Patent ID: 7638260

Claim:
A positive resist composition comprising (A) a resin component which becomes soluble in an alkaline developer under the action of an acid and (B) a compound capable of generating an acid in response to actinic light or radiation, wherein said resin component (A) is a polymer comprising recurring units having the general formula (1): wherein R 1 is each independently hydrogen, methyl or trifluoromethyl, R 2 is hydrogen or CO 2 R 4 , R 3 is a fluorinated substituent group of 1 to 15 carbon atoms, R 4 is a straight, branched or cyclic monovalent hydrocarbon group of 1 to 20 carbon atoms which may contain a heteroatom, m is 1 or 2, n is 1 or 2, a, b, c, and d indicative of ratios of the corresponding recurring units each are a number from more than 0 to less than 1, and a+b+c+d=1, and said compound (B) is a sulfonium salt which is a salt of a sulfonium cation with a sulfonate anion, bis(substituted alkylsulfonyl)imide or tris(substituted alkylsulfonyl)methide, and said sulfonate anion is selected from the group consisting of 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-adamantanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, and 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate.