
[0097] Next, examples of the specific compound that are preferable from the viewpoint of
improving the plasma resistance of the sealing layer are provided.
Specific examples of the specific compound that is an acid include the
above-described monocarhoxylic acids, dicarboxylic acids, tricarboxylic acids,
oxymonocarboxylic acids, oxydicarboxylic acids, oxytricarboxylic acids, aminocarboxylic
acids, and organic acids.
29
More preferable examples of the specific compound that is an acid are polyvalent
carboxylic acids such as naphthalene tetracarboxylic acids (for example,
naphthalene-2,3,6,7-tetracarboxylica cid, naphthalene-l,4,5,8-tetracarboxylica cid), biphenyl
I tetracarboxylic acids (for example, 3,3',4,4'-biphenyltetracarboxylic acid), benzophenone
i tetracarboxylic acids (for exainple, 3,3',4,4'-benzophenonetetracarboxylic acid), benzene
hexacarboxylic acid, pyromellitic acid, trimellitic acid (namely, 1,2,4-benzenetricarboxylic
, .
acid), diphenyl ether tetracarboxylic acid (3,3',4,4'-diphenyl ether tetracarboxylic acid),
phenyleile diacetates (for example, meta-phenylene diacetate, ortho-phenylene diacetate),
bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxyliac cid, ethylenediamine tetraacetic acid, citric
acid, meso-butane-1,2,3,4-tetracarboxyliacc id, and polyacrylic acid, and barbituric acid.
The weight average molecular weight of the polyacrylic acid is preferably from
1,000 to 800,000, more preferably from 1,000 to 600,000, still more preferably from 1,000 to
200,000, yet more preferably from 5,000 to 80,000, yet more preferably from 10,000 to
50,000, and particularly preferably from 20,000 to 30,000. The weight average molecular
weight of polyacrylic acid is measured in the same manner as that in the measurement of the
weight average molecular weight of the polymer contained in the sealing layer.
Examples of the specific compound that is not an acid include ortho-phthalic
aldehyde, terephthalic aldehyde, manganese(I1) diacetate, and benzotriazole.
Among the above compounds, the specific compounds that are acids are preferable.
In particular, polyvalent carboxylic acids are more preferable, and naphthalene tetracarboxylic
acid, biphenyl tetracarboxylic acid, benzophenone tetracarboxylic acid, benzene
hexacarboxylic acid, and pyromellitic acid are particularly preferable.
[0098] It is also preferable that the specific compound is a compound which has, in one
molecule thereof, two or Inore carboxyl groups as the moiety B, and has a structare in which
each of two neighboring carbon atoms bonds to a carboxyl group or a structure in which each
of two non-central carbon atoms from among three consecutive carbon atoms bonds to a
carboxyl group.
With this configuration, an imide bond is more effectively formed through a reaction
between a carboxyl group contained in the specific compound and at least one of a primary
amino group or a secondary amino group (an imino group) contained in the polymer,
particularly in a case in which the sealing layer includes a polymer (for example,
polyethyleneimine) that includes at least one of a primary amino group or a secondary amino
group (an imino group. As a result of the effective formation of the imide bond, the plasma
resistance of the sealing layer is further improved.
The specific compound in this case may be a compound that has the moiety A, or a
30
compound that does not have the illoiety A.
Here, examples of the structure in which each of two neighboring carbon atoms
bonds to a carboxyl group include the structure of citric acid, a structure in which a carboxyl
group is bonded to the ortho position of a benzene ring, and a structure in which carboxyl
groups are bonded to the positions 2 and 3 (or positions 6 and 7) of a naphthalene ring.
Exanples of the structure in which each of two non-central carbon atoms fiom
among three consecutive carbon atoms is bonded to a carboxyl group include a structure in
which carboxyl groups are bonded to the positions 1 and 8 (or positions 4 and 5) ola
naphthalene ring.
