U.S. patent application number 11/376188 was filed with the patent office on 2006-07-20 for pattern formation method and exposure system.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to Masayuki Endo, Masaru Sasago.
Application Number | 20060160032 11/376188 |
Document ID | / |
Family ID | 33410573 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060160032 |
Kind Code |
A1 |
Endo; Masayuki ; et
al. |
July 20, 2006 |
Pattern formation method and exposure system
Abstract
After forming a resist film made from a chemically amplified
resist material, pattern exposure is carried out by irradiating the
resist film with exposing light while supplying, between a
projection lens and the resist film, a solution of water (having a
refractive index of 1.44) that includes an antifoaming agent and is
circulated and temporarily stored in a solution storage. After the
pattern exposure, the resist film is subjected to post-exposure
bake, and the resultant resist film is developed with an alkaline
developer. Thus, a resist pattern made of an unexposed portion of
the resist film can be formed in a good shape.
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: |
33410573 |
Appl. No.: |
11/376188 |
Filed: |
March 16, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10640061 |
Aug 14, 2003 |
|
|
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11376188 |
Mar 16, 2006 |
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Current U.S.
Class: |
430/322 ;
430/395 |
Current CPC
Class: |
G03F 7/2041
20130101 |
Class at
Publication: |
430/322 ;
430/395 |
International
Class: |
G03F 7/00 20060101
G03F007/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 9, 2003 |
JP |
2003-131161 |
Claims
1-9. (canceled)
10. An exposure system comprising: a lens for projecting, on a
resist film, exposing light having passed through a mask; a
solution storage provided between said resist film and said lens
for temporarily storing a solution through which said exposing
light having been projected by said lens passes before reaching
said resist film; an inlet for allowing said solution to flow into
said solution storage; and an outlet for allowing said solution
temporarily stored in said solution storage to flow out of said
solution storage.
11. The exposure system of claim 10, wherein said outlet has a
smaller cross-sectional area than said inlet.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a pattern formation method
for use in semiconductor fabrication and an exposure system
employing the pattern formation method.
[0002] In accordance with the increased degree of integration of
semiconductor integrated circuits and downsizing of semiconductor
devices, there are increasing demands for further rapid development
of lithography technique. Currently, pattern formation is carried
out through photolithography using exposing light of a mercury
lamp, KrF excimer laser, ArF excimer laser or the like, and use of
F.sub.2 laser lasing at a shorter wavelength is being examined.
However, since there remain a large number of problems in exposure
systems and resist materials, photolithography using exposing light
of a shorter wavelength has not been put to practical use.
[0003] In these circumstances, immersion lithography has recently
been proposed for realizing further refinement of patterns by using
conventional exposing light (M. Switkes and M. Rothschild,
"Immersion lithography at 157 nm", J. Vac. Sci. Technol., B19, 2353
(2001)).
[0004] In the immersion lithography, a region in an exposure system
sandwiched between a projection lens and a resist film formed on a
wafer is filled with a solution having a refractive index n, and
therefore, the NA (numerical aperture) of the exposure system has a
value nNA. As a result, the resolution of the resist film can be
improved.
[0005] Now, a conventional pattern formation method using the
immersion lithography will be described with reference to FIGS. 7A
through 7D.
[0006] First, a chemically amplified resist material having the
following composition is prepared: TABLE-US-00001 Base polymer:
poly((norbornene-5-methylene-t-butyl- 2 g carboxylate) - (maleic
anhydride)) (wherein norbornene-
5-methylene-t-butylcarboxylate:maleic anhydride = 50 mol %:50 mol
%) Acid generator: trifluorosulfonium triflate 0.04 g Solvent:
propylene glycol monomethyl ether acetate 20 g
[0007] 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 0.35 .mu.m.
[0008] Then, as shown in FIG. 7B, while supplying water 3 onto the
resist film 2, pattern exposure is carried out by irradiating the
resist film 2 with exposing light 4 of ArF excimer laser with NA of
0.65 through a mask 5. Although a projection lens for projecting
the exposing light 4 having passed through the mask 5 on the
surface of the resist film 2 is not shown in FIG. 7B, a region
sandwiched between the projection lens and the resist film 2 is
filled with the water 3. Thus, an exposed portion 2a of the resist
film 2 becomes soluble in an alkaline developer because an acid is
generated from the acid generator therein while an unexposed
portion 2b of the resist film 2 remains insoluble in an alkaline
developer because no acid is generated from the acid generator
therein.
