Patent ID: 7521168

Claim:
A positive resist composition for an electron beam, EUV or X-ray comprising (A1) a compound that has a reduction potential higher than that of diphenyl iodonium salt and generates an acid upon irradiation of an actinic ray or radiation and (BP) a polymer that is insoluble or hardly soluble in an aqueous alkali solution but becomes soluble in the aqueous alkali solution by the action of an acid, wherein the polymer (BP) comprises a repeating unit derived from hydroxystyrene and is a polymer having a structural unit containing a group represented by formula (X1) or (X2) shown below: wherein R 1b and R 2b , which may be the same or different, each represent a hydrogen atom or an alkyl group; R 3b and R 4b , which may be the same or different, each represent a hydrogen atom, an alkyl group which may have a substituent or a cycloalkyl group which may have a substituent; R 5b represents an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent or an aralkyl group which may have a substituent; m represents an integer of from 1 to 20; n represents an integer of from 0 to 5; and r represents an integer of from 0 to 11; wherein R 6b and R 7b , which may be the same or different, each represent a hydrogen atom or an alkyl group; W represents a divalent organic group; and R 8b represents an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent or an aralkyl group which may have a substituent.