Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2001-11-16
2004-07-27
Ashton, Rosemary (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S910000, C430S922000, C430S923000
Reexamination Certificate
active
06767686
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chemical amplifying type positive resist composition used in the minute processing of a semiconductor.
2. Description of Related Art
A lithography process using a resist composition has usually been adopted in the minute processing of a semiconductor. In lithography, the resolution can be improved with a decrease in wavelength of exposure light in principle as expressed by the equation of Rayleigh's diffraction limit. A g-line with a wavelength of 436 nm, an i-line with a wavelength of 365 nm, and a KrF excimer laser with a wavelength of 248 nm have been adopted as exposure light sources for lithography used in the manufacture of a semiconductor. Thus, the wavelength has become shorter year by year. An ArF excimer laser having a wavelength of 193 nm is considered to be promising as a next-generation exposure light source.
A lens used in an ArF excimer laser exposure machine has a shorter lifetime as compared with lenses for conventional exposure light sources. Accordingly, the shorter time required for exposure to ArF excimer laser light is desirable. For this reason, it is necessary to enhance the sensitivity of a resist. Consequently, there has been used a so-called chemical amplifying type resist, which utilizes the catalytic action of an acid generated by exposure and contains a resin having a group cleavable by the acid.
It is known that, desirably, resins used in a resist for ArF excimer laser exposure have no aromatic ring in order to ensure the transmittance of the resist, but have an alicyclic ring in place of an aromatic ring in order to impart a dry etching resistance thereto. Various kinds of resins such as those described in Journal of Photopolymer Science and Technology, Vol. 9, No. 3, pages 387-398 (1996) by D. C. Hofer, are heretofore known as such resins.
Particularly, it has been reported that when a polymer or copolymer having an alkali-soluble group protected by 2-alkyl-2-adamantyl group or 1-adamantyl-1-alkylalkyl group as disclosed in Journal of Photopolymer Science and Technology, Vol. 9, No. 3, pages 475-487 (1996) by S. Takechi et al., and JP-A-9-73173 is used as a resin of a chemical amplifying type, a high dry etching resistance and a high resolution as well as a good adhesion to a substrate can be attained.
In fact, a polymer or copolymer having an alkali-soluble group protected by 2-alkyl-2-adamantyl group or 1-adamantyl-1-alkylalkyl group provides a high contrast and a high resolution. However, such a resin has a defect that the top of profile is liable to be broadened in T-top shape. It is considered that the cause of this defect resides in a bad affinity between a developing solution and a resin due to a strong hydrophobicity of the adamantly group as well as deactivation of the acid on the resist surface due to basic substances in the surrounding atmosphere. In order to resolve this problem, it is known that a good result may be obtained by adding a much amount of a basic quencher substance. The addition of a much amount of a quencher substance, however, causes lowering in resolution.
An object of the present invention is to provide a chemically amplifying type positive resist composition containing a resin component and an acid generating agent, which is suitable for use in lithography utilizing ArF excimer laser, KrF excimer laser or the like, and is satisfactory in various resist performance characteristics such as sensitivity, resolution, and adhesion to a substrate while providing an excellent profile shape.
SUMMARY OF THE INVENTION
The present invention provides a chemically amplifying type positive resist composition comprising a resin which has an alkali-soluble group protected by 2-alkyl-2-adamantyl group or 1-adamantyl-1-alkylalkyl group, and which, per se, is insoluble or slightly soluble in alkali but becomes soluble in alkali by the action of an acid; and a sulfonium salt acid generating agent represented by the following formula (I):
wherein Q
l
, Q
2
and Q
3
independently represent hydrogen, hydroxyl, alkyl having 1 to 6 carbon atoms or alkoxy having 1 to 6 carbon atoms; and Q
4
represents perfluoroalkyl which may have a cyclic structure.