[0009] After the pattern exposure, as shown in FIG. 7C, the resist
film 2 is baked with a hot plate at a temperature of 110.degree. C.
for 60 seconds, and the resultant resist film is developed with a
2.38 wt % tetramethylammonium hydroxide developer (alkaline
developer). In this manner, a resist pattern 6 made of the
unexposed portion 2b of the resist film 2 can be obtained as shown
in FIG. 7D.
[0010] However, as shown in FIG. 7D, the resist pattern 6 formed by
the conventional method is in a defective shape.
[0011] The present inventors have examined the reason why the
resist pattern 6 formed by the conventional method is in a
defective shape, resulting in finding the following: When a stage
of the exposure system for holding the substrate 1 moves, foams are
formed within the solution 3, and the foams scatter the exposing
light 4. As a result, the exposing light 4 reaches the unexposed
portion 2b of the resist film 2 or the exposed portion 2a of the
resist film 2 is excessively exposed. This causes the defect in the
shape of the resist pattern 6.
[0012] When a resist pattern in such a defective shape is used for
etching a target film, the resultant pattern is also in a defective
shape, which disadvantageously lowers the productivity and the
yield in the fabrication process for semiconductor devices.
SUMMARY OF THE INVENTION
[0013] In consideration of the aforementioned conventional problem,
an object of the invention is forming a resist pattern in a good
shape by reducing foams formed in a solution used for the immersion
lithography.
[0014] In order to achieve the object, the first pattern formation
method of this invention includes the steps of performing pattern
exposure by selectively irradiating a resist film with exposing
light while supplying a solution including an antifoaming agent
onto the resist film; and forming a resist pattern by developing
the resist film after the pattern exposure.
[0015] In the first pattern formation method, even when foams are
formed in the solution supplied onto the resist film, the foams are
vanished by the antifoaming agent. Therefore, the exposing light
can be prevented from scattering, so that the resist pattern can be
formed in a good shape.
[0016] The second pattern formation method of this invention
includes the steps of performing pattern exposure by selectively
irradiating a resist film with exposing light while supplying a
solution onto the resist film; and forming a resist pattern by
developing the resist film after the pattern exposure, and in the
step of performing pattern exposure, the solution supplied onto the
resist film is temporarily stored in a solution storage that is
provided between the resist film and a lens used for projecting the
exposing light to the resist film and has an inlet for allowing the
solution to flow in and an outlet, having a cross-sectional area
smaller than the inlet, for allowing the solution to flow out.
[0017] In the second pattern formation method, since the outlet for
allowing the solution to flow out of the solution storage has a
smaller cross-sectional area then the inlet for allowing the
solution to flow into the solution storage, the pressure of the
solution temporarily stored in the solution storage is high.
Therefore, the size of foams formed in the solution supplied onto
the resist film is reduced and the formed foams are rapidly
vanished. Accordingly, the exposing light can be prevented from
scattering, so that the resist pattern can be formed in a good
shape.
[0018] In the first or second pattern formation method, the
solution supplied onto the resist film is preferably water.
[0019] When water having a high refractive index is used as the
solution, a value nNA can be definitely increased.
[0020] In the first or second pattern formation method, the
solution supplied onto the resist film is preferably
perfluoropolyether.
[0021] When perfluoropolyether is used as the solution, even if a
water-soluble film is formed on the resist film, the water-soluble
film can be prevented from being dissolved in the solution.
[0022] In the second pattern formation method, the solution
supplied onto the resist film preferably includes an antifoaming
agent.
[0023] Thus, the foams formed in the solution supplied onto the
resist film can be more rapidly vanished.
[0024] In the first or second pattern formation method, in the case
where the solution supplied onto the resist film includes an
antifoaming agent, the antifoaming agent is preferably silicone
oil, fatty acid, phosphoric ester, vegetable fat, glycerol fatty
ester, calcium carbonate, magnesium carbonate, lecithin or
polyether.
[0025] Thus, the foams formed in the solution can be definitely
vanished.
