U.S. patent application number 10/170761 was filed with the patent office on 2003-12-25 for photoresist composition for deep ultraviolet lithography comprising a mixture of photoactive compounds.
Invention is credited to Dammel, Ralph R., Kudo, Takanori, Lee, Sangho, Padmanaban, Munirathna, Rahman, M. Dalil.
Application Number | 20030235775 10/170761 |
Document ID | / |
Family ID | 29732579 |
Filed Date | 2003-12-25 |
United States Patent
Application |
20030235775 |
Kind Code |
A1 |
Padmanaban, Munirathna ; et
al. |
December 25, 2003 |
Photoresist composition for deep ultraviolet lithography comprising
a mixture of photoactive compounds
Abstract
The present invention relates to a novel photoresist that can be
developed with an aqueous alkaline solution, and is capable of
being imaged at exposure wavelengths in the deep ultraviolet. The
invention also relates to a process for imaging the novel
photoresist. The novel photoresist comprises a) a polymer
containing an acid labile group, and b) a novel mixture of
photoactive compounds, where the mixture comprises a lower
absorbing compound selected from structure 1 and 2, and a higher
absorbing compound selected from structure 4 and 5, 1 where,
R.sub.1 and R.sub.2 are independently (C.sub.1-C.sub.6)alkyl,
cycloalkyl, cyclohexanone, R.sub.5-R.sub.9 are independently
hydrogen, hydroxyl, (C.sub.1-C.sub.6)alkyl,
C.sub.1-C.sub.6)aliphatic hydrocarbon containing one or more O
atoms, m=1-5, X.sup.- is an anion, and Ar is selected from
naphthyl, anthracyl, and structure 3, 2 where, R.sub.3 is hydrogen
or (C.sub.1-C.sub.6)alkyl, R.sub.4 is independently hydrogen,
(C.sub.1-C.sub.6)alkyl, (C.sub.1-C.sub.6)aliphati- c hydrocarbon
containing one or more O atoms, Y is a single bond or
(C.sub.1-C.sub.6)alkyl, and n=1-4.
Inventors: |
Padmanaban, Munirathna;
(Bridgewater, NJ) ; Kudo, Takanori; (Bedminster,
NJ) ; Lee, Sangho; (Bridgewater, NJ) ; Dammel,
Ralph R.; (Flemington, NJ) ; Rahman, M. Dalil;
(Flemington, NJ) |
Correspondence
Address: |
Sangya Jain
Clariant Corporation
70 Meister Avenue
Somerville
NJ
08876
US
|
Family ID: |
29732579 |
Appl. No.: |
10/170761 |
Filed: |
June 13, 2002 |
Current U.S.
Class: |
430/270.1 ;
430/281.1; 430/311; 430/320; 430/330 |
Current CPC
Class: |
G03F 7/0045 20130101;
Y10S 430/115 20130101; G03F 7/0392 20130101 |
Class at
Publication: |
430/270.1 ;
430/311; 430/320; 430/330; 430/281.1 |
International
Class: |
G03F 007/004; G03F
007/031; G03F 007/20; G03F 007/38 |
Claims
1. A photoresist composition useful for imaging in deep uv
comprising; a) a polymer containing an acid labile group; and, b) a
mixture of photoactive compounds, where the mixture comprises a
lower absorbing compound selected from structure 1 and 2, and a
higher absorbing compound selected from structure 4 and 5, 21where,
R.sub.1 and R.sub.2 are independently (C.sub.1-C.sub.6)alkyl,
cycloalkyl, cyclohexanone, R.sub.5-R.sub.9 are independently
hydrogen, hydroxyl, (C.sub.1-C.sub.6)alkyl,
C.sub.1-C.sub.6)aliphatic hydrocarbon containing one or more O
atoms, m=1-5, X.sup.- is an anion, and Ar is selected from
naphthyl, anthracyl, and structure 3, 22where, R.sub.3 is hydrogen
or (C.sub.1-C.sub.6)alkyl, R.sub.4 is independently hydrogen,
(C.sub.1-C.sub.6)alkyl, (C.sub.1-C.sub.6)aliphatic hydrocarbon
containing one or more O atoms, Y is a single bond or
(C.sub.1-C.sub.6)alkyl, and n=1-4.
2. The composition according to claim 1, where the compound of
structure 1 is selected from a 4-methoxyphenyl-dimethylsulfonium
salt, 3,5-dimethyl-4-methoxyphenyl-dimethyl sulfonium salt,
4-hydroxyphenyl-dimethyl sulfonium salt, and
3,5-dimethyl-4-hydroxyphenyl- -dimethyl sulfonium salt.
3. The composition according to claim 1, where the compound of
structure 2 is selected from 4-methoxyphenyl-methyliodonium salt,
3,5-dimethyl-4-hydroxyphenyl-methyliodonium salt,
4-hydroxyphenyl-methyl iodonium salt and
3,5-dimethyl-4-methoxyphenyl-methyliodonium salt.
4. The composition according to claim 1, where the compound of
structure 4 is selected from a triphenyl sulfonium salt and its
derivatives.
5. The composition according to claim 1, where the compound of
structure 5 is selected from a diphenyl iodonium salt and its
derivatives.
6. The composition according to claim 1, where the polymer is
nonaromatic.
7. The composition according to claim 1, where the molar ratio of
the higher absorbing compound to the lower absorbing compound is
2:1.
8. The composition according to claim 1, where the molar ratio of
higher absorbing compound to the lower absorbing compound is
1:2.
9. A process for imaging a photoresist comprising the steps of: a)
forming on a substrate a photoresist coating from the photoresist
composition of claim 1; b) image-wise exposing the photoresist
coating; c) optionally, postexposure baking the photoresist
coating; and d) developing the photoresist coating with an aqueous
alkaline solution.
10. The process of claim 9, where the image-wise exposure
wavelength is below 200 nm.
11. The process according to claim 9, where the aqueous alkaline
solution comprises tetramethylammonium hydroxide.
12. The process according to claim 9, where the aqueous alkaline
solution further comprises a surfactant.
13. The process according to claim 9, where the substrate is
selected from a microelectronic device and a liquid crystal display
substrate.
Description
FIELD OF INVENTION
[0001] The present invention relates to a novel photoresist
composition that is particularly useful in the field of
microlithography, and especially useful for imaging negative and
positive patterns in the production of semiconductor devices. The
photoresist composition comprises a copolymer and a photoactive
component, where the photoactive component comprises a mixture of
an aromatic onium salt and an alkyaryl onium salt. The novel
photoresist composition provides both good photosensitivity and
also significantly reduces edge roughness of the imaged photoresist
profiles. Such a composition is especially useful for exposure at
193 nanometers (nm) and 157 nm. The invention further relates to a
process for imaging the novel photoresist.
BACKGROUND OF THE INVENTION
[0002] Photoresist compositions are used in microlithography
processes for making miniaturized electronic components such as in
the fabrication of computer chips and integrated circuits.
Generally, in these processes, a thin coating of film of a
photoresist composition is first applied to a substrate material,
such as silicon wafers used for making integrated circuits. The
coated substrate is then baked to evaporate any solvent in the
photoresist composition and to fix the coating onto the substrate.
The photoresist coated on the substrate is next subjected to an
image-wise exposure to radiation.
[0003] The radiation exposure causes a chemical transformation in
the exposed areas of the coated surface. Visible light, ultraviolet
(UV) light, electron beam and X-ray radiant energy are radiation
types commonly used today in microlithographic processes. After
this image-wise exposure, the coated substrate is treated with a
developer solution to dissolve and remove either the radiation
exposed or the unexposed areas of the photoresist.