Among the specific compounds of these types, 3,3',4,4'-diphenyl ether
tetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid,
3,3',4,4'-benzophenonetetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylica cid,
naphthalene-1,4,5,8-tetracarboxylic acid, benzene hexacarboxylic acid, pyromellitic acid,
trimellitic acid, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylica cid,
meso-butane-1,2,3,4-tetracarboxylica cid, and citric acid are particularly preferable.
[0099] It is also preferable that the specific compound is a compound which has both the
moiety A and the moiety B, and in which the moiety A is at least one selected fiom the group
consisting of an aromatic ring structure, an alicyclic structure, a manganese atom, and a
silicon atom, and in which the moiety B is a carboxyl group.
Among the specific compounds of this type, 3,3',4,4'-diphenyl ether tetracarboxylic
acid, 3,3',4,4'-biphenyltetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid,
naphthalene-2,3,6,7-tetracarboxylica cid, naphthalene-l,4,5,8-tetracarboxyliac cid, benzene
hexacarboxylic acid, pyromellitic acid, trimellitic acid,
bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylica cid, and meta-phenylene diacetale are
particularly preferable.
[0100] From the viewpoint of imparting plasma resistance to the sealing layer, the
above-described rinsing liquid according to the third invention may also be used with respect
to a sealing layer that is formed on a portion other than the recess portion, or a sealing layer
formed on a semiconductor substrate on which a copper-containing wiring is not exposed.
[0101] Examples of the plasma include a plasma produced from hydrogen gas, helium gas,
argon gas, nitrogen gas, ammonia gas, or the like. The conditions in which the plasma is
generated is not particularly limited, and are preferably conditions in which the polymer layer
(sealing layer) deposited on at least the side face of the recess portion, which greatly
contributes to the sealing function, is not excessively removed. Examples of such conditions
include conditions in which the total pressure is from 20 mTorr to 200 mTorr, the gas flow
31
rate is fro111 20 SCCIII to 100 sccin, the cathode electrode diameter is from 5 cm to 15 cm, the
discharge electric power is from 20 W to 200 W, and the treatment time (discharge time) is
from 10 sec to 60 sec.
[O102] The amounts of the solvent, acid, reducing agent, ionic con~pounds, pecific
compound, and the like that may be contained in the rinsing liquid (including the rinsing
liquid according to the third invention; the same shall apply hereinafter) are not particularly
limited; these amounts may be adjusted, as appropriate, such that, for example, the pH and the
ionic strength of the rinsing liquid fall within their respective preferable ranges described
above.
[0103] The rinsing liquid can be prepared by mixing, for example, the above-described
solvent, acid, reducing agent, ionic compound, specific compound, and the like. In order to
prevent contamination of the semiconductor circuit, it is preferable that the rinsing liquid is
prepared under a clean environment such as in a clean room or the like, or that contaminants
to the semiconductor circuit are removed by purification, filtration, or the like after the rinsing
liquid is prepared.
[0104] When combined with the removal process described above, the present process is
able to rapidly washing away (rinsing away) the surplus sealing layer formed on the wiring
using the rinsing liquid, while allowing the effective sealing layer that seals the interlayer
insulating layer to be retained. In addition, as described above, oxides of the wiring material
can also be removed, whereby separation between the wiring material and the low dielectric
constant material, or separation between the wiring materials, can be suppressed
[0105] It is also preferable that the washing in the present process is carried out under a
non-oxidizing atmosphere. Carrying out the washing under a non-oxidizing atmosphere
makes it possible to prevent excessive removal of the copper wiring, which would otherwise
occur due to repeated processes in which: copper oxide that was present on the wiring surface
prior to rinsing is removed using the rinsing liquid; thereafter, copper on the wiring surface
further oxidizes into copper oxide; and, again, this copper oxide is dissolved (removed) using
the rinsing liquid. The non-oxidizing atmosphere may be achieved, for example, using a
reducing atmosphere gas.
[0106] In the present process, the washing may be carried out using ordinarily-employed
methods. The method employed therefor is not particularly limited.
The washing time is not particularly limited. The washing time may be set to be,
for example, from 0.1 minutes to 60 minutes, and more preferably from 0.1 minutes to 10
minutes.
