| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to obtain a quarter-micron or more finer pattern and to improve etching resistance by specifying the standard molecular weight (in terms of the polystyrene) of a copolymer having specified recurring units. SOLUTION: The basic resin for the production of a positive photoresist is a copolymer comprising recurring units represented by formula I (wherein R is H or an alkyl; k, m and n are the numbers of the recurring units of the respective types, 0.1<=k/(m+n)<=0.5, 0<=m/(k+n)<=0.5, and 0.1<=n/(k+m)<=0.9). This copolymer is obtained by copolymerizing a monomer of formula II with a norbornene monomer of formula III and a maleic anhydride monomer of formula IV in the presence of a polymerization catalyst. In formula II, R is H or an alkyl. This copolymer has an average molecular weight of 1,000-1,000,000, desirably 5,000-40,000 (in terms of the polystyrene). The polymerization reaction for producing the polymer of formula I is desirably radical polymerization using a radical polymerization initiator.
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