[0026] The exposure system of this invention includes a lens for
projecting, on a resist film, exposing light having passed through
a mask; a solution storage provided between the resist film and the
lens for temporarily storing a solution through which the exposing
light having been projected by the lens passes before reaching the
resist film; an inlet for allowing the solution to flow into the
solution storage; and an outlet for allowing the solution
temporarily stored in the solution storage to flow out of the
solution storage.
[0027] In the exposure system of this invention, a region in the
exposure system sandwiched between a projection lens and a resist
film can be filled with a solution having a refractive index n.
Therefore, the value of the NA (numerical aperture) of the exposure
system can be increased to nNA, so as to improve the resolution of
the resist film.
[0028] In the exposure system of this invention, the outlet
preferably has a smaller cross-sectional area than the inlet.
[0029] When the outlet for allowing the solution to flow out of the
solution storage has a smaller cross-sectional area than the inlet
for allowing the solution to flow into the solution storage, the
pressure of the solution temporarily stored in the solution storage
is high. Therefore, the size of foams formed in the solution
supplied onto the resist film can be reduced and the formed foams
can be rapidly vanished. Accordingly, the exposing light can be
prevented from scattering, so that a resist pattern can be formed
in a good shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a cross-sectional view of a principal part of a
first exposure system used in a pattern formation method according
to Embodiment 1 or 2 of the invention;
[0031] FIGS. 2A, 2B, 2C and 2D are cross-sectional views for
showing procedures in the pattern formation method according to
Embodiment 1 of the invention;
[0032] FIGS. 3A, 3B, 3C and 3D are cross-sectional views for
showing procedures in the pattern formation method according to
Embodiment 2 of the invention;
[0033] FIG. 4 is a cross-sectional view of a principal part of a
second exposure system used in a pattern formation method according
to Embodiment 3 or 4 of the invention;
[0034] FIGS. 5A, 5B, 5C and 5D are cross-sectional views for
showing procedures in the pattern formation method according to
Embodiment 3 of the invention;
[0035] FIGS. 6A, 6B, 6C and 6D are cross-sectional views for
showing procedures in the pattern formation method according to
Embodiment 4 of the invention; and
[0036] 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
[0037] First, a first exposure system used in a pattern formation
method according to Embodiment 1 will be described with reference
to FIG. 1.
[0038] As shown in FIG. 1, a projection lens 12 of the first
exposure system is provided above a resist film 11 formed on a
semiconductor substrate 10, and a solution storage 14 for storing a
solution 13 (with a refractive index n) is provided between the
projection lens 12 and the resist film 11. The solution storage 14
is provided with an inlet 14a for allowing the solution 13 to flow
into and an outlet 14b for allowing the solution 13 to flow out of
the solution storage 14, and the solution 13 having flown into the
solution storage 14 through the inlet 14a is temporarily stored in
the solution storage 14 and then flows out through the outlet 14b.
Accordingly, exposing light 15 passes through a mask 16 having a
desired pattern and is then projected by the projection lens 12 so
as to reach the surface of the resist film 11 through the solution
13. Therefore, the numerical aperture NA of the exposing light that
reaches the surface of the resist film 11 through the solution 13
has a value "n" times as large as that attained when the exposing
light reaches without passing through the solution 13.
[0039] The pattern formation method according to Embodiment 1 of
the invention will now be described with reference to FIGS. 2A
through 2D.
[0040] First, a positive chemically amplified resist material
having the following composition is prepared: TABLE-US-00002 Base
polymer: poly((norbornene-5-methylene-t-butyl- 2 g carboxylate) -
(maleic anhydride)) (wherein norbornene-
5-methylene-t-butylcarboxylate:maleic anhydride = 50 mol %:50 mol
%) Acid generator: trifluorosulfonium triflate 0.04 g Solvent:
propylene glycol monomethyl ether acetate 20 g
[0041] Next, as shown in FIG. 2A, the aforementioned chemically
amplified resist material is applied on a substrate 101 so as to
form a resist film 102 with a thickness of 0.35 .mu.m.