[0004] The trend toward the miniaturization of semiconductor
devices has led to the use of new photoresists that are sensitive
at lower and lower wavelengths of radiation and has also led to the
use of sophisticated multilevel systems to overcome difficulties
associated with such miniaturization.
[0005] There are two types of photoresist compositions:
negative-working and positive-working. The type of photoresist used
at a particular point in lithographic processing is determined by
the design of the semiconductor device. When negative-working
photoresist compositions are exposed image-wise to radiation, the
areas of the photoresist composition exposed to the radiation
become less soluble to a developer solution (e.g. a cross-linking
reaction occurs) while the unexposed areas of the photoresist
coating remain relatively soluble to such a solution. Thus,
treatment of an exposed negative-working resist with a developer
causes removal of the non-exposed areas of the photoresist coating
and the creation of a negative image in the coating, thereby
uncovering a desired portion of the underlying substrate surface on
which the photoresist composition was deposited.
[0006] On the other hand, when positive-working photoresist
compositions are exposed image-wise to radiation, those areas of
the photoresist composition exposed to the radiation become more
soluble to the developer solution (e.g. a rearrangement reaction
occurs) while those areas not exposed remain relatively insoluble
to the developer solution. Thus, treatment of an exposed
positive-working photoresist with the developer causes removal of
the exposed areas of the coating and the creation of a positive
image in the photoresist coating. Again, a desired portion of the
underlying surface is uncovered.
[0007] Photoresist resolution is defined as the smallest feature,
which the resist composition can transfer from the photomask to the
substrate with a high degree of image edge acuity after exposure
and development. In many leading edge manufacturing applications
today, photoresist resolution on the order of less than one-half
micron are necessary. In addition, it is almost always desirable
that the developed photoresist wall profiles be near vertical
relative to the substrate. Such demarcations between developed and
undeveloped areas of the resist coating translate into accurate
pattern transfer of the mask image onto the substrate. This becomes
even more critical as the push toward miniaturization reduces the
critical dimensions on the devices. In cases where the photoresist
dimensions have been reduced to below 150 nanometer(nm), the
roughness of the photoresist patterns has become a critical issue.
Edge roughness, commonly known as line edge roughness, is typically
observed for line and space patterns as roughness along the
photoresist line, and for contact holes as side wall roughness.
Edge roughness can have adverse effects on the lithographic
performance of the photoresist, especially in reducing the critical
dimension latitude and also in transferring the line edge roughness
of the photoresist to the substrate. Hence, photoresists that
minimize edge roughness are highly desirable.
[0008] Photoresists sensitive to short wavelengths, between about
100 nm and about 300 nm are often used where subhalfmicron
geometries are required. Particularly preferred are photoresists
comprising non-aromatic polymers, a photoacid generator, optionally
a dissolution inhibitor, and solvent.
[0009] High resolution, chemically amplified, deep ultraviolet
(100-300 nm) positive and negative tone photoresists are available
for patterning images with less than quarter micron geometries. To
date, there are three major deep ultraviolet (uv) exposure
technologies that have provided significant advancement in
miniaturization, and these use lasers that emit radiation at 248
nm, 193 nm and 157 nm. Photoresists used in the deep uv typically
comprise a polymer which has an acid labile group and which can
deprotect in the presence of an acid, a photoactive component which
generates an acid upon absorption of light, and a solvent.
[0010] Photoresists for 248 nm have typically been based on
substituted polyhydroxystyrene and its copolymers, such as those
described in U.S. Pat. No. 4,491,628 and U.S. Pat. No. 5,350,660.
On the other hand, photoresists for 193 nm exposure require
non-aromatic polymers, since aromatics are opaque at this
wavelength. U.S. Pat. No. 5,843,624 and GB 2,320,718 disclose
photoresists useful for 193 nm exposure. Generally, polymers
containing alicyclic hydrocarbons are used for photoresists for
exposure below 200 nm. Alicyclic hydrocarbons are incorporated into
the polymer for many reasons, primarily since they have relatively
high carbon:hydrogen ratios which improve etch resistance, they
also provide transparency at low wavelengths and they have
relatively high glass transition temperatures. Photoresists
sensitive at 157 nm have been based on fluorinated polymers, which
are known to be substantially transparent at that wavelength.
Photoresists derived from polymers containing fluorinated groups
are described in WO 00/67072 and WO 00/17712.
[0011] The polymers used in a photoresist are designed to be
transparent to the imaging wavelength, but on the other hand, the
photoactive component has been typically designed to be absorbing
at the imaging wavelength to maximize photosensitivity. The
photosensitivity of the photoresist is dependent on the absorption
characteristics of the photoactive component, the higher the
absorption the less the energy required to generate the acid and
the more photosensitive the photoresist is. Aromatic photoactive
compounds, such as triphenyl sulfonium salts, diphenyl iodonium
salts are known to give good photosensitivity at 248 nm, but have
found to be too absorbing at wavelengths below 200 nm and lead to
tapered photoresist profiles. Transparent sulfonium salts based on
alkyl sulfonium salts have found to be too transparent at the
imaging wavelength and result in poor photosensitivity. JP
10319581, EP 1,085,377, EP 1,041,442, and U.S. Pat. No. 6,187,504
disclose alkylaryl sulfonium salts of different structures that can
be used in the photoresist composition.
[0012] The inventors of this application have found that the
photoactive compounds known in the prior art cause unacceptable
levels of line edge roughness, or if the line edge roughness is
acceptable then the photosensitivity is poor. However, the
inventors of this application have also found that if a mixture of
a specific alkylarylsulfonium or alkylaryliodonium salt and an
arylsulfonium or aryliodonium salt is used, the line edge roughness
is significantly reduced while maintaining an acceptable level of
photosensitivity. EP 1,085,377 discloses that mixtures of
alkylarylsulfonium salts may be used with other onium salts,
diazomethane derivatives, glyoxime derivatives and many other
photoactive compounds. A specific mixture of photoactive compounds
is not disclosed which when formulated into a photoresist would
significantly reduce line edge roughness.
[0013] The object of this invention is to provide a novel
photoresist composition, which can provide good lithographic
performance especially in reducing line edge roughness while
maintaining good photosensitivity.
[0014] The present invention pertains to a novel photoresist
composition comprising a polymer and a novel mixture of
photosensitive compounds. The composition is particularly useful
for imaging in the range of 100-300 nm, and more particularly for
157 nm and 193 nm.
SUMMARY OF THE INVENTION
[0015] The present invention relates to a novel photoresist
composition useful for imaging in deep uv comprising a) a polymer
containing an acid labile group, and, b) a novel mixture of
photoactive compounds, where the mixture comprises a lower
absorbing compound selected from structure 1 and 2, and a higher
absorbing compound selected from structure 4 and 5, 3
[0016] where, R.sub.1 and R.sub.2 are independently
(C.sub.1-C.sub.6)alkyl, cycloalkyl, cyclohexanone, R.sub.5-R.sub.9
are independently hydrogen, hydroxyl, (C.sub.1-C.sub.6)alkyl, and
(C.sub.1-C.sub.6)aliphatic hydrocarbon containing one or more O
atoms, m=1-5, X.sup.- is an anion, and Ar is selected from
naphthyl, anthracyl, and structure 3, 4
[0017] where, R.sub.3 is hydrogen or (C.sub.1-C.sub.6)alkyl,
R.sub.4 is independently hydrogen, (C.sub.1-C.sub.6)alkyl,
(C.sub.1-C.sub.6)aliphati- c hydrocarbon containing one or more 0
atoms, Y is a single bond or (C.sub.1-C.sub.6)alkyl, and n=1-4.
[0018] The invention also relates to a process for imaging a
photoresist comprising the steps of a) forming on a substrate a
photoresist coating from the novel photoresist composition, b)
image-wise exposing the photoresist coating, c) optionally,
postexposure baking the photoresist coating, and d) developing the
photoresist coating with an aqueous alkaline solution.
