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
2000-03-30
2001-08-21
Ashton, Rosemary E. (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
C430S914000, C526S271000, C526S281000
Reexamination Certificate
active
06277538
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chemically amplified resist composition, and more particularly, to a photosensitive polymer having a cyclic backbone, and a resist composition for an ArF excimer laser obtained therefrom.
2. Description of the Related Art
As semiconductor devices become highly integrated and complicated to fabricate, fine pattern formation is required.
Further, as the capacity of a semiconductor device increases to exceed 1 giga bit, a pattern size having a design rule of less than 0.2, &mgr;m is required. Accordingly, there are limitations in using a conventional resist material with a KrF excimer laser (248 nm). Thus, a new resist material capable of being developed using an ArF excimer laser (193 nm) has been developed in a lithography process.
The resist material used in the lithography process using the ArF excimer laser has several problems in being commercially used, compared to the conventional resist materials. The most typical problems are transmittance of a polymer and resistance to dry etching. As the widely known ArF resist materials, (meth)acrylate polymers are generally used. In particular, the most typical resist material is a poly(methyl methacrylate-tert-butyl methacrylate-methacrylic acid) terpolymer system manufactured by IBM, Inc. However, such polymers have very weak resistance to dry etching.
Accordingly, to increase the resistance to dry etching, a polymer having a backbone composed of an alicyclic compound such as an isobornyl group, an adamantyl group or a tricyclodecanyl group, is used. However, the resulting resist still exhibits weak resistance to dry etching.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a photosensitive polymer whose backbone has a cyclic structure and contains an alicyclic compound, for obtaining sufficiently strong resistance to dry etching.
It is another objective of the present invention to provide a resist composition containing the photosensitive polymer suitable for use in a lithography process using an ArF excimer laser.
To achieve the first objective, a photosensitive polymer is provided having a weight-average molecular weight of between about 3,000-100,000 and represented by the following formula:
wherein R
1
is tert-butyl, tetrahydropyranyl, 1-alkoxyethyl or 1-alkoxymethyl group, R
2
is hydrogen, cyano (-CN), hydroxy, hydroxymethyl, carboxylic acid, 2-hydroxyethyloxycarbonyl or tert-butoxycarbonyl, or alicyclic compound, R
3
is hydrogen or methyl, R
4
is hydrogen, 2-hydroxyethyl, isobornyl, tert-butyl, adamantyl, norbornyl or menthyl, 1/(l+m+n+p) is between about 0.1-0.5, m/(l+m+n+p) is between about 0.3-0.5, n/(l+m+n+p) is between about 0.0-0.3, and p/(l+m+n+p) is between about 0.0-0.3.
Preferably, R
1
is selected from the group consisting of 1-ethoxyethyl, 1-ethoxypropyl, ethoxymethyl and methoxymethyl.
Also, R
2
is preferably isobornyloxycarbonyl group.
According to another aspect of the present invention, there is provided a resist composition including (a) a photosensitive polymer having a weight-average molecular weight of between about 3,000-100,000 and represented by the following formula:
wherein R
1
is tert-butyl, tetrahydropyranyl, 1-alkoxyethyl or 1-alkoxymethyl, R
2
is hydrogen, cyano, hydroxy, hydroxymethyl, carboxylic acid, 2-hydroxyethyloxycarbonyl or tert-butoxycarbonyl, or alicyclic compound, R
3
is hydrogen or methyl, R
4
is hydrogen, 2-hydroxyethyl, isobornyl, tert-butyl, adamantyl, norbornyl or menthyl, l/(l+m+n+p) is between about 0.1-0.5, m/(l+m+n+p) is between about 0.3-0.5, n/(l+m+n+p) is between about 0.0-0.3, and p/(l+m+n+p) is between about 0.0-0.3, and (b) a photoacid generator (PAG).
Preferably, the PAG is selected from the group consisting of tiarylsulfonium salts, diaryliodonium salts, sulfonates, and mixtures thereof.
The resist composition may further include an organic base. The organic base is preferably contained in the composition in an amount of between about 0.01-2.0 weight percent based on the weight of the polymer.
The organic base may be selected from the group consisting of triethylamine, triisobutylamine, triisooctylamine, diethanol amine, triethanol amine, and mixtures thereof may be used.
According to the present invention, a photosensitive polymer is provided whose backbone has a cyclic structure and contains an alicyclic compound, thereby attaining resistance to dry etching. Also, since the polymer is prepared by using a monomer having two protective groups, a change in solubilities of the resist composition obtained from the polymer before and after exposure is made large, thereby increasing the contrast of the resist composition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
REFERENCES:
patent: 6132926 (2000-10-01), Jung et al.
patent: 6136499 (2000-10-01), Goodall et al.
patent: 6146810 (2000-11-01), Seo et al.
Choi Sang-jun
Jung Dong-Won
Ashton Rosemary E.
Mills & Onello LLP
Samsung Electronics Co,. Ltd
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