Chemically amplified resist composition and pattern forming process

A chemically amplified resist composition comprising a polymer comprising units having a sufficient polarity in their molecule to impart adhesion to the polymer and units protected with an acid labile group and adapted to turn alkali soluble under the action of acid,

• said polymer further comprising recurring units having the general formula (1):
• wherein R1 is each independently hydrogen, fluorine, methyl or trifluoromethyl, Rf is each independently hydrogen, fluorine, trifluoromethyl or pentafluoroethyl, not all Rf are hydrogen, A is a divalent C1-C10 hydrocarbon group in which some or all hydrogen atoms may be substituted by fluorine atoms, or some methylene may be substituted by oxygen, R2, R3 and R4 are each independently a substituted or unsubstituted straight or branched C1-C10 alkyl, alkenyl or oxoalkyl group or a substituted or unsubstituted C6-C18 aryl, aralkyl or aryloxoalkyl group, or at least two of R2, R3 and R4 may bond together to form a ring with the sulfur atom, wherein
• recurring units containing an aromatic ring structure are present in an amount of at least 60 mol % and the recurring units having formula (1) are present in an amount of less than 5 mol %, based on the entire recurring units of the polymer.