Patterning process and resist composition

A resist composition comprising a base resin, a photoacid generator, and an organic solvent, wherein

• the base resin is a copolymer comprising recurring units having lactone as an adhesive group, recurring units having an acid labile group, and recurring units represented by formula (a1) or (a2) in the following general formula (1):
• wherein R1 and R7 are hydrogen or methyl,
• R2 and R8 are a single bond, methylene, ethylene, phenylene, phenylmethylene, phenylethylene, phenylpropylene, or —C(═O)—R12—, wherein R12 is a straight, branched or cyclic C1-C10 alkylene, C6-C10 arylene, or C2-C12 alkenylene group,
• R3 and R9 are hydrogen or a straight, branched or cyclic C1-C10 alkyl, or when R2 and R8 are —C(═O)—R12—, R3 and R9 may bond with R12 to form a ring with the nitrogen atom to which they are attached,
• R4, R5 and R6 are hydrogen or a straight, branched or cyclic C1-C10 alkyl, C6-C14 aryl, or C7-C14 alkenyl group, which may contain a straight, branched or cyclic C1-C6 alkyl, nitro, halogen, cyano, trifluoromethyl, carbonyl, ester, lactone ring, carbonate, maleimide, amide, C1-C6 alkoxy, or sulfo group, R4 and R5, R5 and R6, or R4 and R6 may bond together to form a ring with the carbon atom to which they are attached, exclusive of the case where all of R4, R5 and R6 are hydrogen or alkyl,
• R10 and R11 are a C6-C14 aryl or C7-C14 aralkyl group, which may contain a straight, branched or cyclic C1-C6 alkyl, nitro, halogen, cyano, trifluoromethyl, C1-C6 alkoxy, or carbonyl group.