Positive resist composition and method for forming resist pattern

摘要

A positive resist composition including a resin component (A) containing an acid dissociable dissolution inhibiting group whose alkali solubility increases under action of acid and an acid generator component (B) that generates acid on exposure, wherein the resin component (A) is a copolymer comprising a first structural unit (a1) derived from a hydroxystyrene and a second structural unit (a2) derived from a (meth)acrylate ester containing an alcoholic hydroxyl group, in which 10 mol % or more and 25 mol % or less of a combined total of hydroxyl groups within the structural units (a1) and alcoholic hydroxyl groups within the structural units (a2) are protected with the acid dissociable dissolution inhibiting groups, and a weight average molecular weight of the copolymer prior to protection with the acid dissociable dissolution inhibiting groups is 2,000 or more and 8,500 or less.