U.S. patent application number 11/602377 was filed with the patent office on 2007-04-12 for water-soluble material, chemically amplified resist and pattern formation method using the same.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to Masayuki Endo, Masaru Sasago.
Application Number | 20070082292 11/602377 |
Document ID | / |
Family ID | 34587649 |
Filed Date | 2007-04-12 |
United States Patent
Application |
20070082292 |
Kind Code |
A1 |
Endo; Masayuki ; et
al. |
April 12, 2007 |
Water-soluble material, chemically amplified resist and pattern
formation method using the same
Abstract
A water-soluble material used for forming a water-soluble film
on a chemically amplified resist film includes a water-soluble
polymer, an acid generator and a compound constructing an inclusion
compound for incorporating the acid generator. Also, in a pattern
formation method, a chemically amplified resist film is formed on a
substrate, and a water-soluble film made of a water-soluble
material including a water-soluble polymer, an acid generator and a
compound constructing an inclusion compound for incorporating the
acid generator is formed on the resist film. Thereafter, pattern
exposure is carried out by selectively irradiating the resist film
with exposing light through the water-soluble film, the resultant
resist film is developed and the water-soluble film is removed.
Thus, a resist pattern made of the resist film is formed.
Inventors: |
Endo; Masayuki; (Osaka,
JP) ; Sasago; Masaru; (Osaka, JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,
LTD.
Osaka
JP
|
Family ID: |
34587649 |
Appl. No.: |
11/602377 |
Filed: |
November 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11013333 |
Dec 17, 2004 |
|
|
|
11602377 |
Nov 21, 2006 |
|
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Current U.S.
Class: |
430/270.1 |
Current CPC
Class: |
G03F 7/0045 20130101;
G03F 7/11 20130101; G03F 7/0392 20130101; G03F 7/095 20130101 |
Class at
Publication: |
430/270.1 |
International
Class: |
G03C 1/00 20060101
G03C001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2003 |
JP |
2003-425071 |
Claims
1. A water-soluble material for forming a water-soluble film on a
chemically amplified resist film, comprising: a water-soluble
polymer; an acid generator; a surface active agent; and an
inclusion compound for incorporating said acid generator.
2. The water-soluble material of claim 1, wherein said inclusion
compound is cyclic oligosaccharide.
3-20. (canceled)
21. The water-soluble material of claim 2, wherein said cyclic
oligosaccharide is cyclodextrin.
22. The water-soluble material of claim 21, wherein said
cyclodextrin is .alpha.-cyclodextrin, .beta.-cyclodextrin,
.gamma.-cyclodextrin or .delta.-cyclodextrin.
23. The water-soluble material of claim 1, wherein said
water-soluble polymer is polyvinyl alcohol, polyvinyl pyrrolidone,
polystyrene sulfonic acid, polyacrylic acid or pullulan.
24. The water-soluble material of claim 1, wherein said surface
active agent is a cationic surface active agent or a nonionic
surface active agent.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.119
on Patent Application No. 2003-425071 filed in Japan on Dec. 22,
2003, the entire contents of which are hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a water-soluble material, a
chemically amplified resist and a pattern formation method using
the same for use in pattern formation in fabrication process or the
like for semiconductor devices.
[0003] In accordance with the increased degree of integration of
semiconductor integrated circuits and downsizing of semiconductor
devices, there are increasing demands for higher performance of
lithography technique. In particular, in order to refine patterns,
a chemically amplified resist is currently used as a resist
material. In the chemically amplified resist, an acid is generated
from an acid generator included therein through exposure and post
exposure bake, so as to cause a reaction of the resist by using the
generated acid as a catalyst. Thus, the resolution and the
sensitivity in the exposure are improved.
[0004] Now, a conventional pattern formation method will be
described with reference to FIGS. 7A through 7D.
[0005] First, a positive chemically amplified resist material
having the following composition is prepared: TABLE-US-00001 Base
polymer: poly((t-butyloxycarbonylmethyloxystyrene) 2 g (65 mol
%)-(hydroxystyrene) (35 mol %)) Acid generator: triphenylsulfonium
nonaflate 0.05 g Solvent: propylene glycol monomethyl ether acetate
18 g
[0006] Next, as shown in FIG. 7A, the aforementioned chemically
amplified resist material is applied on a substrate 1 so as to form
a resist film 2 with a thickness of 0.4 .mu.m .
[0007] Then, as shown in FIG. 7B, pattern exposure is carried out
by irradiating the resist film 2 with exposing light 3 of KrF
excimer laser with NA of 0.68 through a mask 4.
[0008] After the pattern exposure, as shown in FIG. 7C, the resist
film 2 is baked with a hot plate at a temperature of 105.degree. C.
for 60 seconds (post exposure bake).
[0009] Next, the resultant resist film is developed with a 2.38 wt
% tetramethylammonium hydroxide aqueous solution (alkaline
developer). In this manner, a resist pattern 2a made of an
unexposed portion of the resist film 2 and having a line width of
0.14 .mu.m is formed as shown in FIG. 7D.
[0010] As shown in FIG. 7D, however, the resist pattern 2a formed
by the conventional pattern formation method has a T-top shaped
defective portion designated as an insoluble skin layer 2b on the
uppermost portions of the side faces thereof (for example, see O.
P. Kishkovich and C. E. Larson, "Amine Control for DUV Lithography:
Identifying Hidden Sources", Proc. SPIE, 3999, 699(2000)).
[0011] When the resist pattern 2a in such a defective shape is used
for etching a target film, the resultant pattern of the target film
is also in a defective shape, which disadvantageously lowers the
productivity and the yield in the fabrication process for
semiconductor devices.
[0012] Such an insoluble skin layer in the T-top shape is formed
when a positive resist is used, and when a negative resist is used,
pattern failure derived from reduction in the film thickness
occurs.
SUMMARY OF THE INVENTION
[0013] In consideration of the aforementioned conventional problem,
an object of the invention is forming a fine resist pattern in a
good shape without forming an insoluble skin layer in
development.
[0014] The present inventors have made various examinations to find
the reason why an insoluble skin layer is formed in a chemically
amplified resist during development, resulting in reaching the
following conclusion: In general, an acid generator included in a
chemically amplified resist does not have high solubility in a
solvent, that is, the resist in this case, and hence, it is
difficult to dissolve a sufficient amount of acid generator in the
resist. Therefore, the amount of an acid generated through the
exposure and the post exposure bake tends to be insufficient.
Furthermore, when the acid generated in the exposure in an upper
portion of the resist film is neutralized and deactivated by an
impurity, such as ammonia, included in the atmosphere, the acid
cannot be obtained in a sufficient amount for the development.
Also, in the case where the amount of acid generator included in
the resist material is originally insufficient, the resolution of
the pattern is further lowered, resulting in forming an insoluble
skin layer.
[0015] Accordingly, the present inventors have found the following:
When a water-soluble film including a compound constructing an
inclusion compound capable of incorporating an acid generator is
formed on a resist film made of a chemically amplified resist or
when the compound constructing an inclusion compound is included in
a resist material itself, the reduced amount of the acid
deactivated in the upper portion of the resist film is compensated,
so as to prevent the formation of an insoluble skin layer.
[0016] The compound constructing an inclusion compound incorporates
a hydrophobic compound to make it dissolve in an aqueous solution.
The compound constructing an inclusion compound is a compound
having a cavity mainly in the center thereof and having a
cylindrical shape with a trapezoidal cross-section (bucket shape),
and a hydrophilic group is coordinated in an outer portion thereof
and a hydrophobic group is included in an inner portion thereof. In
other words, the compound constructing an inclusion compound
exhibits different properties between its outer portion and its
inner portion. Therefore, when the compound constructing an
inclusion compound is included in a water-soluble film formed on a
resist film or in a resist film itself, an acid generator, which is
generally difficult to dissolve in an aqueous solution, is
incorporated into the inclusion compound and hence can be stably
included in the water-soluble film or the resist film.
Specifically, the acid generator and the hydrophobic group present
in the inner portion of the inclusion compound are interacted with
each other, and hence, the acid generator is incorporated into the
inner portion of the inclusion compound. The hydrophilic group
present in the outer portion of the inclusion compound is
interacted with a water-soluble film component or a resist
component, and thus, a large amount of acid generator can be
dissolved in the water-soluble material or the resist. When the
water-soluble film including the compound constructing the
inclusion compound for incorporating the acid generator is formed
on a chemically amplified resist film in this manner and the
pattern exposure is performed through the resultant water-soluble
film, a large amount of acid is generated from the water-soluble
film formed on the resist film. This is because the acid generator
incorporated in the inclusion compound generates the acid through
irradiation with exposing light, and the generated acid is diffused
within the resist film from the upper portion thereof.
Alternatively, when the inclusion compound for incorporating the
acid generator is included in the resist film itself and the
pattern exposure is performed, a large amount of acid is generated
in an exposed portion of the resist film. This is because not only
an acid generator originally included in the resist film but also
the acid generator incorporated in the inclusion compound generate
the acid through irradiation with exposing light. As a result, even
when the generated acid is deactivated to some extent due to the
influence of an impurity included in the atmosphere, the acid
necessary for resolution can be sufficiently kept in the resist
film owing to the acid generated from the inclusion compound. Thus,
the formation of an insoluble skin layer can be prevented,
resulting in forming a fine pattern in a good shape. Since the
inclusion compound is composed of entangled linear polymers and
hence minimally has carbon multiple bonds such as an aromatic ring,
even when the acid generator is incorporated therein, sufficient
exposure for generating the acid can be attained.
[0017] The present invention was devised on the basis of the
aforementioned findings, and according to the present invention,
the formation of an insoluble skin layer formed in the upper
portion of a resist pattern is prevented by adding a compound
constructing an inclusion compound capable of incorporating an acid
generator to a resist film or a water-soluble film formed on a
resist film. Specifically, the invention is practiced as
follows:
[0018] The water-soluble material of the invention is used for
forming a water-soluble film on a chemically amplified resist film
and includes a water-soluble polymer; an acid generator; a surface
active agent; and an inclusion compound for incorporating the acid
generator.
[0019] When pattern exposure is performed with the water-soluble
film made of the water-soluble material of the invention formed on
a chemically amplified resist film, a large amount of acid is
generated from the inclusion compound incorporating the acid
generator in the water-soluble film. The generated acid is
uniformly dispersed from an upper portion of the chemically
amplified resist film, and therefore, even when the acid generated
in the upper portion of the resist film is deactivated due to the
influence of an impurity included in the atmosphere, the amount of
acid is sufficient for resolution, and hence, formation of an
insoluble skin layer can be prevented. As a result, a fine resist
pattern can be formed in a good shape.
[0020] The chemically amplified resist of this invention includes
an acid generator; and an inclusion compound for incorporating the
acid generator.
[0021] In the chemically amplified resist of this invention, a
large amount of acid is generated in pattern exposure from the
inclusion compound incorporating the acid generator. Therefore,
even when the acid generated in an upper portion of the resist film
is deactivated due to the influence of an impurity included in the
atmosphere, the amount of acid is sufficient for resolution, and
hence, formation of an insoluble skin layer can be prevented. As a
result, a fine resist pattern can be formed in a good shape.
[0022] In the water-soluble material or the chemically amplified
resist of the invention, the inclusion compound is preferably
cyclic oligosaccharide.
[0023] In this case, the cyclic oligosaccharide is preferably
cyclodextrin. As is generally known, cyclodextrin has a structure
having a trapezoidal cylindrical shape (bucket shape) and
constructs an inclusion compound by incorporating a guest compound
into the inside of the cylindrical shape. As the cyclodextrin,
.alpha.-cyclodextrin, .beta.-cyclodextrin, .gamma.-cyclodextrin or
.delta.-cyclodextrin may be used. The content of the cyclodextrin
is appropriately not smaller than 0.001 wt % and not larger than 1
wt %, which does not limit the invention.
[0024] In the water-soluble material of the invention, the
water-soluble polymer may be polyvinyl alcohol, polyvinyl
pyrrolidone, polystyrene sulfonic acid, polyacrylic acid or
pullulan.
[0025] The water-soluble material of the invention preferably
further includes a surface active agent. Thus, the effect of the
inclusion compound is promoted owing to the polarization function
of the surface active agent. This is because the inclusion compound
is improved in its hydrophilic property.
[0026] In this case, the surface active agent may be a cationic
surface active agent or a nonionic surface active agent. The
content of the surface active agent is appropriately not smaller
than 1.times.10.sup.-4 wt % and not larger than 1.times.10.sup.-2
wt %, which does not limit the invention.
[0027] The first pattern formation method of this invention
includes the steps of forming a chemically amplified resist film on
a substrate; forming, on the resist film, a water-soluble film
including a water-soluble polymer, an acid generator and an
inclusion compound for incorporating the acid generator; performing
pattern exposure by selectively irradiating the resist film with
exposing light through the water-soluble film; and developing the
resist film after removing the water-soluble film after the pattern
exposure.
[0028] According to the first pattern formation method of the
invention, a large amount of acid is generated in the pattern
exposure from the inclusion compound incorporating the acid
generator in the water-soluble film. The generated acid is
uniformly dispersed from an upper portion of the chemically
amplified resist film, and therefore, even when the acid generated
in the upper portion of the resist film is deactivated due to the
influence of an impurity included in the atmosphere, the amount of
acid is sufficient for resolution, and hence, formation of an
insoluble skin layer can be prevented. As a result, a fine resist
pattern can be formed in a good shape.
[0029] The second pattern formation method of this invention
includes the steps of forming a chemically amplified resist film on
a substrate; forming, on the resist film, a water-soluble film
including a water-soluble polymer, an acid generator and an
inclusion compound for incorporating the acid generator; performing
pattern exposure by selectively irradiating the resist film with
exposing light through the water-soluble film; and developing the
resist film and removing the water-soluble film after the pattern
exposure.
[0030] According to the second pattern formation method of the
invention, a large amount of acid is generated in the pattern
exposure from the inclusion compound incorporating the acid
generator in the water-soluble film. The generated acid is
uniformly dispersed from an upper portion of the chemically
amplified resist film, and therefore, even when the acid generated
in the upper portion of the resist film is deactivated due to the
influence of an impurity included in the atmosphere, the amount of
acid is sufficient for resolution, and hence, formation of an
insoluble skin layer can be prevented. As a result, a fine resist
pattern can be formed in a good shape.
[0031] In the first pattern formation method, the water-soluble
film is removed from above the resist film before the development,
and in the second pattern formation method, the water-soluble film
is removed from above the resist film during the development. In
the first pattern formation method, the development is ordinarily
proceeded because the water-soluble film is removed before the
development. In the second pattern formation method, the solution
property of the resist can be controlled and hence is improved
because the water-soluble film is removed during the development.
The control of the solution property will be described later.
[0032] The third pattern formation method of this invention
includes the steps of forming a chemically amplified resist film
including an acid generator and an inclusion compound for
incorporating the acid generator; performing pattern exposure by
selectively irradiating the resist film with exposing light; and
developing the resist film after the pattern exposure.
[0033] According to the third pattern formation method, in the
development of the resist film performed after the pattern
exposure, a large amount of acid is generated from the inclusion
compound included in the resist film and incorporating the acid
generator. Therefore, even when the acid generated in an upper
portion of the resist film is deactivated due to the influence of
an impurity included in the atmosphere, the amount of acid is
sufficient for resolution, and hence, formation of an insoluble
skin layer can be prevented. As a result, a fine resist pattern can
be formed in a good shape.
[0034] In any of the first through third pattern formation methods,
the inclusion compound is preferably cyclic oligosaccharide.
[0035] In this case, the cyclic oligosaccharide is preferably
cyclodextrin.
[0036] In this case, the cyclodextrin may be .alpha.-cyclodextrin,
.beta.-cyclodextrin, .gamma.-cyclodextrin or
.delta.-cyclodextrin.
[0037] In the first or second pattern formation method, the
water-soluble polymer may be polyvinyl alcohol, polyvinyl
pyrrolidone, polystyrene sulfonic acid, polyacrylic acid or
pullulan.
[0038] In the first or second pattern formation method, the
water-soluble material preferably further includes a surface active
agent.
[0039] In this case, the surface active agent may be a cationic
surface active agent or a nonionic surface active agent.
[0040] In any of the first through third pattern formation methods,
the exposing light may be KrF excimer laser, ArF excimer laser,
F.sub.2 laser, ArKr laser, Ar.sub.2 laser, extreme UV of a
wavelength band not shorter than 1 nm and not longer than 30 nm, or
electron beams.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIGS. 1A, 1B, 1C and 1D are cross-sectional views for
showing procedures in a pattern formation method using a
water-soluble material according to Embodiment 1 of the
invention;
[0042] FIGS. 2A and 2B are cross-sectional views for showing other
procedures in the pattern formation method using the water-soluble
material of Embodiment 1;
[0043] FIGS. 3A, 3B, 3C and 3D are cross-sectional views for
showing procedures in a pattern formation method using a
water-soluble material according to Embodiment 2 of the
invention;
[0044] FIG. 4 is a cross-sectional view of another procedure in the
pattern formation method using the water-soluble material of
Embodiment 2;
[0045] FIG. 5 is a graph for explaining control of solubility of a
resist in the pattern formation method using the water-soluble
material of Embodiment 2;
[0046] FIGS. 6A, 6B, 6C and 6D are cross-sectional views for
showing procedures in a pattern formation method using a chemically
amplified resist according to Embodiment 3 of the invention;
and
[0047] FIGS. 7A, 7B, 7C and 7D are cross-sectional views for
showing procedures in a conventional pattern formation method.
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
[0048] A pattern formation method using a water-soluble material
according to Embodiment 1 of the invention will now be described
with reference to FIGS. 1A through 1D, 2A and 2B.
[0049] First, a positive chemically amplified resist material
having the following composition is prepared: TABLE-US-00002 Base
polymer: poly((t-butyloxycarbonylmethyloxystyrene) 2 g (65 mol
%)-(hydroxystyrene) (35 mol %)) Acid generator: triphenylsulfonium
triflate 0.05 g Solvent: propylene glycol monomethyl ether acetate
18 g
[0050] Next, as shown in FIG. 1A, the aforementioned chemically
amplified resist material is applied on a substrate 101 so as to
form a resist film 102 with a thickness of 0.4 .mu.m.
[0051] Then, as shown in FIG. 1B, a water-soluble film 103 with a
thickness of 0.08 .mu.m made of a water-soluble material having the
following composition is formed on the resist film 102 by, for
example, spin coating: TABLE-US-00003 Base polymer: polyvinyl
alcohol 1 g Acid generator: diphenyliodonium triflate 0.04 g
Compound constructing inclusion compound: .alpha.-cyclodextrin 0.07
g Solvent: water 7.5 g
[0052] Next, as shown in FIG. 1C, pattern exposure is carried out
by irradiating the resist film 102 through the water-soluble film
103 with exposing light 105 of KrF excimer laser with NA of 0.68
having passed through a mask 104.
[0053] After the pattern exposure, as shown in FIG. 1D, the resist
film 102 is baked with a hot plate at a temperature of 105.degree.
C. for 60 seconds (post exposure bake).
[0054] Then, as shown in FIG. 2A, after removing the water-soluble
film 103 with water, the resultant resist film 102 is developed
with a 2.38 wt % tetramethylammonium hydroxide aqueous solution
(alkaline developer). In this manner, a resist pattern 102a made of
an unexposed portion of the resist film 102 and having a line width
of 0.14 .mu.m is formed as shown in FIG. 2B.
[0055] In this manner, in the pattern formation method of
Embodiment 1, the pattern exposure is performed with the
water-soluble film 103 including the acid generator and
.alpha.-cyclodextrin, that is, the compound constructing an
inclusion compound for incorporating the acid generator, formed on
the resist film 102. Therefore, in the pattern exposure, a large
amount of acid is generated from the acid generator incorporated in
the inclusion compound of the water-soluble film 103 through
irradiation with the exposing light. The acid thus generated in a
large amount is diffused in an upper portion of the resist film 102
through the following post exposure bake. Therefore, even when the
acid generated in the upper portion of the resist film 102 is
deactivated due to the influence of an impurity or the like
included in the atmosphere, a shortage of the acid necessary for
resolution can be avoided, resulting in forming the resist pattern
102a in a good shape.
[0056] The cyclodextrin included in the water-soluble film 103 is
not limited to .alpha.-cyclodextrin but may be .beta.-cyclodextrin,
.gamma.-cyclodextrin, .delta.-cyclodextrin or the like instead.
[0057] The base polymer of the water-soluble film 103 is not
limited to polyvinyl alcohol but may be polyvinyl pyrrolidone,
polystyrene sulfonic acid, polyacrylic acid or pullulan
instead.
Embodiment 2
[0058] A pattern formation method using a water-soluble material
according to Embodiment 2 of the invention will now be described
with reference to FIGS. 3A through 3D and 4.
[0059] First, a positive chemically amplified resist material
having the following composition is prepared: TABLE-US-00004 Base
polymer: poly((t-butyloxycarbonylmethyloxystyrene) 2 g (65 mol
%)-(hydroxystyrene) (35 mol %)) Acid generator: triphenylsulfonium
triflate 0.05 g Solvent: propylene glycol monomethyl ether acetate
18 g
[0060] Next, as shown in FIG. 3A, the aforementioned chemically
amplified resist material is applied on a substrate 201 so as to
form a resist film 202 with a thickness of 0.4 .mu.m.
