Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2000-12-07
2004-04-20
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S270100, C430S905000, C522S031000, C568S018000, C568S034000, C568S035000
Reexamination Certificate
active
06723483
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a sulfonium salt compound used as an acid generator and a photo polymerization initiator.
In accordance with the recent trend of higher density integration in semiconductor elements, wavelengths of light sources for irradiation instruments used in fine processing, particularly those used in lithography, become shorter and shorter, and in compliance with this trend, use has generally been made of chemically amplified resist compositions wherein an action of an acid generated from an acid generator as a photo sensitive compound is utilized. As the acid generators used in the chemically amplified resist compositions, onium salts such as sulfonium salts and iodonium salts, o-nitrobenzyl aryl sulfonate compounds, diazodisulfone compounds, disulfone compounds, dicarboxyimide sulfonate compounds, 2-acyloyl-2-aryl sulfonyl propane compounds, triaryl sulfonyloxybenzene compounds, and the like have been so far evaluated, and some of them have already been made into practical use, and even now further study has been conducted for the purpose of improvement thereof in compliance with rules and regulations for minimization.
Particularly the study for improvement has been focused on sulfonium salt compounds, among others, because they have been highlighted also as cationic type photo polymerization initiators.
Recently a proposal has been made on a process of combination use of aliphatic diazodisulfone compounds which generate weak acid upon being sensitized to radioactive rays with onium salts which generate strong acid upon being sensitized to radioactive rays (e.g. JP-A-10-48826), but this process is accompanied with such a drawback that use of sulfonium salts, of which counter anion is an aryl sulfonate, etc. often causes plugging of a filter of a spin coator with fine particles which are formed during storage arid thus those fine particles are transcribed upon a pattern formation so that the planned circuit cannot be formed.
Further, when sulfonium salts having SbF
6
−
, AsF
6
−
, PF
6
−
, BF
4
−
, CF
3
SO
3
−
, etc. as a counter anion, among others, are used, there are observed such drawbacks that acids generated are of high volatile, a large dimension deviation and deformation is caused by Delay Time due to the strength of the acid, influence of vicinal effects is uncontrolled, and the like (e.g. JP-A-5-249682; JP-A-8-123032, etc.) and side walls of a pattern are rough, and therefore these sulfonium salts are not appropriate as an acid generator for a resist.
Still further, sulfonium salts, wherein an alkyl group is substituted by an ortho-position of an aromatic ring, such as diphenyl-o-methylphenylsulfonium triflate, diphenyl-o-ethylphenylsulfonium triflate, diphenyl-o-isopropylphenylsulfonium triflate and diphenyl-3,4-dimethylphenylsulfonium triflate have been also proposed (e.g. JP-A2-296801; JP-A-5-255240; JP-A-6-130669; K. M. Welsh et al., Polym. Mater. Sci. Eng., 1989, 61, 181; K. Maeda et al., ACS Symp. Ser. 1994, 512, 130; Y. Endo et al., Bull. Pharm. Chem., 1981, 29(12), 3753; etc.), but they are also sulfonium salts having a triflate group (CF
3
SO
3
—) as a counter anion and therefore the same problems as above have been observed.
Additionally, sulfonium salts, wherein an alkoxy group is substituted by an meta-position of an aromatic ring, such as diphenyl-m-tert-butoxyphenylsulfonium triflate, diphenyl-m-tert-butoxyphenylsulfonium pentafluorobenzenesulfonate, diphenyl-3,4-tert-butoxyphenylsulfonium triflate and diphenyl-3,4-di-tertbutoxyphenylsulfonium tosylate have been proposed(e.g. JP-A-9-12537; JP-A-9-15848; JP-A-9-211866; JP-A-10-7650, etc.), but use of a triflate group as a counter anion causes the same problem as above and use of a tosylate group and a pentafluorobenzenesulfonate group as a counter anion causes a poor solubility in a solvent for a resist and formation of fine particles during storage, and therefore these sulfonium salts are not a appropriate as an acid generator for a resist.
SUMMARY OF THE INVENTION
The present invention has been completed under such circumstances as mentioned above and the theme of the invention is to provide sulfonium salt compounds which can be used more practically as an acid generator for a resist and as a cationic type photo polymerization initiator.
The present invention provides the following.
(1) A compound, which is shown by the general formula [1]
(wherein R
1
and R
2
are each independently a hydrogen atom or a lower alkyl group, provided that at least one of R
1
and R
2
are a lower alkyl group, R
3
s are each independently an alkyl group, n is an integer of 0 to 3, i is an integer of 1 to 3, j is an integer of 0 to 2, provided that i+j=3, and Y
−
is an anion derived from an organic sulfonic acid of the general formula [2]
R
4
—SO
3
H [2]
[wherein R
4
is an alkyl group or an aryl group which may have an alkyl group as a substituent]).
(2) A compound, which is shown by the general formula [3]
(wherein X is a phenyl group which has a substituent at an ortho- and/or a meta-position, m is an integer of 1 to 3, q is an integer of 0 to 2, provided that m+q=3, p is an integer of 1 or 2 and Z
p−
is an anion derived from an a carboxylic acid).
(3) An acid generator comprising the above compound.
(4) An acid generator composition comprising the above compound and a diazodisulfone compound.
(5) A resist composition comprising the above compound.
(6) A method for generation of an acid comprising irradiating the composition comprising the above compound with a light.
(7) A method for formation of a pattern comprising
(i) a process of coating the above resist composition on a substrate,
(ii) a process of irradiating, after heating, a light having a wavelength of 220 nm or less on the substrate through a mask, and
(iii) a process of developing using a developing solution, after heat treatment, if necessary.
(8) A cationic type photo polymerization initiator comprising the above compound.
(9) A method for polymerization of an &agr;,&bgr;-ethylenically unsaturated monomer comprising using the polymerization initiator in the above (8).
PREFERRED EMBODIMENTS OF THE INVENTION
The present inventors have conducted extensive study in order to realize the object mentioned above to arrive at the finding the compounds shown by the above general formula [1] and [3] act as an excellent acid generator for a resist or a cationic type photo polymerization initiator and finally the present invention has been accomplished on the basis of this finding.
In the general formula [1], the lower alkyl group shown by R
1
and R
2
may be straight chained, branched or cyclic and includes one having generally 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, which is specifically exemplified by a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a neopentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 1,2-dimethylbutyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, etc.
In the general formula [1], the alkyl group shown by R
3
may be straight chained, branched or cyclic and includes one having generally 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, which is specifically exemplified by the same as in the lower alkyl of R
1
and R
2
, a n-heptyl group, an isoheptyl group, a n-octyl group, an isooctyl group, a n-nonyl group, a n-decyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, etc.
In the formula [2], the alkyl group shown by R
4
may be straight chained, branched or cyclic and includes one having generally 1 to 20 carbon atoms, preferably 6 to 12 carbon atoms, which are specifically exemplified by a methyl group, an ethyl group, a
Fukasawa Kazuhito
Imazeki Shigeaki
Oono Keiji
Sakamoto Kazunori
Sumino Motoshige
Armstrong Kratz Quintos Hanson & Brooks, LLP
Chu John S.
Wako Pure Chemical Industries Ltd.
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