[0107]
The method for manufacturing a semiconductor device according to the first
invention may further include usually-perfonlled processes as other processes, such as a
wiring formation process and a barrier layer formation process.
The wiring formation process is, for example, a process of forming a wiring on the
recess portion after the removal process described above.
The wiring fo~mationp rocess may be carried out employing known process
conditions. For example, a copper wiring may be formed using a metal CVD method, a
sputtering method, or an electroplating method, and the film may be silloothened using CMP.
Subsequently, a cap film is formed on the surface of the film. Further, if necessary, a hard
mask may be formed, and the processes described above may be repeated, to form a
multilayer structure.
[0108] Further, the method for manufacturing a semiconductor device according to the first
invention may further includc a barrier layer (copper barrier layer) formation process that is
performed before the wiring formation process. By forming a barrier layer, diffusion of
metal components into the interlayer insulating layer can more effectively be suppressed.
The barrier layer formation process can be carried out employing
ordinarily-employed process conditions. For example, after the removal process described
above (in a case in which the washing process described above is included to be performed
after the removal process, after the washing process), a barrier layer formed of a titanium
compound (titanium nitride or the like), a tantalum compound (tantalum nitride or the like), a
ruthenium compound, a manganese compound, a cobalt compound (COW or the like), a
tungsten compound, or the like can be formed using, for example, a vapor phase growth
method (CVD).
[0109] Moreover, the method for manufacturing a semiconductor device accortling to the
first invention may include a post-rinsing process of further washing off the rinsing liquid
remaining on the semiconductor substrate, after the washing process (before or after the
removal process). The post-rinsing process may be performed using ordinarily-employed
methods, and is not particularly limited. Specifically, washing may be performed using a
post-rinsing method as described in JP-ANo. 2008-47831. Further, the rinsing liquid
(hereinafter referred to as "post-rinsing liquid") for use in the post-rinsing process may be any
liquid that can remove the rinsing liquid described above through dissolution or
decomposition, without particular limitations. Specifically, an organic solvent having
polarity such as an alcohol, water, a mixture of an organic solvent having polarity and water,
or a solvent that includes ozone or an acid having degradability such as nitric acid or sulfuric
acid, may be used.
3 3
[0110] Next, the use of the above-described rinsing liquid according to the third invention is
further described.
The rinsing liquid according to the third invention is suitable as a rinsing liquid for
improving the plasiua resistance of the sealing layer for a semiconductor.
For example, in a case in which the method for manufacturing a semiconductor
device according to the fjrst inve~ltionin cludes the washing process described above, the
rinsing liquid according to the third invention is suitable as the rinsing liquid for use in the
washing process.
However, the rinsing liquid according to the third invention may generally be used
for uses in which the plasma resistance of a sealing layer for a seilliconductor formed on a
surface of an interlayer insulating layer of a semiconductor device provided with the
interlayer insulating layer is to be improved, in addition to the use in the method for
manufacturing a semiconductor device according to the first invention.
For example, the rinsing liquid according to the third invention is also suitable as a
rinsing liquid for improving the plasma resistance of a sealing layer for a semiconductor that
is formed on a surface of an interlayer insulating layer of a semiconductor substrate provided
with the interlayer insulating layer, and that is derived from a polymer having a cationic
functional group and a weight average molecular weight of from 2,000 to 1,000,000. More
specifically, the rinsing liquid according to the third invention is suitable as a rinsing liquid
for use in the washing process of the following method of manufacturing a semiconductor
device, which includes a plasma process.
Namely, the method of manufacturing a semiconductor device, which includes a
plasma process, a manufacturing method that includes: a sealing composition application
process of applying a sealing composition for a semiconductor which includes a. polymer
having a cationic functional group and a weight average molecular weight of from 2,000 to
1,000,000 and in which each of the content of sodium and the content of potassium is 10 ppb
by mass or less on an elemental basis, to a surface of an interlayer insulating layer of a
semiconductor substrate provided with the interlayer insulating layer (which may be p~ovided
with a recess portion), to form a sealing layer for a semiconductor on the surface of the
interlayer insulating layer; a washing process of washing the formed sealing layer for a
semiconductor with a rinsing liquid; and a plasma process of exposing, after the washing
process, a face of the semiconductor substrate at a side at which the sealing layer for a
semiconductor has been formed to a plasma.
