Polymer compound, acid generator, positive resist composition, and method for formation of resist patterns

Abstract

The invention provides a polymer compound capable of forming a positive resist composition that can form a high-resolution pattern with a reduced level of LER, an acid generator formed from such a polymer compound, a positive resist composition that includes such a polymer compound, and a method for forming a resist pattern that uses such a positive resist composition. The polymer compound includes a structural unit (a1) derived from an (α-lower alkyl) acrylate ester having an acid-dissociable, dissolution-inhibiting group, a structural unit (a2) represented by a general formula (a2-1) shown below [wherein, R represents a hydrogen atom or a lower alkyl group; A represents a divalent organic group; B represents a monovalent organic group; X represents a sulfur atom or iodine atom; n represents either 1 or 2; and Y represents a straight-chain, branched or cyclic alkyl group in which at least one hydrogen atom may be substituted with a fluorine atom], and a structural unit (a3) derived from an (α-lower alkyl) acrylate ester that contains a polar group-containing aliphatic polycyclic group.

Dependencies are inferred from the claim text.