[0061] Then, as shown in FIG. 3B, a water-soluble film 203 with a
thickness of 0.07 .mu.m made of a water-soluble material having the
following composition is formed on the resist film 202 by, for
example, the spin coating: TABLE-US-00005 Base polymer: polyvinyl
pyrrolidone 1 g Acid generator: triphenylsulfonium nonaflate 0.05 g
Compound constructing inclusion compound: 0.08 g
.beta.-cyclodextrin Surface active agent: cetylmethylammonium
chloride 0.0002 g Solvent: water 7.5 g
[0062] Next, as shown in FIG. 3C, pattern exposure is carried out
by irradiating the resist film 202 through the water-soluble film
203 with exposing light 205 of KrF excimer laser with NA of 0.68
having passed through a mask 204.
[0063] After the pattern exposure, as shown in FIG. 3D, the resist
film 202 is baked with a hot plate at a temperature of 105.degree.
C. for 60 seconds (post exposure bake).
[0064] Then, as shown in FIG. 4, the water-soluble film 203 is
removed and the resultant resist film 202 is developed with a 2.38
wt % tetramethylammonium hydroxide aqueous solution (alkaline
developer). In this manner, a resist pattern 202a made of an
unexposed portion of the resist film 202 and having a line width of
0.14 .mu.m is formed as shown in FIG. 4.
[0065] In this manner, in the pattern formation method of
Embodiment 2, the pattern exposure is performed with the
water-soluble film 203 including the acid generator,
.beta.-cyclodextrin, that is, the compound constructing an
inclusion compound for incorporating the acid generator, and the
surface active agent formed on the resist film 202. Therefore, in
the pattern exposure, a large amount of acid is generated from the
acid generator incorporated in the inclusion compound of the
water-soluble film 203 through irradiation with the exposing light
205. The acid thus generated in a large amount is diffused in an
upper portion of the resist film 202 through the following post
exposure bake. Therefore, even when the acid generated in the upper
portion of the resist film 202 is deactivated due to the influence
of an impurity or the like included in the atmosphere, a shortage
of the acid necessary for resolution can be avoided, resulting in
forming the resist pattern 202a in a good shape.
[0066] The cyclodextrin included in the water-soluble film 203 is
not limited to .beta.-cyclodextrin but may be .alpha.-cyclodextrin,
.gamma.-cyclodextrin, .delta.-cyclodextrin or the like instead.
[0067] The base polymer of the water-soluble film 203 is not
limited to polyvinyl pyrrolidone but may be polyvinyl alcohol,
polystyrene sulfonic acid, polyacrylic acid or pullulan
instead.
[0068] The surface active agent included in the water-soluble film
203 is not limited to cetylmethylammonium chloride, that is, a
cationic surface active agent, but may be a nonionic surface active
agent. Examples of the cationic surface active agent are, apart
from cetylmethylammonium chloride, stearylmethylammonium chloride,
stearyltrimethylammonium chloride, distearyldimethylammonium
chloride, stearyldimethylbenzylammonium chloride,
dodecylmethylammonium chloride, dodecyltrimethylammonium chloride,
benzylmethylammonium chloride, benzyltrimethylammonium chloride,
and benzalkonium chloride.
[0069] Also, examples of the nonionic surface active agent are
nonyl phenol ethoxylate, octylphenyl polyoxyethylene ether, lauryl
polyoxyethylene ether, cetyl polyoxyethylene ether, sucrose fatty
ester, polyoxyethylene lanolin fatty ester, polyoxyethylene
sorbitan fatty ester, polyoxyethylene glycol mono fatty ester,
fatty monoethanolamide, fatty diethanolamide and fatty
triethanolamide.
[0070] Furthermore, it is not always necessary to include the
surface active agent in the water-soluble film 203. On the
contrary, any of the aforementioned cationic surface active agents
and nonionic surface active agents may be included in the
water-soluble film 103 of Embodiment 1.
[0071] In the pattern formation method of Embodiment 2, differently
from that of Embodiment 1, the water-soluble film 203 is removed
during the development, namely, with the developer. Thus, the
solution property of the resist film 202 can be controlled. Now,
the control of the solution property will be described with
reference to FIG. 5.
