Patent ID: 7368218

Claim:
A resist composition comprising a polymer comprising recurring units of the general formulae (1a), (2a), and (1b): wherein R 1 is each independently hydrogen or methyl, R 2 is each independently hydrogen, an acyl group of 1 to 10 carbon atoms, or an acid labile group, R 3 is hydrogen, methyl or —CO 2 R 8 , R 4 is hydrogen, methyl or —CH 2 CO 2 R 8 , R 5 to R 7 are each independently hydrogen, methyl or —CO 2 R 9 , R 8 is each independently hydrogen or a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms, R 9 is hydrogen or a straight, branched or cyclic alkyl group of 1 to 10 carbon atoms, X is —CH 2 —, —O— or —S—, with the proviso that X is not —CH 2 — when all R 5 to R 7 are hydrogen, a1, a2 and b1 are numbers satisfying 0 ≦a 1/( a 1 +a 2 +b 1)≦0.9, 0 ≦a 2/( a 1 +a 2 +b 1)≦0.9, 0<( a 1 +a 2)/( a 1 +a 2 +b 1)≦0.9, and 0 <b 1/( a 1 +a 2 +b 1)≦0.8.