Positive resist composition and method of forming resist pattern

摘要

A positive resist composition including: a base material component (A) which exhibits increased solubility in an alkali developing solution under the action of acid; and an acid generator component (B) which generates acid upon exposure; dissolved in an organic solvent (S), wherein the base material component (A) includes a resin component (A1) having 4 types of specific structural units, and the organic solvent (S) includes from 60 to 99% by weight of an alcohol-based organic solvent (S1) and from 1 to 40% by weight of at least one organic solvent (S2) selected from the group consisting of propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether and cyclohexanone.