[0042] Then, as shown in FIG. 2B, while supplying, between a
projection lens 106 and the resist film 102, a solution 103 of
water (having a refractive index n of 1.44) that includes 100
p.p.m. of silicone oil working as an antifoaming agent and is
circulated and temporarily stored in the solution storage 14 (shown
in FIG. 1), pattern exposure is carried out by irradiating the
resist film 102 with exposing light 104 of ArF excimer laser with
NA of 0.65 through a mask not shown. Thus, an exposed portion 102a
of the resist film 102 becomes soluble in an alkaline developer
because an acid is generated from the acid generator therein while
an unexposed portion 102b of the resist film 102 remains insoluble
in an alkaline developer because no acid is generated from the acid
generator therein.
[0043] After the pattern exposure, as shown in FIG. 2C, the resist
film 102 is baked with a hot plate at a temperature of 100.degree.
C. for 60 seconds, and the resultant resist film is developed with
a 2.38 wt % tetramethylammonium hydroxide developer (alkaline
developer). In this manner, a resist pattern 105 made of the
unexposed portion 102b of the resist film 102 and having a line
width of 0.09 .mu.m can be formed in a good shape as shown in FIG.
2D.
[0044] In Embodiment 1, since the solution 103 includes the
antifoaming agent, foams formed in moving a stage for holding the
substrate 101 can be vanished by the antifoaming agent. As a
result, the exposing light 104 can be prevented from scattering, so
that the resist pattern 105 can be formed in a good shape.
Embodiment 2
[0045] A pattern formation method according to Embodiment 2 of the
invention will now be described with reference to FIGS. 1 and 3A
through 3D. In the pattern formation method of Embodiment 2, the
first exposure system shown in FIG. 1 is used as in Embodiment
1.
[0046] First, a negative chemically amplified resist material
having the following composition is prepared: TABLE-US-00003 Base
polymer: poly((norbornene-5-methylenecarboxylate) - 2 g (maleic
anhydride)) (wherein norbornene-5-methylene- carboxylate:maleic
anhydride = 50 mol %:50 mol %) Crosslinking agent:
1,3,5-N-(trihydroxymethyl)melamine 0.7 g Acid generator:
trifluorosulfonium triflate 0.04 g Solvent: propylene glycol
monomethyl ether acetate 20 g
[0047] 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 0.35 .mu.m.
[0048] Then, as shown in FIG. 3B, while supplying, between a
projection lens 206 and the resist film 202, a solution 203 of
water (having a refractive index n of 1.44) that includes 100
p.p.m. of silicone oil working as an antifoaming agent and is
circulated and temporarily stored in the solution storage 14 (shown
in FIG. 1), pattern exposure is carried out by irradiating the
resist film 202 with exposing light 204 of ArF excimer laser with
NA of 0.65 through a mask not shown. Thus, an exposed portion 202a
of the resist film 202 becomes insoluble in an alkaline developer
due to the function of the crosslinking agent because an acid is
generated from the acid generator therein while an unexposed
portion 202b of the resist film 202 remains soluble in an alkaline
developer because no acid is generated from the acid generator
therein.
[0049] After the pattern exposure, as shown in FIG. 3C, the resist
film 202 is baked with a hot plate at a temperature of 120.degree.
C. for 90 seconds, and the resultant resist film is developed with
a 2.38 wt % tetramethylammonium hydroxide developer (alkaline
developer). In this manner, a resist pattern 205 made of the
exposed portion 202a of the resist film 202 and having a line width
of 0.09 .mu.m can be formed in a good shape as shown in FIG.
3D.
[0050] In Embodiment 2, since the solution 203 includes the
antifoaming agent, foams formed in moving the stage for holding the
substrate 201 can be vanished by the antifoaming agent. As a
result, the exposing light 204 can be prevented from scattering, so
that the resist pattern 205 can be formed in a good shape.
[0051] Examples of the antifoaming agent included in the solution
103 or 203 in the pattern formation method of Embodiment 1 or 2 are
a foam breaker, a foam inhibitor and a defoaming agent, which does
not limit the invention. A foam breaker is adsorbed onto a foam and
enters the surface film of the foam through the function of surface
tension. Thereafter, the foam breaker expands over the surface film
of the foam through the surface tension, and this reduces the
thickness of the surface film, so that the surface film can be
ultimately broken. A foam inhibitor is adsorbed onto the surface
film of a foam together with a foaming substance in a solution.
