U.S. patent number RE37,179 [Application Number 09/420,604] was granted by the patent office on 2001-05-15 for radiation sensitive resin composition.
This patent grant is currently assigned to JSR Corporation. Invention is credited to Eiichi Kobayashi, Toshiyuki Ota, Akira Tsuji, Mikio Yamachika.
United States Patent |
RE37,179 |
Yamachika , et al. |
May 15, 2001 |
**Please see images for:
( Certificate of Correction ) ** |
Radiation sensitive resin composition
Abstract
A radiation sensitive resin composition which comprises (A) a
polymer which becomes alkali-soluble in the presence of an acid and
(B) a radiation sensitive acid generator which generates an acid
upon irradiation with a radiation, said polymer (A) comprising two
recurring units represented by the general formulas (1) and (2) and
a recurring unit which acts to reduce the solubility of the polymer
is an alkali developer after the irradiation: ##STR1## wherein
R.sup.1 represents a hydrogen atom or a methyl group and R.sup.2
represents a hydrogen atom or a methyl group. Said composition
provides a chemically amplified positive resist which can give a
fine pattern with a good pattern shape, and said resist is freed
from volume shrinkage, peeling failure and adhesive failure, is
excellent in dry etching resistance and effectively reacts with
various radiations to give a good pattern shape which is excellent
in photolithographic process stability, said pattern shape having
no thinned portion at the upper part.
Inventors: |
Yamachika; Mikio (Austin,
TX), Kobayashi; Eiichi (Yokkaichi, JP), Tsuji;
Akira (Yokkaichi, JP), Ota; Toshiyuki (Seoul,
KR) |
Assignee: |
JSR Corporation (Tokyo,
JP)
|
Family
ID: |
26549164 |
Appl.
No.: |
09/420,604 |
Filed: |
October 21, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
352848 |
Dec 2, 1994 |
05679495 |
Oct 21, 1997 |
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Foreign Application Priority Data
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Dec 3, 1993 [JP] |
|
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5-339490 |
Oct 7, 1994 [JP] |
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6-270332 |
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Current U.S.
Class: |
430/191; 430/165;
430/192; 430/193; 430/270.1; 430/905; 430/909; 430/910 |
Current CPC
Class: |
G03F
7/039 (20130101); G03F 7/0045 (20130101); Y10S
430/11 (20130101); Y10S 430/111 (20130101); Y10S
430/106 (20130101) |
Current International
Class: |
G03F
7/039 (20060101); G03F 7/004 (20060101); G03F
007/023 () |
Field of
Search: |
;430/270.1,191,165,192,193,905,909,910 |
References Cited
[Referenced By]
U.S. Patent Documents
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5034305 |
July 1991 |
Nguyen-Kim et al. |
5064746 |
November 1991 |
Schwalm |
5073474 |
December 1991 |
Schwalm et al. |
5130392 |
July 1992 |
Schwalm et al. |
5252427 |
October 1993 |
Bauer et al. |
5346803 |
September 1994 |
Crivello et al. |
5350660 |
September 1994 |
Urano et al. |
5352564 |
October 1994 |
Takeda et al. |
5443690 |
August 1995 |
Takechi et al. |
5498506 |
March 1996 |
Wengenroth et al. |
5576143 |
November 1996 |
Aoai et al. |
5580695 |
December 1996 |
Murata et al. |
|
Foreign Patent Documents
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63-250642 |
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Oct 1988 |
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JP |
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2-27660 |
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Jun 1990 |
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JP |
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3-44290 |
|
Jul 1991 |
|
JP |
|
3-206458 |
|
Sep 1991 |
|
JP |
|
4-39665 |
|
Feb 1992 |
|
JP |
|
4-257259 |
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Sep 1992 |
|
JP |
|
5-113667 |
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May 1993 |
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JP |
|
5-181279 |
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Jul 1993 |
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JP |
|
Primary Examiner: Chu; John S.
Attorney, Agent or Firm: Piper Marbury Rudnick & Wolfe
LLP Kelber; Steven B.
Claims
What is claimed is:
1. A radiation sensitive resin composition which consists
essentially of (A) a polymer which becomes alkali-soluble in the
presence of an acid and (B) a radiation sensitive acid generator
which generates an acid upon irradiation with a radiation, said
polymer (A) comprising two recurring units A and B represented by
the general formulas (1) and (2), respectively, and a recurring
unit C which acts to reduce the solubility of the polymer in an
alkali developer after the irradiation: ##STR11##
wherein R.sup.1 represents a hydrogen atom or a methyl group and
R.sup.2 represents a hydrogen atom or a methyl group, and wherein
the recurring unit C is derived from at least one organic compound
which is free from any acidic substituent and selected from the
group consisting of styrene, .alpha.-methylstyrene,
p-methylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate,
propyl (meth) acrylate, (meth) acrylamide and (meth)
arylonitrile.
2. The radiation sensitive resin composition according to claim 1,
wherein the recurring unit represented by the general formula (1)
corresponds to at least one monomer selected from the group
consisting of vinylphenol and .alpha.-isopropenylphenol.
3. The radiation sensitive resin composition according to claim 1,
wherein the recurring unit represented by the general formula (2)
corresponds to at least one monomer selected from the group
consisting of tert-butyl acrylate and tert-butyl methacrylate.
4. The radiation sensitive resin composition according to claim 1,
wherein the polystyrene-reduced weight-average molecular-weight
(Mw) of the polymer (A) is 1,500 to 300,000.
5. The radiation sensitive resin composition according to claim 1,
wherein the polystyrene-reduced weight-average molecular-weight of
the polymer (A) is 3,000 to 300,000.
6. The radiation sensitive resin composition according to claim 1,
wherein the ratio of the polystyrene-reduced weight-average
molecular-weight (Mw) of the polymer (A) to the polystyrene-reduced
number-average molecular-weight (Mn) of the polymer (A) (Mw/Mn) is
1 to 5.
7. The radiation sensitive resin composition according to claim 6,
wherein the ratio (Mw/Mn) is 1.5 to 3.5.
8. The radiation sensitive resin composition according to claim 1,
wherein the proportion of the number of the recurring units
represented by the general formula (1) in the polymer (A) is 5 to
75% of the total number of all the recurring units contained in the
polymer (A).
9. The radiation sensitive resin composition according to claim 1,
wherein the proportion of the number of the recurring units
represented by the general formula (2) in the polymer (A) is 10 to
70% of the total number of all the recurring units contained in the
polymer (A).
10. The radiation sensitive resin composition according to claim 1,
wherein the proportion of the number of the recurring units which
act to reduce the solubility of the polymer (A) in the alkali
developer in the polymer (A) is 0.5 to 50% of the total number of
all the recurring units contained in the polymer (A).
11. The radiation sensitive resin composition according to claim 1,
wherein the radiation sensitive acid generator (B) is at least one
compound selected from the group consisting of onium salts,
halogen-containing compounds, sulfone compounds, sulfonate
compounds and quinonediazide compounds.
12. The radiation sensitive resin composition according to claim 1,
wherein the amount of the radiation sensitive acid generator (B)
used is 0.05 to 20 parts by weight per 100 parts by weight of the
polymer (A).
13. The radiation sensitive resin composition according to claim 1,
wherein the amount of the radiation sensitive acid generator (B)
used is 0.1 to 15 parts by weight per 100 parts by weight of the
polymer (A).
14. The radiation sensitive resin composition according to claim 1,
which further contains an alkali-solubility controller.
15. The radiation sensitive resin composition according to claim
14, wherein the alkali-solubility controller is a compound having
an acidic functional group which has been substituted by an
acid-decomposable group.
16. The radiation sensitive resin composition according to claim 1,
which further contains an acid-diffusion controller.
17. The radiation sensitive resin composition according to claim
16, wherein the acid-diffusion controller is a nitrogen-containing
compound whose basicity is not changed by irradiation or
heating.
18. A radiation sensitive resin composition which consists
essentially of (A) a polymer which becomes alkali-soluble in the
presence of an acid and (B) a radiation sensitive acid generator
which generates an acid upon irradiation with a radiation, said
polymer (A) comprising two recurring units A and B represented by
the general formulas (1) and (2) and a recurring unit C which acts
to reduce the solubility of the polymer in an alkali developer
after the irradiation: ##STR12##
wherein R.sup.1 represents a hydrogen atom or a methyl group and
R.sup.2 represents a hydrogen atom or a methyl group, and wherein
the recurring unit C is derived from at least one organic compound
which is free from any acidic substituent and selected from the
group consisting of hetero atom-containing aromatic vinyl
compounds, vinyl ketone compounds and hetero atom-containing
alicyclic ring compounds.
19. The radiation sensitive resin composition according to claim
11, wherein the onium salt is at least one compound selected from
the group consisting of diphenyliodonium triflate, diphenyliodonium
pyrenesulfonate, diphenyliodonium dodecylbenzenesulfonate,
triphenylsulfonium triflate, triphenylsulfonium
hexafluoroantimonate, diphenyliodonium hexafluoroantimonate,
triphenylsulfonium naphthalenesulfonate, (hydroxyphenyl)
benzylmethylsulfonium toluenesulfonate.