DESCRIPTION OF THE INVENTION
[0019] The present invention relates to a novel photoresist that
can be developed with an aqueous alkaline solution, and is capable
of being imaged at exposure wavelengths below 200 nm. The invention
also relates to a process for imaging the novel photoresist. The
novel photoresist comprises a) a polymer containing an acid labile
group, and b) a novel mixture of photoactive compounds, where the
mixture comprises a higher absorbing compound selected from an
aromatic sulfonium salt (structure 4) and an aromatic iodonium salt
(structure 5) and a lower absorbing compound selected from
structure 1 and 2. 5
[0020] where, R.sub.1 and R.sub.2 are independently
(C.sub.1-C.sub.6)alkyl, cycloalkyl, cyclohexanone, R.sub.5-R.sub.9
are independently hydrogen, hydroxyl, (C.sub.1-C.sub.6)alkyl, and
(C.sub.1-C.sub.6)aliphatic hydrocarbon containing one or more O
atoms, m=1-5, X.sup.- is an anion, and Ar is selected from
naphthyl, anthracyl and structure 3, 6
[0021] where, R.sub.3 is hydrogen or (C.sub.1-C.sub.6)alkyl,
R.sub.4 is independently hydrogen, (C.sub.1-C.sub.6)alkyl,
(C.sub.1-C.sub.6)aliphati- c hydrocarbon containing one or more O
atoms, Y is a single bond or (C.sub.1-C.sub.6)alkyl, and n=1-4.
[0022] The aromatic sulfonium salts, such as triphenyl sulfonium
salt, derivatives of triphenyl sulfonium salt, diphenyl iodonium
salt and derivatives of diphenyl iodonium salt, provide the higher
absorbing component, while the compounds of structure 1 or 2
provide the lower absorbing component. It has unexpectedly been
found that by combining a higher absorbing photoactive component
with a lower absorbing photoactive component that the edge
roughness of the photoresist pattern can be greatly reduced while
maintaining acceptable photosensitivity. It has further been found
that the optimum lithographic performance is obtained when the
ratio of the higher absorbing component and the lower absorbing
component is in the molar ratio 1:2 to 2:1, and preferably about
1:1. Line edge roughness improvement of greater than 20% is
acceptable, greater than 35% is preferable, greater than 50% is
more preferable and greater than 75% is most preferable. Acceptable
levels of line edge roughness are obtained while maintaining good
photosensitivity by using the components of this invention.
[0023] The higher absorbing photoactive components are aromatic
iodonium and sulfonium salts of structure 4 and 5. 7
[0024] where, R.sub.5-R.sub.9 are independently hydrogen, hydroxyl,
(C.sub.1-C.sub.6)alkyl, and (C.sub.1-C.sub.6)aliphatic hydrocarbon
containing one or more O atoms, m=1-5, and X.sup.- is an anion.
Examples are diphenyliodonium salts, triphenylsulfonium salts and
the like. Examples of X.sup.- are trifluoromethane sulfonate
(triflate), 1,1,1,2,3,3-hexafluoropropanesulfonate,
perfluorobutanebutanesulfonate (nonaflate), camphor sulfonate,
perfluorooctane sulfonate, benzene sulfonate and toluenesulfonate.
Some examples, without limitation are, of sulfonium salts are
triphenylsulfonium salts, trialkylphenylsulfonium salts,
(p-tert-butoxyphenyl)triphenylsulfonium salts,
bis(p-tert-butoxyphenyl)phenylsulfonium salts, and
tris(p-tert-butoxyphenyl)sulfonium salts. Some examples, without
limitation, of iodonium salts are diphenyliodonium salts,
di(alkylphenyl)iodonium salts etc. The counter ion, X.sup.-, may be
any ion that gives good lithographic properties, and examples of
which are fluoroalkylsulfonates such as
1,1,1-trifluoromethanesulfonate and nonafluorobutanesulfonate,
arylsulfonates such as tosylate, benzenesulfonate,
4-fluorobenzenesulfonate, and alkylsulfonates such as mesylate and
butanesulfonate. Preferred salts are diphenyliodonium
trifluoromethane sulfonate, diphenyliodonium
nonafluorobutanesufonate, triphenylsulfonium
trifluromethanesuflonate, and triphenylsulfonium
nonafluorobutanesufonate.
[0025] The lower absorbing photoactive component is a compound of
structure 1 or 2. 8
[0026] where, R.sub.1 and R.sub.2 are independently
(C.sub.1-C.sub.6)alkyl, cycloalkyl, cyclohexanone, X.sup.- is an
anion, and Ar is selected from naphthyl, anthracyl, and structure
3, 9
[0027] where, R.sub.3 is hydrogen or (C.sub.1-C.sub.6)alkyl,
R.sub.4 is independently hydrogen, (C.sub.1-C.sub.6)alkyl,
(C.sub.1-C.sub.6)aliphati- c hydrocarbon containing one or more O
atoms, Y is a single bond or (C.sub.1-C.sub.6)alkyl, and n=1-4.
[0028] The alkyl group generally has up to 6 linear or branched
carbon atoms and can be groups such as methyl, ethyl, propyl,
butyl, pentyl, hexyl, isopropyl, and t-butyl. The
(C.sub.1-C.sub.6)aliphatic hydrocarbon containing one or more O
atoms can be any alkyl group with linkages such as ether, keto,
carboxyl, or other O based linkages. The cycloalkyl group has up to
16 carbon atoms, examples of which are cyclopentyl, cyclohexyl,
cyclooctyl, norbornyl, isonorbornyl and adamantyl. The aromatic
group, Ar, may be connected directly to the sulfonium ion or have a
linking alkylene group with up to 6 alkyl carbon atoms. The
aromatic group may be phenyl, naphthyl or anthracyl and their
derivatives. The phenyl group has the structure 3, examples of
which are 4-methoxyphenyl, 4-hydroxyphenyl, 3,5-dimethyl,
4-hydroxyphenyl and 3,5-dimethyl,4-methoxyphenyl. Other groups that
illustrate the derivatives of the naphthyl and anthracyl
functionality, but are not limited to, are alkylnaphthyl,
dialkylnaphthyl, alkylanthracyl, dialkylanthracyl, alkoxynaphthyl,
alkoxyanthracyl, dialkoxynaphthyl, dialkoxyanthracyl examples of
which are methylnaphthyl, ethylnaphthyl, methylanthracyl,
ethylanthracyl, methoxy naphthyl, ethoxynaphthyl, methoxynaphthyl,
ethoxyanthracyl and others.
[0029] In one of the preferred embodiments Y is a single bond, in
which, the aromatic group is connected directly to the sulfonium
ion, and the aromatic group is phenyl or substituted phenyl,
preferably methoxydimethylphenyl dimethyl sulfonium salts,
methoxyphenyl dimethylsulfonium salts, hydroxydimethylphenyl
dimethyl sulfonium salts, and hydroxyphenyl dimethylsulfonium
salts.
[0030] Examples of the lower absorbing photoactive compound,
without limitations, are 4-methoxyphenyl-dimethylsulfonium
triflate, 3,5-dimethyl-4-hydroxyphenyl-dimethyl sulfonium triflate,
3,5-dimethyl-4-methoxyphenyl-dimethyl sulfonium triflate,
3,5-dimethyl-4-hydroxyphenyl-dimethyl sulfonium nonaflate,
3,5-dimethyl-4-methoxyphenyl-dimethyl sulfonium nonaflate,
4-methoxyphenyl-methyliodonium triflate or nonaflate,
3,5-dimethyl-4-hydroxyphenyl-methyliodonium triflate or nonaflate,
and 3,5-dimethyl-4-methoxyphenyl-methyl iodonium triflate or
nonaflate.
