(A-iii) A polymer comprising recurring units represented by the following general formula (2): wherein R4 is hydrogen or methyl, R5 is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms, x is 0 or a positive integer, y is a positive integer, and x+y is up to 5, in which hydrogen atoms of the phenolic hydroxyl groups are substituted by acid labile groups of at least one type in a pro