20. The radiation sensitive resin composition according to claim 1,
wherein the ratio of the polystyrene-reduced weight-average
molecular weight (Mw) of the polymer (A) to the polystyrene-reduced
number average molecular weight (Mn) of the polymer (A) is 1 to
5.
21. The radiation sensitive resin composition according to claim 1,
which further contains an alkali-solubility controller.
22. The radiation sensitive resin composition according to claim 1,
which further contains an acid-diffusion controller.
23. The radiation sensitive resin composition according to claim
18, which further contains an alkali-solubility controller.
24. The radiation sensitive resin composition according to claim
18, which further contains an acid-diffusion controller..Iadd.
25. A radiation sensitive resin composition which comprises (A) a
polymer which becomes alkali-soluble in the presence of an acid and
(B) a radiation sensitive acid generator which generates an acid
upon irradiation with a radiation, said polymer (A) comprising two
recurring units A and B represented by the general formulas (1) and
(2), respectively, and a recurring unit C which acts to reduce the
solubility of the polymer in an alkali developer after the
irradiation: ##STR13##
wherein R.sup.1 represents a hydrogen atom or a methyl group and
R.sup.2 represents a hydrogen atom or a methyl group, and wherein
the recurring unit C is derived from at least one organic compound
which is free from any acidic substituent and selected from the
group consisting of styrene, alpha-methylstyrene, p-methylstyrene,
methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth)
acrylate, (meth) acrylamide and (meth)
arylonitrile..Iaddend..Iadd.
26. The radiation sensitive resin composition according to claim
25, wherein the recurring unit represented by the general formula
(1) corresponds to at least one monomer selected from the group
consisting of vinylphenol and
alpha-isopropenylphenol..Iaddend..Iadd.
27. The radiation sensitive resin composition according to claim
25, wherein the recurring unit represented by the general formula
(2) corresponds to at least one monomer selected from the group
consisting of tert-butyl acrylate and tert-butyl
methacrylate..Iaddend..Iadd.
28. The radiation sensitive resin composition according to claim
25, wherein the polystyrene-reduced weight-average molecular-weight
(Mw) of the polymer (A) is 1,500 to 300,000..Iaddend..Iadd.
29. The radiation sensitive resin composition according to claim
25, wherein the polystyrene-reduced weight-average molecular-weight
of the polymer (A) is 3,000 to 300,000..Iaddend..Iadd.
30. The radiation sensitive resin composition according to claim
25, wherein the ratio of the polystyrene-reduced weight-average
molecular-weight (Mw) of the polymer (A) to the polystyrene-reduced
number-average molecular-weight (Mn) of the polymer (A) (Mw/Mn) is
1 to 5..Iaddend..Iadd.
31. The radiation sensitive resin composition according to claim
30, wherein the ratio (Mw/Mn) is 1.5 to 3.5..Iaddend..Iadd.
32. The radiation sensitive resin composition according to claim
25, wherein the proportion of the number of the recurring units
represented by the general formula (1) in the polymer (A) is 5 to
75% of the total number of all the recurring units contained in the
polymer (A)..Iaddend..Iadd.
33. The radiation sensitive resin composition according to claim
25, wherein the proportion of the number of the recurring units
represented by the general formula (2) in the polymer (A) is 10 to
70% of the total number of all the recurring units contained in the
polymer (A)..Iaddend..Iadd.
34. The radiation sensitive resin composition according to claim
25, wherein the proportion of the number of the recurring units
which act to reduce the solubility of the polymer (A) in the alkali
developer in the polymer (A) is 0.5 to 50% of the total number of
all the recurring units contained in the polymer
(A)..Iaddend..Iadd.
35. The radiation sensitive resin composition according to claim
25, wherein the radiation sensitive acid generator (B) is at least
one compound selected from the group consisting of onium salts,
halogen-containing compounds, sulfone compounds, sulfonate
compounds and quinonediazide compounds..Iaddend..Iadd.
36. The radiation sensitive resin composition according to claim
25, wherein the amount of the radiation sensitive acid generator
(B) used is 0.05 to 20 parts by weight per 100 parts by weight of
the polymer (A)..Iaddend..Iadd.
37. The radiation sensitive resin composition according to claim
25, wherein the amount of the radiation sensitive acid generator
(B) used is 0.1 to 15 parts by weight per 100 parts by weight of
the polymer (A)..Iaddend..Iadd.
38. The radiation sensitive resin composition according to claim
25, which further contains an alkali-solubility
controller..Iaddend..Iadd.
39. The radiation sensitive resin composition according to claim
38, wherein the alkali-solubility controller is a compound having
an acidic functional group which has been substituted by an
acid-decomposable group..Iaddend..Iadd.
40. The radiation sensitive resin composition according to claim
25, which further contains an acid-diffusion
controller..Iaddend..Iadd.
41. The radiation sensitive resin composition according to claim
40, wherein the acid-diffusion controller is a nitrogen-containing
compound whose basicity is not changed by irradiation or
heating..Iaddend..Iadd.
42. A radiation sensitive resin composition which comprises (A) a
polymer which becomes alkali-soluble in the presence of an acid and
(B) a radiation sensitive acid generator which generates an acid
upon irradiation with a radiation, said polymer (A) comprising two
recurring units A and B represented by the general formulas (1) and
(2) and a recurring unit C which acts to reduce the solubility of
the polymer in an alkali developer after the irradiation:
##STR14##
wherein R.sup.1 represents a hydrogen atom or a methyl group and
R.sup.2 represents a hydrogen atom or a methyl group, and wherein
the recurring unit C is derived from at least one organic compound
which is free from any acidic substituent and selected from the
group consisting of hetero atom-containing aromatic vinyl
compounds, vinyl ketone compounds and hetero atom-containing
alicyclic ring compounds..Iaddend..Iadd.
43. The radiation sensitive resin composition according to claim
35, wherein the onium salt is at least one compound selected from
the group consisting of diphenyliodonium triflate, diphenyliodonium
pyrenesulfonate, diphenyliodonium dodecylbenzenesulfonate,
triphenylsulfonium triflate, triphenylsulfonium
hexafluoroantimonate, diphenyliodonium hexafluoroantimonate,
triphenylsulfonium naphthalenesulfonate,
(hydroxyphenyl)benzylmethylsulfonium
toluenesulfonate..Iaddend..Iadd.
44. The radiation sensitive resin composition according to claim
25, wherein the ratio of the polystyrene-reduced weight-average
molecular weight (Mw) of the polymer (A) to the polystyrene-reduced
number average molecular weight (Mn) of the polymer (A) is 1 to
5..Iaddend..Iadd.
45. The radiation sensitive resin composition according to claim
25, which further contains an alkali-solubility
controller..Iaddend..Iadd.
46. The radiation sensitive resin composition according to claim
25, which further contains an acid-diffusion
controller..Iaddend..Iadd.
47. The radiation sensitive resin composition according to claim
42, which further contains an alkali-solubility
controller..Iaddend..Iadd.
48. The radiation sensitive resin composition according to claim
42, which further contains an acid-diffusion
controller..Iaddend..Iadd.
49. The composition of claim 1, wherein said composition further
consists essentially of a solvent..Iaddend..Iadd.
50. The composition of claim 49, wherein said composition further
consists essentially of a surfactant..Iaddend..Iadd.
51. The composition of claim 49, wherein said composition further
consists essentially of a sensitizer..Iaddend..Iadd.
52. The composition of claim 51, wherein said sensitizer is added
in amount of no more than fifty parts by weight, per one hundred
parts by weight of solid content of said radiation sensitive resin
composition..Iaddend..Iadd.
53. The composition of claim 50, wherein said surfactant is present
in amounts of no more than two parts by weight per one hundred
parts by weight of solid content of said radiation sensitive resin
composition..Iaddend..Iadd.
54. The composition of claim 49, wherein said composition further
consists essentially of a dye or pigment..Iaddend..Iadd.
55. The composition of claim 49, wherein said composition further
consists essentially of an adhesion promoter..Iaddend..Iadd.
56. The composition of claim 49, wherein said composition further
consists essentially of at least one additive selected from the
group consisting of a halation-preventing agent, a storage
stabilizer, a defoaming agent and a shape-improving
agent..Iaddend..Iadd.
57. The composition of claim 49, wherein said solvent comprises
ethyl lactate..Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to a radiation sensitive resin composition.
More particularly, it relates to a radiation sensitive resin
composition which can be used as a resist particularly suitable for
fine processing using a radiation such as ultraviolet ray, deep
ultraviolet ray, X ray or charged particle beam.
In the field of fine processing, a representative of which is the
production of an integrated circuit device, a lithographic
technique is now being developed which enables fine processing in
the order of subhalfmicron to be effected with good
reproducibility. Representative resists which have recently been
used in the lithographic process include positive resists using an
alkali-soluble resin such as a novolak resin or the like and a
quinonediazide type radiation sensitive compound. However, the
performance of these resists approaches its limit and the use
thereof in the fine processing in the order of subhalfmicron is
accompanied by a great difficulty.