In this manufacturing method, in a case in which the interlayer insulating layer is
provided with a recess portion, the sealing layer for a semiconductor may be formed on at
34
least one of the wall face of the recess portion of the interlayer insulating layer or the portion
(flat portion) other than the recess portion of the interlayer insulating layer.
Here, in a case in which ihe sealing layer for a semiconductor is fonned on the wall
face of the recess portion of the interlayer insulating layer and the portion (flat portion) other
than the recess portion, the procedures in the washing process and the procedures in the
plasma process may be performed with respect to the sealing layer fonned on the wall face of
the recess portion, or on the sealing layer for a sen~iconductorfo rmed on the poitioil (flat
portion) other than the recess portion.
In this manufacturiilg method, the seiniconductor substrate to which the sealing
composition for a semiconductor is to be applied may be provided with, for example, a wiring
that includes copper or a semiconductor circuit (transistor).
[Olll] Examples of the plasma in the plasma process described above include a plasma
produced from a hydrogen gas, a helium gas, a nitrogen gas, an ammonia gas, or the like.
Specific examples of the mode of the plasma process include a plasma cleaning process of
cleaning, with a plasma, the semiconductor substrate on which the sealing layer for a
semiconductor has been formed, and a plasma CVD process of forming a layer on the
semiconductor substrate on which the sealing layer for a semiconductor has been formed,
using a plasma CVD method.
The conditions in which exposure to the plasma is performed is not particularly
limited. Conditions in which the polymer layer (sealing layer) deposited on at least the side
face of the recess portion and greatly contributing to the sealing function is not excessively
removed are preferably adopted. Examples of such conditions include conditions in which
the total pressure is from 20 mTon to 200 mTorr, the gas flow rate is from 20 sccm to 100
sccm, the cathode electrodc diameter is from 5 cm to 15 cm, the discharge eleclric power is
from 20 W to 200 W, and the treatment time (discharge time) is from 10 sec to 60 sec.
In the method of manufacturing a semiconductor device that includes the plasma
process described above, preferable ranges of the sealing composition application process and
preferable ranges of the washing process are respectively the same as the preferable ranges of
the sealing composition application process and the preferable ranges of the washing process
in the method for manufacturing a semiconductor device according to the first invention.
The method of manufacturing a semiconductor device that includes the plasma
process may include the removal process described above, between the sealing composition
application process and the washing process.
A mode of the method of manufacturing a semiconductor device that includes a
plasma process in which the removal process described above is provided between the
3 5
washing process and the plasma process is included in the scope of the method for
manufacturing a seiniconductor device according to the first invention.
Preferable modes of the method of manufacturing a semiconductor device that
includes a plasma process are the same as the preferable modes of the method for
manufacturing a semiconductor device according to the first invention, except that the
removal process described above is not provided between the washing process and the plasma
process, and that the modes are not limited to a mode in which the interlayer insulating film is
provided with a recess portion (for example, a mode in which a wiring that includes copper is
exposed on the bottom face of the recess portion of the interlayer insulating layer).
A more specific example of the mode of the method of manufacturing a
semiconductor device that includes a plasma process is a mode that includes:
a sealing composition application process of applying a sealing composition for a
semiconductor to at least the bottom face and the side face of a recess portion oS a
semiconductor substrate, to form a sealing layer for a semiconductor on at least the bottom
face and the side face of the recess portion, the sealing composition for a semiconductor
including a polymer which has a cationic functional group and a weight average molecular
weight of from 2,000 to 1,000,000 and in which each of the content of sodium and the content
of potassium is 10 ppb by mass or less on an elemental basis, the semiconductor substrate
including an interlayer insulating layer that is provided with the recess portion and a wiring
that includes copper, and at least a part of the surface of the wiring being exposed on at least a
part of the bottom face of the recess portion;
a washing process of washing the formed sealing layer for a semiconductor, using a
rinsing liquid; and
a plasma process of exposing, after the washing process, a face of thc sc~niconductor
substrate at a side at which the sealing layer for a semiconductor has been formed to a plasma.
