Polymers, resist compositions and patterning process

A polymer comprising recurring units of the general formula (1) and recurring units of at least one type selected from the general formulae (2a) to (2d) and having a weight average molecular weight of 1,000 to 500,000,

• wherein R1 is a fluorine atom or a fluorinated alkyl group of 1 to 4 carbon atoms, R2 is a single bond or a straight, branched or cyclic alkylene or fluorinated alkylene group of 1 to 20 carbon atoms, R3 and R4 each are a hydrogen atom, a fluorine atom or a straight, branched or cyclic alkyl or fluorinated alkyl group of 1 to 20 carbon atoms, at least one of R3 and R4 contains at least one fluorine atom, R5 is hydrogen or an acid labile group, R6 is an acid labile group, an adhesive group or a straight, branched or cyclic alkyl or fluorinated alkyl group of 1 to 20 carbon atoms, and “a” is 1 or 2.