That is to say, these negative and positive resists have heretofore
had such a problem that a sufficient theoretical focal depth cannot
be achieved when a fine pattern of 0.35 .gamma.m or less is
intended to be formed by a lithographic technique using an
ultraviolet ray such as g ray (wavelength: 436 nm) or i ray
(wavelength: 365 nm) or the like from a mercury vapor lamp.
Under such circumstances, research has been energetically conducted
on a lithographic process using deep ultraviolet rays, X rays or
electron beams which can achieve a broader depth of focus in the
formation of a fine pattern. However, conventional resists have
various problems in respects of pattern shape, sensitivity,
contrast, development and the like when deep ultraviolet rays, X
rays or electron beams are used. That is to say, in the case of
deep ultraviolet rays, the light absorption of the resist is too
great, and hence, in the case of a negative resist, the pattern
shape tends to become a so-called reverse taper shape in which the
lower part of the pattern is narrower than the upper part, while
even in the case of a positive resist, the pattern shape becomes a
taper shape and the sensitivity and contrast and the like are also
lowered. In the case of a higher energy radiation such as X ray and
electron beam, in general, the lowering of sensitivity is greater
than in the case of deep ultraviolet ray, and particularly, in the
case of a positive resist, such a phenomenon that the solubility in
a developing solution is lowered upon irradiation with a radiation
in some cases through the solubility should be originally increased
upon irradiation.
On the other hand, as a next generation resist, attention is paid
to a chemically amplified resist containing a radiation sensitive
acid generator (namely, a compound generating an acid upon
irradiation with a radiation), and this resist has such an
advantage that the catalytic action of the acid generated increases
the sensitivity to various radiations.
As those chemically amplified resists which show relatively good
resist performance, there are known, for example, those containing
a resin having a tert-butyl ester group or a tert-butoxycarbonyl
group (for example, Japanese Patent Application Kokoku No.
2-27,660), those containing a resin having a silyl group (for
example, Japanese Patent Application Kokai No. 3-44,290), those
containing a resin having an acrylic acid component (for example,
Japanese Patent Application Kokai No. 4-39,665) and the like.
However, it has ben pointed out that these chemically amplified
resists have the respective inherent problems and various
difficulties accompany the putting them to practical use. That is
to say, in the system in which a resin having a tert-butyl ester
group or a tert-butoxycarbonyl group is used, the chemical reaction
based on the catalytic action of the acid generated is accompanied
by the liberation of a gas component such as an isobutene gas or a
carbon dioxide gas, so that the volume shrinkage is caused upon
irradiation with a radiation, and consequently, the pattern shape
tends to be distorted and hence the formation of a high precision
pattern is difficult. The system in which a resin having a silyl
group is used has a good pattern-formability; however, it has such
a disadvantage that as compared with other systems using a resin
free from silyl group, it is inferior in peelability from a
substrate. In addition, in the system in which a resin comprising
an acrylic acid component is used, there is such a disadvantage
that the adhesiveness between the resist and the silicon substrate
is insufficient, and there is such a problem that the dry etching
resistance is lower than that of a resist using an aromatic
resin.
In order to solve the above-mentioned problems, attention has
recently been paid to resins having both acrylic acid ester
structure and phenol skeleton (see, for example, Japanese Patent
Application Kokai Nos. 4-251,259; 5-181,279 and 5-113,667).
Resists using these resins have such advantages that the dry
etching resistance is improved as compared with that of a resin
having only an acrylic acid recurring unit. However, since a
carboxylic acid is formed in the exposed portion, the
solubility-in-alkali-developer rate becomes too high, and there is
such a disadvantage that when a resist pattern is actually formed
on a substrate, the upper part of the pattern formed becomes too
thin to form an ideally rectangular pattern.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a radiation sensitive
resin composition freed from the above-mentioned problems.
It is a further object of this invention to provide a radiation
sensitive resin composition which is free from volume shrinkage,
peeling failure and adhesive failure, can form a high precision
pattern and has high dry etching resistance.
It is a still further object of this invention to provide a
radiation sensitive resin composition excellent as a resist which
can effectively decompose upon irradiation with various radiations
to form a pattern which is excellent in photolithographic process
stability and has the rectangular shape whose upper part is not
thinned.
It is another object of this invention to provide a radiation
sensitive resin composition excellent in pattern shape,
sensitivity, contrast, developability and the like particularly
when it is irradiated with deep ultraviolet rays, X rays or
electron beams.
Other objects and advantages of this invention will become apparent
from the following description.
According to this invention, there is provided a radiation
sensitive resin composition which comprises (A) a polymer which
becomes alkali-soluble in the presence of an acid and (B) a
radiation sensitive acid generator which generates an acid upon
irradiation with a radiation, said polymer (A) comprising two
recurring units represented by the general formulas (1) and (2) and
a recurring unit which acts to reduce the solubility of the polymer
of the irradiated portion in an alkali developer after irradiation
with a radiation: ##STR2##
wherein R.sup.1 represents a hydrogen atom or a methyl group and
R.sup.2 represents a hydrogen atom or a methyl group.
DETAILED DESCRIPTION OF THE INVENTION
Polymer (A)
The polymer (A) is a polymer having a recurring unit represented by
the general formula (1) (referred to hereinafter as the recurring
unit A), a recurring unit represented by the general formula (2)
(referred to hereinafter as the recurring unit B) and a recurring
unit which acts to reduce the solubility of the polymer of the
irradiated portion in an alkali developer after irradiation with a
radiation (referred to hereinafter as the recurring unit C):
##STR3##
wherein R.sup.1 represents a hydrogen atom or a methyl group and
R.sup.2 represents a hydrogen atom or a methyl group.
In the general formula (1), R.sup.1 is either hydrogen atom or
methyl group and the polymer (A) can have both the recurring unit
of formula (1) in which R.sup.1 is a hydrogen atom and the
recurring unit of formula (1) in which R.sup.1 is a methyl group.
The proportion of the number of the recurring units A is preferably
5 to 75%, more preferably 20 to 70%, based on the total number of
all the recurring units contained in the polymer (A). When the
proportion of the recurring unit A is less than 5%, the
adhesiveness to a substrate is inferior and there is a possibility
of the resist pattern to peel, and when the proportion is more than
75%, the difference between the solubility-in-alkali-developer rate
of the irradiated portion and that of the unirradiated portion
becomes small and hence the resolution has a tendency to
reduce.
In the general formula (2), R.sup.2 is either a hydrogen atom or a
methyl group and the polymer (A) can have both the recurring unit
of formula (2) in which R.sup.2 is a hydrogen atom and the
recurring unit of formula (2) in which R.sup.2 is a methyl group.
The proportion of the number of the recurring units B is preferably
10 to 70%, more preferably 20 to 50%, based on the total number of
all the recurring units in the polymer (A). When the proportion of
the recurring unit B is less than 10%, the
solubility-in-alkali-developer rate of the irradiated portion
becomes so low that no pattern is formed. On the other hand, when
the proportion of the recurring unit B is more than 70%, the amount
of the benzene ring in the polymer (A) becomes insufficient and
hence the dry etching resistance has a tendency to lower.
The recurring unit C is introduced by copolymerization into the
polymer (A) in order to improve the pattern shape and resolution
performance, and the proportion of the number of the recurring
units C can vary depending upon the proportions of the recurring
units A and B; however, it is preferably 0.5 to 50%, more
preferably 1 to 30%, based on the total number of all the recurring
units contained in the polymer (A). When the proportion of the
recurring unit C is less than 0.5%, its effect on reducing the
solubility-in-alkali-developer rate of the irradiated portion is
lacking, so that the upper part of the resist pattern tends to
become thinned, while when the proportion is more than 50%, the
solubility-in-alkali-developer rate becomes so low that the
sensitivity of the resist has a tendency to reduce.
The polymer (A) can be produced by radical polymerization, thermal
polymerization or the like of the respective monomers corresponding
to the recurring unit A, the recurring unit B and the recurring
unit C. The monomer corresponding to the recurring unit A (referred
to hereinafter as the monomer a) is vinylphenol or
.alpha.-isopropenylphenol, the monomer corresponding to the
recurring unit B (referred to hereinafter as the monomer b) is
tert-butyl acrylate or tert-butyl methacrylate, and the monomer
corresponding to the recurring unit C (referred to hereinafter as
the monomer c) is a monomer having a low solubility in the alkali
developer, that is, a monomer free from an acidic substituent such
as sulfonic acid group, carboxyl group, phenolic hydroxyl group or
the like.
Said monomer c includes organic compounds having a carbon--carbon
double bond copolymerizable with the monomer a and the monomer b
and having no said acidic substituent, and examples of the organic
compounds include vinyl group-containing compounds, (meth)acryloyl
group-containing compounds and the like.
Specific examples of the vinyl group-containing compounds as the
monomer c include aromatic alkenyl compounds such as styrene,
.alpha.-methylstyrene, p-methylstyrene, chlorostyrene and the like;
hetero atom-containing aromatic vinyl compounds such as
vinylpyridine and the like; vinyl ester compounds such as vinyl
acetate and the like; vinyl ketone compound such as methyl vinyl
ketone, ethyl vinyl ketone and the like; vinyl ether compounds such
as methyl vinyl ether, ethyl vinyl ether and the like; hetero
atom-containing alicyclic vinyl compounds such as vinylpyrrolidone,
vinyl lactam and the like. Specific examples of the (meth)acryloyl
group-containing compound which is one of the monomers c include
methyl (meth) acrylate, ethyl (meth)acrylate, propyl(meth)acrylate,
(meth) acrylamide, (meth)acrylonitrile and the like.
The polystyrene-reduced weight-average molecular weight of the
polymer (A) (referred to hereinafter as Mw) is preferably 1,500 to
300,000, more preferably 3,000 to 100,000 from the viewpoint of
retaining the sensitivity, heat resistance, developability and
resolving power.
Moreover, the ratio of the polystyrene-reduced weight-average
molecular weight Mw of the polymer (A) to the polystyrene-reduced
number-average molecular weight (referred to hereinafter as Mn) of
the polymer (A) [the ratio is referred to hereinafter as Mw/Mn] is
preferably 1 to 5, more preferably 1.5 to 3.5 from the viewpoint of
retaining the sensitivity, heat resistance, developability and
resolving power.
As the polymer (A), there may be used a mixed polymer consisting of
at least two polymer mixtures selected from a mixture of the
polymers different in the proportions of the monomer a, the monomer
b and the monomer c copolymerized in the above-mentioned range and
a mixture of the polymers different in Mw and/or Mw/Mn in the
above-mentioned ranges. Even when the mixed polymer is used as the
polymer (A), it is preferable that the proportions of the monomer
a, the monomer b and the monomer c copolymerized in the mixed
polymer, Mw and/or Mw/Mn fall within the above-mentioned
ranges.
Radiation Sensitive Acid Generator (B)
The radiation sensitive acid generator (B) used in this invention,
namely, the compound which generates an acid upon irradiation with
a radiation includes, for example, onium salt compounds,
halogen-containing compounds, sulfone compounds, sulfonate
compounds and quinonediazide compounds. More specifically, the
following compounds are included:
(I) Onium salt compound
Iodonium salts, sulfonium salts, phosphonium salts, diazonium
salts, pyridinium salts and the like are included. Preferable are
diphenyliodonium triflate, diphenyliodonium pyrenesulfonate,
diphenyliodonium dodecylbenzenesulfonate, triphenylsulfonium
triflate, triphenylsulfoniumhexafluoroantimonate, diphenyliodonium
hexafluoroantimonate, triphenylsulfoniumnaphthalenesulfonate,
(hydroxyphenyl) benzylmethylsulfonium toluenesulfonate and the
like.
Particularly preferable are triphenylsulfonium triflate,
diphenyliodoniumhexafluoroantimonate and the like.
(II) Halogen-containing compound
Haloalkyl group-containing heterocyclic compounds, haloalkyl
group-containing hydrocarbon compounds and the like are included.
Preferable are (trichloromethyl)-s-triazine derivatives such as
phenyl-bis(trichloromethyl)-s-triazine,
methoxyphenyl-bis(trichloromethyl)-s-triazine,
naphthyl-bis(trichloromethyl)-s-triazine and the like;
1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane; and the like.
(III) Sulfone compound
.beta.-ketosulfone, .beta.-sulfonylsulfone and their .alpha.-diazo
compounds thereof and the like. Preferable are
phenacylphenylsulfone, mesitylphenacylsulfone,
bis(phenylsulfonyl)methane, bis(phenylsulfonyl)diazomethane and the
like.
(IV) Sulfonate compound
Alkylsulfonic acid esters, haloalkylsulfonic acid esters,
arylsulfonic acid esters, iminosulfonates, imidosulfonates and the
like are included.
Preferable imidosulfonate compounds are, for example,
N-(trifluoromethylsulfonyloxy)succinimide,
N-(trifluoromethylsulfonyloxy)phthalimide,
N-(trifluoromethylsulfonyloxy)naphthylimide,
N-(trifluoromethylsulfonyloxy)diphenylmaleimide,
N-(trifluoromethylsulfonyloxy)-bicyclo-[2,2,1]-hept-5-ene-2,3-dicarboximid
e,
N-(trifluoromethylsulfonyloxy)-7-oxabicyclo-[2,2,1]-hept-5-ene-2,3-dicarbo
ximide,
N-(trifluoromethylsulfonyloxy)-bicyclo-[2,2,1]-heptan-5,6-oxy-2,3-dicarbox
imide, N-(camphanylsulfonyloxy) succinimide,
N-(camphanylsulfonyloxy)phthalimide,
N-(camphanylsulfonyloxy)naphthylimide,
N-(camphanylsulfonyloxy)diphenylmaleimide,
N-(camphanylsulfonyloxy)bicyclo-[2,2,1]-hept-5-ene-2,3-dicarboximide,
N-(camphanylsulfonyloxy)-7-oxabicyclo-[2,2,1]-hept-5-ene-2,3-dicarboximide
,
N-(camphanylsulfonyloxy)-bicyclo-[2,2,1]-heptan-5,6-oxy-2,3-dicarboximide,
N-(4-methylphenylsulfonyloxy) succinimide,
N-(4-methylphenylsulfonyloxy)phthalimide,
N-(4-methylphenylsulfonyloxy)naphthylimide,
N-(4-methylphenylsulfonyloxy)diphenylmaleimide,
N-(4-methylphenylsulfonyloxy)-bicyclo-[2,2,1]-hept-5-ene-2,3-dicarboximide
,
N-(4-methylphenylsulfonyloxy)-7-oxabicyclo-[2,2,1]-hept-5-ene-2,3-dicarbox
imide,
N-(4-methylphenylsulfonyloxy)-bicyclo-[2,2,1]-heptan-5,6-oxy-2,3-dicarboxi
mide, N-(2-trifluoromethylphenylsulfonyloxy) succinimide,
N-(2-trifluoromethylphenylsulfonyloxy) phthalimide,
N-(2-trifluoromethylphenylsulfonyloxy) naphthylimide,
N-(2-trifluoromethylphenylsulfonyloxy) diphenylmaleimide,
N-(2-trifluoromethylphenylsulfonyloxy)bicyclo-[2,2,1]-hept-5-ene-2,3-dicar
boximide,
N-(2-trifluoromethylphenylsulfonyloxy)-7-oxabicyclo-[2,2,1]-hept-5-ene-2,3
-dicarboximide,
N-(2-trifluoromethylphenylsulfonyloxy)-bicyclo-[2,2,1]-heptan-5,6-oxy-2,3-
dicarboximide and the like.
As other sulfonate compounds than the imidosulfonate compounds,
preferable are, for example, benzoin tosylate, pyrogallol
tristriflate, pyrogallolmethanesulfonic acid triester,
nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate and the like.
In the radiation sensitive resin composition of this invention,
particularly preferably sulfonate compounds include
pyrogallolmethanesulfonic acid triester,
N-(trifluoromethylsulfonyloxy)-bicyclo-[2,2,1]-hept-5-ene-2,3-dicarboximid
e, N-(camphanylsulfonyloxy) naphthylimide,
N-(2-trifluoromethylphenylsulfonyloxy) phthalimide,
N-(trifluoromethylsulfonyloxy)-bicyclo-[2,2,1]-hept-5-ene-2,3-dicarboximid
e, N-(camphanylsulfonyloxy)naphthylimide,
N-(2-trifluoromethylphenylsulfonyloxy)phthalimide and the like.
(V) Quinonediazide compound
1,2-Quinonediazidesulfonic acid ester compounds of polyhydroxy
compounds are included. Preferable are compounds having a
1,2-quinonediazidesulfonyl group such as
1,2-benzoquinonediazide-4-sulfonyl group,
1,2-naphthoquinonediazide-4-sulfonyl group,
1,2-naphthoquinonediazide-5-sulfonyl group, a
1,2-naphthoquinonediazide-6-sulfonyl group or the like.
Particularly preferable are compounds having a
1,2-naphthoquinonediazide-4-sulfonyl group or a
1,2-naphthoquinonediazide-5-sulfonyl group; and like compounds.