[0031] One of the preferred mixtures of photoactive compounds is a
mixture of triphenylsulfonium triflate or nonaflate with
3,5-dimethyl,4-methoxyph- enylsulfonium triflate or nonaflate.
[0032] The polymer of the invention is one that has acid labile
groups that make the polymer insoluble in aqueous alkaline
solution, but such a polymer in the presence of an acid
catalytically deprotects the polymer, wherein the polymer then
becomes soluble in an aqueous alkaline solution. The polymers
preferably are transparent below 200 nm, and are essentially
non-aromatic, and preferably are acrylates and/or cycloolefin
polymers. Such polymers are, for example, but not limited to, those
described in U.S. Pat. No. 5,843,624, U.S. Pat. No. 5,879,857, WO
97/33,198, EP 789,278 and GB 2,332,679. Nonaromatic polymers that
are preferred for irradiation below 200 nm are substituted
acrylates, cycloolefins, substituted polyethylenes, etc. Aromatic
polymers based on polyhydroxystyrene and its copolymers may also be
used, especially for 248 nm exposure. Preferred comonomers are
methacrylates.
[0033] Polymers based on acrylates are generally based on
poly(meth)acrylates with at least one unit containing pendant
alicyclic groups, and with the acid labile group being pendant from
the polymer backbone and/or from the alicyclic group. Examples of
pendant alicyclic groups, may be adamantyl, tricyclodecyl,
isobornyl, menthyl and their derivatives. Other pendant groups may
also be incorporated into the polymer, such as mevalonic lactone,
gamma butyrolactone, alkyloxyalkyl, etc. More preferred structures
for the alicyclic group are: 10
[0034] The type of monomers and their ratios incorporated into the
polymer are optimized to give the best lithographic performance.
Such polymers are described in R. R. Dammel et al., Advances in
Resist Technology and Processing, SPIE, Vol. 3333, p144, (1998).
Examples of these polymers include poly(2-methyl-2-adamantane
methacrylate-co-mevalonic lactone methacrylate),
poly(carboxy-tetracyclododecyl methacrylate-co-tetrahydrop-
yranylcarboxytetracyclododecyl methacrylate),
poly(tricyclodecylacryl
ate-co-tetrahydropyranylmethacrylate-co-methacrylicacid),
poly(3-oxocyclohexyl methacrylate-co-adamantylmethacrylate).
[0035] Polymers synthesized from cycloolefins, with norbornene and
tetracyclododecene derivatives, may be polymerized by ring-opening
metathesis, free-radical polymerization or using metal organic
catalysts. Cycloolefin derivatives may also be copolymerized with
cyclic anhydrides or with maleimide or its derivatives. Examples of
cyclic anhydrides are maleic anhydride and itaconic anhydride. The
cycloolefin is incorporated into the backbone of the polymer and
may be any substituted or unsubstituted multicyclic hydrocarbon
containing an unsaturated bond. The monomer can have acid labile
groups attached. The polymer may be synthesized from one or more
cyclo olefin monomers having an unsaturated bond. The cyclo olefin
monomers may be substituted or unsubstituted norbornene, or
tetracyclododecane. The substituents on the cyclo olefin may be
aliphatic or cycloaliphatic alkyls, esters, acids, hydroxyl,
nitrile or alkyl derivatives. Examples of cyclo olefin monomers,
without limitation, are: 11
[0036] Other cyclo olefin monomers which may also be used in
synthesizing the polymer are: 12
[0037] Such polymers are described in the following reference and
incorporated herein, M-D. Rahman et al, Advances in Resist
Technology and Processing, SPIE, Vol. 3678, p1193, (1999). Examples
of these polymers include poly((t-butyl
5-norbornene-2-carboxylate-co-2-hydroxyethyl
5-norbornene-2-carboxylate-co-5-norbornene-2-carboxylic
acid-co-maleic an hydride), poly(t-butyl
5-norbornene-2-carboxylate-co-isobornyl-5-norborne-
ne-2-carboxylate-co-2-hydroxyethyl
5-norbornene-2-carboxylate-co-5-norborn- ene-2-carboxylic
acid-co-maleic anhydride), poly(tetracyclododecene-5-carb-
oxylate-co-maleic anhydride), poly(t-butyl
5-norbornene-2-carboxylate-co-m- aleic
anhydride-co-2-methyladamantyl methacrylate-co-2-mevalonic lactone
methacrylate), poly(2-methyladamantyl methacrylate-co-2-mevalonic
lactone methacylate) and the like.
[0038] Polymers containing mixtures of acrylate monomers,
cycloolefinic monomers and cyclic anhydrides, where such monomers
are described above, may also be combined into a hybrid polymer.
Preferably the cyclo olefin monomer is selected from t-butyl
norbornene carboxylate (BNC), hydroxyethyl norbornene carboxylate
(HNC), norbornene carboxylic acid(NC), t-butyl
tetracyclo[4.4.0.1..sup.2,61..sup.7,10] dodec-8-ene-3-carboxylate,
and t-butoxycarbonylmethyl tetracyclo[4.4.0.1..sup.2,61..sup.7,10]
dodec-8-ene-3-carboxylate; more preferably the cyclo olefins are
selected from t-butyl norbornene carboxylate (BNC), hydroxyethyl
norbornene carboxylate (HNC), and norbornene carboxylic acid(NC).
The preferred acrylate monomers are selected from mevaloniclactone
methacrylate (MLMA), 2-methyladamantyl methacrylate (MAdMA),
isoadamantyl methacrylate, 3-hydroxy-1-methacryloxy- adamatane,
3,5-dihydroxy-1-methacryloxyadamantane, .beta.-methacryloxy-.ga-
mma.-butyrolactone, and .alpha.-methacryloxy-.gamma.-butyrolactone.
More preferably the acrylate monomers are selected from
mevaloniclactone methacrylate (MLMA) and 2-methyladamantyl
methacrylate (MAdMA). The cyclic anhydride is preferably maleic
anhydride.
[0039] The cyclo olefin and the cyclic anhydride monomer are
believed to form an alternating polymeric structure, and the amount
of the acrylate monomer incorporated into the polymer can be varied
to give the optimal lithographic properties. The percentage of the
acrylate monomer relative to the cyclo olefin/anhydride monomers
within the polymer ranges from about 95 mole % to about 5 mole %,
preferably from about 75 mole % to about 25 mole %, and most
preferably from about 55 mole % to about 45 mole %.
[0040] Fluorinated non-phenolic polymers, useful for 157 nm
exposure, also exhibit line edge roughness and can benefit from the
use of the novel mixture of photoactive compounds described in the
present invention. Such polymers are described in WO 00/17712 and
WO 00/67072 and incorporated herein by reference. Example of one
such polymer is
poly(tetrafluoroethylene-co-norbornene-co-5-hexafluoroisopropanol-substit-
uted 2-norbornene.
[0041] Polymers synthesized from cycloolefins and cyano containing
ethylenic monomers are described in the U.S. patent application
Ser. No. 09/854,312 and incorporated herein by reference, may also
be used.
[0042] The molecular weight of the polymers is optimized based on
the type of chemistry used and on the lithographic performance
desired. Typically, the weight average molecular weight is in the
range of 3,000 to 30,000 and the polydispersity is in the range 1.1
to 5, preferably 1.5 to 2.5.
[0043] The solid components of the present invention are dissolved
in an organic solvent. The amount of solids in the solvent or
mixture of solvents ranges from about 5 weight% to about 50
weight%. The polymer may be in the range of 5 weight% to 90 weight%
of the solids and the photoacid generator may be in the range of 2
weight% to about 50 weight% of the solids. Suitable solvents for
such photoresists may include propylene glycol mono-alkyl ether,
propylene glycol alkyl (e.g. methyl) ether acetate,
ethyl-3-ethoxypropionate, xylene, diglyme, amyl acetate, ethyl
lactate, butyl acetate, 2-heptanone, ethylene glycol monoethyl
ether acetate, and mixtures thereof.