[0072] In general, when the solution property of a resist in a
developer is high, the dissolving rate is abruptly increased when
exposure exceeds a given threshold value as shown with a graph A of
a broken line in FIG. 5. As the change of the dissolving rate
against the exposure is more abrupt, a difference in the solubility
between an exposed portion and an unexposed portion of the resist
film 202 is larger, and hence, higher resolution can be attained,
namely, the resist pattern 202a can be formed in a better shape.
Accordingly, in the case where the water-soluble film 203 is
removed simultaneously with the development, the dissolving rate is
wholly lowered during the removal of the water-soluble film 203 as
shown with a graph B of a solid line in FIG. 5, and hence, the
change in a portion surrounded with a circle C in the graph B can
be reduced to be approximated to a flat portion of the graph A. As
a result, in the case where the actual resist has the solution
property as shown with the graph B, the dissolving rate attained
with smaller exposure can be adjusted to attain a comparatively
constant solution state with small exposure and a low dissolving
rate within a given range. Accordingly, the difference in the
solubility between an exposed portion and an unexposed portion of
the resist film 202 can be substantially increased, resulting in
easily forming a resist pattern in a good shape.
Embodiment 3
[0073] A pattern formation method using a chemically amplified
resist according to Embodiment 3 of the invention will now be
described with reference to FIGS. 6A through 6D.
[0074] First, a positive chemically amplified resist material
having the following composition is prepared: TABLE-US-00006 Base
polymer: poly((t-butyloxycarbonylmethyloxystyrene) 2 g (65 mol
%)-(hydroxystyrene) (35 mol %)) Compound constructing inclusion
compound: .alpha.-cyclodextrin 0.25 g Acid generator:
triphenylsulfonium triflate 0.2 g Solvent: propylene glycol
monomethyl ether acetate 18 g
[0075] Next, as shown in FIG. 6A, the aforementioned chemically
amplified resist material is applied on a substrate 301 so as to
form a resist film 302 with a thickness of 0.4 .mu.m.
[0076] Then, as shown in FIG. 6B, pattern exposure is carried out
by irradiating the resist film 302 with exposing light 305 of KrF
excimer laser with NA of 0.68 through a mask 304.
[0077] After the pattern exposure, as shown in FIG. 6C, the resist
film 302 is baked with a hot plate at a temperature of 105.degree.
C. for 60 seconds (post exposure bake).
[0078] Then, as shown in FIG. 6D, the resultant resist film 202 is
developed with a 2.38 wt % tetramethylammonium hydroxide aqueous
solution (alkaline developer). In this manner, a resist pattern
302a made of an unexposed portion of the resist film 302 and having
a line width of 0.14 .mu.m is formed as shown in FIG. 6D.
[0079] In this manner, in the pattern formation method of
Embodiment 3, the chemically amplified resist material including
the acid generator includes .alpha.-cyclodextrin, that is, the
compound constructing an inclusion compound for incorporating the
acid generator. Therefore, in the pattern exposure, a large amount
of acid is generated from the acid generator incorporated in the
inclusion compound through irradiation with the exposing light 305.
The acid thus generated in a large amount is diffused in the resist
film 302 through the following post exposure bake. Therefore, even
when the acid generated in an upper portion of the resist film 302
is deactivated due to the influence of an impurity or the like
included in the atmosphere, a shortage of the acid necessary for
resolution can be avoided, resulting in forming the resist pattern
302a in a good shape.
[0080] The cyclodextrin included in the chemically amplified resist
is not limited to .alpha.-cyclodextrin but may be
.beta.-cyclodextrin, .gamma.-cyclodextrin, .delta.-cyclodextrin or
the like instead.
[0081] In each of Embodiments 1 through 3, the exposing light used
for the pattern exposure is not limited to the KrF excimer laser
but may be ArF excimer laser, F.sub.2 laser, ArKr laser, Ar.sub.2
laser, extreme UV of a wavelength band not shorter than 1 nm and
not longer than 30 nm or electron beams.
[0082] Although the positive chemically amplified resist is used in
each of Embodiments 1 through 3, the present invention is
applicable to a negative chemically amplified resist.
[0083] As described so far, according to the water-soluble
material, the chemically amplified resist and the pattern formation
method of the invention, occurrence of pattern failure caused by an
insoluble skin layer in a resist pattern after development can be
prevented, and therefore, the resist pattern can be formed in a
good shape. Thus, the invention is useful as a water-soluble
material, a chemically amplified resist and a pattern formation
method using the same for use in pattern formation of fabrication
process or the like of semiconductor devices.
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