Specifically, the following compounds are mentioned:
1,2-Quinonediazidesulfonic acid esters of (poly) hydroxyphenyl aryl
ketones such as 2,3,4-trihydroxybenzophenone,
2,4,6-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone,
2,2',3,4-tetrahydroxybenzophenone,
3'-methoxy-2,3,4,4'-tetrahydroxybenzophenone,
2,2',4,4'-tetrahydroxybenzophenone,
2,2',3,4,4'-pentahydroxybenzophenone,
2,2',3,4,6'-pentahydroxybenzophenone,
2,3,3',4,4',5'-hexahydroxybenzophenone,
2,3',4,4',5',6-hexahydroxybenzophenone and the like;
1,2-quinonediazidesulfonic acid esters of bis-[(poly)
hydroxyphenyl]alkanes such as bis(4-hydroxyphenyl) methane,
bis(2,4-dihydroxyphenyl)methane,
bis(2,3,4-trihydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)
propane, 2,2-bis(2,4-dihydroxyphenyl)propane, 2,2-bis-(2,
3,4-trihydroxyphenyl)propane and the like;
1,2-quinonediazidesulfonic acid esters of (poly)
hydroxyphenylalkanes such as 4,4'-dihydroxytriphenylmethane,
4,4',4"-trihydroxytriphenylmethane,
2,2',5,5'-tetramethyl-2",4,4'-trihydroxytriphenylmethane,
3,3',5,5'-tetramethyl-2",4,4'-trihydroxytriphenylmethane,
4,4',5,5'-tetramethyl-2,2',2"-trihydroxytriphenylmethane,
2,2',5,5'-tetramethyl-4,4',4"-trihydroxytriphenylmethane,
1,1,1-tris(4-hydroxyphenyl) ethane,
1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,1-bis
(4-hydroxyphenyl)-1-(4'-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl)ethane
and the like;
1,2-quinonediazidesulfonic acid esters of (poly)
hydroxyphenylflavans such as
2,4,4-trimethyl-2',4',7-trihydroxy-2-phenylflavan,
2,4,4-trimethyl-2',4',5',6,7-pentahydroxy-2-phenylflavan and the
like.
Particularly preferable are 1,2-naphthoquinonediazide-4-sulfonic
acid ester compounds of
1,1-bis(4-hydroxyphenyl)-1-(4'-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl)e
thanes represented by the following structural formula (3):
##STR4##
wherein D represents a substituent of the formula (4): ##STR5##
or a hydrogen atom.
In the formula (3), the proportion of D being a substituent of the
formula (4) is preferably 75 to 95% on average, particularly
preferably 80 to 90% on average.
These radiation sensitive acid generators (B) may be used alone or
in admixture of two or more.
The amount of the radiation sensitive acid generator (B) used is
preferably 0.05 to 20 parts by weight, more preferably 0.1 to 15
parts by weight, per 100 parts by weight of the polymer (A). When
the amount of the radiation sensitive acid generator (B) used is
less than 0.05 part by weight, it is difficult in some cases to
cause chemical reaction effectively with an acid catalyst generated
by irradiation with a radiation. On the other hand, when the amount
of the radiation sensitive acid generator is more than 20 parts by
weight, there is a fear that uneven coating is caused when the
composition is applied to a substrate and scum and the like are
formed during development.
Into the radiation sensitive resin composition of this invention
may be incorporated, if necessary, an alkali-solubility controller,
an acid-diffusion controller or the like as explained below.
Alkali-Solubility Controller
The alkali-solubility controller is a compound which has such
properties that the alkali-solubility of the radiation sensitive
resin composition is controlled, and when it is decomposed, for
example, is hydrolyzed, in the presence of an acid, the
alkali-solubility-controlling effect of the alkali-solubility
controller on the radiation sensitive resin composition is reduced
or lost, or the alkali-solubility of the radiation sensitive resin
composition is accelerated by the controller after
decomposition.
As such an alkali-solubility controller, there may be mentioned,
for example, compounds whose acidic functional groups such as
phenolic hydroxyl group, carboxyl group and the like have been
substituted by acid-decomposable groups.
The alkali-solubility controller may be either a low molecular
weight compound or a high molecular weight compound, and preferable
controllers are compounds obtained by substituting an
acid-decomposable group for the acidic functional group of
polyphenol compounds having two or more phenolic hydroxy groups,
such as bisphenol A, bisphenol F, bisphenol S and the like, and
carboxylic acid compounds such as hydroxyphenylacetic acid and the
like.
Specifically, compounds represented by the following structural
formulas (a) and (b) are included: ##STR6##
Also, as the high molecular eight alkali-solubility controller,
there may be used an acid-decomposable group-containing resin.
The term "acid-decomposable group" used herein means a substituent
which is decomposed in the presence of an acid to make the compound
or resin, the acidic functional groups of which have been
substituted by the acid decomposable groups, alkali-soluble.
Such acid-decomposable groups include, for example, substituted
methyl groups, 1-substituted ethyl groups, 1-branched alkyl groups,
allyl groups, germyl groups, alkoxycarbonyl groups, acyl groups,
cyclic acid-decomposable groups and the like.
The above-mentioned substituted methyl groups include, for example,
methoxymethyl group, methylthiomethyl group, ethoxymethyl group,
ethylthiomethyl group, methoxyethoxymethyl group, benzyloxymethyl
group, benzylthiomethyl group, phenacyl group, bromophenacyl group,
methoxyphenacyl group, (methylthio)phenacyl group,
cyclopropylmethyl group, benzyl group, diphenylmethyl group,
triphenylmethyl group, bromobenzyl group, nitrobenzyl group,
methoxybenzyl group, methylthiobenzyl group, ethoxybenzyl group,
ethylthiobenzyl group, piperonyl group and the like.
The above-mentioned 1-substituted ethyl groups include, for
example, 1-methoxyethyl group, 1-methylethyl group,
1,1-dimethoxyethyl group, 1-ethoxyethyl group, 1-ethylthioethyl
group, 1,1-diethoyxethyl group, 1-phenoxyethyl group,
1-phenylthioethyl group, 1,1-diphenoxyethyl group, 1-benzyloxyethyl
group, 1-benzylthioethyl group, 1-cyclopropylethyl group,
1-phenylethyl group, 1,1-diphenylethyl group,
.alpha.-methylphenacyl group and the like.
The above-mentioned 1-branched alkyl groups include, for example,
isopropyl group, sec-butyl group, tert-butyl group,
1,1-dimethylpropyl group, 1-methylbutyl group, 1,1-dimethylbutyl
group and the like.
The above-mentioned silyl groups include, for example,
trimethylsilyl group, ethyldimethylsilyl group, diethylmethylsilyl
group, triethylsilyl group, dimethylisopropylsilyl group,
methyldiisopropylsilyl group, tri-isopropylsilyl group,
tert-butyldimethylsilyl group, di-tert-butylmethylsilyl group,
tri-tert-butylsilyl group, dimethylphenylsilyl group,
methyldiphenylsilyl group, triphenylsilyl group and the like.
The above-mentioned germyl groups include, for example,
trimethylgermyl group, ethyldimethylgermyl group,
diethylmethylgermyl group, triethylgermyl group,
dimethylisopropylgermyl group, methyldiisopropylgermyl group,
triisopropylgermyl group, tert-butyldimethylgermyl group,
di-tert-butylmethylgermyl group, tri-tert-butylgermyl group,
dimethylphenylgermyl group, methyldiphenylgermyl group,
triphenylgermyl group and the like.
The above-mentioned alkoxycarbonyl groups include, for example,
methoxycarbonyl group, ethoxycarbonyl group, isopropoxycarbonyl
group, tert-butoxycarbonyl group, tert-pentyloxycarbonyl group and
the like.
The above-mentioned acyl groups include, for example, acetyl group,
propionyl group, butyryl group, heptanoyl group, hexanoyl group,
valeryl group, pivoloyl group, isovaleryl group, lauloyl group,
myristoyl group, palmitoyl group, stearoyl group, oxalyl group,
malonyl group, succinyl group, glutaryl group, adipoyl group,
piperoyl group, suberoyl group, azelaoyl group, sebacoyl group,
acryloyl group, propioloyl group, methacryloyl group, crotonoyl
group, oleoyl group, maleoyl group, fumaroyl group, mesaconoyl
group, camphoroyl group, benzoyl group, phthaloyl group,
isophthaloyl group, terephthaloyl group, naphthoyl group, toluoyl
group, hydroatropoyl group, atropoyl group, cinnamoyl group, furoyl
group, thenoyl group, nicotinoyl group, isonicotinoyl group,
toluenesulfonyl group, mesyl group and the like.
The above-mentioned cyclic acid-decomposable groups include, for
example, cyclopropyl group, cyclopentel group, cyclohexyl group,
cyclohexenyl group, oxocyclohexenyl group, 4-methoxycyclohexyl
group, tetrahydropyranyl group, tetrahydrofuranyl group,
tetrahydrothiopyranyl group, tetrahydrothiofuranyl group,
3-bromotetrahydropyranyl group, 4-methoxytetrahydropyranyl group,
4-methoxytetrahydrothiopyranyl group,
3-tetrahydrothiophene-1,1-dioxide group, 2-1,3-dioxolanyl group,
2-1,3-dithioxolanyl group, benzo-2-1,3-dioxolanyl group,
benzo-2-1,3-dioxolanyl group and the like.
Among these acid-decomposable groups, preferable are tert-butyl
group, benzyl group, tert-butoxycarbonyl group,
tert-butoxycarbonylmethyl group, tertrahydropyranyl group,
tetrahydrofuranyl group, tetrahydrothiopyranyl group,
tetrahydrothiofuranyl group and trimethylsilyl group and the
like.