[0044] Various other additives such as colorants, non-actinic dyes,
anti-striation agents, plasticizers, adhesion promoters,
dissolution inhibitors, coating aids, photospeed enhancers and
surfactants may be added to the photoresist composition before the
solution is coated onto a substrate. Surfactants that improve film
thickness uniformity, such as fluorinated surfactants, can be added
to the photoresist solution. A sensitizer that transfers energy
from a particular range of wavelengths to a different exposure
wavelength may also be added to the photoresist composition. Often
bases are also added to the photoresist to prevent t-tops or
bridging at the surface of the photoresist image. Examples of bases
are amines, ammonium hydroxide, and photosensitive bases.
Particularly preferred bases are trioctylamine, diethanolamine and
tetrabutylammonium hydroxide.
[0045] The prepared photoresist composition solution can be applied
to a substrate by any conventional method used in the photoresist
art, including dipping, spraying, and spin coating. When spin
coating, for example, the photoresist solution can be adjusted with
respect to the percentage of solids content, in order to provide
coating of the desired thickness, given the type of spinning
equipment utilized and the amount of time allowed for the spinning
process. Suitable substrates include silicon, aluminum, polymeric
resins, silicon dioxide, doped silicon dioxide, silicon nitride,
tantalum, copper, polysilicon, ceramics, aluminum/copper mixtures;
gallium arsenide and other such Group III/V compounds. The
photoresist may also be coated over antireflective coatings.
[0046] The photoresist coatings produced by the described procedure
are particularly suitable for application to silicon/silicon
dioxide wafers, such as are utilized in the production of
microprocessors and other miniaturized integrated circuit
components. An aluminum/aluminum oxide wafer can also be used. The
substrate may also comprise various polymeric resins, especially
transparent polymers such as polyesters.
[0047] The photoresist composition solution is then coated onto the
substrate, and the substrate is treated at a temperature from about
70.degree. C. to about 150.degree. C. for from about 30 seconds to
about 180 seconds on a hot plate or for from about 15 to about 90
minutes in a convection oven. This temperature treatment is
selected in order to reduce the concentration of residual solvents
in the photoresist, while not causing substantial thermal
degradation of the solid components. In general, one desires to
minimize the concentration of solvents and this first temperature.
Treatment is conducted until substantially all of the solvents have
evaporated and a thin coating of photoresist composition, on the
order of half a micron (micrometer) in thickness, remains on the
substrate. In a preferred embodiment the temperature is from about
95.degree. C. to about 120.degree. C. The treatment is conducted
until the rate of change of solvent removal becomes relatively
insignificant. The film thickness, temperature and time selection
depends on the photoresist properties desired by the user, as well
as the equipment used and commercially desired coating times. The
coated substrate can then be imagewise exposed to actinic
radiation, e.g., ultraviolet radiation, at a wavelength of from
about 100 nm (nanometers) to about 300 nm, x-ray, electron beam,
ion beam or laser radiation, in any desired pattern, produced by
use of suitable masks, negatives, stencils, templates, etc.
[0048] The photoresist is then subjected to a post exposure second
baking or heat treatment before development. The heating
temperatures may range from about 90.degree. C. to about
150.degree. C., more preferably from about 100.degree. C. to about
130.degree. C. The heating may be conducted for from about 30
seconds to about 2 minutes, more preferably from about 60 seconds
to about 90 seconds on a hot plate or about 30 to about 45 minutes
by convection oven.
[0049] The exposed photoresist-coated substrates are developed to
remove the image-wise exposed areas by immersion in a developing
solution or developed by spray development process. The solution is
preferably agitated, for example, by nitrogen burst agitation. The
substrates are allowed to remain in the developer until all, or
substantially all, of the photoresist coating has dissolved from
the exposed areas. Developers include aqueous solutions of ammonium
or alkali metal hydroxides. One preferred developer is an aqueous
solution of tetramethyl ammonium hydroxide. After removal of the
coated wafers from the developing solution, one may conduct an
optional post-development heat treatment or bake to increase the
coating's adhesion and chemical resistance to etching conditions
and other substances. The post-development heat treatment can
comprise the oven baking of the coating and substrate below the
coating's softening point or UV hardening process. In industrial
applications, particularly in the manufacture of microcircuitry
units on silicon/silicon dioxide-type substrates, the developed
substrates may be treated with a buffered, hydrofluoric acid base
etching solution or dry etching. Prior to dry etching the
photoresist may be treated to electron beam curing in order to
increase the dry-etch resistance of the photoresist.
[0050] Each of the documents referred to above are incorporated
herein by reference in its entirety, for all purposes. The
following specific examples will provide detailed illustrations of
the methods of producing and utilizing compositions of the present
invention. These examples are not intended, however, to limit or
restrict the scope of the invention in any way and should not be
construed as providing conditions, parameters or values which must
be utilized exclusively in order to practice the present invention.
Unless otherwise specified, all parts and percents are by
weight.
EXAMPLES
[0051] The refractive index (n) and the absorption (k) values of
the photoresist in the Examples below were measured on a J. A.
Woollam VASE32 ellipsometer.
[0052] The triphenyl sulfonium nonafluorobutane sulfonate used in
the photoresist formulation is available from Toyo Gosei Company
Ltd. Japan.
[0053] The line edge roughness (LER) was measured on a KLA8100 CD
SEM tool using 600V acceleration voltage, 100K magnification and
with a threshold of 50%. The length of the photoresist line
measured was 1.5 .mu.m. LER was the (3.sigma.) value calculated
using 24 data points on each side of the photoresist line.
