U.S. patent application number 09/811398 was filed with the patent office on 2001-10-18 for (meth) acrylate, polymer, photoresist composition, and pattern forming process making use of the composition.
This patent application is currently assigned to NEC Corporation. Invention is credited to Hasegawa, Etsuo, Iwasa, Shigeyuki, Maeda, Katsumi, Nakano, Kaichiro.
Application Number | 20010031429 09/811398 |
Document ID | / |
Family ID | 14237361 |
Filed Date | 2001-10-18 |
United States Patent
Application |
20010031429 |
Kind Code |
A1 |
Maeda, Katsumi ; et
al. |
October 18, 2001 |
(Meth) acrylate, polymer, photoresist composition, and pattern
forming process making use of the composition
Abstract
A photoresist composition contains a photoacid generator and a
polymer represented by the following formula: 1 wherein R.sup.4,
R.sup.6 and R.sup.9 each represents a hydrogen atom or a methyl
group, R.sup.5 and R.sup.7 each represents a C.sub.17-23 divalent
hydrocarbon group containing a bridged cyclic hydrocarbon group,
R.sup.8 represents an acid-decomposable group, R.sup.10 represents
a hydrogen atom or a C.sub.1-12 hydrocarbon group, x+y+z equals to
1, and x, y and z stand for 0 to 1, 0 to 1, and 0 to 0.9,
respectively, and having a weight average molecular weight of from
1,000 to 500,000. According to the present invention, a chemical
modification photoresist composition having high transparency to
radiation of 220 nm and shorter and improved in etching resistance
can be provided.
Inventors: |
Maeda, Katsumi; (Tokyo,
JP) ; Iwasa, Shigeyuki; (Tokyo, JP) ; Nakano,
Kaichiro; (Tokyo, JP) ; Hasegawa, Etsuo;
(Tokyo, JP) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET 2ND FLOOR
ARLINGTON
VA
22202
|
Assignee: |
NEC Corporation
Tokyo
JP
|
Family ID: |
14237361 |
Appl. No.: |
09/811398 |
Filed: |
March 20, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09811398 |
Mar 20, 2001 |
|
|
|
09058349 |
Apr 10, 1998 |
|
|
|
6248499 |
|
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|
Current U.S.
Class: |
430/326 ;
430/270.1 |
Current CPC
Class: |
Y10S 430/111 20130101;
C08F 220/283 20200201; G03F 7/0045 20130101; G03F 7/039
20130101 |
Class at
Publication: |
430/326 ;
430/270.1 |
International
Class: |
G03F 007/30; G03F
007/40; G03F 007/038 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 16, 1997 |
JP |
09-099064 |
Claims
What is claimed is:
1. A process for forming a pattern, which comprises the following
steps: coating a substrate with a photoresist composition
comprising 70 to 99.8 wt. % of a polymer produced by
homopolymerization of a (meth)acrylate represented by the following
formula (1): 24wherein R.sup.1 represents a hydrogen atom or a
methyl group, R.sup.2 represents a C.sub.17-23 divalent hydrocarbon
group containing a bridged cyclic hydrocarbon group, and R.sup.3
represents an acid-decomposable group or a hydrogen atom or
copolymerization of the (meth)acrylate with another copolymerizable
compound and having a weight average molecular weight of from 1,000
to 500,000 and 0.2 to 30 wt. % of a photoacid generator capable of
generating an acid upon exposure to radiation; exposing the
thus-coated photoresist composition to radiation having a
wavelength of from 180 to 220 nm; baking the thus-exposed
photoresist composition; and then developing the thus-baked
photoresist composition.
2. A process for forming a pattern, which comprises the following
steps: coating a substrate with a photoresist composition
comprising 70 to 99.8 wt. % of a polymer represented by the
following formula (2): 25wherein R.sup.4, R.sup.6 and R.sup.9 each
represents a hydrogen atom or a methyl group, R.sup.5 and R.sup.7
each represents a C.sub.17-23 divalent hydrocarbon group containing
a bridged cyclic hydrocarbon group, R.sup.8 represents an
acid-decomposable group, R.sup.10 represents a hydrogen atom or a
C.sub.1-12 hydrocarbon group, x+y+z equals to 1, and x, y and z
stand for 0 to 1, 0 to 1, and 0 to 0.9, respectively, wherein at
least one of x and y is greater than zero, and having a weight
average molecular weight of from 1,000 to 500,000 and 0.2 to 30 wt.
% of a photoacid generator capable of generating an acid upon
exposure to radiation; exposing the thus-coated photoresist
composition to radiation having a wavelength of from 180 to 220 nm;
baking the thus-exposed photoresist composition; and then
developing the thus-baked photoresist composition.
3. The process as defined in claim 1, wherein said exposure
radiation is ArF excimer laser.
4. The process as defined in claim 2, wherein said exposure
radiation is ArF excimer laser.
Description
RELATED APPLICATION
[0001] This application is a division of co-pending Application
Ser. No. 09/058,349, filed on Apr. 10, 1998, the entire contents of
which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a (meth)acrylate, a polymer, a
photoresist composition, and a pattern forming process making use
of the composition. More specifically, the present invention is
concerned with a photoresist composition and a pattern forming
process, which are suitable for use in a lithographic step in the
fabrication of a semiconductor device, especially in lithography
making use of radiation of 220 nm or shorter in wavelength as
exposure radiation.
[0004] 2. Description of the Related Art
[0005] In the field of fabrication of various electronic devices
requiring small geometry processing of the half micron order and
led by semiconductor devices, there is an ever-increasing demand
toward devices of still higher density and integration. This has
led to still severer requirements for lithographic technology which
is adopted for the formation of submicrometer patterns.
[0006] As one of measures for achieving miniaturization of a
pattern, there is an approach to shorten the wavelength of exposure
radiation which is used upon formation of a resist pattern. For a
mass-fabrication process of 256 Mb DRAMs (processing dimension:
.ltoreq.0.25 .mu.m), use of KrF excimer laser (wavelength: 248 nm)
of shorter wavelength than i-line (wavelength: 365 nm) as an
exposure radiation source in place of i-line is positively
considered these days.
[0007] However, a radiation source of a still shorter wavelength is
considered to be needed for the fabrication of DRAMs having an
integration degree of 1 Gb or higher which requires still smaller
geometry processing technology (processing dimension: .ltoreq.0.18
.mu.m). In particular, use of photolithography making use of ArF
excimer laser (wavelength: 193 nm) has been reported recently
(Donald C. Hoffer, et al., Journal of Photopolymer Science and
Technology, 9(3), 387-397 (1996).