The above-mentioned acid-decomposable group-containing resin can be
produced, for example, by introducing at least one
acid-decomposable group into an alkali-soluble resin or
polymerizing or copolymerizing at least one monomer having at least
one acid-decomposable group or polycondensing or copolycondensing
at least one polycondensing component having at least one
acid-decomposable group.
Incidentally, the proportion of the acid-decomposable group
introduced into the acid-decomposable group-containing resin (the
ratio of the number of acid-decomposable groups to the total number
of acidic functional groups and acid-decomposable groups in the
acid-decomposable group-containing resin) is preferably 15 to 100%,
more preferably 15 to 80% and most preferably 15 to 60%.
The Mw of the acid-decomposable group-containing resin is
preferably 1,000 to 150,000, more preferably 3,000 to 100,000.
These acid-decomposable group-containing resins may be used alone
or in admixture of two or more.
The proportion of the alkali-solubility controller added in this
invention is preferably 100 parts by weight or less per 100 parts
by weight of the polymer (A). When the amount of the
alkali-solubility controller is more than 100 parts by weight, the
coatability of the composition, coating-film strength and the like
have a tendency to reduce.
The alkali-solubility controller may be used alone or in admixture
of two or more in each case of a low molecular weight compound or a
high molecular weight compound (namely, the acid-decomposable
group-containing resin) and a mixture of the low molecular weight
compound and the high molecular weight compound may also be
used.
Acid-Diffusion Controller
The acid-diffusion controller has such an action as to control the
diffusion phenomenon in the resist coating-film of the acid
generated from the acid generator by irradiation with a radiation
and control the undesirable chemical reactions in the unirradiated
area. When the acid-diffusion controller is used, the pattern
shape, particularly the degree of formation of a visor in the upper
part of the pattern ("T"-shape), the dimension fidelity to mask
dimension and the like can be further improved.
Such acid-diffusion controllers are preferably nitrogen-containing
organic compounds whose basicity is not changed by irradiation with
a radiation or heating, and specific examples thereof include
ammonia, hexylamine, heptylamine, octylamine, nonylamine,
decylamine, dibutylamine, dipentylamine, dihexylamine,
diheptylamine, dioctylamine, dinonylamine, didecylamine,
trimethylamine, triethylamine, tripropylamine, tributylamine,
tripentylamine, trihexylamine, triheptylamine, trioctylamine,
trinonylamine, tridecylamine, aniline, N-methylaniline,
N,N-dimethylaniline, 2-methylaniline, 3-methylaniline,
4-methylaniline, 4-nitroaniline, 1-naphthylamine, 2-naphthylamine,
diphenylamine, ethylenediamine, tetramethylenediamine,
hexamethylenediamine, pyrrolidone, piperidine, imidazole,
4-methylimidazole, 4-methyl-2-phenylimidazole, thiabendazole,
pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine,
4-ethylpyridine, 1-methyl-4-phenylpyridine,
2-(1-ethylpropyl)pyridine, nicotinamide, dibenzoylthiamine,
riboflavin tetrabutyrate, 4,4-diaminodiphenylmethane,
4,4'-diaminodiphenyl ether, 4,4,-diaminobenzophenone,
4,4,-diaminodiphenylamine, 2,2-bis(4-aminophenyl)propane,
2-(3-aminophenyl)-2-(4-aminophenyl)propane,
2-(4-aminophenyl)-2-(3-hydroxyphenyl)propane,
2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane,
1,4-bis[1-(4-aminophenyl)-1-methylethyl]benzene,
1,3-bis[1-(4-aminophenyl)-1-methylethyl]benzene, dimethyl
succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine
polycondensate, poly[{6-(1,1,3,3-tetramethylbutyl)imino-1,
3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)
imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl) imino}], bis
(1,2,2,6,6-pentamethyl-4-piperidyl)-2-(3,5-di-tert-butyl-4-hydroxybenzyl)-
2-butylmalonate and the like.
These acid-diffusion controllers may be used alone or in admixture
of two or more.
The proportion of the acid-diffusion controller added in this
invention is preferably 0.001 to 10 parts by weight, more
preferably 0.005 to 5 parts by weight, per 100 parts by weight of
the polymer (A). In this case, when the amount of the
acid-diffusion controller used is less than 0.001 part by weight,
there is a fear that the pattern shape and dimension fidelity may
not be improved under some processing conditions, and when the
proportion is more than 10 parts by weight, the sensitivity as a
resist and the developability in the exposed portion have a
tendency to lower.
Various Additives
The radiation sensitive resin composition of this invention may, if
necessary, contain various additives such as a surfactant, a
sensitizer and the like.
The above surfactant has an action to improve the coatability of
the radiation sensitive resin composition, striation,
developability of coating-film of the composition and the like.
Such surfactants include, for example, polyoxyethylene lauryl
ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether,
polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl
ether, polyoxyethylene glycol dilaurate and polyoxyethylene glycol
distearate and also include KP341 (a trade name of Shin-Ets
Chemical Co., Ltd.), Polyflow No. 75, No. 95 (trade names of
Kyoeisha Yushi Kagaku Kogyo K. K.), F Top EF301, EF303, EF352
(trade names of Tokem Products), Megafac F171, F172, F173 (trade
names of DAINIPPON INK & CHEMICALS, INC.), Fluorad FC430, FC431
(trade names of Sumitomo 3M Limited), Asahi Guard AG710, Surflon
S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (trade names
of Asahi Glass Co., Ltd.) and the like.
The amount of the surfactant added is preferably 2 parts by weight
or less per 100 parts by weight of the solid content of the
radiation sensitive resin composition.
The above-mentioned sensitizer has an action to absorb the energy
of radiation and transfer the energy to the radiation sensitive
acid generator (B) to thereby increase the amount of acid produced
and has also an effect that the sensitivity of resist obtained from
the radiation sensitive resin composition of this invention is
enhanced. The sensitizer is preferably a ketone, a benzene, an
acetophenone, a benzophenone, a naphthalene, a biacetyl, an eocin,
rose bengal, a pyrene, an anthracene, a phenolthiazine or the
like.
The amount of the sensitizer added is preferably 50 parts by weight
or less, more preferably 30 parts by weight or less, per 100 parts
by weight of the solid content of the radiation sensitive resin
composition.
By compounding a dye or pigment with the composition, the influence
of halation during irradiation with a radiation can be softened and
by compounding an adhesion promoters with the composition, the
adhesion properties of the coating-film to a substrate can be
improved.
Moreover, other additives include halation-preventing agents such
as azo compounds, amine compounds and the like, storage
stabilizers; defoaming agents; shape-improving agents; and the
like.
Solvent
The radiation sensitive resin composition of this invention is
dissolved in a solvent so that the solid concentration becomes, for
example, 5 to 50% by weight, preferably 20 to 40% by weight when it
is used, and then filtered through a filter having a pore diameter,
for example, about 0.2.mu. to prepare a composition solution.
The solvent to be used in the preparation of the composition
solution includes, for example, ethylene glycol monoalkyl ethers
such as ethylene glycol monomethyl ether, ethylene glycol monoethyl
ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl
ether and the like; ethylene glycol monoalkyl ether acetates such
as ethylene glycol monomethyl ether acetate, ethylene glycol
monoethyl ether acetate, ethylene glycol monopropyl ether acetate,
ethylene glycol monobutyl ether acetate and the like; diethylene
glycol dialkyl ethers such as diethylene glycol dimethyl ether,
diethylene glycol diethyl ether, diethylene glycol dipropyl ether,
diethylene glycol dibutyl ether and the like; propylene glycol
monoalkyl ethers such as propylene glycol monomethyl ether,
propylene glycol monoethyl ether, propylene glycol monopropyl
ether, propylene glycol monobutyl ether and the like; propylene
glycol dialkyl ethers such as propylene glycol dimethyl ether,
propylene glycol diethyl ether, propylene glycol dipropyl ether,
propylene glycol dibutyl ether and the like; propylene glycol
monoalkyl ether acetates such as propylene glycol monomethylether
acetate, propylene glycol monoethyl ether acetate, propylene glycol
monopropyl ether acetate, propylene glycol monobutyl ether acetate
and the like; lactic acid esters such as methyl lactate, ethyl
lactate, n-propyl lactate, isopropyl lactate, n-butyl lactate,
isobutyl lactate and the like; aliphatic carboxylic acid esters
such as methyl formate, ethyl formate, n-propyl formate, isopropyl
formate, n-butyl formate, isobutyl formate, n-amyl formate, isoamyl
formate, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl
acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl
acetate, n-hexyl acetate, methyl propionate, ethyl propionate,
n-propyl propionate, isopropyl propionate, n-butyl propionate,
isobutyl propionate, methyl butyrate, ethyl butyrate, n-propyl
butyrate, isopropyl butyrate, n-butyl butyrate, isobutyl butyrate
and the like; other esters such as ethyl hydroxyacetate, ethyl
2-hydroxy-2-methylpropionate, methyl 3-methoxy-2-methylpropionate
(methyl .beta.-methoxybutyrate), methyl,
2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl
ethoxyacetate, methyl 3-methoxypropionate, ethyl
3-methoxypropionate, methyl 3-ethoxypropionate, ethyl
3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl
acetate, 3-methyl-3-methoxybutyl propionate,
3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, ethyl
acetoacetate, methyl pyruvate, ethyl pyruvate and the like;
aromatic hydrocarbons such as toluene, xylene and the like; ketones
such as methyl ethyl ketone, 2-heptanone, 3-heptanone, 4-heptanone,
cyclohexanone and the like; amides such as N-methylformamide,
N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide,
N-methylpyrrolidone and the like; lactones such as
.gamma.-butyrolactone and the like; etc.