[O 11 21 <>

Example
32
(C + B)
x 3
Oxalic
acid
0.39
4.0
5.6
N. D.
N. D.
N. D.
0.80
[0183] TABLE 6
Example
30
(C +B)
x 3
EDTA
0.39
5.0
11.0
N. D.
N. D.
N. D.
0.79
Formation
of Sealing
Layer
Washing
Evaluation
after Heat
Treatment
Evaluation
after
Plasma
Treatment
Example
33
(C-. B)
x 3
Formic
acid
0.39
4.5
4.9
N. D.
N. D.
N. D.
0.51
Example
31
(C -. B)
x 3
Citric
acid
0.39
4.5
7.2
N. D.
Present
N. D.
0.89
Procedures
Example
34
(C + B)
x 3.
o-PhALD
0.34
7.0
3.3
N. D.
N. D.
N. D.
0.79
Rinsing
Liquid
Thickness of
Sealing Layer
[nml
FT-IR
Sealing
Property
Plasma
Resistance
Additional Compound
Content ofAdditional
compound (mmoVL)
PH
on Si
on Cu
pp
Presence or Absence of
h i d e Bond
Toluene Adsorption
Amount (%)
Change in Thickness of
Sealhg Layer due to
Plasma Treatment
(relative value)
Example
35
(C -+ B)
x 3
MnDA
0.39
6.0
3.2
N. D.
N. D.
N. D.
0.66
Example
36
(C + B)
x 3
ETA
0.39
6.0
2.6
N. D.
N. D.
N. D.
0.62
[0184] The additional compounds noted in Tables 4 to 6 are as follows
- Additional Compound -
OPDA: 3,3',4,4'-diphenyl ether tetracarboxylic acid
BPDA: 3,3',4,4'-biphenyltetracarboxylic acid
BTDA: 3,3',4,4'-benzophenonetetracarboxylic acid
2367NDA: naphthalene-2,3,6,7-lelracarboxyliacc id
1458NDA: naphthalene-l,4,5,8-tetracarboxylica cid
MeA: benzene hexacarboxylic acid
PMDA: pyromellitic acid
TMA: trimellitic acid
m-PhDA: meta-phenylene diacetic acid
PAA: polyacrylic acid (having a weight average molecular weight of 25,000)
BcDA: bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxyliacc id
MBTCA: meso-butane-l,2,3,4-tetracarboxylica cid
EDTA: ethylenediamine tetraacetic acid
o-PhALD: ortho-phthalaldebyde
MnDA: manganese(I1) diacetate
BTA: benzotriazole
[0185] In Tables 4 to 6, "N. D." (No Data) refers to absence of measurement results.
[0186] As shown in Tables 4 to 6, it was contimed that a change in thickness of the sealing
layer due to plasma treatment can be suppressed (namely, the plasma resistance of the sealing
layer can be improved) by adding a compound having, in one molecule thereof, at least one of
a moiety A that blocks an active species or a moiety B that forms a bond with the polymer
when heated (the specific compound) into the rinsing liquid.