[0008] There is accordingly an outstanding desire for the
development of a resist which can be successfully employed in
photolithography making use of ArF radiation. Such an ArF exposure
resist is required to achieve an improvement in the cost
performance of laser because, inter alia, the gas life of the
excimer laser light source is short and a laser apparatus itself is
expensive.
[0009] In addition to such a high resolution as permitting a still
further reduction in the processing dimension, the ArF resist is
also required to exhibit still higher sensitivity. As a method for
providing a resist with higher sensitivity, chemical amplification
making use of a photoacid generator as a sensitizer is known
widely. As a representative example, JP Kokoku 2-27660 discloses a
resist which is composed, in combination, of triphenylsulfonium
hexafluoroarsenate and poly(p-tert-butoxycarbonylox-
y-.alpha.-methylstyrene). Chemical modification resists are now
extensively employed as KrF eximer laser resists [for example,
Hiroshi Ito, C. Grantwillson, American Chemical Society Symposium
Series 242, 11-23 (1984)]. A chemically amplified resist is
characterized in that protonic acid, which is generated from a
photoacid generator as a component of the resist upon exposure to
radiation, undergoes an acid-catalyzed reaction with a resist resin
or the like when subjected to a heat treatment after the exposure.
As a result, chemically amplified resists have attained far higher
sensitivity over conventional resists the photoreaction
efficiencies (reactions per photon) of which are lower than 1.
Nowadays, most of newly developed resists are of the chemically
amplified type, and the adoption of a chemical amplification
mechanism has become indispensable in the development of a
high-sensitivity material which can meet the trend toward an
exposure radiation source of shorter wavelength.
[0010] In lithography making use of radiation of a short wavelength
of 220 nm or shorter led by ArF eximer laser, however, a resin
component of a chemically amplified photoresist for use in the
formation of submicrometer patterns is required to have new
properties unsatisfiable by conventional materials, that is, high
transparency for exposure light of 220 nm or shorter and resistance
to dry etching.
[0011] In the conventional lithography which uses g-beam (438 nm),
i-line (365 nm) or KrF eximer laser (248 nm), a resin having an
aromatic ring in its structural units, such as a novolac resin or
poly(p-vinylphenol), is used as a resin component of a photoresist
composition, so that the resin is allowed to exhibit resistance to
etching owing to the dry etching resistance of these aromatic
rings. However, a resin containing aromatic rings shows extremely
strong absorption for radiation of a wavelength shorter than 220
nm. Exposure radiation is therefore mostly absorbed at a resist
surface and is unable to pass to a substrate, so that no
submicrometer resist pattern can be formed. Conventional resins
cannot accordingly be applied to photolithography which makes use
of short-wavelength radiation of 220 nm or shorter. As a
consequence, there is an outstanding strong desire for a resin
material which does not contain aromatic rings, has etching
resistance, and is transparent to wavelengths of 220 nm and
shorter.
[0012] Proposed examples of high molecular compounds having
transparency to ArF eximer laser (193 nm) and dry etching
resistance include a copolymer containing adamantyl methacrylate
units, which is an alicyclic polymer [Takechi, et al., Journal of
Photopolymer Science and Technology, 5(3), 439-446 (1992)], a
copolymer containing isobornyl methacrylate units [R. D. Allen, et
al., Journal of Photopolymer Science and Technology, 8(4), 623-636
(1995); ibid., 9(3), 465-474 (1996)], and a copolymer containing
menthyl methacrylate units [Shida, et al., Journal of Photopolymer
Science and Technology, 9(3), 457-464 (1996)].
[0013] In the above-exemplified resins, however,
adamantyl-containing residue units, isobornyl-containing residue
units or menthyl-containing residue units--which possess dry
etching resistance--do not contain residual groups which can
exhibit a difference between the solubility before exposure and
that after the exposure. In addition, these alicyclic groups do not
contain groups (for example, carboxyl groups) which provide the
resins with solubility in an aqueous alkaline solution and also
with adhesion to substrates. Accordingly, a homopolymer of a
monomer containing an alicyclic group has high hydrophobicity and
poor adhesion to substrates under processing (for example, silicon
substrates) and can hardly form uniform coating films with good
reproducibility. Moreover, due to the lack of any residual groups
which make it possible to exhibit a difference between a
dissolution rate before exposure and that after the exposure, no
pattern can be formed by exposure. The above-described resins can
hence be used as resin components in resists only when they are
converted into copolymers with a comonomer capable of exhibiting a
difference in solubility, such as t-butyl methacrylate or
tetrahydropyranyl methacrylate, or with a comonomer capable of
imparting substrate adhesion such as methacrylic acid. These
comonomers have considerably low dry etching resistance and,
nonetheless, their contents are required to be as high as about 50
mole %. Accordingly, such copolymers are significantly reduced in
dry etching resistance and have little utility as
dry-etching-resistant resins.
[0014] There is accordingly a strong desire for a new resist resin
material, which has high transparency to radiation of 220 nm or
shorter, possesses high etching resistance, contains functional
groups permitting exhibition of a difference between the solubility
before exposure and that after the exposure, permits development in
an aqueous alkaline solution after exposure, and is equipped with
improved substrate adhesion.
[0015] As a novel resin capable of satisfying these requirements,
the present inventors already developed the resin disclosed in JP
Kokai 8-259626. A further improvement in dry etching resistance is
however desired.
SUMMARY OF THE INVENTION
[0016] An object of the present invention is therefore to provide a
chemically amplified photoresist composition--which is suitable for
use in lithography making use of exposure radiation of 220 nm or
shorter, especially of 180 to 220 nm, can exhibit a difference
between the solubility before exposure and that after the exposure,
permits development in an aqueous alkaline solution after exposure,
possesses high substrate adhesion, has high transparency to
radiation of 220 nm or shorter, and is equipped with improved
etching resistance--and also to provide a pattern forming process
making use of the photoresist composition.
[0017] The present invention thus relates to a (meth)acrylate
represented by the following formula (1): 2
[0018] wherein R.sup.1 represents a hydrogen atom or a methyl
group, R.sup.2 represents a C.sub.17-23 divalent hydrocarbon group
containing a bridged cyclic hydrocarbon group, and R.sup.3
represents an acid-decomposable group or a hydrogen atom.
[0019] This invention also pertains to a polymer available by
homopolymerization of the (meth)acrylate represented by the formula
(1) or copolymerization of the (meth)acrylate with another
copolymerizable compound and having a weight average molecular
weight of from 1,000 to 500,000.