These solvents may be used alone or in admixture of two or
more.
The amount of the solvent used in the composition solution in this
invention is preferably 20 to 3,000 parts by weight, more
preferably 50 to 3,000 parts by weight, and most preferably 100 to
2,000 parts by weight, per 100 parts by weight of the total solid
content of the polymer (A), the radiation sensitive acid generator
(B) and the optionally added dissolution controller and/or
additives.
In the formation of a resist pattern from the radiation sensitive
resin composition of this invention, the composition solution is
applied to a substrate such as a silicon wafer, an aluminum-coated
wafer or the like by a means such as a spin coating, a flow
coating, a roll coating or the like to form a resist coating-film,
and the resist coating-film is irradiated with a radiation so that
the desired pattern is formed. The radiation used in this case is
appropriately selected from ultraviolet rays such as i ray and the
like; deep ultraviolet rays such as excimer laser and the like; X
rays such as synchrotron radiation or the like; and charged
particle beams such as electron beam and the like depending upon
the kind of the radiation sensitive acid generator (B) used. The
irradiation conditions such as irradiation dose and the like are
appropriately selected depending upon the compounding recipe of the
radiation sensitive resin composition, the kind of the additives
and the like.
In the formation of a resist pattern using the radiation sensitive
resin composition of this invention, it is possible to provide a
protective coating-film on the resist coating-film for preventing
the influence of basic impurities or the like contained in the
working atmosphere.
In this invention, in order to enhance the apparent sensitivity of
the resist coating-film, it is preferable to effect baking after
the irradiation (post-exposure baking). The heating conditions for
the post-exposure baking may be varied depending upon the
compounding recipe of the radiation sensitive resin composition of
this invention, the kind of additives and the like; however, the
heating temperature is preferably 30.degree. to 200.degree. C.,
more preferably 50.degree. to 150.degree. C.
Subsequently, the irradiated resist coating-film is developed with
an alkali developer to form the desired resist pattern. The alkali
developer includes, for example, alkaline compounds such as sodium
hydroxide, potassium hydroxide, sodium carbonate, sodium silicate,
sodium metasilicate, ammonia water, ethylamine, n-propylamine,
diethylamine, di-n-propylamine, triethylamine, methyldiethylamine,
dimethylethanolamine, triethanolamine, tetramethylammonium
hydroxide, tetraethylammonium hydroxide, choline, pyrrole,
piperidine, 1,8-diazabicyclo-[5,4,0]-7-undecene,
1,5-diazabicyclo-[4,3, 0]-5-nonene and the like, and an aqueous
alkaline solution having a concentration of preferably 1 to 10% by
weight, more preferably 2 to 5% by weight is used as the
developer.
To the above developer may be added an aqueous organic solvent such
as methanol, ethanol or the like and a surfactant in appropriate
amounts.
Incidentally, when a developer consisting of such an aqueous
alkaline solution is used, the resulting resist pattern is washed
with water after the development.
The positive radiation sensitive resin composition of this
invention can form a highly precise pattern without causing volume
shrinkage, peeling failure and adhesive failure and is excellent in
dry etching resistance.
Moreover, the positive radiation sensitive resin composition of
this invention reacts effectively with various radiations, is
excellent in photolithographic process stability and, in
particular, the upper part of the pattern shape formed does not
become thinner than the lower part and a rectangular pattern can be
formed.
Furthermore, the positive radiation sensitive resin composition of
this invention is excellent in pattern shape, sensitivity,
contrast, developability and the like particularly when deep
ultraviolet rays, X rays or electron beams are used.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
This invention is explained in more detail below referring to
Examples and Comparative Examples; however, this invention should
not be construed to be limited thereto.
In the Examples, various characteristics were evaluated as
follows.
Mw and Mw/Mn
Using a GPC column manufactured by TOSOH CORP. (two G2000H.sub.XL
columns, one G3000H.sub.XL column and one G4000H.sub.XL column),
the Mw was measured by a gel permeation chromatograph method in
which a monodisperse standard polystyrene was used as a standard
under the analysis conditions that the flow rate was 1.0 ml/min,
the eluent was tetrahydrofuran, and the column temperature was
40.degree. C.
Optimum Dose of Radiation Irradiated
After irradiation with various radiation doses, like mentioned
above, then the development with a 2.38% by weight aqueous
tetrahydroammonium hydroxide solution, water-washing and drying
were conducted to form a resist pattern on a silicon wafer with the
irradiated-resist coating film. And then the radiation dose
necessary for forming a 0.5-.mu.m line-and-space pattern (1L1S) in
a 1:1 width was determined as the optimum radiation dose.
Resolution
The minimum dimension of the resist pattern resolved when a
radiation was irradiated at the optimum radiation dose was
determined as the resolution.
Pattern Shape
The lower side dimension La and the upper side dimension Lb of the
square cross-section of the 1L1S pattern of a line width of 0.5
.mu.m formed on a silicon wafer were measured using a scanning type
electron microscope. When the resulting pattern satisfied
0.85.ltoreq.Lb/La.ltoreq.1 and the pattern had no thinned portion
in the vicinity of the substrate and no overhang at the top (no
"T"-shape), said pattern shape was determined good. When patterns
did not satisfy these conditions, they were determined bad.
Process Stability
An irradiation was applied to a resist coating-film formed on a
silicon wafer and, immediately thereafter, the resist coating-film
was subjected to post exposure baking and development to obtain a
resist pattern. Separately, the resist coating-film irradiated with
a radiation was allowed to stand for two hours after the
irradiation and then subjected to post exposure baking and
development to obtain another resist pattern. The shapes of the two
resist patterns obtained were compared.
Synthesis Example 1
In 50 g of dioxane were dissolved 20 g of vinylphenol, 20 g of
tert-butyl acrylate and 8.5 g of styrene, and then 8.2 g of
2,2'-azobisisobutyronitrile was added thereto, after which the
resulting solution was bubbled with a nitrogen gas for 30 minutes.
Thereafter, the solution was heated to 60.degree. C. while the
bubbling was continued to effect polymerization for seven hours.
After the polymerization, the solution was poured into a large
amount of hexane to coagulate the polymer and the polymer was then
recovered. The polymer was dissolved in acetone and then the
resulting solution was poured into hexane again to coagulate the
polymer. This operation was repeated several times to remove
completely the unreacted monomers, after which the polymer was
dried at 50.degree. C. under vacuum overnight. The polymer thus
obtained was white and the yield was 55%. As a result of .sup.1
H-NMR and .sup.13 C-NMR analyses, it was found that the composition
of the polymer was such that vinylphenol, tert-butyl acrylate and
styrene were copolymerized at a proportion of approximately 2:2:1.
Mw was 24,000 and Mw/Mn was 2.8. This polymer is referred to
hereinafter as Polymer (I).
Synthesis Example 2
The same procedure as in Synthesis Example 1 was repeated, except
that 22 g of isopropenylphenol was substituted for the 20 g of
vinyphenol, to synthesize a polymer. The polymer obtained was white
and the yield was 45%. As a result of .sup.1 H-NMR and .sup.13
C-NMR analyses, it was found that the composition of the polymer
was such that isopropenylphenol, tert-butyl acrylate and styrene
were copolymerized at a ratio of approximately 2:3:1. Mw was 28,000
and Mw/Mn was 2.6. This polymer is referred to hereinafter as
Polymer (II).
Synthesis Example 3
The same procedure as in Synthesis Example 1 was repeated, except
that 15 g of tert-butyl methacrylate was substituted for the 20 g
of tert-butyl acrylate and 3 g of methyl methacrylate was
substituted for the 8.5 g of styrene, to synthesize a polymer. The
polymer obtained was white and the yield was 60%. As a result of
.sup.1 H-NMR and .sup.13 C-NMR analyses, it was found that the
composition of the polymer was such that vinylphenol, tert-butyl
methacrylate and methyl methacrylate were copolymerized at a ratio
of approximately 5:3:1. Mw was 22,000 and Mw/Mn was 2.7. This
polymer is referred to hereinafter as Polymer (III).
Synthesis Example 4
The same procedure as in Synthesis Example 3 was repeated, except
that 1.2 g of acrylonitrile was substituted for the 3 g of methyl
methacrylate, to synthesize a polymer. The polymer thus obtained
was yellowish white and the yield was 55%. As a result of .sup.1
H-NMR and .sup.13 C-NMR analyses, it was found that the composition
of the polymer was such that vinylphenol, tert-butyl methacrylate
and acrylonitrile were copolymerized at a ratio of approximately
5:3:1. Mw was 29,000 and Mw/Mn was 2.4. This polymer is referred to
hereinafter as Polymer (V).
