US Patent 7914968 Positive resist composition and method of forming resist pattern

A positive resist composition including a resin component (A) and an acid-generator component (B), the resin component (A) including a structural unit (a1) derived from hydroxystyrene, and a structural unit (a2) having an acetal-type acid dissociable dissolution inhibiting group, and the acid-generator component (B) including an acid generator (B1-i) having at least one anion moiety selected from the group consisting of anion moieties represented by general formula (b-3), (b-4), and (b-5), an acid generator (B1-ii) having an anion moiety represented by general formula (b-6) shown below, or an acid generator (B1-iii) having a cation moiety represented by general formula (b′-3) shown below: