Chemical amplification type resist composition

A chemical amplification type resist composition comprising a polymer having a molecular weight dispersity of 1.0 to 1.5 selected from the group consisting of a polymer comprising recurring units of formula (1) and recurring units of formula (2), a polymer comprising recurring units of formula (2), a polymer comprising recurring units of formula (2) and recurring units of formula (4), a polymer comprising recurring units of formula (3), and a polymer comprising recurring units of formula (4),

• 13
• wherein R1 is an alkyl, alkoxyalkyl, acetyl or carbonylalkoxy group, each unit may be of one type or a mixture of at least two types, p is a positive number, q is 0 or a positive number, satisfying 0<p/(p+q)≦1,
• 14
• wherein R2 is hydrogen or methyl, and R3 is a tertiary hydrocarbon group of 4 to 30 carbon atoms,
• 15
• wherein R4 is a tertiary hydrocarbon group of 4 to 30 carbon atoms, R5 to R8 are independently selected from the group consisting of a hydrogen atom, ester group, alkoxycarbonylalkyl group, lactone group, carboxyl group, and cyclic acid anhydride group, or two of R5 to R8, taken together, may form a cyclic lactone group or acid anhydride group, r is a positive number, s is 0 or a positive number, satisfying 0<r/(r+s)≦1,
• 16
• wherein R9 is a tertiary hydrocarbon group of 4 to 30 carbon atoms, and n is equal to 0 or 1.