DETAILED DESCRIPTION OF EMBODIMENTS
The resin for constituting the resist composition of the invention is a resin which has an alkali-soluble group protected by 2-alkyl-2-adamantyl group or 1-adamantyl-1-alkylalkyl group, and which, per se, is insoluble or slightly soluble in alkali but becomes soluble in alkali due to the action of an acid. The alkali-soluble group includes carboxylic acid group, phenolic hydroxyl group, hexafluoroisopropanol group and the like. Usually carboxylic acid group is used for ArF excimer laser resists. Specific examples include resins having a polymerization unit represented by the following formula (IIa), (IIb), (IIc) or (IId):
wherein R
1
and R
3
represent hydrogen or methyl; and R
2
, R
4
and R
5
represent alkyl.
The polymerization units represented by the formulae (IIa) to (IId) secure transmittance of the resist and contribute to improvement of dry etching resistance in virtue of the presence of adamantane ring which is an alicyclic ring. In addition, 2-alkyl-2-adamantyl group and 1-adamantyl-1-alkylalkyl group in the units are cleaved by the action of an acid to generate a carboxylic acid. Therefore, the units contribute to enhancement of solubility of a resist film in alkali after exposure to a light.
R
2
in the formulae (IIa) to (IId) is alkyl. This alkyl can have, for example, about 1 to 8 carbon atoms. Usually, alkyl has advantageously a straight chain but may have a branched chain when it has three or more carbon atoms. Specific examples of R
2
includes methyl, ethyl, propyl, isopropyl, butyl and the like. Amongst them, a resin having methyl or ethyl, inter alia ethyl, as R
2
is preferable for adhesion of resists to a substrate and improvement in resolution.
Specific examples of monomers for leading to the polymerization units represented by the formulae (IIa) to (IId) include 2-methyl-2-adamantyl acrylate, 2-ethyl-2-adamantyl acrylate, 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, 1-adamantyl-1-methylethyl acrylate, 1-adamantyl-1-methylethyl methacrylate, 2-methyl-2-adamantyl 5-norbornene-2-carboxylate, 2-ethyl-2-adamantyl 5-norbornene-2-carboxylate, 1-(1-adamantyl)-1-methylethyl 5-norbornene-2-carboxylate and the like. Use of 2-adamantyl-2-alkyl (meth)acrylate as a monomer is particularly preferred because it provides an excellent resolution.
The resin may have a polymerization unit of monomers, such as those listed below, in addition to the above described polymerization units.
3-hydroxy-1-adamantyl (meth)acrylate,
3,5-dihydroxy-1-adamantyl (meth)acrylate,
&agr;-(meth)acryloyloxy-&ggr;-butyrolactone,
&bgr;-(meth)acryloyloxy-&ggr;-butyrolactone,
maleic anhydride,
itaconic anhydride,
5-(meth)acryloyloxy-2,6-norbornanecarbolactone,
2-norbornene,
2-hydroxy-5-norbornene,
5-norbornene-2-carboxylic acid,
methyl 5-norbornene-2-carboxylate,
t-butyl 5-norbornene-2-carboxylate,
1-cyclohexyl-1-methylethyl 5-norbornene-2-carboxylate,
1-(4-methylcyclohexyl)-1-methylethyl 5-norbornene-2-carboxylate,
1-(4-hydroxycyclohexyl)-1-methylethyl 5-norbornene-2-carboxylate,
1-methyl-1-(4-oxocyclohexy)ethyl 5-norbornene-2-carboxylate,
1-(1-adamantyl)-1-methylethyl 5-norbornene-2-carboxylate,
1-methylcyclohexyl 5-norbornene-2-carboxylate,
2-methyl-2-adamantyl 5-norbornene-2-carboxylate,
2-ethyl-2-adamantyl 5-norbornene-2-carboxylate,
2-hydroxy-1-ethyl 5-norbornene-2-carboxylate,
5-norbornene-2-methanol,
5-norbornene-2,3-dicarboxylic acid anhydride,
(meth)acrylonitrile and the like.
Generally, the resin for the chemically amplifying type positive resist composition per se, is insoluble or slightly soluble in alkali. However, a part of groups is cleaved by the action of an acid and after then becomes soluble in alkali. In the resin specified in the present invention, 2-alkyl-2-adamantyl group and 1-adamantyl-1-alkylalkyl group are cleaved by the action o
Moriuma Hiroshi
Ohashi Kenji
Uetani Yasunori
Ashton Rosemary
Sumitomo Chemical Company Limited
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