U.S. patent application number 11/715852 was filed with the patent office on 2007-07-05 for semiconductor manufacturing apparatus and pattern formation method.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to Masayuki Endo, Masaru Sasago.
Application Number | 20070153245 11/715852 |
Document ID | / |
Family ID | 34436988 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070153245 |
Kind Code |
A1 |
Endo; Masayuki ; et
al. |
July 5, 2007 |
Semiconductor manufacturing apparatus and pattern formation
method
Abstract
A semiconductor manufacturing apparatus includes a liquid
supplying section for supplying a liquid onto a stage for holding a
wafer on which a resist film is formed; an exposing section for
irradiating the resist film with exposing light through a mask with
the liquid provided on the resist film; and a removing part for
removing, from the liquid, a gas included in the liquid. Thus, the
liquid from which the gas has been removed is provided on the
resist film, and therefore, foams included in the liquid or formed
during the exposure can be removed. Accordingly, exposure
abnormality such as diffraction abnormality can be prevented,
resulting in forming a resist pattern in a good shape.
Inventors: |
Endo; Masayuki; (Osaka,
JP) ; Sasago; Masaru; (Osaka, JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, NW
WASHINGTON
DC
20005-3096
US
|
Assignee: |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,
LTD.
Osaka
JP
|
Family ID: |
34436988 |
Appl. No.: |
11/715852 |
Filed: |
March 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10983655 |
Nov 9, 2004 |
7195860 |
|
|
11715852 |
Mar 9, 2007 |
|
|
|
Current U.S.
Class: |
355/30 ; 355/53;
359/649; 359/656; 430/302; 430/322; 430/331 |
Current CPC
Class: |
G03F 7/70341
20130101 |
Class at
Publication: |
355/030 ;
430/302; 430/322; 430/331; 355/053; 359/649; 359/656 |
International
Class: |
G03B 27/52 20060101
G03B027/52; G03B 27/42 20060101 G03B027/42; G02B 3/00 20060101
G02B003/00; G03C 5/00 20060101 G03C005/00; G03F 7/00 20060101
G03F007/00; G03F 7/26 20060101 G03F007/26; G02B 21/02 20060101
G02B021/02; G02B 9/00 20060101 G02B009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 13, 2003 |
JP |
JP 2003-383784 |
May 17, 2004 |
JP |
JP 2004-146217 |
Claims
1. A semiconductor manufacturing apparatus comprising: a stage
having a substrate on which a resist film is formed; a liquid
supplying section for providing a liquid onto said stage; an
exposing section which irradiates said resist film with exposing
light through a mask with said liquid provided on said resist film;
and a removing unit which removes a gas included in said
liquid.
2. The semiconductor manufacturing apparatus of claim 1, wherein
said removing unit degases said liquid supplied onto said resist
film and is disposed between said liquid supplying section and said
exposing section or within said liquid supplying section.
3. The semiconductor manufacturing apparatus of claim 1, wherein
said liquid supplying section includes a unit which sprays said
liquid.
4. A semiconductor manufacturing apparatus comprising: a stage
having a substrate on which a resist film is formed; a liquid
supplying section for providing a liquid onto said stage; an
exposing section which irradiates said resist film with exposing
light through a mask with said liquid provided on said resist film;
and a degassing section which removes a gas included in said
liquid, wherein said degassing section includes: a removing part
which removes a gas from said liquid having been provided from said
liquid supplying section; a first supplying path which provides,
onto said resist film, said liquid from which said gas has been
removed; and a second supplying path which provides, to said
removing part, said liquid having been provided onto said resist
film.
5. A semiconductor manufacturing apparatus comprising: an exposing
section which irradiates, with exposing light through a mask, a
resist film formed on a substrate, with a liquid provided on said
resist film; a supplying section which provides said liquid between
said resist film and said exposing section; a collecting section
which collects said liquid having been supplied onto said resist
film; and a controlling section which controls a liquid supplying
operation of said supplying section, a liquid collecting operation
of said collecting section and an operation of a stage having said
substrate.
6. The semiconductor manufacturing apparatus of claim 5, wherein
said controlling section controls the liquid supplying operation
and the liquid collecting operation and adjusts the operation of
said stage in such a manner that a flow rate and a flowing
direction of said liquid caused on said resist film by the liquid
supplying operation and the liquid collecting operation
substantially accord with a movement rate and a moving direction of
said stage.
7. The semiconductor manufacturing apparatus of claim 4, wherein
said liquid collected through said collecting path to said removing
part is degassed in said removing part and provides onto said
resist film through said supplying path.
8. The semiconductor manufacturing apparatus of claim 5, wherein
said collecting section and said supplying section are mutually
connected, and said liquid having been collected by said collecting
section flows into said supplying section.
9. The semiconductor manufacturing apparatus of claim 4, wherein
said liquid is composed of water or perfluoropolyether.
10. The semiconductor manufacturing apparatus of claim 4, wherein
said exposing light is KrF excimer laser, ArF excimer laser,
F.sub.2 laser, Kr.sub.2 laser, ArKr laser, Ar.sub.2 laser or
Xe.sub.2 laser.
11. A semiconductor manufacturing apparatus comprising: a stage
having a substrate on which a resist film is formed; a supplying
section which provides a liquid onto said stage; and an exposing
section which irradiates said resist film with exposing light
through a mask with said liquid provided on said resist film,
wherein said supplying section includes a bath which stores said
liquid and a spraying nozzle for providing said liquid into said
bath.
12. The semiconductor manufacturing apparatus of claim 11, wherein
said exposing section and said supplying section are disposed
within one chamber.
13. The semiconductor manufacturing apparatus of claim 11, wherein
said exposing section is disposed within a chamber and said
supplying section is disposed outside said chamber.
14. The semiconductor manufacturing apparatus of claim 11, wherein
said liquid is composed of water or perfluoropolyether.
15. The semiconductor manufacturing apparatus of claim 11, wherein
said liquid includes an antifoaming agent.