[0020] This invention is also concerned with a polymer represented
by the following formula (2): 3
[0021] wherein R.sup.4, R.sup.6 and R.sup.9 each represents a
hydrogen atom or a methyl group, R.sup.5 and R.sup.7 each
represents a C.sub.17-23 divalent hydrocarbon group containing a
bridged cyclic hydrocarbon group, R.sup.8 represents an
acid-decomposable group, R.sup.10 represents a hydrogen atom or a
C.sub.1-12 hydrocarbon group, x+y+z equals to 1, and x, y and z
stand for 0 to 1, 0 to 1, and 0 to 0.9, respectively, and having a
weight average molecular weight of from 1,000 to 500,000.
[0022] This invention also relates to a photoresist composition
comprising 70 to 99.8 wt. % of one of the above-described polymers
of the present invention and 0.2 to 30 wt. % of a photoacid
generator capable of generating an acid upon exposure to
radiation.
[0023] According to the present invention, it is possible to
provide a photoresist material, which can exhibit a difference
between the solubility before exposure and that after the exposure,
permits development in an aqueous alkaline solution after exposure,
possesses high substrate adhesion, has high transparency to
radiation of 220 nm or shorter, and is equipped with excellent
etching resistance, thereby making it possible to form
submicrometer patterns by ArF eximer laser beam in the fabrication
of semiconductor devices.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] The present invention will hereinafter be described in
detail by its embodiments.
[0025] In the formula (1), R.sup.1 represents a hydrogen atom or a
methyl group, and R.sup.2 represents a C.sub.17-23 divalent
hydrocarbon group containing a bridged cyclic hydrocarbon group.
Specific examples of R.sup.2 can include
hexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.0.sup.2,7.0.sup-
.9,14]heptadecanediyl,
methylhexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.0.sup.2-
,7.0.sup.9,14]heptadecanediyl,
octacyclo[8.8.0.1.sup.2,9.1.sup.4,7.1.sup.1- 1,18.1.sup.13,16.
0.sup.3,8.0.sup.12,17]docosanediyl,
methyloctacyclo[8.8.0.1.sup.2,9.
1.sup.4,7.1.sup.11,18.1.sup.13,16.0.sup.-
3,8.0.sup.12,17]docosanediyl groups, as shown in Table 1.
[0026] R.sup.3 represents a hydrogen atom or an acid-decomposable
group. Specific examples can include t-butyl, tetrahydropyran-2-yl,
tetrahydrofuran-2-yl, 4-methoxytetrahydropyran-4-yl, 1-ethoxyethyl,
1-butoxy-ethyl, 1-propoxyethyl, and 3-oxocyclohexyl groups.
[0027] As an example of polymers available by homopolymerization of
the (meth)acrylate represented by the formula (1) or
copolymerization of the (meth)acrylate with another copolymerizable
compound, the polymer represented by the formula (2) can be
mentioned.
[0028] In the formula (2), R.sup.4, R.sup.6 and R.sup.9 each
represents a hydrogen atom or a methyl group. R.sup.5 and R.sup.7
each represents a C.sub.17-23 divalent hydrocarbon group containing
a bridged cyclic hydrocarbon group. Specific examples can include
hexacyclo[6.6.1.1.sup.3,- 6.1.sup.10,13.0.sup.2,7.
0.sup.9,14]heptadecanediyl, methylhexacyclo[6.6.1.1.sup.3,6.
1.sup.10,13.0.sup.2,7.0.sup.9,14]heptade- canediyl,
octacyclo[8.8.0. 1.sup.2,9.1.sup.4,7.1.sup.11,18.1.sup.13,16.0.s-
up.3,8.0.sup.12,17]docosanediyl and
methyloctacyclo[8.8.0.1.sup.2,9.1.sup.-
4,7.1.sup.11,18.1.sup.13,16.0.sup.3,8. 0.sup.12,17]docosanediyl
groups, as shown in Table 1.
[0029] R.sup.8 represents an acid-decomposable group. Specific
examples can include t-butyl, tetrahydropyran-2-yl,
tetrahydrofuran-2-yl, 4-methoxytetrahydropyran-4-yl, 1-ethoxyethyl,
1-butoxyethyl, 1-propoxyethyl, and 3-oxocyclohexyl groups.
[0030] R.sup.10 represents a hydrogen atom or a C.sub.1-12
hydrocarbon group. Specific examples can include methyl, ethyl,
n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, cyclohexyl,
dimethylcyclohexyl, tricyclo[5.2. 1.0.sup.2,6]decyl, norbonyl,
adamantyl, and isobornyl groups.
1TABLE 1 Chemical structure R.sup.2,R.sup.5,R.sup.7 of group
Hexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.
0.sup.2,7.0.sup.9,14]heptadecanedi- yl group 4
Methylhexacyclo[6.6.1.1.sup.3,6.
1.sup.10,13,0.sup.2,7.0.sup.9,14]heptadecane- diyl group 5
Octacyclo[8.8.0.1.sup.2,9.1.sup.4,7.
1.sup.11,18.1.sup.13,16.0.sup.3,8.0- .sup.12,17]- docosanediyl
group 6 Methyloctacyclo[8.8.0.1.- sup.2,9.
1.sup.4,7.1.sup.11,18.1.sup.13,16.0.sup.3,8.
0.sup.12,17]docosanediyl group 7
[0031] Among (meth)acrylates represented by the formula (1) a vinyl
monomer of the formula (1) in which R.sup.1 is a methyl group,
R.sup.2 is a hexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.
0.sup.2,7.0.sup.9,14]heptadecane- diyl group, and 3 is a
tetrahydropyran-2-yl group can be synthesized, for example, as will
be described hereinafter.
[0032] First, 8-methoxycarbonyltetracyclo[4.4.0.1.sup.2,5.
1.sup.7,10]-3-dodecene and dicyclopentadiene are reacted at 170 to
180.degree. C. for 17 hours, whereby
methoxycarbonyl-hexacyclo[6.6.1.1.su-
p.3,6.1.sup.10,13.0.sup.2,7.0.sup.9,14]heptadecene is obtained.
[0033] The methoxycarbonylhexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.
0.sup.2,7.0.sup.9,14]heptadecene is next subjected to alkaline
hydrolysis, followed by the protection of the carboxyl group with a
tetrahydropyranyl group so that
tetrahydropyranyloxycarbonylhexacyclo[6.6-
.1.1.sup.3,6.1.sup.10,13. 0.sup.2,7.0.sup.9,14] is obtained.