Synthetic Example 1
Synthesis of 4-methoxyphenyl Dimethyl Sulfonium Triflate
[0054] To a 500 ml round bottomed flask equipped with a
thermometer, a mechanical stirrer, and a condenser,
1-methoxy-4-(methylthio) benzene (25 g, 0.162 mole), silver
triflate (42.2 g, 0.164 mole) and 300 g tetrahydrohydrofuran (THF)
were added. The mixture was heated at 40.degree. C. to dissolve all
the solids. A clear solution was cooled to room temperature and
iodomethane (23.5 g, 0.166 mole) was added dropwise from a dropping
funnel. The precipitate formed immediately during the addition of
iodomethane. An exotherm was observed and the temperature rose to
55.degree. C. The reaction mixture was stirred for 4 hours and the
precipitate was filtered out. The solution was dark and the THF was
reduced under vacuum. The solution was added drop wise to one liter
of ether. The precipitate was dissolved in dichloromethane (200 ml)
and filtered to remove silver oxide. The filtrate was drowned in
ether (1 liter) and the white precipitate was filtered and dried
under vacuum at 35.degree. C. (white crystals). The yield was 16.0
g (33%). The solid product gave the following analytical .sup.1H
NMR(Acetone-d6) results: 3.43 (s, 6H, 2CH.sub.3); 3.93 (s, 3H,
OCH.sub.3); 7.29 (d, 2H, aromatic); 8.13 (d, 2H, aromatic). The
absorptivity was 71.21 L/g.cm. 13
Synthetic Example 2
4-Hydroxy-3,5-dimethyl Phenyl Dimethyl Sulphonium Chloride
[0055] 61 g of dimethylphenol (0.5 mole), 39 g (0.5 mole) of
dimethylsulfoxide (DMSO), and 400 ml of methanol were placed in a 1
liter round bottom flask equipped with a thermometer and a
condenser. The mixture was cooled in a liquid nitrogen-isopropyl
alcohol bath while hydrogen chloride gas was bubbled in at
10.degree. C. for 6 hours. A precipitate was formed and a part of
the methanol was removed by rotavap. The crystals were filtered and
washed with ether several times. The solid product gave the
following analytical results .sup.1H NMR(Acetone-d6), 2.34 (s, 6H,
2CH.sub.3); 3.23 (s, 6H, 2CH.sub.3); 7.80 (s, 2H, aromatic). 14
Synthetic Example 3
4-Hydroxy-3,5-dimethyl Phenyl Dimethyl Sulphonium Triflate
[0056] 2.185 g of 4-Hydroxy-3,5-dimethyl phenyl dimethyl sulphonium
chloride were placed in a flask and 10 g of water were added,
followed by 2.56 g of silver trifluoro methane sulfonate in
acetone. A precipitate of AgCl formed immediately. The mixture was
stirred for 30 minutes and the precipitate was filtered off. The
solution was extracted with dichloromethane, dried over sodium
sulphate and filtered. The solution was drowned into ether and a
precipitate formed which was filtered and dried in the vacuum dryer
at less than 40.degree. C. The solid product gave the following
analytical results: .sup.1H NMR(Acetone-d6), 2.40 (s, 6H,
2CH.sub.3); 3.10 (s, 6H, 2CH.sub.3); 7.65 (s, 2H, aromatic). 15
Synthetic Example 4
4-Methoxy-3,5-dimethyl Phenyl Dimethyl Sulphonium Triflate
[0057] 4-Hydroxy-3,5-dimethyl phenyl dimethyl sulphonium chloride
(10.0 g, 0.054 mole) was placed in a 250 ml round bottom flask with
a stirrer, a condenser and a thermowatch. Deionized water (100 ml)
and 3.4 g of NaOH (50%) were added. Dimethyl sulphate (6.8 g 0.054
mole) was added with a syringe. The mixture was stirred at room
temperature for 20 minutes and then heated at 55.degree. C. for 4
hours. After neutralization the reaction mix was added to acetone,
and the salt precipitated out, which was filtered. The crude
product in water was treated with silver trifluoromethane sulfonate
and silver chloride was precipitated out. After filtering the salt,
the solution was extracted with dichloromethane. The
dichloromethane layer was washed with water, dried over sodium
sulphate and drowned in ether. The precipitate was filtered and
washed with ether. It was dried under vacuum. The solid product
gave the following analytical results: .sup.1H NMR(Acetone-d6),
2.40 (s, 6H, 2CH.sub.3);3.47 (s, 6H, 2CH.sub.3); 3.85 (s, 3H,
OCH.sub.3); 7.89 (d, 2H, aromatic). 16
Synthetic Example 5
4-Hydroxy-3,5-dimethyl Phenyl Dimethyl Sulphonium Nonaflate
[0058] 2.185 g of 4-Hydroxy-3,5-dimethyl phenyl dimethyl
sulphonium, 100 g water, and 3.38 g of potassium perflouro butane
sulfonate in acetone were added in a flask. A precipitate formed
immediately. The mixture was stirred for 30 minutes, the solution
was extracted with dichloromethane, dried over sodium sulphate and
filtered. The solution was drowned into ether, a precipitate was
formed, filtered and dried in the vacuum dryer at less than
40.degree. C. The solid product gave the following analytical
results: .sup.1H NMR(Acetone-d6), 2.32 (s, 6H, 2CH.sub.3); 3.4 (s,
6H, 2CH.sub.3); 7.78 (s, 2H, aromatic). The absorptivity was 56.15
L/g.cm. 17
Synthetic Example 6
4-Methoxy-3,5-dimethyl Phenyl Dimethyl Sulphonium Nonaflate
[0059] 5.0 g (0.023 mole) of 4-Hydroxy-3,5-dimethyl phenyl dimethyl
sulphonium chloride was placed in a flask equipped with a
condenser, a thermometer, and a mechanical stirrer. 45 g of water
and 0.92 g of sodium hydroxide were added, and an intense color
appeared. Dimethyl sulphate (2.2 ml) was added at room temperature
and the mixture was heated at 60.degree. C. for 10 minutes. The
solution changed to almost colorless. The heating was stopped after
15 minutes and the solution was cooled to room temperature. 7.78 g
of potassium perfluoro butane sulfonate in acetone(50 ml) was added
drop wise and mixed for 2 hours. It was extracted with
dichoromethane and the dicholoromethane layer was washed with
water, dried over sodium sulfate, and filtered. The solution was
drowned into ether, and the-precipitate formed was filtered and
dried in the vacuum dryer at less than 40.degree. C. The solid
product gave the following analytical results: .sup.1H
NMR(Acetone-d6), 2.32 (s, 6H, 2CH.sub.3); 3.4 (s, 6H, 2CH.sub.3);
3.85 (s, 3H, OCH.sub.3); 7.78 (s, 2H, aromatic). The absorptivity
is 32.82 L/g.cm. 18
Synthetic Example 7
4-Methoxy Benzyl Dimethyl Sulphonium Triflate
[0060] 4-Methoxy benzyl mercaptan (25.0 g, 0.16 mole) was added to
a 250 ml round bottom flask with an overhead stirrer, a condenser,
and a thermometer. 50 g THF and 12.5 g of NaOH in water (50%) were
added. Dimethyl sulphate (20.18 g, 0.16 mole, 15.2 ml) was added
very slowly with a syringe. The mixture was stirred at room
temperature for 20 minutes and then heated at 55.degree. C. for 90
minutes. Silver trifluoromethane sulfonate (41 g, 0.16 mole) was
added and the silver salt was precipitated out. After filtering the
salt, the solution was diluted with acetone and water, extracted
with ether, and the aqueous layer was extracted with
dichloromethane. The dichloromethane layer was washed with water,
dried over sodium sulphate and drowned in ether. A precipitate was
formed, which was filtered and washed with ether. It was dried
under vacuum. The solid product gave the following analytical
results: 1H NMR(DMSO-d6), 2.75 (s, 6H, 2CH3);3.80 (s, 3H, OCH3);
4.61 (s, 2H, CH2); 6.85-7.45 (m, 4H, aromatic). 19
Synthetic Example 8
Poly(t-butyl Norbornene carboxylate-co-mevaloniclactone
Methacrylate-co-2-methyladamantyl Methacrylate-co-maleic
Anhydride)
[0061] A hybrid copolymer was synthesized by reacting 126.45 g of
t-butyl norbornene carboxylate (BNC), 129.2 g of mevaloniclactone
methacrylate (MLMA) and 152.73 g of 2-methyladamantyl methacrylate
(MAdMA) and 191.78 g of maleic anhydride(MA) in presence of 5
weight% of AIBN in tetrahydrofuran(THF) at 50% solid. The reaction
was carried out for 8 hours and the polymer was isolated from
diethyl ether twice(1/10 v/v ratio). The weight average molecular
weight (Mw) as measured on a Gel Permeation Chromatograph (GPC)
using polystyrene standards and THF solvent, was 5780.
Synthetic Example 9
Poly(2-methyladamantyl Methacrylate-co-mevaloniclactone
Methacrylate)
[0062] Polymerization was carried out using a feed of 1:1 molar
ratio of 20
[0063] MAdMA and MLMA in tetrahydrofuran (THF) (25% solids) using
AIBN initiator (10 weight% with respect to monomers) at 70.degree.
C. under nitrogen atmosphere. The reaction mixture was stirred at
70.degree. C. for 5 hours. The polymer solution was poured into
methanol after the reaction was finished. The white powder was
filtered, dissolved in THF (30% solids) again and re-precipitated,
filtered and dried under vacuum until constant weight was obtained.