16-26. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.119
on Patent Application Nos. 2003-383784 and 2004-146217 respectively
filed in Japan on Nov. 13, 2003 and May 17, 2004, the entire
contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a semiconductor
manufacturing apparatus used for manufacturing semiconductor
integrated circuits by employing immersion lithography and a
pattern formation method using the semiconductor manufacturing
apparatus.
[0003] 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.
[0004] In these circumstances, immersion lithography has been
recently proposed for realizing further refinement of patterns by
using conventional exposing light (for example, see M. Switkes and
M. Rothschild, "Immersion lithography at 157 nm", J. Vac. Sci.
Technol., Vol. B19, p. 2353 (2001)).
[0005] 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 liquid 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.
[0006] Now, a conventional pattern formation method employing the
immersion lithography will be described with reference to FIGS. 13A
through 13D.
[0007] First, a positive chemically amplified resist material
having the following composition is prepared:
[0008] Base polymer:
poly((norbornene-5-methylene-t-butylcarboxylate) (50 mol %)-(maleic
anhydride) (50 mol %)) . . . 2 g
[0009] Acid generator: triphenylsulfonium triflate . . . 0.06 g
[0010] Quencher: triethanolamine . . . 0.002 g
[0011] Solvent: propylene glycol monomethyl ether acetate . . . 20
g
[0012] Next, as shown in FIG. 13A, 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.
[0013] Then, as shown in FIG. 13B, with a liquid (water) 3 provided
on 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 0.68 through a mask 5.
[0014] After the pattern exposure, as shown in FIG. 13C, the resist
film 2 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. In this manner,
a resist pattern 2a made of an unexposed portion of the resist film
2 and having a line width of 0.09 .mu.m is formed as shown in FIG.
13D. As shown in FIG. 13D, however, the resist pattern formed by
the conventional pattern formation method is in a defective
shape.
SUMMARY OF THE INVENTION
[0015] The present inventors have variously examined the reason why
the resist pattern formed by the conventional immersion lithography
is in a defective shape, resulting in finding the following: When a
movable stage provided in the exposure system for holding a wafer
moves, fine foams are formed within the liquid 3, and these foams
cause abnormality of aberration and diffraction of a projection
lens. In particular, when the movable stage is moved with a liquid
standing up above the surface of the wafer, the air is swallowed up
into the liquid in the form of foams through a boundary between a
resist film and the liquid.
[0016] Accordingly, when the pattern exposure is performed through
the liquid including such fine foams; the resultant resist pattern
is in a defective shape. For example, as shown in FIG. 13D, the
resist pattern 2a formed by the conventional pattern formation
method employing the immersion lithography is in a defective shape.
When a resist pattern 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.
[0017] In consideration of the aforementioned conventional problem,
an object of the invention is forming a resist pattern in a good
shape by employing the immersion lithography.
[0018] In order to achieve the object, according to the present
invention, in a semiconductor manufacturing apparatus employing the
immersion lithography and a pattern formation method using the
apparatus, a gas included in a liquid provided on a resist film in
exposure is removed.
[0019] Specifically, a degassing mechanism or a mechanism for
spraying an immersion liquid is used for removing the gas.
(Aspects Using Degassing Mechanism)
[0020] The first semiconductor manufacturing apparatus of this
invention using a degassing mechanism includes a stage for placing
a substrate on which a resist film is formed; a liquid supplying
section for supplying a liquid onto the stage; an exposing section
for irradiating the resist film with exposing light through a mask
with the liquid provided on the resist film; and a degassing
section for removing a gas included in the liquid, and the
degassing section includes a removing part for removing a gas from
the liquid having been supplied from the liquid supplying section;
a supplying path for supplying, onto the resist film, the liquid
from which the gas has been removed; and a recovering path for
recovering, to the removing part, the liquid having been supplied
onto the resist film.
[0021] In the first semiconductor manufacturing apparatus, the
liquid from which the gas has been removed by the degassing section
is provided on the resist film, and therefore, the liquid used in
the exposure includes no foams. As a result, a fine pattern can be
formed in a good shape.
[0022] The second semiconductor manufacturing apparatus of this
invention using a degassing mechanism includes a liquid supplying
section for supplying a liquid to be provided on a stage for
placing a substrate on which a resist film is formed; an exposing
section for irradiating the resist film with exposing light through
a mask with the liquid provided on the resist film; and a degassing
section for removing, from the liquid, a gas included in the
liquid, and the degassing section degases the liquid provided on
the stage by the liquid supplying unit.
[0023] In the second semiconductor manufacturing apparatus, the
liquid provided on the stage is degassed by the degassing section,
and hence, the liquid having been degassed is provided on the
resist film. Therefore, the liquid used in the exposure includes no
foams. As a result, a fine pattern can be formed in a good
shape.
[0024] The third semiconductor manufacturing apparatus of this
invention using the degassing mechanism includes an exposing
section for irradiating, with exposing light through a mask, a
resist film formed on a substrate that is placed on a stage and on
which the resist film is formed, with a liquid provided on the
resist film; a liquid supplying section for supplying the liquid
between the resist film and the exposing section; a liquid
recovering section for recovering the liquid having been supplied
onto the resist film; and a controlling section for controlling a
liquid supplying operation of the liquid supplying section, a
liquid recovering operation of the liquid recovering section and an
operation of the stage.
[0025] In the third semiconductor manufacturing apparatus, the
controlling section appropriately adjusts a flow rate and a flowing
direction of the liquid caused on the stage and a movement rate and
a moving direction of the stage. Therefore, the air can be
prevented from being swallowed up into the liquid through the edge
of the substrate in moving the stage, and hence, no foams are
formed. As a result, a fine pattern can be formed in a good
shape.
