Patent ID: 7125641

Claim:
A polymer comprising recurring units of the following general formula (1a) or (1b) and having a weight average molecular weight of 1,000 to 500,000, wherein R 1 is a straight, branched or cyclic fluorinated alkyl group of 1 to 20 carbon atoms which may contain a hydrophilic group such as hydroxyl, R 2 is hydrogen, fluorine or a straight, branched or cyclic alkyl or fluorinated alkyl group of 1 to 20 carbon atoms, R 3 and R 4 each are a single bond or a straight, branched or cyclic alkylene or fluorinated alkylene group of 1 to 20 carbon atoms, R 5 is hydrogen or an acid labile group, “a” is 1 or 2, U11 and U12 are numbers satisfying 0<U11<1 and 0<U12<1.