A polymer comprising recurring units derived from a sulfonium salt of specific structure having a polymerizable group is coated to form a resist film which is amenable to precise micropatterning because of improved LWR, CDU and resolution.

A salt represented by formula (I): ##STR00001##
wherein Q.sup.1 and Q.sup.2 independently represent a fluorine atom or a C.sub.1 to C.sub.6 perfluoroalkyl group, R.sup.1 and R.sup.2 each independently represent a hydrogen atom, a fluorine atom or a C.sub.1 to C.sub.6 perfluoroalkyl group, z represents an integer of 0 to 6, R.sup.3 represents a hydrogen atom, a fluorine atom, a C.sub.1 to C.sub.12 alkyl group or a C.sub.1 to C.sub.12 fluorinated alkyl group, R.sup.4 represents a C.sub.1 to C.sub.12 fluorinated alkyl group, L.sup.2 represents a single bond, a C.sub.1 to C.sub.12 divalent saturated hydrocarbon group, etc., R.sup.5 represents a hydrogen atom, a halogen atom or a C.sub.1 to C.sub.6 alkyl group that may have a halogen atom, L.sup.1 represents a group represented by formula (b1-1), etc., * represents a bonding site to —CR.sup.3R.sup.4; L.sup.b2 and L.sup.b3 each independently represent a single bond or a C.sub.1 to C.sub.22 divalent saturated hydrocarbon group; Z.sup.+ represents an organic cation.

A salt represented by formula (I): ##STR00001##
wherein Q.sup.1 and Q.sup.2 independently represent a fluorine atom or a C.sub.1 to C.sub.6 perfluoroalkyl group, R.sup.1 and R.sup.2 each independently represent a hydrogen atom, a fluorine atom or a C.sub.1 to C.sub.6 perfluoroalkyl group, z represents an integer of 0 to 6, R.sup.3 represents a hydrogen atom, a fluorine atom, a C.sub.1 to C.sub.12 alkyl group or a C.sub.1 to C.sub.12 fluorinated alkyl group, R.sup.4 represents a C.sub.1 to C.sub.12 fluorinated alkyl group, L.sup.2 represents a single bond, a C.sub.1 to C.sub.12 divalent saturated hydrocarbon group, etc., R.sup.5 represents a hydrogen atom, a halogen atom or a C.sub.1 to C.sub.6 alkyl group that may have a halogen atom, L.sup.1 represents a group represented by formula (b1-1), etc., * represents a bonding site to —CR.sup.3R.sup.4; L.sup.b2 and L.sup.b3 each independently represent a single bond or a C.sub.1 to C.sub.22 divalent saturated hydrocarbon group; Z.sup.+ represents an organic cation.

A carboxylic acid onium salt of formula (1) exerts a satisfactory acid diffusion control (or quencher) function. A resist composition comprising the carboxylic acid onium salt can be processed by DUV or EUV lithography to form a resist pattern with improved resolution, reduced LWR and minimal defects after development.

##STR00001##

A carboxylic acid onium salt of formula (1) exerts a satisfactory acid diffusion control (or quencher) function. A resist composition comprising the carboxylic acid onium salt can be processed by DUV or EUV lithography to form a resist pattern with improved resolution, reduced LWR and minimal defects after development.

##STR00001##

A novel sulfonium salt having high sensitivity with respect to active energy rays, a photoacid generator including the sulfonium salt, and a photosensitive composition containing the photoacid generator. The sulfonium salt is represented by formula (a1). In the formula, R.sup.1 and R.sup.2 each independently represent the group that is represented by formula (a2) or an alkyl group that may be substituted by a halogen atom, R.sup.1 and R.sup.2 are bonded to each other and may form a ring with the sulfur atom within the formula, R.sup.3 is the group represented by formula (a3) or the group represented by formula (a4), A.sup.1 represents S or the like, X.sup.− represents a monovalent anion, and R.sup.1 and R.sup.2 are not both an alkyl group which may be substituted with a halogen atom. In formulas (a2) to (a4), the ring Z.sup.1 represents an aromatic hydrocarbon ring, R.sup.4, R.sup.6, R.sup.9, and R.sup.10 each represents a specific monovalent group, R.sup.5, R.sup.7, and R.sup.8 each represents a specific divalent group, A.sup.2 and A.sup.3 each represents S or the like, m1 represents an integer of 0 or more, and n1 and n2 each represent 0 or more.

##STR00001##

A novel sulfonium salt having high sensitivity with respect to active energy rays, a photoacid generator including the sulfonium salt, and a photosensitive composition containing the photoacid generator. The sulfonium salt is represented by formula (a1). In the formula, R.sup.1 and R.sup.2 each independently represent the group that is represented by formula (a2) or an alkyl group that may be substituted by a halogen atom, R.sup.1 and R.sup.2 are bonded to each other and may form a ring with the sulfur atom within the formula, R.sup.3 is the group represented by formula (a3) or the group represented by formula (a4), A.sup.1 represents S or the like, X.sup.− represents a monovalent anion, and R.sup.1 and R.sup.2 are not both an alkyl group which may be substituted with a halogen atom. In formulas (a2) to (a4), the ring Z.sup.1 represents an aromatic hydrocarbon ring, R.sup.4, R.sup.6, R.sup.9, and R.sup.10 each represents a specific monovalent group, R.sup.5, R.sup.7, and R.sup.8 each represents a specific divalent group, A.sup.2 and A.sup.3 each represents S or the like, m1 represents an integer of 0 or more, and n1 and n2 each represent 0 or more.

##STR00001##

A monomer having an onium salt structure represented by formula (1) gives a polymer which is fully compatible with resist components. A resist composition comprising the polymer has advantages including reduced acid diffusion, high sensitivity, high resolution, a good balance of lithography properties, and less defects, and is quite effective for precise micropatterning.

##STR00001##

A monomer having an onium salt structure represented by formula (1) gives a polymer which is fully compatible with resist components. A resist composition comprising the polymer has advantages including reduced acid diffusion, high sensitivity, high resolution, a good balance of lithography properties, and less defects, and is quite effective for precise micropatterning.

##STR00001##

A resist composition including a compound represented by formula (b1) in which R.sup.b1 represents an aryl group which may have a substituent; R.sup.b2 and R.sup.b3 each independently represents an aryl group which may have a substituent or an alkyl group which may have a substituent; provided that at least one of the aryl group represented by R.sup.b1 and the aryl group or the alkyl group represented by R.sup.b2 or R.sup.b3 has a substituent containing a halogen atom, and at least one of the aryl group represented by R.sup.b1 and the aryl group or the alkyl group represented by R.sup.b2 or R.sup.b3 has a substituent containing a sulfonyl group; and X.sup.− represents a counteranion ##STR00001##