[0026] In the third semiconductor manufacturing apparatus, the
controlling section preferably controls the liquid supplying
operation and the liquid recovering operation and adjusts the
operation of the stage in such a manner that a flow rate and a
flowing direction of the liquid caused on the resist film by the
liquid supplying operation and the liquid recovering operation
substantially accord with a movement rate and a moving direction of
the stage.
[0027] In the first semiconductor manufacturing apparatus, the
liquid recovered through the recovering path to the removing part
is preferably degassed in the removing part and supplied onto the
resist film through the supplying path.
[0028] In the third semiconductor manufacturing apparatus, the
liquid recovering section and the liquid supplying section are
preferably mutually connected, and the liquid having been recovered
by the liquid recovering section preferably flows into the liquid
supplying section. Thus, the cost of the liquid can be reduced and
the liquid can be stably supplied.
[0029] The first pattern formation method of this invention using a
degassing mechanism includes the steps of forming a resist film on
a substrate; performing pattern exposure by selectively irradiating
the resist film with exposing light with a liquid provided on the
resist film; and forming a resist pattern by developing the resist
film after the pattern exposure, and the step of performing pattern
exposure includes a sub-step of removing a gas included in the
liquid provided on the resist film.
[0030] In the first pattern formation method, the liquid provided
on the resist film is always degassed, and hence, no foams are
formed in the liquid used in the exposure. As a result, a fine
pattern can be formed in a good shape.
[0031] The second pattern formation method of this invention using
a degassing mechanism includes the steps of forming a resist film
on a substrate; performing pattern exposure by selectively
irradiating the resist film with exposing light with a liquid
provided on the resist film after placing, on a stage, the
substrate on which the resist film is formed; and forming a resist
pattern by developing the resist film after the pattern exposure,
and the step of performing pattern exposure includes a sub-step of
supplying the liquid onto the resist film and recovering the liquid
from above the resist film in such a manner that a flow rate and a
flowing direction of the liquid caused on the resist film
substantially accord with a movement rate and a moving direction of
the stage.
[0032] In the second pattern formation method, in the step of
performing pattern exposure, the air can be prevented from being
swallowed up into the liquid provided on the stage through the edge
of the substrate in moving the stage, and hence, no foams are
formed. As a result, a fine pattern can be formed in a good
shape.
[0033] The first or second pattern formation method preferably
further includes, after the step of performing pattern exposure, a
step of recovering the liquid for recycle.
(Aspects Using Mechanism For Supplying Immersion Liquid Through
Spray)
[0034] The present inventors have found that foams formed in an
immersion liquid are remarkably reduced by spraying the liquid to
be stored and that spraying the immersion liquid on a foam itself
reduces the diameter of the foam and increases the flow rate, so as
to improve foam breaking power.
[0035] Specifically, when a liquid is sprayed, the diameter of each
liquid drop is very small and the flow rate of the liquid drop is
higher as compared with a general case where the liquid is allowed
to flow into a vessel. Accordingly, for example, when a liquid is
supplied through spray on a liquid previously stored in a vessel,
the force of the sprayed liquid colliding against the liquid face
of the previously stored liquid is larger than that obtained in the
case where the liquid is allowed to flow into the vessel. At this
point, since drops of the sprayed liquid have very small diameters,
the spayed liquid is rapidly permeated in the liquid surface of the
stored liquid because the repulsion of the liquid surface is small.
In other words, when a liquid is sprayed, foams are minimally
formed, and in the case where the sprayed liquid collides against a
previously formed foam, the foam is easily vanished.
[0036] The following aspects of the present invention were devised
on the basis of the aforementioned finding. In the case where an
immersion liquid is temporalily stored, the immersion liquid is
sprayed to be stored, so as to vanish foams formed in the liquid to
be provided between a resist film and a projection lens. These
aspects are specifically practiced as follows:
[0037] The fourth semiconductor manufacturing apparatus of this
invention includes a stage for placing a substrate on which a
resist film is formed; a liquid supplying section for supplying a
liquid onto the stage; and an exposing section for irradiating the
resist film with exposing light through a mask with the liquid
provided on the resist film, and the liquid supplying section
includes a storing part for storing the liquid and a spraying
nozzle for spraying the liquid into the storing part.
[0038] In the fourth semiconductor manufacturing apparatus, foams
formed in the immersion liquid to be provided between the exposing
section and the resist film can be vanished. Accordingly, the
abnormality of aberration of the projection lens can be prevented,
resulting in forming a resist pattern in a good shape.
[0039] In the fourth semiconductor manufacturing apparatus, the
liquid supplying section preferably includes a nozzle for allowing
another liquid to flow into the storing part. Thus, when another
liquid is allowed to flow into a vessel to be stored through the
nozzle and the liquid is sprayed on the stored liquid through the
spraying nozzle, the sprayed liquid is mixed with the stored liquid
while vanishing foams formed in the stored liquid. Furthermore,
since the sprayed liquid can be added to the stored liquid little
by little, the composition of the mixed liquid can be easily
adjusted. However, the sprayed liquid and the stored liquid need
not have different compositions but may have the same
composition.
[0040] In this case, the nozzle for allowing another liquid to flow
is preferably a spray nozzle.
[0041] In the fourth semiconductor manufacturing apparatus, the
exposing section and the liquid supplying section are preferably
disposed within one chamber.
[0042] Alternatively, in the fourth semiconductor manufacturing
apparatus, it is preferred that the exposing section is disposed
within a chamber and that the liquid supplying section is disposed
outside the chamber. Thus, the inside of the chamber can be
prevented from being contaminated by the liquid stored in the
storing part.
[0043] The third pattern formation method of this invention
includes the steps of forming a resist film on a substrate;
spraying a liquid to be stored; performing pattern exposure by
selectively irradiating the resist film with exposing light with
the stored liquid provided on the resist film; and forming a resist
pattern by developing the resist film after the pattern
exposure.
[0044] In the third pattern formation method, the liquid is sprayed
to be stored and the stored liquid is provided on the resist film,
and hence, foams formed in the liquid can be vanished. Accordingly,
the abnormality of aberration of a projection lens can be
prevented, resulting in forming a resist pattern in a good
shape.