[0034] Further, one hydroxyl group is introduced per molecule by
using a boran-tetrahydrofuran complex, followed by the reaction
with methacryloyl chloride, whereby the target methacrylate is
obtained.
[0035] The polymer, which is available by homopolymerization of the
(meth)acrylate represented by the formula (1) or copolymerization
of the (meth)acrylate represented by the formula (1) with another
copolymerizable compound, can be obtained by a conventional
polymerization process such as radical polymerization or ionic
polymerization. This polymerization can be conducted, for example,
by stirring the (meth)acrylate by itself or in combination with the
another copolymerizable monomer under heat at 50 to 70.degree. C.
for 0.5 to 12 hours in dry tetrahydrofuran under an atmosphere of
an inert gas (argon, nitrogen or the like) in the presence of a
suitable radical polymerization initiator [for example,
azobisisobutyronitrile (AIBN); monomer/initiator molar ratio: 8 to
200] added therein.
[0036] Further, the weight average molecular weight of the polymer
according to the present invention ranges from 1,000 to 500,000,
with 5,000 to 200,000 being more preferred. A copolymer having
desired composition, molecular weight and the like can be obtained
by choosing the charge ratio of monomers for the copolymer and
other polymerization conditions.
[0037] The photoacid generator, which is an essential element of
each photoresist composition according to the present invention,
may desirably be a photochemical acid generator which generates an
acid upon exposure to radiation of 400 nm or shorter, preferably
radiation in a range of from 180 nm to 220 nm. Any photoacid
generator is usable, insofar as its mixture with the
above-described high molecular compound or the like in the present
invention is sufficiently soluble in an organic solvent and the
resulting solution can be formed into a uniform coating film by a
film-forming method such as spin coating. Such photochemical acid
generators can be used either singly or in combination.
[0038] Examples of photoacid generators usable in the present
invention can include the triphenylsulfonium salt derivatives
described by J. V. Crivello et al. in Journal of the Organic
Chemistry, 43(15), 3055-3058 (1978), onium salts including the
triphenylsulfonium salt derivatives as typical examples (for
example, compounds such as sulfonium salts, iodonium salts,
phosphonium salts, diazonium salts and ammonium salts),
2,6-dinitrobenzyl esters [O. Nalamasu, et al., SPIE Proceedings,
1262, 32 (1990)], 1,2,3-tri(methane-sulfonyloxy)benzene (Takumi
Ueno, et al., Proceedings of PME '89, 413-424, Kodansha Ltd.
(1990)]3, and sulfosuccimides disclosed in JP Kokai 5-134416.
[0039] The content of the photoacid generator is generally from 0.2
to 30 parts by weight, preferably from 1 to 15 parts by weight per
100 parts of the whole components including itself. A content
smaller than 0.2 part by weight may lead to a significant reduction
in sensitivity, thereby making it difficult to form patterns. On
the other hand, a content greater than 30 parts by weight may
develop problems such that the formation of a uniform coating film
becomes difficult and a residue (scam) tends to occur after
development.
[0040] The content of the polymer is generally from 70 to 99.8
parts by weight, preferably 85 to 99 parts by weight per 100 parts
by weight of the whole components including itself.
[0041] Any solvent can be used suitably in the present invention,
insofar as it is an organic solvent capable of achieving sufficient
dissolution of the polymer and the photoacid generator and the
resulting solution can be formed into a uniform coating film by a
coating method such as spin coating. Such solvents can be used
either singly or in combination. Specific examples can include, but
are not limited to, n-propyl alcohol, isopropyl alcohol, n-butyl
alcohol, tert-butyl alcohol, methylcellosolve acetate,
ethylcellosolve acetate, propylene glycol monoethyl ether acetate,
methyl lactate, ethyl lactate, 2-methoxybutyl acetate,
2-ethoxyethyl acetate, methyl pyruvate, ethyl pyruvate, methyl
3-methoxypropionate, ethyl 3-methoxypropionate,
N-methyl-2-pyrrolidinone, cyclohexanone, cyclopentanone,
cyclohexanol, methyl ethyl ketone, 1,4-dioxane, ethylene glycol
monomethyl ether, ethylene glycol monomethyl ether acetate,
ethylene glycol monoethyl ether, ethylene glycol monoisopropyl
ether, diethylene glycol monomethyl ether, and diethylene glycol
dimethyl ether.
[0042] Although the "basic" components of the photoresist
composition of the present invention are the above-described
photoacid generator, resin and solvent, one or more of other
components such as dissolution inhibitors, surfactant, pigments,
stabilizers, coating property improvers and dyes may also be added
as needed.
[0043] Each photoresist composition according to the present
invention is usable as a new photoresist material having high
transparency to radiation of 220 nm or shorter, high dry etching
resistance and improved substrate adhesion. Use of the photoresist
composition according to the present invention in lithography
making use of far ultraviolet radiation of 220 nm or shorter as
exposure radiation makes it possible to form submicrometer
patterns.
[0044] The present invention also relates to process for forming a
pattern, which comprises the following steps: coating a substrate
with the photoresist composition of the present invention, exposing
the thus-coated photoresist composition to radiation having a
wavelength of from 180 to 220 nm, baking the thus-exposed
photoresist composition, and then developing the thus-baked
photoresist composition. In this process, prebaking may be
conducted after the coating step if desired. Further, the exposure
radiation may desirably be ArF eximer laser.
[0045] The present invention will hereinafter be described further
by Examples. It is however to be noted that the present invention
is not limited to or by them.
EXAMPLE 1
[0046] Synthesis of a methacrylate of the formula (1) in which
R.sup.1 is a methyl group, R.sup.2 is a
hexacyclo-[6.6.1.1.sup.3,6.1.sup.10,13.0.sup-
.2,7.0.sup.9,14]heptadecanediyl group, and R.sup.3 is a
tetrahydropyran-2-yl group. 8
[0047] Into a 300-m.LAMBDA. eggplant-type flask, 65 g of
8-methoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene,
87 g of dicyclopentadiene and 0.14 g of methylhydroquinone were
added, followed by a reaction at 170 to 180.degree. C. for 17
hours.
[0048] After the reaction mixture was allowed to cool down, the
reaction mixture was distilled under reduced pressure so that
unreacted
8-methoxycarbonyltetracyclo-[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene
and dicyclopentadiene were eliminated. Hot methanol was then added
to the residue, an insoluble matter was filtered off, and the
resulting filtrate was concentrated under reduced pressure. The
residue was recrystallized from methanol, whereby 10 g of
12-methoxycarbonylhexacyclo[6.6.1.
