Patent ID: 8501384

Claim:
A positive resist composition comprising as a base resin a polymer having carboxyl groups whose hydrogen is substituted by an acid labile group having the general formula (1): wherein W is an ethylene, propylene, butylene or pentylene group which bonds at opposite ends to carbon atoms C A and C B ; R 1 is hydrogen or a straight, branched or cyclic C 1 -C 6 alkyl group, which bonds to a carbon atom in W, with the proviso that R 1 is not hydrogen when W is ethylene or propylene; m is an integer of 1 to 4, with the proviso that when m is 2 or more, R 1 may be the same or different and R 1 may bond together to form a C 3 -C 9 ring with a carbon atom in W; R 2 is selected from the group consisting of C 1 -C 4 alkyl, alkoxy, alkanoyl, alkoxycarbonyl, nitro, C 6 -C 10 aryl, halogen, and cyano; n is an integer of 1 to 4; and R is hydrogen or a straight, branched or cyclic C 1 -C 12 alkyl, C 2 -C 12 alkenyl, C 2 -C 12 alkynyl or C 6 -C 10 aryl group which may have an oxygen or sulfur atom.