[0045] In the third pattern formation method, in the step of
spraying a liquid, the liquid is stored by spraying the liquid on
another liquid previously stored. Thus, since the sprayed liquid is
added to the previously stored liquid, the sprayed liquid is mixed
with the stored liquid while vanishing foams formed in the stored
liquid. Furthermore, since the sprayed liquid can be added to the
stored liquid little by little, the composition of the mixed liquid
can be easily adjusted. However, the sprayed liquid and the stored
liquid need not have different compositions but may have the same
composition.
[0046] In the third pattern formation method, the step of spraying
a liquid and the step of performing pattern exposure are preferably
executed in parallel.
[0047] In any of the semiconductor manufacturing apparatuses and
the pattern formation methods of the invention, when the exposing
light is UV such as g-line or i-line, or far UV such as KrF excimer
laser or ArF excimer laser, the liquid is preferably water.
[0048] Alternatively, in any of the semiconductor manufacturing
apparatuses and the pattern formation methods of the invention,
when the exposing light is vacuum UV such as F.sub.2 laser, the
liquid is preferably perfluoropolyether.
[0049] In any of the semiconductor manufacturing apparatuses and
the pattern formation methods of the invention, the immersion
liquid preferably includes an antifoaming agent. Thus, foams formed
in the liquid can be largely removed by the antifoaming agent, and
hence, pattern failure derived from the influence of the foams
occurring in the exposure can be largely reduced.
[0050] As the antifoaming agent, a foam breaker, a foam inhibitor
or a defoaming agent may be used. 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
liquid. 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 liquid surface. A defoaming agent is
adsorbed onto the surface film of a foam in a liquid. When such
foams are adsorbed to one another in the liquid, 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 liquid surface at a high speed.
[0051] As described so far, in the semiconductor manufacturing
apparatus and the pattern formation method using the same according
to this invention, no foams are formed in a liquid provided on a
resist film, and hence, the abnormality of the aberration of a
projection lens and exposure abnormality such as focus failure can
be prevented. As a result, a resist pattern can be formed in a good
shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] FIG. 1 is a schematic cross-sectional view of a principal
part of a semiconductor manufacturing apparatus used for realizing
a pattern formation method employing immersion lithography
according to Embodiment 1 of the invention;
[0053] FIGS. 2A, 2B, 2C and 2D are cross-sectional views for
showing procedures in the pattern formation method using the
semiconductor manufacturing apparatus of Embodiment 1 of the
invention;
[0054] FIG. 3 is a schematic cross-sectional view of a principal
part of a semiconductor manufacturing apparatus according to a
modification of Embodiment 1;
[0055] FIG. 4 is a schematic cross-sectional view of a principal
part of a semiconductor manufacturing apparatus used for realizing
a pattern formation method employing the immersion lithography
according to Embodiment 2 of the invention;
[0056] FIGS. 5A, 5B, 5C and 5D are cross-sectional views for
showing procedures in the pattern formation method using the
semiconductor manufacturing apparatus of Embodiment 2;
[0057] FIG. 6 is a schematic cross-sectional view of a principal
part of a semiconductor manufacturing apparatus used for realizing
a pattern formation method employing the immersion lithography
according to Embodiment 3 of the invention;
[0058] FIG. 7 is a schematic cross-sectional view of a principal
part of a semiconductor manufacturing apparatus according to
Modification 1 of Embodiment 3;
[0059] FIG. 8 is a schematic cross-sectional view of a principal
part of a semiconductor manufacturing apparatus according to
Modification 2 of Embodiment 3;
[0060] FIG. 9 is a schematic cross-sectional view of a principal
part of a semiconductor manufacturing apparatus according to
Modification 3 of Embodiment 3;
[0061] FIGS. 10A, 10B, 10C and 10D are cross-sectional views for
showing procedures in a pattern formation method according to
Embodiment 4 of the invention;
[0062] FIGS. 11A, 11B, 11C and 11D are cross-sectional views for
showing procedures in a pattern formation method according to
Embodiment 5 of the invention;
[0063] FIGS. 12A, 12B, 12C and 12D are cross-sectional views for
showing procedures in a pattern formation method according to
Embodiment 6 of the invention; and
[0064] FIGS. 13A, 13B, 13C and 13D are cross-sectional views for
showing procedures in a conventional pattern formation method.
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
[0065] FIG. 1 schematically shows the cross-sectional structure of
a principal part of a semiconductor manufacturing apparatus used
for realizing a pattern formation method employing immersion
lithography according to Embodiment 1 of the invention.
[0066] As shown in FIG. 1, the semiconductor manufacturing
apparatus of Embodiment 1 includes an optical system 30 that is
provided within a chamber 10 and works as a light source for
exposing a design pattern onto a resist film (not shown) applied on
a principal surface of a wafer 20; a degassing section 40 for
degassing (defoaming) a liquid 25 provided on the resist film of
the wafer 20 in the exposure for increasing the value of the
numerical aperture of exposing light; and a liquid supplying
section 45 for supplying the liquid 25 to the degassing section
40.
[0067] Below the optical system 30, an exposing section (projection
lens) 34 for projecting, through the liquid 25 onto the resist
film, the exposing light emitted from the optical system 30 and
entering through a mask (reticle) 32 having a design pattern to be
transferred onto the resist film and a movable stage 36 for holding
the wafer 20 are disposed. The exposing section 34 is held to be in
contact with the surface of the liquid 25 provided on the resist
film of the wafer 20 so as to cover the movable stage 36 (or the
wafer 20) in the exposure. Also, the movable stage 36 is held on a
surface plate 38 movably against the exposing section 34.
[0068] The degassing section 40 includes a degassing section body
41 for degassing the liquid 25; a recovering path 42 for recovering
the liquid 25 having been provided onto the movable stage 36 to the
degassing section body 41; and a supplying path 43 for supplying
the liquid 25 having been degassed onto the movable stage 36.
