Patent ID: 7255973

Claim:
A positive resist composition comprising a polymer comprising units A having an exo-form ester group represented by the general formula (1a) and units B having an ester group having two hexafluoroisopropanol groups represented by the general formula (1b) in a molar proportion satisfying: 0.1≦ A /( A+B )≦0.8 and 0.01≦ B /( A+B )≦0.9, wherein R 1 is hydrogen, methyl or CH 2 CO 2 R 14 , R 2 is hydrogen, methyl or CO 2 R 14 , R 3 is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms or a substituted or unsubstituted aryl group of 6 to 20 carbon atoms, R 4 to R 9 , R 12 and R 13 are each independently hydrogen or a monovalent hydrocarbon group of 1 to 15 carbon atoms which may contain a heteroatom, R 10 and R 11 are hydrogen, or a pair of R 4 and R 5 , R 6 and R 8 , R 6 and R 9 , R 7 and R 9 , R 7 and R 13 , R 8 and R 12 , R 10 and R 11 , or R 11 and R 12 , taken together, may form a ring, each R being a divalent hydrocarbon group of 1 to 15 carbon atoms which may contain a heteroatom when they form a ring, or a pair of R 4 and R 13 , R 10 and R 13 , or R 6 and R 8 which are attached to adjoining carbon atoms may bond together directly to form a double bond, R 14 is hydrogen or a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms, the formula also represents an enantiomer, wherein R 15 is hydrogen or methyl, R 16 and R 17 each are hydrogen or an acid labile group.