Synthesis Example 5
In 59 g of propylene glycol monomethyl ether were dissolved 22 g of
isopropenylphenol, 11 g of tert-butyl acrylate, 2 g of
.alpha.-methylstyrene and 1 g of methyl vinyl ketone, and then, 2.5
g of benzoyl peroxide was added to the resulting solution, after
which the solution was bubbled with a nitrogen gas for 30 minutes.
Thereafter, the solution was heated to 80.degree. C. while the
bubbling was continued to effect polymerization for 48 hours. After
the polymerization, the solution was poured into a large amount of
hexane to coagulate a polymer. This polymer was dissolved in
acetone and then coagulated in hexane again. This operation was
repeated several times to remove the unreacted monomers completely
and the polymer was dried at 50.degree. C. under vacuum overnight.
The polymer thus obtained was white and the yield was 55%. As a
result of .sup.1 H-NMR and .sup.13 C-NMR analyses, it was found
that the composition of the polymer was such that
isopropenylphenol, tert-butyl acrylate, .alpha.-methylstyrene and
methyl vinyl ketone were copolymerized at a ratio of approximately
13:7:2:1. Mw was 18,000 and Mw/Mn was 3.2. This polymer is referred
to hereinafter as Polymer (V).
Synthesis Example 6
The same procedure as in Synthesis Example 5 was repeated, except
that 10 g of vinylphenol, 12 g of isopropenylphenol, 10 g of
tert-butyl methacrylate and 3 g of styrene were dissolved in 50 g
of toluene, to produce a polymer. The polymer thus obtained was
white and the yield was 55%. As a result of .sup.1 H-NMR and
.sup.13 C-NMR analyses, it was found that the composition of the
polymer was such that vinylphenol, isopropenylphenol, tert-butyl
methacrylate and styrene were copolymerized at a ratio of
approximately 4:3:3:1. Mw was 31,000 and Mw/Mn was 2.5. This
polymer is referred to hereinafter as Polymer (VI).
Comparative Synthesis Example 1
In 50 ml of dioxane were dissolved 12 g of polyhydroxystyrene and 5
g of triethylamine. To this mixed solution was added 4 g of
di-tert-butyl carbonate while the solution was stirred, and then
stirred at room temperature for 6 hours, after which oxalic acid
was added to the solution to neutralize the triethylamine. This
solution was poured into a large amount of water to coagulate a
polymer and the polymer was washed with pure water several times to
obtain a white polymer. The yield was 85%. As a result of .sup.1
H-NMR and .sup.13 C-NMR analyses, it was found that the composition
of the polymer was such that vinylphenol, and
tert-butoxycarbonyloxyvinylphenol were copolymerized at a ratio of
approximately 7:3. Mw was 9,200 and Mw/Mn was 2.8. This polymer is
referred to hereinafter as Polymer (VII).
Comparative Synthesis Example 2
The same procedure as in Synthesis Example 1 was repeated, except
that 24 g of vinylphenol and 19 g of tert-butyl methacrylate were
dissolved in 50 g of dioxane, to produce a polymer. The polymer
obtained was white and the yield was 65%. As a result of .sup.1
H-NMR and .sup.13 C-NMR analyses, it was found that the composition
of the polymer was such that vinylphenol and tert-butyl
methacrylate were copolymerized at a ratio of approximately 7:3. Mw
was 23,000 and Mw/Mn was 2.3. This polymer is referred to
hereinafter as Polymer (VIII).
Examples 1 to 16 and Comparative Examples 1 and 2
The polymer (A), the radiation sensitive acid generator (B) and
optionally the dissolution controller, the acid-diffusion
controller and the solvent shown in Table 1 were mixed in the
proportion shown in Table 1 to form a uniform solution, and
thereafter, the solution was filtered through a membrane filter
having a pore diameter of 0.2 .mu.m to prepare a resist
solution.
The resist solution was coated on a silicon wafer by a spin coater
and then prebaked at 90.degree. C. for 100 seconds to form a resist
coating-film having a film thickness of 1.0 .mu.m, after which the
resist coating-film was irradiated with the various radiations
shown in Table 2 and thereafter subjected to post exposure baking
at 90.degree. C. for 120 seconds. Subsequently, the irradiated and
baked resist coating-film was developed with 2.38% by weight
aqueous tetramethylammonium hydroxide solution by a dipping method
at 23.degree. C. for 60 seconds, and then washed with water for 30
seconds. The results obtained are shown in Table 2.
TABLE 1 Alkali- Acid- Acid solubility diffusion Polymer generator
controller controller Solvent Part Part Part Part Part Kind by wt.
Kind by wt. Kind by wt. Kind by wt. Kind by wt. Example 1 I 100 P1
3 -- -- -- -- EL 350 2 I 70 P2 3 D1 30 -- -- EL/EEP 200/100 3 II
100 P3 5 -- -- -- -- EL/BA 200/100 4 III 100 P1 3 -- -- -- -- PGMEA
300 5 IV 100 P2 3 -- -- -- -- MAX 300 6 V 100 P4 10 -- -- -- -- MMP
300 7 VI 80 P1 3 D2 20 -- -- EL/MMP 150/150 8 I 100 P5 5 -- -- --
-- EL 350 9 II 70 P6 3 D1 30 -- -- EL/EEP 200/100 10 II 100 P1/P5
3/2 -- -- -- -- PGMEA 300 11 III 100 P7 3 -- -- -- -- EL/BA 200/100
12 V 100 P5/P7 2/2 -- -- -- -- MMP 300 13 I 100 P1 3 -- -- C1 1.2
EL 350 14 II 100 P3 5 -- -- C3 2.0 EL/BA 200/100 15 I 100 P5 5 --
-- C4 2.0 EL 350 16 II 100 P1/P5 3/2 -- -- C2 1.2 PGMEA 300 Comp.
Ex. 1 VII 100 P1 3 -- -- -- -- ECA 300 2 VIII 100 P2 3 -- -- -- --
PGMEA 300
TABLE 1 Alkali- Acid- Acid solubility diffusion Polymer generator
controller controller Solvent Part Part Part Part Part Kind by wt.
Kind by wt. Kind by wt. Kind by wt. Kind by wt. Example 1 I 100 P1
3 -- -- -- -- EL 350 2 I 70 P2 3 D1 30 -- -- EL/EEP 200/100 3 II
100 P3 5 -- -- -- -- EL/BA 200/100 4 III 100 P1 3 -- -- -- -- PGMEA
300 5 IV 100 P2 3 -- -- -- -- MAX 300 6 V 100 P4 10 -- -- -- -- MMP
300 7 VI 80 P1 3 D2 20 -- -- EL/MMP 150/150 8 I 100 P5 5 -- -- --
-- EL 350 9 II 70 P6 3 D1 30 -- -- EL/EEP 200/100 10 II 100 P1/P5
3/2 -- -- -- -- PGMEA 300 11 III 100 P7 3 -- -- -- -- EL/BA 200/100
12 V 100 P5/P7 2/2 -- -- -- -- MMP 300 13 I 100 P1 3 -- -- C1 1.2
EL 350 14 II 100 P3 5 -- -- C3 2.0 EL/BA 200/100 15 I 100 P5 5 --
-- C4 2.0 EL 350 16 II 100 P1/P5 3/2 -- -- C2 1.2 PGMEA 300 Comp.
Ex. 1 VII 100 P1 3 -- -- -- -- ECA 300 2 VIII 100 P2 3 -- -- -- --
PGMEA 300
In Tables 1 and 2, the symbols used for the acid generator and
solvent have the following meanings:
Radiation sensitive acid generator
P1: Triphenylsulfonium triflate
P2: Diphenyliodonium hexafluoroantimonate
P3: Pyrogallolmethanesulfonic acid triester
P4: Compound represented by the following structural formula (3):
##STR7##
wherein D represents the substituent shown by the formula (4) or a
hydrogen atom; ##STR8##
and 85% on average of D is the substituent shown by the formula (4)
and 15% on average of D is a hydrogen atom.
P5:
N-(Trifluoromethylsulfonyloxy)-bicyclo-[2,2,1]-hept-5-ene-2,3-dicarboximid
e
P6: N-(Camphanylsulfonyloxy)naphthylimide
P7: N-(2-Trifluoromethylphenylsulfonyloxy)phthalimide
Alkali-solubility controller
D1: Compound represented by the structural formula (d1):
##STR9##
D2: Compound represented by the structural formula (d2):
##STR10##
Acid-diffusion controller
C1: Tripropylamine
C2: Tri-n-butylamine
C3: Diaminodiphenylmethane
C4: Octylamine
Solvent
EL: Ethyl lactate
EEP: Ethyl 3-ethoxypropionate
MMP: Methyl 3-methoxypropionate
PGMEA: Propylene glycol monomethyl ether acetate
BA: Butyl acetate
MAK: Methyl amyl ketone
ECA: Ethyl Cellosolve acetate
* * * * *