[0069] The liquid 25 having been recovered to and degassed by the
degassing section body 41 is supplied onto the movable stage 36
again so as to be used in next exposure. At this point, the
degassing section body 41 may not recover the whole liquid 25
having been supplied onto the movable stage 36 but may mix a part
of the recovered liquid 25 with a fresh liquid 25 newly supplied
from the liquid supplying section 45, degas the mixed liquid 25 in
the degassing section body 41 and provide the degassed liquid 25
onto the movable stage 36 again.
[0070] The degassing section body 41 may employ any of a nitrogen
dissolving method, a gas-liquid separating film method using a film
of amorphous fluoropolymer or the like with a filter mesh size of,
for example, approximately 0.1 .mu.m, a thermal degassing method, a
vacuum degassing method, a nitrogen gas bubbling method, a film
degassing method, a reducer adding method, a reducing method using
a catalytic resin and other known techniques.
[0071] Now, the pattern formation method using the semiconductor
manufacturing apparatus of FIG. 1 will be described with reference
to FIGS. 2A through 2D.
[0072] First, a positive chemically amplified resist material
having the following composition is prepared:
[0073] Base polymer:
poly((norbornene-5-methylene-t-butylcarboxylate) (50 mol %)-(maleic
anhydride) (50 mol %)) . . . 2 g
[0074] Acid generator: triphenylsulfonium triflate . . . 0.06 g
[0075] Quencher: triethanolamine amine . . . 0.002 g
[0076] Solvent: propylene glycol monomethyl ether acetate . . . 20
g
[0077] Next, as shown in FIG. 2A, the aforementioned chemically
amplified resist material is applied on a substrate 20 so as to
form a resist film 21 with a thickness of 0.35 .mu.m.
[0078] Then, as shown in FIG. 2B, with a liquid 25 of water
provided between the resist film 21 and the projection lens 34,
pattern exposure is carried out by irradiating the resist film 21
with exposing light 35 of ArF excimer laser with NA of 0.65 through
a mask (not shown). At this point, as shown in FIG. 1, the liquid
25 is degassed in the degassing section body 41 through the
recovering path 42 of the degassing section 40 during the exposure
when it is supplied onto the resist film 21 and the resultant
degassed liquid 25 is restored onto the movable stage 36 through
the supplying path 43.
[0079] After the pattern exposure, as shown in FIG. 2C, the resist
film 21 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. In this
manner, a resist pattern 21a made of an unexposed portion of the
resist film 2 and having a line width of 0.09 .mu.m is formed as
shown in FIG. 2D.
[0080] In this manner, according to the pattern formation method of
Embodiment 1, the liquid 25 provided on the resist film 21 is
degassed (defoamed) during the pattern exposure. Therefore, even
when foams are formed within the liquid 25 due to the movement of
the movable stage 36, the formed foams are removed. As a result, it
is possible to prevent abnormality of the aberration and the
diffraction of the exposing light 35 that are otherwise caused by
the foams when the exposing light passes through the liquid 25.
Accordingly, exposure abnormality such as focus failure is
prevented, so that the resist pattern 21a made of the resist film
21 can be formed in a good shape.
[0081] The present inventors have confirmed through measurement
with laser scanning of the liquid 25 that the diffraction of light
is not affected if 100 ml of the liquid 25 includes approximately
30 or less foams with a diameter of approximately 0.1 .mu.m or
more. Accordingly, in the exposure shown in FIG. 2B, the liquid 25
may be always degassed or appropriately degassed so as to satisfy
this condition.
Modification of Embodiment 1
[0082] Now, a modification of Embodiment 1 will be described with
reference to the accompanying drawing.
[0083] FIG. 3 schematically shows the cross-sectional structure of
a principal part of a semiconductor manufacturing apparatus used
for realizing a pattern formation method employing the immersion
lithography according to the modification of Embodiment 1. In FIG.
3, like reference numerals are used to refer to like elements shown
in FIG. 1 so as to omit the description.
[0084] As shown in FIG. 3, in the semiconductor manufacturing
apparatus of this modification, a liquid 25 provided onto a wafer
20 is directly supplied from a liquid supplying section 45, and the
liquid 25 having been provided onto the wafer 20 is degassed by a
degassing section 40 during exposure. The liquid 25 supplied from
the liquid supplying section 45 may or may not be previously
degassed. Moreover, there is no need to always perform the
degassing process but it may be appropriately performed when, for
example, foams are formed within the liquid 25.
[0085] Alternatively, the liquid 25 having been used in the
exposure may be recovered to the degassing section 40 and degassed
therein, so that the degassed liquid 25 may be supplied onto the
wafer 20 again thereafter.
[0086] In this manner, according to this modification, the liquid
25 provided onto the resist film is always or appropriately
degassed (defoamed) in the pattern exposure. Therefore, even when
foams are formed in the liquid 25 due to the movement of the
movable stage 36, the formed foams are removed. As a result, it is
possible to prevent the abnormality of the aberration and the
diffraction of the exposing light that are otherwise caused by the
foams when the exposing light passes through the liquid 25.
Accordingly, the exposure abnormality such as focus failure is
prevented, so that the resist pattern made of the resist film can
be formed in a good shape.
Embodiment 2
[0087] FIG. 4 schematically shows the cross-sectional structure of
a principal part of a semiconductor manufacturing apparatus used
for realizing a pattern formation method employing the immersion
lithography according to Embodiment 2 of the invention. In FIG. 4,
like reference numerals are used to refer to like elements shown in
FIG. 1 so as to omit the description.
[0088] As shown in FIG. 4, in the semiconductor manufacturing
apparatus of Embodiment 2, a liquid used for increasing the value
of the numerical aperture of exposing light is partially provided
onto the principal surface of a wafer 20, namely, provided in the
form of drops, instead of employing the pooling method of
Embodiment 1 and the modification in which the whole wafer 20 is
immersed in the liquid.
