Patent ID: 7763412

Claim:
A positive resist composition, comprising a resin (A), which contains acid-dissociable, dissolution-inhibiting groups and exhibits increased alkali solubility under action of acid, and a compound (B) that generates acid on irradiation, wherein said resin (A′) is a mixture of a cyclic group-containing principal chain polymer (A′1), and a polymer (A′2) comprising solely structural units (a′) derived from a (meth)acrylate ester and/or (meth)acrylic acid, wherein said cyclic group-containing principal chain polymer (A′1) comprises a structural unit (a1) represented by a general formula (a-1) shown below, a structural unit (a2) represented by a general formula (a-2) shown below, and a structural unit (a3) represented by a general formula (a-3) shown below, wherein said polymer (A′2) comprises a structural unit (a′1) derived from a (meth)acrylate ester containing an acid-dissociable, dissolution-inhibiting group, a structural unit (a′2) derived from a (meth)acrylate ester containing a lactone ring, and a structural unit (a′3) derived from a (meth)acrylate ester containing a polar group-containing aliphatic hydrocarbon group: [wherein in said formula (a-1), R 1 represents an alkyl group of two or more carbon atoms, s represents either 0 or 1, and t represents an integer from 1 to 3], [wherein in said formula (a-2), R 2 and R 3 each represent, independently, a hydrogen atom or a lower alkyl group, and s represents either 0 or 1], and [wherein in said formula (a-3), R 4 represents an organic group containing an alkali-soluble group, and s represents either 0 or 1].