1.sup.3,6.1.sup.10,13.0.sup.2,7.0.sup.9,14]heptadecene were
obtained as white crystals.
[0049] Next, 3.6 g of the
12-methoxycarbonylhexacyclo-[6.6.1.1.sup.3,6.1.s-
up.10,13.0.sup.2,7.0.sup.9,14]heptadecene were dissolved in 30
m.LAMBDA. of 95% ethanol, into which 1.25 g of potassium hydroxide
were added. The resultant mixture was then heated under reflux. Two
hours later, the reaction mixture was allowed to cool down and was
then concentrated to 1/3 volume in an evaporator. Water (50
m.LAMBDA.) and ether (50 m.LAMBDA.) were added, and the resultant
water layer was separated. When the water layer was acidified with
3% HCl, a white precipitate was formed. The precipitate was
collected by filtration and was then washed with water until the
washing became neutral, whereby 2.2 g of
12-carboxyhexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.
0.sup.2,7.0.sup.9,14]hep- tadecene were obtained.
[0050] Next, 2.1 g of the 12-carboxyhexacyclo[6.6.1.
1.sup.3,6.1.sup.10,13.0.sup.2,7.0.sup.9,14]heptadecene and 1.71 g
of 3,4-dihydro-2H-pyran were dissolved in 50 m.LAMBDA. of
tetrahydrofuran, into which 0.03 g of p-toluenesulfonic acid were
added. The resultant mixture was reacted at room temperature for 2
hours. The reaction mixture was diluted with 100 m.LAMBDA. of ethyl
ether, followed by the successive washing with a 3% aqueous
solution of Na.sub.2CO.sub.3, 3% aqueous solution of sodium
chloride, and water. An organic layer was dried over MgSO.sub.4.
The ethyl ether and unreacted 3,4-dihydro-2H-pyran were distilled
off under reduced pressure by an evaporator, whereby 2 g of
12-tetrahydropyranyloxycarbonylhexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.0.su-
p.2,7.0.sup.9,14]heptadecene were obtained as a viscous liquid.
[0051] Further, the 2 g of the
12-tetrahydropyranyloxycarbonylhexacyclo[6.-
6.1.1.sup.3,6.1.sup.10,13.0.sup.2,7.0.sup.9,14]heptadecene were
dissolved in 8 m.LAMBDA. of dry THF, followed by cooling to
0.degree. C. After the atmosphere was purged with argon, 6
m.LAMBDA. of a 1 M solution of a boran-THF complex in THF were
added dropwise. Subsequent to stirring at 0.degree. C. for 1 hour,
the mixture was stirred further at room temperature for 1 hour. The
resultant mixture was then cooled to 0.degree. C., to which 0.5
m.LAMBDA. of water was added dropwise, followed by the further
dropwise addition of 1.1 m.LAMBDA. of a 3 M aqueous solution of
NaOH and 0.7 m.LAMBDA. of 30% H.sub.2O.sub.2 at temperatures not
higher than 200.degree. C. After the thus-obtained mixture was
stirred at room temperature for 1.5 hours, the water layer was
saturated with NaCl, followed by the dilution with 100 m.LAMBDA. of
ethyl ether. The resulting ether layer was washed with a saturated
aqueous solution of sodium chloride and water and dried over
MgSO.sub.4. The ethyl ether was then distilled off, whereby 2 g of
hydroxy-tetrahydropyranyloxycarbonylhexacyclo[6.6.1.1.sup.3,6.1.sup.10,13-
.0.sup.2,7. 0.sup.9,143] were obtained.
[0052] Then, the 2 g of the
hydroxy-tetrahydropyranyloxycarbonylhexacyclo[-
6.6.1.1.sup.3,6.1.sup.10,13.0.sup.2,7. 0.sup.9,14] and 0.53 g of
pyridine were dissolved in 8 m.LAMBDA. of dry THF. After the
resultant solution was cooled to 0.degree. C., a solution of 0.7 g
of methacryloyl chloride in 1 m.LAMBDA. of THF was added dropwise.
Subsequent to stirring for 1 hour, the mixture was allowed to react
further overnight at room temperature. The precipitated pyridine
hydrochloride was filtered off. The filtrate was diluted with 20
m.LAMBDA. of ethyl ether. The resulting solution was washed
successively with 0.5 N hydrochloric acid, a saturated aqueous
solution of sodium chloride, a 3% aqueous solution of
Na.sub.2CO.sub.3, and a saturated aqueous solution of sodium
chloride, and was then dried over MgSO.sub.4. The ethyl ether was
distilled off under reduced pressure and the residue was subjected
to column fractionation [hexane/ethyl acetate=5/1 (by volume),
adsorbent: silica gel], whereby 2 g of the target methacrylate were
obtained as a viscous liquid. IR (cm.sup.-1): 3048,
2940(.upsilon.CH), 1740, 1713(.upsilon.C=0), 1640 (.upsilon.C=C) ,
1168 (.upsilon.C-0).
EXAMPLE 2
[0053] Synthesis of a methacrylate of the formula (1) in which
R.sup.1 is a methyl group, R.sup.2 is a
hexacyclo-[6.6.1.1.sup.3,6.1.sup.10,13.0.sup-
.2,7.0.sup.9,14]heptadecanediyl group, and R.sup.3 is a hydrogen
atom. 9
[0054] Two grams of the methacrylate obtained in Example 1 were
dissolved in 14 m.LAMBDA. of a mixed solvent of acetic acid,
tetrahydrofuran and water (4/2/1 by volume), followed by a reaction
at 40 to 45.degree. C. for 45 minutes. The reaction mixture as
poured into 250 m.LAMBDA. of ice water. Precipitated crystals were
collected by filtration, washed several times with water, and then
washed with hexane, whereby 0.79 g of the target product was
obtained. .sup.1H-NMR (CDCl.sub.3, internal standard:
tetramethylsilane) ppm: 1.0-1.88(m), 1.93-2.75(m), 1.91(3H,s),
4.99(1H,s), 5.51(1H,s), 6.04(1H,s), 9.5-11.3(1H,br). IR
(cm.sup.-1): 2800-3600(.upsilon.OH), 2950, 3048(.upsilon.CH),
1712(.upsilon.C=0), 1634(.upsilon.C=C), 1172 (.upsilon.C-0).