[0089] In the dropping method of this embodiment, the liquid 25 in
the form of drops is allowed to flow during the movement of the
movable stage 36 at a flow rate for preventing the air from being
swallowed up into the liquid 25. Specifically, the movement rate V1
of the movable stage 36 against the surface plate 38 is set to be
substantially equal to the flow rate V2 against the surface plate
38 of the liquid 25 provided between the wafer 20 (the resist film)
and the exposing section 34. Thus, the relative rate between the
wafer 20 and the liquid 25 is substantially zero, and therefore,
the air can be prevented from being swallowed up into the liquid 25
through the edge of the wafer 20.
[0090] Specifically, the semiconductor manufacturing apparatus
includes a liquid supplying section 50 for providing the liquid 25
previously having been degassed onto the wafer 20 through a
supplying nozzle 51; a liquid recovering unit 53 for recovering the
liquid 25 having been provided on the wafer 20 through a recovering
nozzle 52; and a controlling section 54 for controlling the
operations of the liquid supplying section 50, the liquid
recovering unit 53 and the movable stage 36.
[0091] The controlling section 54 controls the liquid supplying
section 50 and the liquid recovering unit 53 so as to synchronize
the flow rate V2 and the flowing direction of the liquid 25 caused
on the wafer 20 with the movement rate V1 and the moving direction
of the movable stage 36. For example, with supplying nozzles and
recovering nozzles additionally provided apart from the supplying
nozzle 51 and the recovering nozzle 52, when the moving direction
of the movable stage 36 is changed, the controlling section 54 may
select any of the plural supplying nozzles and the plural
recovering nozzles so as to make the liquid 25 flow along a
direction according to the changed moving direction of the resist
film.
[0092] In this manner, since the movement rate V1 and the moving
direction of the movable stage 36 substantially accord with the
flow rate V2 and the flowing direction of the liquid 25 provided on
the wafer 20 in Embodiment 2, the air can be prevented from being
swallowed up into the liquid 25 through the interface between the
liquid 25 and the resist film.
[0093] Specifically, the present inventors have confirmed the
following: In the case where the movement rate V1 of the movable
stage 36 is, for example, 100 mm/s through 1000 mm/s, if a
difference between the flow rate V2 of the liquid and the movement
rate V1 is .+-.10% or less, the number of foams with a diameter of
0.1 .mu.m or more included in 100 ml of the liquid is approximately
30 or less.
[0094] Now, the pattern formation method using the semiconductor
manufacturing apparatus of FIG. 4 will be described with reference
to FIGS. 5A through 5D.
[0095] First, a positive chemically amplified resist material
having the following composition is prepared:
[0096] Base polymer:
poly((norbornene-5-methylene-t-butylcarboxylate) (50 mol %)-(maleic
anhydride) (50 mol %)) . . . 2 g
[0097] Acid generator: triphenylsulfonium triflate . . . 0.06 g
[0098] Quencher: triethanolamine amine . . . 0.002 g
[0099] Solvent: propylene glycol monomethyl ether acetate . . . 20
g
[0100] Next, as shown in FIG. 5A, the aforementioned chemically
amplified resist material is applied on a substrate 20 so as to
form a resist film 21 with a thickness of 0.35 .mu.m.
[0101] Then, as shown in FIG. 5B, a liquid 25 of water is supplied
to and recovered from a portion between the resist film 21 and the
projection lens 34 at a flow rate V2 synchronized with the movement
rate V1 of the movable stage 36 with a rate difference of .+-.10%
or less. Under these conditions, pattern exposure is carried out by
irradiating the resist film 21 with exposing light 35 of ArF
excimer laser with NA of 0.65 through a mask (not shown). At this
point, as shown in FIG. 4, the liquid 25 is always or appropriately
degassed in the degassing section 40 also during the exposure when
it is supplied onto the resist film 21.
[0102] After the pattern exposure, as shown in FIG. 5C, the resist
film 21 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. In this
manner, a resist pattern 21a made of an unexposed portion of the
resist film 21 and having a line width of 0.09 .mu.m is formed as
shown in FIG. 5D.
[0103] Alternatively, the liquid 25 having been recovered by the
liquid recovering unit 53 is transferred (circulated) to the liquid
supplying section 50 so as to be supplied onto the wafer 20 again.
Thus, the immersion liquid 25 can be repeatedly recycled, resulting
in effectively reducing the cost and an exhausted substance.
[0104] In this manner, in the pattern formation method of
Embodiment 2, the flow rate V2 of the liquid 25 having been
previously degassed and provided on the resist film 21 is made to
substantially synchronize with the movement rate V1 of the movable
stage (with a rate difference of, for example, .+-.10% or less) in
the pattern exposure, and therefore, even when the movable stage 36
is moved, foams are not formed within the liquid 25. As a result,
since the abnormality of the aberration and the diffraction of
exposing light 35 otherwise caused by foams when the exposing light
passes through the liquid 25 can be prevented, exposure abnormality
such as focus failure is prevented, so that the resist pattern 21a
made of the resist film 21 can be formed in a good shape.
[0105] Although water is used as the liquid 25 used for increasing
the value of the numerical aperture of the exposing light in
Embodiment 1, the modification of Embodiment 1 and Embodiment 2,
perfluoropolyether may be used instead of water.
[0106] Also, although the ArF excimer laser is used as the exposing
light, KrF excimer laser, F.sub.2 laser, Kr.sub.2 laser, ArKr
laser, Ar.sub.2 laser or Xe.sub.2 laser may be used instead.
Embodiment 3
[0107] FIG. 6 schematically shows the cross-sectional structure of
a principal part of an exposure system, that is, a semiconductor
manufacturing apparatus, used for realizing a pattern formation
method employing the immersion lithography according to Embodiment
3 of the invention.
