Patent ID: 7449276

Claim:
A positive photoresist composition that is used in a method for forming a resist pattern that includes an exposure step using an electron beam, comprising a resin component (A) that exhibits increased alkali solubility under action of acid, an acid generator component (B) that generates acid on exposure, and an organic solvent (C), wherein said component (A) comprises a copolymer a first structural unit (a 1 ) derived from hydroxystyrene and a second structural unit (a 2 ) derived from a (meth)acrylate ester having an alcoholic hydroxyl group, and a portion of hydroxyl groups of said structural units (a 1 ) and alcoholic hydroxyl groups of said structural units (a 2 ) are protected with acid dissociable, dissolution inhibiting group, wherein both the hydroxyl groups of (a 1 ) and the alcoholic hydroxyl groups of (a 2 ) are partially protected by acid dissociable, dissolution inhibiting groups, wherein a weight average molecular weight of said copolymer of said resin component (A), prior to protection with said acid dissociable, dissolution inhibiting groups, is at least 2,000 but no more than 8.500.