EXAMPLE 3
[0055] Synthesis of a methacrylate of the formula (1) in which
R.sup.1 is a methyl group, R.sup.2 is a
hexacyclo-[6.6.1.1.sup.3,6.1.sup.10,130.sup.- 2,7.0.sup.9,14
]heptadecanediyl group, and R.sup.3 is a t-butyl group. 10
[0056] Five grams of the methacrylate described in Example 2 and
obtained as in Example 2 were dissolved in 20 m.LAMBDA. of toluene,
followed by cooling to 0.degree. C. Into the resultant solution,
5.9 g of trifluoroacetic anhydride were added dropwise and further,
6.2 g of t-butyl alcohol were added dropwise. The resultant mixture
was reacted for 1 hour under ice cooling. The reaction mixture as
poured into 100 m.LAMBDA. of ice water. An organic layer was
extracted with 100 m.LAMBDA. of ethyl ether, and the extract was
washed successively with a 5% aqueous solution of NaOH, a saturated
aqueous solution of sodium chloride and water. After the organic
layer was dried over magnesium sulfate, the ethyl ether was
distilled off under reduced pressure. The residue was purified by
chromatography on a silica gel column (developer: hexane/ethyl
acetate=5/1 by volume), whereby 2 g of the target product was
obtained as a viscous liquid. IR (cm.sup.-1): 3040,
2959(.upsilon.CH), 1720(.upsilon.C.apprxeq.0), 1631(.upsilon.C=C),
1156 (.upsilon.C-0).
EXAMPLE 4
[0057] Synthesis of a methacrylate of the formula (1) in which
R.sup.1 is a methyl group, R.sup.2 is a
hexacyclo-[6.6.1.1.sup.3,6.1.sup.10,13.0.sup-
.2,7.0.sup.9,14]heptadecanediyl group, and R.sup.3 is an
ethoxyethyl group. 11
[0058] Two grams of the methacrylate described in Example 2 and
obtained as in Example 2 and 1 g of ethyl vinyl ether were
dissolved in 10 m.LAMBDA. of methylene chloride, into which 0.028 g
of pyridinium p-toluene-sulfonate was added, followed by a reaction
at room temperature. Two hours later, the reaction mixture was
diluted with 40 m.LAMBDA. of ethyl ether, followed by successive
washing with a 3% aqueous solution of sodium carbonate, a saturated
aqueous solution of sodium chloride and water. After an organic
layer was dried over magnesium sulfate, the ethyl ether and
unreacted ethyl vinyl ether were distilled off, whereby 2 g of the
target product was obtained as a viscous liquid. IR (cm.sup.-1):
3040, 2950(.upsilon.CH) , 1720(.upsilon.C=0) , 1634(.upsilon.C=C)
1170(.upsilon.C-0).
EXAMPLE 5
[0059] Synthesis of an acrylate of the formula (1) in which R.sup.1
is a hydrogen atom, R.sup.2 is a
hexacyclo-[6.6.1.1.sup.3,6.1.sup.10,13.0.sup.-
2,7.0.sup.9,14]heptadecanediyl group, and R.sup.3 is an
tetrahydropyran-2-yl group. 12
[0060] A synthesis was conducted in a similar manner as in Example
1 except for the use of acryloyl chloride in place of maethacryloyl
chloride, whereby the target product was obtained. IR (cm.sup.-1):
3050, 2940(.upsilon.CH), 1739, 1710(.upsilon.=0), 1636,
1618(.upsilon.C=C), 1170 (.upsilon.C-0).
EXAMPLE 6
[0061] Synthesis of a methacrylate of the formula (1) in which
R.sup.1 is a methyl group, R.sup.2 is a
methyl-hexacyclo[6.6.1.1.sup.3,6.1.sup.10,13-
.0.sup.2,7.0.sup.9,14]hepta-decanediyl group, and R.sup.3 is a
tetrahydropyran-2-yl group. 13
[0062] A synthesis was conducted in a similar manner as in Example
1 except for the use of
8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1.sup.2,-
5.1.sup.7,10]-3-dodecene in lieu of
8-methoxycarbonyltetracyclo[4.4.0.1.su-
p.2,5.1.sup.7,10]-3-dodecene, whereby the target product was
obtained. IR (cm.sup.-1): 3050, 2945(.upsilon.CH), 1739,
1713(.upsilon.C=0), 1640(.upsilon.C=C), 1168 (.upsilon.C-O).
EXAMPLE 7
[0063] Synthesis of a methacrylate of the formula (1) in which
R.sup.1 is a methyl group, R.sup.2 is an
octacyclo-[8.8.0.1.sup.2,9.1.sup.4,7.1.sup.-
11,18.1.sup.13,14.0.sup.3,8.0.sup.12,17]-docosanediyl group, and
R.sup.3 is a tetrahydropyran-2-yl group. 14
[0064] A synthesis was conducted in a similar manner as in Example
1 except for the use of
12-methoxycarbonyl-hexacyclo[6.6.1.1.sup.3,6.1.sup.-
10,13,0.sup.2,7.0.sup.9,14]heptadecene, the synthesis intermediate
in Example 1, instead of
8-methoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7-
,10]-3-dodecene, whereby the target product was obtained. IR
(cm.sup.-1): 33050, 2940(.upsilon.CH), 1740, 1715(.upsilon.C=0),
1636(.upsilon.C=C), 1170(.upsilon.C-O).
EXAMPLE 8
[0065] Synthesis of a polymer of the methacrylate described in
Example 2, said polymer being represented by the formula (2) in
which R.sup.4 is a methyl group, R.sup.5 is a
hexacyclo[6.6.1.1.sup.3,6.
1.sup.10,13.0.sup.2,7.0.sup.9,14]heptadecanediyl group, y is 0, and
z is 0. 15
[0066] In a 100-m.LAMBDA. eggplant-type flask, 3.9 g of the
methacrylate obtained as in Example 2 were dissolved in 30
m.LAMBDA. of dry tetrahydrofuran, into which 196 mg of AIBN were
added. The resultant mixture was stirred at 60 to 65.degree. C.
under an argon gas atmosphere. Ten hours later, the reaction
mixture was allowed to cool down and was then poured into 300
m.LAMBDA. of ligroin. The resulting precipitate was collected by
filtration. The precipitate was purified once more by
reprecipitation, whereby 2.34 g of the target product were obtained
(yield: 60%). Its weight average molecular weight (Mw) as
determined by GPC was 24,300 (calculated based on polystyrene).