When the foam inhibitor is adsorbed, the surface tension of the
surface film of the foam is lowered, so as to reduce the thickness
of the surface film. Therefore, the foam becomes unstable and
breaks when it reaches the solution surface. A defoaming agent is
adsorbed onto the surface film of a foam in a solution. When such
foams are adsorbed to one another in the solution, the foams are
broken on the adsorbed interfaces, and hence, the foams are
combined to form a large foam. The large foam has a large ascending
force and hence ascends to the solution surface at a high
speed.
[0052] The antifoaming agent may be but is not limited to silicone
oil, fatty acid, phosphoric ester, vegetable fat, glycerol fatty
ester, calcium carbonate, magnesium carbonate, lecithin or
polyether.
[0053] A sufficient effect can be generally attained when the
content of the antifoaming agent is approximately several p.p.m.
through 1%, and the content may be larger or smaller.
[0054] In consideration of light transmittance, in the case where
the exposing light 104 or 204 is V, such as a g-line or an i-line,
or far UV, such as KrF excimer laser or ArF excimer laser, the
solution 103 or 203 is preferably water (having a refractive index
n of 1.44), and in the case where the exposing light 104 or 204 is
vacuum UV such as F.sub.2 laser, the solution 103 or 203 is
preferably perfluoropolyether (having a refractive index n of
1.37).
Embodiment 3
[0055] First, a second exposure system used in a pattern formation
method according to Embodiment 3 of the invention will be described
with reference to FIG. 4.
[0056] As shown in FIG. 4, a projection lens 22 of the second
exposure system is provided above a resist film 21 formed on a
semiconductor substrate 20, and a solution storage 24 for storing a
solution 23 (with a refractive index n) is provided between the
projection lens 22 and the resist film 21. The solution storage 24
is provided with an inlet 24a for allowing the solution 23 to flow
into and an outlet 24b for allowing the solution 23 to flow out of
the solution storage 24, and the solution 23 having flown into the
solution storage 24 through the inlet 24a is temporarily stored in
the solution storage 24 and then flows out through the outlet 24b.
Accordingly, the numerical aperture NA of exposing light 25 that
reaches the surface of the resist film 21 through the solution 23
has a value "n" times as large as that attained when the exposing
light reaches without passing through the solution 23.
[0057] In the second exposure system, the outlet 24b has a smaller
cross-sectional area than the inlet 24a. Therefore, the pressure of
the solution 23 stored in the solution storage 24 is higher than
the pressure of the solution 13 stored in the solution storage 14
of the first exposure system in which the outlet 14b and the inlet
14a have the same cross-sectional area. Accordingly, foams formed
in the solution 23 in moving a stage for holding the substrate 20
can be rapidly vanished, and hence, the foams formed within the
solution 23 can be reduced.
[0058] The outlet 24b can be provided with a smaller
cross-sectional area than the inlet 24a as follows: In the case
where the outlet 24b and the inlet 24a are the same in number, the
cross-sectional area of each outlet 24b is set to be smaller than
that of each inlet 24a. In the case where the outlet 24b and the
inlet 24a are the same in the cross-sectional area, the number of
outlets 24b is set to be smaller than the number of inlets 24a.
[0059] The pattern formation method according to Embodiment 3 of
the invention will now be described with reference to FIGS. 5A
through 5D.
[0060] First, a chemically amplified resist material having the
following composition is prepared: TABLE-US-00004 Base polymer:
poly((norbornene-5-methylene-t-butyl- 2 g carboxylate) - (maleic
anhydride)) (wherein norbornene-5-
methylene-t-butylcarboxylate:maleic anhydride = 50 mol %:50 mol %)
Acid generator: trifluorosulfonium triflate 0.04 g Solvent:
propylene glycol monomethyl ether acetate 20 g
[0061] Next, as shown in FIG. 5A, the aforementioned chemically
amplified resist material is applied on a substrate 301 so as to
form a resist film 302 with a thickness of 0.35 .mu.m.