[0108] As shown in FIG. 6, the exposure system of Embodiment 3
includes an illumination optical system 130 provided within a
chamber 110 and working as a light source for exposing a design
pattern onto a resist film (not shown) applied on a wafer 120; and
a liquid supplying section 140 for supplying, onto the resist film
of the wafer 120, an immersion liquid 121A used for increasing the
value of the numerical aperture of exposing light in the
exposure.
[0109] Below the illumination optical system 130, a projection lens
131 for projecting, onto the resist film through the liquid 121A,
the exposing light emitted from the illumination optical system 130
and entering through a mask (reticle) 122 having a design pattern
to be transferred onto the resist film; a wafer stage 132 for
holding the wafer 120; and a surface plate 133 for holding the
wafer stage 132 are disposed. The projection lens 131 is held to be
in contact with the surface of the liquid 121A supplied onto the
resist film of the wafer 120 during the exposure.
[0110] The liquid supplying section 140 includes a vessel 141 for
temporarily storing the liquid 121A, a supplying nozzle 142 for
supplying the stored liquid 121A onto the wafer 120, and a storing
spray nozzle 143 for spraying fresh liquid 121A to be stored in the
vessel 141.
[0111] In Embodiment 3, the liquid supplying section 140 stores the
liquid 121A sprayed into the vessel 141, and thereafter, the stored
liquid 121A is supplied onto the wafer 120 through the supplying
nozzle 142.
[0112] According to Embodiment 3, since the liquid supplying
section 140 includes the storing spray nozzle 143 for spraying the
liquid 121A into the vessel 141 to be stored, foams formed within
the liquid 121A to be provided between the resist film and the
projection lens 131 can be vanished within the vessel 141. As a
result, the abnormality of aberration and defocusing of the
projection lens 131 can be prevented, so as to form a resist
pattern made of a resist film in a good shape.
Modification 1 of Embodiment 3
[0113] FIG. 7 schematically shows the cross-sectional structure of
a principal part of an exposure system according to Modification 1
of Embodiment 3. In FIG. 7, like reference numerals are used to
refer to like elements shown in FIG. 6 so as to omit the
description.
[0114] As shown in FIG. 7, in the exposure system of Modification
1, a liquid 121B stored in the liquid supplying section 140 is
supplied onto the wafer 120 through the supplying nozzle 142, and
at the same time, a fresh liquid 121B is sprayed into the vessel
141 to be stored. Also in this manner, foams formed in the liquid
121B to be provided between the resist film and the projection lens
131 can be vanished within the vessel 141, and hence, the
abnormality of aberration and defocusing of the projection lens 131
can be prevented.
Modification 2of Embodiment 3
[0115] FIG. 8 schematically shows the cross-sectional structure of
a principal part of an exposure system according to Modification 2
of Embodiment 3. In FIG. 8, like reference numerals are used to
refer to like elements shown in FIG. 6 so as to omit the
description.
[0116] As shown in FIG. 8, in the exposure system of Modification
2, the liquid supplying section 140 is provided with, in addition
to the storing spray nozzle 143, a storing nozzle 144 for allowing
another liquid to flow into the vessel 141.
[0117] In Modification 2, a first liquid is first stored in the
vessel 141 through the storing nozzle 144, and then, a second
liquid is sprayed through the storing spray nozzle 143 to be mixed
with the first liquid. As described above, when the second liquid
is sprayed into the first liquid previously stored, since drops of
the sprayed second liquid have very small diameters, the second
liquid is rapidly permeated in the liquid surface of the first
liquid because the repulsion of the liquid surface is small. As a
result, few foams are formed in the sprayed second liquid, and in
addition, when the sprayed liquid collides against a foam, the foam
is easily vanished. Accordingly, even when a liquid 121C is mixed
in the vessel 141, foams otherwise formed in the liquid 121C to be
provided between the resist film and the projection lens 131 can be
vanished within the vessel 141, and therefore, the abnormality of
aberration and defocusing of the projection lens 131 can be
prevented.
[0118] It is noted that the first liquid and the second liquid may
have the same composition. Furthermore, the storing nozzle 144 for
introducing the first liquid into the vessel 141 may be a spray
nozzle capable of spraying the first liquid.
[0119] Also, with respect to the timing of mixing the first liquid
and the second liquid, the mixture may be completed before
supplying the liquid 121C onto the wafer 120 or these liquids may
be mixed while supplying the liquid 121C onto the wafer 120.
Modification 3 of Embodiment 3
[0120] FIG. 9 schematically shows the cross-sectional structure of
a principal part of an exposure system according to Modification 3
of Embodiment 3. In FIG. 9, like reference numerals are used to
refer to like elements shown in FIG. 6 so as to omit the
description.
[0121] As shown in FIG. 9, in the exposure system of Modification
3, the liquid supplying section 140 is provided outside the chamber
110. Thus, in spraying the liquid 121A into the vessel 141 to be
stored, it is possible to prevent the inside of the chamber 110
from being contaminated by the liquid 121A scattered out of the
vessel 141. As a result, the cleanness of the exposure environment
can be highly kept.
Embodiment 4
[0122] Now, a pattern formation method using the exposure system
according to Embodiment 3 shown in FIG. 6 or Modification 3 shown
in FIG. 9 will be described as Embodiment 4 with reference to FIGS.
11A through 10D.
[0123] First, a positive chemically amplified resist material
having the following composition is prepared:
[0124] Base polymer:
poly((norbornene-5-methylene-t-butylcarboxylate) (50 mol %)-(maleic
anhydride) (50 mol %)) . . . 2 g
[0125] Acid generator: triphenylsulfonium triflate . . . 0.06 g
[0126] Solvent: propylene glycol monomethyl ether acetate . . . 20
g
[0127] Next, as shown in FIG. 10A, the aforementioned chemically
amplified resist material is applied on a substrate 120 so as to
form a resist film 123 with a thickness of 0.35 .mu.m.