EXAMPLE 9
[0067] Synthesis of a copolymer of the methacrylate described in
Example 1 and the methacrylate described in Example 2, said
copolymer being represented by the formula (2) in which R.sup.4 and
R.sup.6 are methyl groups, R.sup.5 and R.sup.7 are
hexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.0.s-
up.2,7.0.sup.9,14]heptadecanediyl groups, R.sup.8 is a
tetrahydropyran-2-yl group, x is 0.5, y is 0.5, and z is 0. 16
[0068] In a 100-m.LAMBDA. eggplant-type flask, 2 g of the
methacrylate obtained as in Example 1 and 1.62 g of the
methacrylate obtained as in Example 2 were dissolved in 30
m.LAMBDA. of dry tetrahydrofuran, into which 196 mg (40
mmol/.LAMBDA.) of AIBN were added. The resultant mixture was
stirred at 60 to 65.degree. C. under an argon gas atmosphere. One
hour later, the reaction mixture was allowed to cool down and was
then poured into 300 m.LAMBDA. of ligroin. The resulting
precipitate was collected by filtration. The precipitate was
purified once more by reprecipitation, whereby 1.92 g of the target
product were obtained (yield: 53%). Its weight average molecular
weight (Mw) as determined by GPC was 21,500. The values of x and y
were determined by .sup.1H-NMR.
EXAMPLES 10 & 11
[0069] Polymerization was conducted as in Example 9 except that the
charge ratio of the methacrylate described in Example 1 to the
methacrylate described in Example 3 was changed. The
copolymerization ratios (x/y) and weight average molecular weights
of the resultant polymers are shown in Table 2.
2 TABLE 2 Charge Weight average Example ratio x/y molecular weight
10 0.2/0.8 0.21/0.79 20,800 12 0.8/0.2 0.82/0.18 21,900
EXAMPLES 12 & 13
[0070] Polymerization was conducted as in Example 9 except that the
amount (concentration) of AIBN was changed. The copolymerization
ratios (x/y) and weight average molecular weights of the resultant
polymers are shown in Table 3.
3 TABLE 3 Concentration Weight average Example of AIBN x/y
molecular weight 12 10 mmol/l 0.49/0.51 84,000 13 80 mmol/l 0.5/0.5
6,400 9 40 mmol/l 0.5/0.5 21,500
EXAMPLE 14
[0071] Synthesis of a copolymer of the methacrylate described in
Example 2 and the methacrylate described in Example 5, said
copolymer being represented by the formula (2) in which R.sup.4 is
a methyl group, R.sup.6 is a hydrogen atom, R.sup.5 and R.sup.7 are
hexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.0.sup.2,7.0.sup.9,14]heptadecanediy-
l groups, R.sup.8 is a tetrahydropyran-2-yl group, x is 0,5, y is
0.5, and z is 0. 17
[0072] The title copolymer was synthesized as in Example 9 except
for the use of the acrylate described in Example 5 instead of the
methacrylate described in Example 1. Its weight average molecular
weight was 22,000.
EXAMPLE 15
[0073] Synthesis of a copolymer of the methacrylate described in
Example 2 and the methacrylate described in Example 6, said
copolymer being represented by the formula (2) in which R.sup.4 and
R.sup.6 are methyl groups, R.sup.5 is a hexacyclo[6.6.1.1.sup.3,6.
1.sup.10,13.0.sup.2,7.0.s- up.9,14]heptadecanediyl group, R.sup.7
is a methylhexacyclo[6.6.1.1.sup.3,-
6.1.sup.10,13.0.sup.2,7.0.sup.9,14]-heptadecanediyl group, R.sup.8
is a tetrahydropyran-2-yl group, x is 0.5, y is 0.5, and z is 0.
18
[0074] The title copolymer was synthesized as in Example 9 except
for the use of the methacrylate described in Example 6 instead of
the methacrylate described in Example 1. Its weight average
molecular weight was 21,200.
EXAMPLE 16
[0075] Synthesis of a copolymer of the methacrylate described in
Example 2 and the methacrylate described in Example 3, said
copolymer being represented by the formula (2) in which R.sup.4 and
R.sup.6 are methyl groups, R.sup.5 and R.sup.7 are
hexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.0.s-
up.2,7.0.sup.9,14]heptadecanediyl groups, R.sup.8 is a tert-butyl
group, x is 0.5, y is 0.5, and z is 0. 19
[0076] The title copolymer was synthesized as in Example 9 except
for the use of the methacrylate described in Example 3 instead of
the methacrylate described in Example 1. Its weight average
molecular weight was 23,500.
EXAMPLE 17
[0077] Synthesis of a copolymer of the methacrylate described in
Example 2 and the methacrylate described in Example 4, said
copolymer being represented by the formula (2) in which R.sup.4 and
R.sup.6 are methyl groups, R.sup.5 and R.sup.7 are
hexacyclo[6.6.1.1..sup.3,6.1.sup.10,13.0.- sup.2,7.
0.sup.9,14]heptadecanediyl groups, R.sup.8 is an ethoxyethyl group,
x is 0.5, y is 0.5, and z is 0. 20
[0078] The title copolymer was synthesized as in Example 9 except
for the use of the methacrylate described in Example 4 instead of
the methacrylate described in Example 1. Its weight average
molecular weight was 20,600.
EXAMPLE 18
[0079] Synthesis of a copolymer of the methacrylate described in
Example 2 and the methacrylate described in Example 7, said
copolymer being represented by the formula (2) in which R.sup.4 and
R.sup.6 are methyl groups, R.sup.5 is a hexacyclo[6.6.1.1.sup.3,6.
1.sup.10,13.0.sup.2,7.0.s- up.9,14]heptadecanediyl groups, R.sup.7
is a methyloctacyclo[8.8.0.1.sup.2-
,9.1.sup.4,7.1.sup.11,18.1.sup.13,16.0.sup.3,8.0.sup.12,17]docosanediyl,
R.sup.8 is a tetrahydropyran-2-yl group, x is 0.5, y is 0.5, and z
is 0. 21
[0080] The title copolymer was synthesized as in Example 9 except
for the use of the methacrylate described in Example 7 instead of
the methacrylate described in Example 1. Its weight average
molecular weight was 24,300.
