Patent ID: 7534550

Claim:
A positive resist composition comprising: a resin component (A) that exhibits increased alkali solubility under action of acid; and an acid generator component (B) that generates acid upon irradiation, wherein said component (A) is a copolymer comprising a structural unit (a1) derived from an (α-lower alkyl)acrylate ester that contains a monocyclic or polycyclic group-containing acid dissociable, dissolution inhibiting group, a structural unit (a2) derived from an (α-lower alkyl)acrylate ester that contains a lactone ring, a structural unit (a3) derived from an (α-lower alkyl)acrylate ester that contains a polar group-containing polycyclic group, and a structural unit (a4) represented by a general formula (1) shown below: (wherein, R 11 represents a lower alkyl group or a hydrogen atom, and R 12 represents a carboxyl group), and wherein a proportion of said structural unit (a4) within said component (A) is at least 3 mol % but less than 10 mol %.