[0062] Then, as shown in FIG. 5B, while supplying, between a
projection lens 306 and the resist film 302, a solution 303 of
water that is circulated and temporarily stored in the solution
storage 24 (shown in FIG. 4), pattern exposure is carried out by
irradiating the resist film 302 with exposing light 304 of ArF
excimer laser with NA of 0.65 through a mask not shown. Thus, an
exposed portion 302a of the resist film 302 becomes soluble in an
alkaline developer because an acid is generated from the acid
generator therein while an unexposed portion 302b of the resist
film 302 remains insoluble in an alkaline developer because no acid
is generated from the acid generator therein.
[0063] After the pattern exposure, as shown in FIG. 5C, the resist
film 302 is baked with a hot plate at a temperature of 100.degree.
C. for 60 seconds, and the resultant resist film is developed with
a 2.38 wt % tetramethylammonium hydroxide developer (alkaline
developer). In this manner, a resist pattern 305 made of the
unexposed portion 302b of the resist film 302 and having a line
width of 0.09 .mu.m can be formed in a good shape as shown in FIG.
5D.
[0064] In Embodiment 3, since the cross-sectional area of the
outlet 24b for allowing the solution to flow out of the solution
storage 24 is smaller than that of the inlet 24a for allowing the
solution to flow into the solution storage 24 in the second
exposure system, the pressure of the solution 303 temporarily
stored in the solution storage 24 is high. Therefore, the size of
foams formed in the solution 303 is reduced and the formed foams
are rapidly vanished. As a result, the exposing light 304 can be
prevented from scattering, so that the resist pattern 305 can be
formed in a good shape.
Embodiment 4
[0065] A pattern formation method according to Embodiment 4 of the
invention will now be described with reference to FIGS. 6A through
6D. In the pattern formation method of Embodiment 4, the second
exposure system shown in FIG. 4 is used as in Embodiment 3.
[0066] First, a negative chemically amplified resist material
having the following composition is prepared: TABLE-US-00005 Base
polymer: poly((norbornene-5-methylenecarboxylate) - 2 g (maleic
anhydride)) (wherein norbornene-5-methylene- carboxylate:maleic
anhydride = 50 mol %:50 mol %) Crosslinking agent:
1,3,5-N-(trihydroxymethyl)melamine 0.7 g Acid generator:
trifluorosulfonium triflate 0.04 g Solvent: propylene glycol
monomethyl ether acetate 20 g
[0067] Next, as shown in FIG. 6A, the aforementioned chemically
amplified resist material is applied on a substrate 401 so as to
form a resist film 402 with a thickness of 0.35 .mu.m.
[0068] Then, as shown in FIG. 6B, while supplying, between a
projection lens 406 and the resist film 402, a solution 403 of
water that is circulated and temporarily stored in the solution
storage 24 (shown in FIG. 4), pattern exposure is carried out by
irradiating the resist film 402 with exposing light 404 of ArF
excimer laser with NA of 0.65 through a mask not shown. Thus, an
exposed portion 402a of the resist film 402 becomes insoluble in an
alkaline developer due to the function of the crosslinking agent
because an acid is generated from the acid generator therein while
an unexposed portion 402b of the resist film 402 remains soluble in
an alkaline developer because no acid is generated from the acid
generator therein.
[0069] After the pattern exposure, as shown in FIG. 6C, the resist
film 402 is baked with a hot plate at a temperature of 120.degree.
C. for 90 seconds, and the resultant resist film is developed with
a 2.38 wt % tetramethylammonium hydroxide developer (alkaline
developer). In this manner, a resist pattern 405 made of the
exposed portion 402a of the resist film 402 and having a line width
of 0.09 .mu.m can be formed in a good shape as shown in FIG.
6D.
[0070] In Embodiment 4, since the cross-sectional area of the
outlet 24b for allowing the solution to flow out of the solution
storage 24 is smaller than that of the inlet 24a for allowing the
solution to flow into the solution storage 24 in the second
exposure system, the pressure of the solution 403 temporarily
stored in the solution storage 24 is high. Therefore, the size of
foams formed in the solution 403 is reduced and the formed foams
are rapidly vanished. As a result, the exposing light 404 can be
prevented from scattering, so that the resist pattern 405 can be
formed in a good shape.
[0071] Although the solution 303 or 403 of Embodiment 3 or 4 does
not include an antifoaming agent, it may include an antifoaming
agent similar to that used in Embodiment 1 or 2. Thus, the foams
formed in the solution 303 or 403 can be more rapidly vanished.
* * * * *