The polymerization yield was about 65%. The Mw and number average
molecular weight (Mn) as measured on a GPC using polystyrene
standards and THF solvent were 14000 and 8000, respectively.
Comparative Example 1
[0064] 1.5222 g of poly(2-methyladamantyl
methacrylate-co-2-mevalonic lactone methacrylate) of Synthetic
Example 9, 0.0514 g (60 .mu.mol/g) of triphenylsulfonium
nonafluorobutanesulfonate (absorptivity 117.74 L/g.cm), 0.1444 g of
1 weight% ethyl lactate solution of diethanolamine and 0.018 g of
110 ppm ethyl lactate solution of a surfactant (FC-430,
fluoroaliphatic polymeric ester, supplied by 3M Corporation, St.
Paul Minn.) were dissolved in 13.26 g of ethyl lactate to give a
photoresist solution. The n & k values at 193 nm for this
photoresist film were 1.7287 and 0.02432, respectively. Separately,
a silicon substrate coated with a bottom antireflective coating
(B.A.R.C.) was prepared by spin coating the bottom anti-reflective
coating solution (AZ.RTM. EXP ArF-1 B.A.R.C. available from
Clariant Corporation, Somerville, N.J.) onto the silicon substrate
and baking at 175.degree. C. for 60 sec. The B.A.R.C film thickness
was 39 nm. The photoresist solution was then coated on the B.A.R.C
coated silicon substrate. The spin speed was adjusted such that the
photoresist film thickness was 330 nm. The photoresist film was
baked at 115.degree. C. for 60 sec. The substrate was then exposed
in a 193 nm ISI ministepper (numerical aperture of 0.6 and
coherence of 0.7) using a chrome on quartz binary mask. After
exposure, the wafer was post-exposure baked at 110.degree. C. for
60 sec. The imaged photoresist was then developed using a 2.38
weight% aqueous solution of tetramethyl ammonium hydroxide for 60
sec. The line and space patterns were then observed on a scanning
electron microscope. The photoresist had a photosensitivity of 20
mJ/cm.sup.2 and a linear resolution of 0.12 .mu.m. The line edge
roughness (3.sigma.) as measured on a KLA8100 CD SEM for 130 nm L/S
(1: 1 pitch at best focus) was 12 nm.
Comparative Example 2
[0065] 26.05 g of polymer of Synthetic Example 8, 0.820 g (56
.mu.mol/g) of triphenylsulfonium nonafluorobutanesulfonate
(absorptivity 117.74 L/g.cm), 13.4g of 1 weight% propylene glycol
monomethyl ether acetate (PGMEA) solution of
1,3,3-trimethyl-6-azabicyclo(3.2.1)octane and 0.24g of 10 weight%
propyleneglycol monomethyether acetate (PGMEA) solution of a
surfactant (FC-430, fluoroaliphatic polymeric ester, supplied by 3M
corporation, Minnesota) were dissolved in 159.5 g of PGMEA. The
solution was filtered using 0.2 .mu.m filter and processed in a
similar manner to that described in Comparative Example 1 except
the photoresist film was baked at 110.degree. C. for 90 sec,
post-exposure baked at 130.degree. C. for 90 sec and development
was carried out for 30 sec. The n & k values at 193 nm were
1.7108 and 0.028, respectively. The photoresist had a
photosensitivity of 17 mJ/cm.sup.2 and a linear resolution of 0.09
.mu.m. The line edge roughness (3.sigma.) as measured on a KLA8100
CD SEM for 130 nm L/S was 11 nm (130 nm, 1:2 pitch at best
focus).
Comparative Example 3
[0066] 43.92 g of the polymer as in Synthetic Example 8, 0.11234 g
of dimethyl, p-methoxyphenyl sulfonium nonafluorobutanesulfonate
(Synthesis Example 6), 1.622 g of 1% PGMEA solution of
3-trimethyl-6-azabicyclo[3.2.- 1]octane, and 0.036 g of 10 weight%
propyleneglycol monomethyether acetate (PGMEA) solution of a
surfactant (fluoroaliphatic polymeric ester, supplied by 3M
corporation, Minnesota) were dissolved in 24.30 g of PGMEA. The
solution was filtered using 0.2 .mu.m filter and processed in a
similar manner to that described in Comparative Example 2. The
n&k values at 193 nm were 1.7158 and 0.01670 respectively. The
photoresist had a sensitivity of 80 mJ/cm.sup.2 and a linear
resolution of 0.09 .mu.m. The line edge roughness (3.sigma.) as
measured on a KLA8100 CD SEM for 130 nm L/S was 5 nm (130 nm, 1:2
pitch at best focus).
Comparitive Example 4
[0067] 1.544 g of poly(2-methyladamantyl
methacrylate-co-2-mevalonic lactone methacrylate) as in Synthetic
Example 9, 0.0295 g (60 .mu.mol/g) of dimethyl, p-methoxyphenyl
sulfon iu m nonafluorobutanesulfonate (Synthesis Example 6), 0.1461
g of 1 weight% ethyl lactate solution of diethanolamine and 0.018 g
of 120 ppm ethyl lactate solution of a surfactant (FC-430,
fluoroaliphatic polymeric ester, supplied by 3M Corporation, St.
Paul Minn.) were dissolved in 13.26 g of ethyl lactate to give a
photoresist solution. The photoresist was processed in a similar
way to comparative example 1. The n& k values at 193 nm were
1.7294 and 0.012716, respectively. The photoresist had a
photosensitivity of 63 mJ/cm.sup.2 and a linear resolution of 0.12
.mu.m. The line edge roughness (3c) as measured on a KLA8100 CD SEM
for 130 nm L/S (1:1 pitch, best focus) was 5 nm.
Example 1
[0068] 2.5527 g of poly(2-methyladamantyl
methacrylate-co-2-mevalonic lactone methacrylate) as in Synthetic
Example 9, 0.0431 g (30 .mu.mol/g) of triphenylsulfonium
nonafluorobutane sulfonate, 0.0244 g (30 .mu.mol/g) of dimethyl,
p-methoxyphenyl sulfonium nonafluorobutanesulfonate, 0.4831 g of 1
weight% ethyl lactate solution of diethanolamine and 0.03 g of 10
weight% ethyl lactate solution of a surfactant (fluoroaliphatic
polymeric ester, supplied by 3M Corporation, St. Paul Minn.) were
dissolved in 21.887 g of ethyl lactate to give a photoresist
solution. The photoresist was processed in a similar manner to
comparative example 1. The photoresist had n and k values of 1.7120
and 0.017 respectively. The photoresist had a photosensitivity of
34 mJ/cm.sup.2 and a linear resolution of 0.12 .mu.m. The line edge
roughness (3.sigma.) as measured on a KLA8100 CD SEM for 130 nm L/S
was 5.5 nm, which was a 54% improvement in line edge roughness over
Comparative Example 1.
Example 2
[0069] 2.5506 g of the polymer as in Synthetic Example 8, 0.0430 g
of triphenylsulfonium nonafluorobutanesulfonate, 0.0244 g of
dimethyl, p-methoxyphenyl sulfonium nonafluorobutanesulfonate,
0.7036 g of 1% PGMEA solution of
3-trimethyl-6-azabicyclo[3.2.1]octane, and 0.03 g of 10 weight%
propyleneglycol monomethyether acetate (PGMEA) solution of a
surfactant (fluoroaliphatic polymeric ester, supplied by 3M
corporation, Minnesota) were dissolved in 21.65 g of PGMEA. The
solution was filtered using 0.2 .mu.m filter and processed in a
similar manner to that described in Comparative Example 2. The
photoresist had n&k values of 1.7144 and 0.023088 respectively.