EXAMPLE 19
[0081] Synthesis of a terpolymer of the methacrylate described in
Example 1, the methacrylate described in Example 2 and
tricyclo[5.2.1.0.sup.2,6]d- ecyl methacrylate, said terpolymer
being represented by the formula (2) in which R.sup.4, R.sup.6 and
R.sup.9 are methyl groups, R.sup.5 and R.sup.7 are
hexacyclo[6.6.1.1..sup.3,6.1.sup.10,13.0.sup.2,7.0.sup.9,14]heptadeca-
nediyl groups, R.sup.8 is a tetrahydropyran-2-yl group, R.sup.10 is
a tricyclo[5.2.1.0.sup.2,6]decyl group, x is 0.5, y is 0.3, and z
is 0.2. 22
[0082] In a 100-m.LAMBDA. eggplant-type flask, 3 g of the
methacrylate described in Example 1, 4.05 g of the methacrylate
described in Example 2 and 1 g of tricyclo[5.2.1.0.sup.2,6]decyl
methacrylate (product of Hitachi Chemical Co., Ltd.; Product No.
FA-513M) were dissolved in 66 m.LAMBDA. of dry tetrahydrofuran,
into which 433 mg (40 mmol/.LAMBDA.) of AIBN were added. The
resultant mixture was stirred at 60 to 65.degree. C. under an argon
gas atmosphere. One hour later, the reaction mixture was allowed to
cool down and was then poured into 700 m.LAMBDA. of ligroin. The
resulting precipitate was collected by filtration. The precipitate
was purified once more by reprecipitation, whereby 4.2 g of the
target product were obtained (yield: 52%). Its weight average
molecular weight was 23,800.
EXAMPLE 20
[0083] Two grams of the copolymer described in Example 9 were
dissolved in 10 g of diethylene glycol dimethyl ether, followed by
filtration through a 0.2-.mu.m TEFLON filter. The thus-prepared
solution was next spin-coated on a 3-inch silicon wafer. Baking was
then conducted for 60 seconds on a hot plate of 90.degree. C.,
whereby a thin film of 0.7 .mu.m in thickness was formed.
[0084] Using a reactive ion etching (RIE) apparatus ("DEM 451",
trade name; manufactured by Anelva Corporation), the etch rate of
the thus-obtained thin film by CF.sub.4 gas was measured. As
etching conditions, the power, pressure and gas flow rate were set
at 100 W, 5 Pa and 30 sccm, respectively. The results are shown in
Table 4.
[0085] Similarly, the etch rates of the copolymer and terpolymer
obtained in Examples 18 and 19, respectively, were measured. The
results are also shown in Table 4. The measurement result of a
coating film of a resin as a reference example, which is disclosed
in JP Kokai 8-259626 and represented by the following structure
(the number of carbons in each bridging cyclic hydrocarbon group:
10): 23
[0086] is also presented in Table 4. Further, the measurement
results of coating films of a novolac resin ("PFI-15A", trade name;
product of Sumitomo Chemical Co., Ltd.), poly(vinylphenol) used as
a base resin in KrF resists and poly(methyl methacrylate) as a
resin containing no bridging cyclic hydrocarbon groups in its
molecular structure, as comparative examples, are also presented in
Table 4. Incidentally, the etch rate of each polymer is shown as a
relative value by assuming that the etch rate of the novolac resist
is 1.
4 TABLE 4 Etch rate (relative value) Polymer of Example 9 0.95
Polymer of Example 18 0.90 Polymer of Example 19 0.85 Referential
Example 1.2 Poly(methyl methacrylate) 1.9 Poly(vinylphenol) 1.2
Novolac resist (PFI-15A) 1
[0087] From the above-described results, it is readily envisaged
that each polymer according to the present invention has a low etch
rate for CF.sub.4 gas and is hence excellent in dry etching
resistance. From a comparison with the referential example, it is
also appreciated that etching resistance can be improved further by
increasing the numbers of carbon atoms in the bridging hydrocarbon
groups represented by R.sup.5 and R.sup.7 in the formula (2)--in
the present invention, the number of carbons is 17 to 23.
EXAMPLES 21 & 22
[0088] A resist of the following composition was prepared.
5 (a) Polymer (Example 9) 2 g (b) Photoacid generator 0.02 g
(triphenylsulfonium triflate) (c) Diethylene glycol dimethyl ether
10.5 g
[0089] The above mixture was filtered through a 0.2-.mu.m TEFLON
filter to prepare a resist. The resist was spin-coated on a 3-inch
quartz substrate and was then baked at 90.degree. C. for 1 minute
on a hot plate, whereby a thin film of 1 .mu.m in thickness was
formed.
[0090] Wavelength dependency of the transmittance of the
thus-obtained thin film was measured by using a spectrophotometer
for ultraviolet and visible region. The transmittance at 193.4 nm,
which is a central wavelength of ArF excimer laser, is shown in
Table 5.
[0091] A similar measurement was also conducted on the polymer
obtained in Example 16.
[0092] As is shown in Table 5, each photoresist according to the
present invention has been confirmed to show sufficient
transparency as a single-layer resist.
6 TABLE 5 Transmittance (%/.mu.m) Example 21 Resist containing the
55 polymer of Example 9 Example 22 Resist containing the 60 polymer
of Example 16
EXAMPLES 23 & 24
[0093] Using the resists prepared in Examples 21 and 22,
respectively, films were formed to a thickness of 0.5 .mu.m on Si
substrates to prepare wafers. These wafers were placed in a
laboratory contact exposure apparatus which had been fully purged
with nitrogen gas. Masks, which were made of quartz plates and
carried thereon patterns drawn with chromium thereon, were brought
into close contact with the individual resist films. Through the
masks, ArF exciter laser was irradiated. Immediately after the
exposure, the resist films were baked at 90.degree. C. for 60
seconds on a hot plate. Development was conducted for 60 seconds by
the dipping method in a 0.238% aqueous solution of TMAH
(tetramethylammonium hydroxide) of 23.degree. C., followed by
rinsing for 60 seconds with deionized water.
[0094] As a result, only exposed areas of the resist films were
dissolved in the developer and were hence removed so that positive
patterns were obtained. Further, the developed patterns were
observed by a scanning electron microscope (SEM; "SE-4100", trade
name; manufactured by Hitachi Ltd.). Problems such as pattern
peeling were not observed. The results of measurements of their
sensitivities and resolutions are shown in Table 6.
7 TABLE 6 Resolution Sensitivity Ex. (.mu.mL/S) (mJ/cm.sup.2) 23
Resist containing the 0.2 2 polymer of Example 9 24 Resist
containing the 0.2 8 polymer of Example 16
[0095] From the above results, each photoresist composition
according to the present invention has been found to have excellent
resolution characteristics. As problems such as pattern peeling did
not take place, each photoresist composition according to the
present invention has also been confirmed to be excellent in
substrate adhesion.
* * * * *