In particular, it was confirmed that the effect in terms of improving the plasma
resistance is remarkably high in a case in which the specific compound is a compound that
has, in one molecule thereof, two or more carboxyl groups as the moiety B, and that has, in
one molecule thereof, at least one of a structure in which each of two neighboring carbon
atoms bonds to a carboxyl group or a structure in which each of two non-central carbon atoms
from among three consecutive carbon atoms bonds to a carboxyl group (OPDA, BPDA,
BTDA, 2367NDA, 1458NDA, MeA, PMDA, TMA, BcDA, MBTCA, or citric acid), or in a
case in which the specific compound is a compound that has the moiety A and the moiety B,
and in which the moiety A is at least one selected from the group consisting of an aromatic
ring structure, an alicyclic structure, a manganese atom, and a silicon atom, and in which the
moiety B is a carboxyl group (OPDA, BPDA, BTDA, 2367NDA, 1458NDA, MeA, PMDA,
65
TMA, nl-PhDA, or BcDA)
Further, it was confirmed that the thickness of the sealing layer on Cu can be reduced
I although certain degrees of the sealing property with respect to the low-k Glin and the
thickness of the sealing layer on Si can be maintained, also in a case in which a rinsing liquid
i that includes the specific compound is used.
'1 [0187] [Examples 37 and 381 I Evaluations were performed in the same manner as that in Exan~ples 16 and 24,
/I except that the sample was heated before the plasma treatment was heated, and that the
\I temperature of the surface of the sample at the time of plasma treatment was thus changed to
I I 250°C. The results of the evaluations are indicated in the following Table 7
[0188] TABLE 7
Example
37
Layer
I Additional Compound I BPDA / PMDA
Example
38
Formation
of Sealing
I I I
Thickness of 1 on Si 1 19.9 1 13.2
(C -. B)
x 3
Procedures
Rinsing
Washing
Liquid
(C -+ B)
x 3
I I
Evaluation
after Heat
Treatment
0.39
Content of Additional
Compound (mmolk)
Sealing Layer
[nml
1 Evaluation
1 after
[0189] As shown in Table 7, it was confirmed that a change in thickness of the sealing layer
due to plasma treatment can be suppressed (namely, the plasma resistance of the sealing layer
0.39
FT-IR
Plasma
Treatment
can be improved) also in a case in which the temperature of the surface of the sample at the
time of plasma treatment is set at 250°C, similar to Examples 16 and 24 (, in which the
temperature of the surface of the sample at the time of plasma treatment was room
on Cu
Sealing
Property
temperature).
66
Plasma
Resistance
N. D.
N. D.
Presence or Absence of
Imide Bond
Toluene Adsorption
Amount (%)
Change in Thiclaess of
N. D.
N. D.
Sealing Layer due to
Plasma Treatment
N. D. N. D.
(relative value) I
0 97 0.96
[0190] The disclosures of Japanese Patent Application No. 2012-158979 and Japanese
Patent Application No. 2013-039944 are incorporated by reference herein in their entirety
All publications, patent applications, and technical standards mentioned in this
specification are herein incorporated by reference to the same extent as if such individual
publication, patent application, or technical standard was specifically and individually
indicated to be incorporated by reference.
CLAIMS
1. A method for manufacturing a semiconductor device, the method comprising:
a sealing con~positiona pplication process of applying a sealing composition for a
semiconductor to at least a bottom face and a side face of a recess portion of a semiconductor
substrate, to form a sealing layer for a semiconductor on at least the bottom face and the side
face of the recess portion, the sealing composition for a semiconductor including a polymer
having a cationic functional group and a weight average inolecular weight of from 2,000 to
1,000,000, each of the content of sodium and the content of potassium in the sealing
composition for a semiconductor being 10 ppb by mass or less on an elemental basis, and the
semiconductor substrate being provided with an interlayer insulating layer having the recess
portion and a copper-containing wiring of which at least a part of a surface thereof is exposed
on at least a part of the bottom face of the recess portion; and
a removal process of subjecting a surface of the semiconductor substrate at a side at
which the sealing layer for a semiconductor has been formed to heat treatment under a
temperature condition of from 200°C to 425OC, to remove at least a part of the sealing layer
for a semiconductor that has been formed on an exposed face of the wiring.
2. The method for manufacturing a semiconductor device according to claim 1,
wherein the polymer has a cationic functional group equivalent weight of from 27 to 430.
3. The method for manufacturing a semiconductor device according to claim 1 or 2,
wherein the polymer is polyethyleneimine or a polyethyleneimine derivative.