The photoresist had a sensitivity of 22 mJ/cm.sup.2 and a linear
resolution of 0.09 .mu.m. The line edge roughness (3.sigma.) as
measured on a KLA8100 CD SEM for 130 nm L/S was 6.2 nm, which was a
44% improvement in line edge roughness over Comparative Example
2.
Example 3
[0070] 2.7401 g of the polymer as in Synthetic Example 8, 0.0694 g
of triphenylsulfonium nonafluorobutanesulfonate, 0.0523 g of
dimethyl, p-methoxyphenyl sulfonium nonafluorobutanesulfonate,
1.3227 g of 1% PGMEA solution of
3-trimethyl-6-azabicyclo[3.2.1]octane, and 0.03 g of 10 weight%
propyleneglycol monomethyether acetate (PGMEA) solution of a
surfactant (fluoroaliphatic polymeric ester, supplied by 3M
corporation, Minnesota) were dissolved in 20.78 g of PGMEA. The
solution was filtered using 0.2 .mu.m filter and processed in a
similar manner to that described in Comparative Example 2. The
photoresist had a photosensitivity of 21 mJ/cm.sup.2 and a linear
resolution of 0.09 .mu.m. The line edge roughness (3.sigma.) as
measured on a KLA8100 CD SEM for 130 nm L/S was 6.2 nm, which was a
46% improvement in line edge roughness over Comparative Example
2.
Example 4
[0071] 2.5507 g of poly(2-methyladamantyl
methacrylate-co-2-mevalonic lactone methacrylate) as in Synthesis
Example 9, 0.0431 g of triphenylsulfonium nonafluorobutane
sulfonate, 0.0288 g of cyclohexyl, 2-oxocyclohexyl, methyl
sulfonium trifluoromethane sulfonate (absorptivity 3.32 L/g.cm),
0.2414 g of 1 weight% ethyl lactate solution of diethanolamine and
0.03 g of 10 weight% ethyl lactate solution of a surfactant
(fluoroaliphatic polymeric ester, supplied by 3M Corporation, St.
Paul Minn.) were dissolved in 22.1 g of ethyl lactate to give a
photoresist solution. The photoresist was processed in a similar
manner to comparative example 1. The photoresist had a
photosensitivity of 23 mJ/cm.sup.2 and a linear resolution of 0.12
.mu.m. The line edge roughness (3.sigma.) as measured on a KLA8100
CD SEM for 130 nm L/S was 5.5 nm, which was a 54% improvement in
line edge roughness over Comparative Example 1.
Example 5
[0072] 2.5548 g of poly(2-methyladamantyl
methacrylate-co-2-mevalonic lactone methacrylate), 0.0431 g of
triphenylsulfonium nonafluorobutane sulfonate, 0.0288 g of
bis(phenylsulfonyl)diazomethane (absorptivity 169.49 L/g.cm) from
Midori Kagaku Company, 0.2417 g of 1 weight% ethyl lactate solution
of diethanolamine and 0.03 g of 10 weight% ethyl lactate solution
of a surfactant (fluoroaliphatic polymeric ester, supplied by 3M
Corporation, St. Paul Minn.) were dissolved in 22.1 g of ethyl
lactate to give a photoresist solution. The photoresist was
processed in a similar manner to comparative example 1. The
photoresist had a photosensitivity of 24 mJ/cm.sup.2 and a linear
resolution of 0.13 .mu.m. The line edge roughness (3.sigma.) as
measured on a KLA8100 CD SEM for 130 nm L/S was 7.0 nm, which was a
41% improvement in line edge roughness over Comparative Example
1.
Example 6
[0073] 2.5496 g of poly(2-methyladamantyl
methacrylate-co-2-mevalonic lactone methacrylate), 0.0430 g of
triphenylsulfonium nonafluorobutane sulfonate, 0.0288 g of
[bis(p-chlorophenylsulfonyl)diazomethane] (absorptivity 146.49
L/g.cm) from Midori Kagaku Company, 0.2413 g of 1 weight% ethyl
lactate solution of diethanolamine and 0.03 g of 10 weight% ethyl
lactate solution of a surfactant (fluoroaliphatic polymeric ester,
supplied by 3M Corporation, St. Paul Minn.) were dissolved in 22.1
g of ethyl lactate to give a photoresist solution. The photoresist
was processed in a similar manner to comparative example 1. The
formulation had a sensitivity of 23 mJ/cm.sup.2 and a linear
resolution of 0.12 .mu.m. The line edge roughness (3.sigma.) as
measured on a KLA8100 CD SEM for 130 nm L/S was 7.5 nm, which was a
38% improvement in line edge roughness over Comparative Example
1.
Example 7
[0074] 2.5556 g of poly(2-methyladamantyl
methacrylate-co-2-mevalonic lactone methacrylate), 0.0431 g of
triphenylsulfonium nonafluorobutane sulfonate, 0.0239 g of
[5-Norbornene-2,3-trifluoromethanesulfonimide] (absorptivity 71.42
L/g.cm) from Midori Kagaku Company, 0.2418 g of 1 weight% ethyl
lactate solution of diethanolamine and 0.03 g of 10 weight% ethyl
lactate solution of a surfactant (fluoroaliphatic polymeric ester,
supplied by 3M Corporation, St. Paul Minn.) were dissolved in 22.1
g of ethyl lactate to give a photoresist solution. The resist was
processed similar to comparative example 1. The formulation had a
sensitivity of 21 mJ/cm.sup.2 and a linear resolution of 0.13
.mu.m. The line edge roughness (3.sigma.) as measured on a KLA8100
CD SEM for 130 nm L/S was 7.8 nm, which was a 35% improvement in
line edge roughness over Comparative Example 1.
Example 8
[0075] 2.5512 g of poly(2-methyladamantyl
methacrylate-co-2-mevalonic lactone methacrylate), 0.0430 g of
triphenylsulfonium nonafluorobutane sulfonate, 0.0283 g of
[4,5-dihydroxy-1-napthalene dimethylsulfonium trifluoromethane
sulfonate] (absorptivity 50.62 L/g.cm)from Midori Kagaku Company,
0.2414 g of 1 weight% ethyl lactate solution of diethanolamine and
0.03 g of 10 weight% ethyl lactate solution of a surfactant
(fluoroaliphatic polymeric ester, supplied by 3M Corporation, St.
Paul Minn.) were dissolved in 22.1 g of ethyl lactate to give a
photoresist solution. The photoresist was processed in a similar
manner as comparative example 1. The photoresist had a
photosensitivity of 21 mJ/cm.sup.2 and a linear resolution of 0.13
.mu.m. The line edge roughness (3%) as measured on a KLA8100 CD SEM
for 130 nm L/S was 8.0 nm, which was a 33% improvement in line edge
roughness over Comparative Example 1.
Example 9
[0076] 2.5512 g of poly(2-methyladamantyl
methacrylate-co-2-mevalonic lactone methacrylate), 0.0430 g of
triphenylsulfonium nonafluorobutane sulfonate, 0.0283 g of
[4,6-dihydroxy-1-napthalene dimethylsulfonium trifluoromethane
sulfonate] (absorptivity 60.34 L/g.cm) from Midori Kagaku Company,
0.2414 g of 1 weight% ethyl lactate solution of diethanolamine and
0.03 g of 10 weight% ethyl lactate solution of a surfactant
(fluoroaliphatic polymeric ester, supplied by 3M Corporation, St.
Paul Minn.) were dissolved in 22.1 g of ethyl lactate to give a
photoresist solution. The photoresist was processed in a similar
manner to comparative example 1. The photoresist had a
photosensitivity of 0.22 mJ/cm.sup.2 and a linear resolution of
0.13. The line edge roughness (3.sigma.) as measured on a KLA8100
CD SEM for 130 nm L/S was 7.5 nm, which was a 38% improvement in
line edge roughness over Comparative Example 1.
* * * * *