Patent ID: 7601479

Claim:
A polymer comprising recurring units of the general formulae (1) to (4) and having a weight average molecular weight of 1,000 to 50,000, wherein R 1 , R 3 , R 4 and R 7 are each independently hydrogen or methyl, R 5 and R 6 are each independently hydrogen or hydroxyl, R 8 is a group having a lactone structure, and R 2 is an acid labile group selected from groups represented by the general formulae (R 2 -7) and (R 2 -8): wherein a broken line depicts a bond position, and R 14 and R 15 are each independently a straight, branched or cyclic C 1 -C 10 alkyl group, or R 14 and R 15 , taken together, may form a ring with the carbon atom to which they are bonded.