4. The method for manufacturing a semiconductor device according to claim 1 or 2,
the method comprising a washing process of washing at least the side face and the bottom
face of the recess portion with a rinsing liquid having a temperature of from 15°C to 1 OO°C,
after the sealing composition appiication process but before the removal process.
5. The method for manufacturing a semiconductor device according to claim 4,
wherein the temperature of the rinsing liquid is from 30°C to 100°C.
6. The method for manufacturing a semiconductor device according to claim 1 or 2,
the method comprising a washing process of washing at least the side face and the bottom
face of the recess portion with a rinsing liquid having a pH at 25'C of 6 or lower, after the
68
sealing composition application process but before the removal process
7. The method for manufacturing a semiconductor device according to claim 6,
wherein the rinsing liquid includes a compound having, in one molecule thereof, at least one
of a moiety A that blocks an active species or a moiety B that forms a bond with the polymer
1 when heated.
8. Arinsing liquid for use in removal of at least a part of the sealing layer for a
semiconductor that is formed in the sealing composition application process in the method for
manufacturing a semiconduclor device according to claim 1 or 2, the rinsing liquid having a
pH at 25°C of 6 or lower.
9. A rinsing liquid for a sealing layer for a semiconductor, the sealing layer being
formed on a surface of an interlayer insulating layer of a semiconductor substrate that
includes the interlayer insulating layer, and being derived from a polymer having a cationic
: I
functional group and a weight average molecular weight of from 2,000 to 1,000,000,
. I the rinsing liquid comprising a compound having, in one molecule thereof, at least ~ I one of a moiety Athat blocks an active species or a moiety B that forms a bond with the
I i polymer when heated.
!
I
, I
! 10. The rinsing liquid according to claim 9, wherein the compound has, in one
molecule thereof, two or more carboxyl groups as the moiety B, and
wherein the compound has, in one molecule thereof, at least one of a structure in
which each of two neighboring carbon atoms bonds to a carboxyl group or a structure in
which each of two non-central carbon atoms from among three consecutive carbon atoms
bonds to a carboxyl group.
11. The rinsing liquid according to claim 9, wherein the compound has the rnoiety
A and the moiety B, the moiety A is at least one selected from the group consisting of an
aromatic ring structure, an alicyclic structure, a manganese atom, and a silicon atom, and the
moiety B is a carboxyl group.
12. A semiconductor device comprising, on a semiconductor substrate:
an interlayer insulating layer having a recess portion:
a first wiring that includes copper, and that is formed on the recess portion;
a sealing layer for a senliconductor that is present at least between a side face of the
recess portion of the interlayer insulating layer and the first wiring, and that includes a
polymer having a cationic functional group and a weight average molecular weight of from
2,000 to 1,000,000; and
a second wiring that contains copper, that has an upper face constituting at least a
part of a bottom face of the recess portion, and that is electrically connected to the first wiring
via the upper face,
wherein a thiclmess of the sealing layer for a semiconductor in a connection portion
,- * . Y - .- .- ., . . .~. ~. ~. -~, , .~ . ~
between the first wiring and the second wiring is 5 nm or less.
13. A semiconductor device comprising, on a semiconductor substrate:
an interlayer insulating layer;
a first wiring that includes copper; and
a sealing layer for a semiconductor that is present between the interlayer insulating
layer and the first wiring, and that includes a polymer having a cationic functional group and
a weight average molecular weight of from 2,000 to 1,000,000,
wherein the sealing layer for a semiconductor includes at least one selected from the
group consisting of an imide bond and an amide bond, and also includes at least one selected
from the group consisting of an aromatic ring structure, a manganese atom, and a silicon
I
atom.
14. The semiconductor device according to claim 12 or 13, wherein the polymer
has a cationic functional group equivalent weight of from 27 to 430.
15. The semiconductor device according to claim 12 or 13, wherein the polymer is
polyethyleneimine or a polyethyleneimine derivative.
16. The semiconductor device according to claim 12 or 13, wherein the interlayer
insulating layer is a porous interlayer insulating layer having an average pore radius of from
0.5 nm to 3.0 lun.