Positive resist composition and process for formation of resist patterns

摘要

A positive resist composition includes a resin component (A) and an acid generator component (B), wherein the component (A) is a copolymer that includes a structural unit (a1) derived from an (alpha-lower alkyl)acrylate ester that contains a monocyclic or polycyclic group-containing acid dissociable, dissolution inhibiting group, a structural unit (a2) derived from an (alpha-lower alkyl)acrylate ester that contains a lactone ring, a structural unit (a3) derived from an (alpha-lower alkyl)acrylate ester that contains a polar group-containing polycyclic group, and a structural unit (a4).