[0128] Then, as shown in FIG. 10B, with a liquid 121A of water
provided between the resist film 123 and the projection lens 131,
pattern exposure is carried out by irradiating the resist film 123
with exposing light 134 of ArF excimer laser with NA of 0.65
through a mask. At this point, as shown in FIG. 6 or 9, the liquid
121A having been defoamed is supplied from the liquid supplying
section 140 that temporalily stores the liquid 121A.
[0129] After the pattern exposure, as shown in FIG. 10C, the resist
film 123 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 solution (alkaline
developer). In this manner, a resist pattern 123a made of an
unexposed portion of the resist film 123 and having a line width of
0.09 .mu.m is formed as shown in FIG. 10D.
[0130] According to Embodiment 4, since the liquid 121A supplied
onto the resist film 123 during the pattern exposure includes no
foams, the abnormality of aberration and defocusing of the
projection lens 131 can be prevented, and hence, the resist pattern
123a made of the resist film 123 can be formed in a good shape.
Embodiment 5
[0131] Now, a pattern formation method using the exposure system
according to Modification 1 of Embodiment 3 shown in FIG. 7 will be
described as Embodiment 5 with reference to FIGS. 11A through
11D.
[0132] First, a positive chemically amplified resist material
having the following composition is prepared:
[0133] Base polymer:
poly((norbornene-5-methylene-t-butylcarboxylate) (50 mol %)-(maleic
anhydride) (50 mol %)) . . . 2 g
[0134] Acid generator: triphenylsulfonium triflate . . . 0.06 g
[0135] Solvent: propylene glycol monomethyl ether acetate . . . 20
g
[0136] Next, as shown in FIG. 11A, the aforementioned chemically
amplified resist material is applied on a substrate 120 so as to
form a resist film 123 with a thickness of 0.35 .mu.m.
[0137] Then, as shown in FIG. 11B, with a liquid 121B of water
provided between the resist film 123 and the projection lens 131,
pattern exposure is carried out by irradiating the resist film 123
with exposing light 134 of ArF excimer laser with NA of 0.65
through a mask. At this point, as shown in FIG. 7, the liquid 121B
is sprayed into the vessel 141 of the liquid supplying section 140
to be stored therein even while it is supplied onto the wafer
120.
[0138] After the pattern exposure, as shown in FIG. 11C, the resist
film 123 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 % tetramethylamn onium hydroxide solution (alkaline
developer). In this manner, a resist pattern 123a made of an
unexposed portion of the resist film 123 and having a line width of
0.09 .mu.m is formed as shown in FIG. 11D.
[0139] According to Embodiment 5, since the liquid 121B supplied
onto the resist film 123 during the pattern exposure includes no
foams, the abnormality of aberration and defocusing of the
projection lens 131 can be prevented, and hence, the resist pattern
123a made of the resist film 123 can be formed in a good shape.
Embodiment 6
[0140] Now, a pattern formation method using the exposure system
according to Modification 2 of Embodiment 3 shown in FIG. 8 will be
described as Embodiment 6 with reference to FIGS. 12A through
12D.
[0141] First, a positive chemically amplified resist material
having the following composition is prepared:
[0142] Base polymer:
poly((norbornene-5-methylene-t-butylcarboxylate) (50 mol %)-(maleic
anhydride) (50 mol %)) . . . 2 g
[0143] Acid generator: triphenylsulfonium triflate . . . 0.06 g
[0144] Solvent: propylene glycol monomethyl ether acetate . . . 20
g
[0145] Next, as shown in FIG. 12A, the aforementioned chemically
amplified resist material is applied on a substrate 120 so as to
form a resist film 123 with a thickness of 0.35 .mu.m.
[0146] Then, as shown in FIG. 12B, with a liquid 121C of water
provided between the resist film 123 and the projection lens 131,
pattern exposure is carried out by irradiating the resist film 123
with exposing light 134 of ArF excimer laser with NA of 0.65
through a mask. At this point, as shown in FIG. 8, the liquid 121C
is a mixture, obtained in the vessel 141 of the liquid supplying
section 140, of liquids having been introduced respectively through
the storing nozzle 144 and the storing spray nozzle 143, whereas
the liquid 121C is water in this case. It is noted that the liquid
121C may be kept on being sprayed to be stored in the vessel 141 of
the liquid supplying section 140 even while it is supplied onto the
wafer 120.
[0147] After the pattern exposure, as shown in FIG. 12C, the resist
film 123 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 solution (alkaline
developer). In this manner, a resist pattern 123a made of an
unexposed portion of the resist film 123 and having a line width of
0.09 .mu.m can be formed as shown in FIG. 12D.
[0148] According to Embodiment 6, since the liquid 121C supplied
onto the resist film 123 during the pattern exposure includes no
foams, the abnormality of aberration and defocusing of the
projection lens 131 can be prevented, and hence, the resist pattern
123a made of the resist film 123 is formed in a good shape.
[0149] In each of Embodiments 4 through 6, the liquid 121A, 121B or
121C preferably includes an antifoaming agent. Thus, foams formed
in the liquid can be largely removed by the antifoaming agent, and
hence, pattern failure derived from the influence of the foams
occurring in the exposure can be further reduced.
[0150] As the antifoaming agent, a foam breaker, a foam inhibitor
or a defoaming agent may be used. Specifically, silicone oil, fatty
acid, phosphoric ester, vegetable fat, glycerol fatty ester,
calcium carbonate, magnesium carbonate, lecithin or polyether may
be used. The content of such an antifoaming agent is approximately
several ppm through 1%.
[0151] Although the ArF excimer laser is used as the exposing light
134, KrF excimer laser, F.sub.2 laser, Kr.sub.2 laser, ArKr laser,
Ar.sub.2 laser or Xe.sub.2 laser may be used instead.
[0152] Also, when the exposing light is vacuum UV such as F.sub.2
laser, the immersion liquid may be perfluoropolyether.
* * * * *