Photoresist composition, resist-pattern forming method, polymer, and compound

A polymer comprising a structural unit shown by a formula (1),

• wherein R1 represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, Z represents a group that forms a divalent alicyclic group having 3 to 20 carbon atoms together with a carbon atom bonded to X, X represents an alkanediyl group having 1 to 6 carbon atoms, Y represents a hydrogen atom or —CR2R3(OR4), and R2 to R4 independently represent a hydrogen atom or a monovalent hydrocarbon group, provided that R3 and R4 optionally bond to each other to form a cyclic ether structure together with a carbon atom bonded to R3 and an oxygen atom bonded to R4.

A compound shown by a formula (i),

• wherein R1 represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, Z represents a group that forms a divalent alicyclic group having 3 to 20 carbon atoms together with a carbon atom bonded to X, X represents an alkanediyl group having 1 to 6 carbon atoms, Y represents a hydrogen atom or —CR2R3(OR4), and R2 to R4 independently represent a hydrogen atom or a monovalent hydrocarbon group, provided that R3 and R4 optionally bond to each other to form a cyclic ether structure together with a carbon atom bonded to R3 and an oxygen atom bonded to R4.