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with a bulky structure having at least 7 carbon atoms, such as a norbomyl group, a tricyclodecanyl group, a tetracyclo› decanyl group, a tetracyclododecanyl group and an adaman› tyl group, are preferred from the viewpoint of inhibition of any in-film diffusion in the PEB (post-exposure bake) opera- tion and enhancement of MEEF (Mask Error Enhancement Factor). 

The aryl group may be monocyclic or polycyclic. As the aryl group, there can be mentioned, for example, a phenyl group, a naphthyl group, a phenanthryl group or an anthryl group. Of these, a naphthyl group exhibiting a relatively low light absorbance at 193 nm is preferred. 

The heterocyclic group may be monocyclic or polycyclic. The polycyclic structure is superior in the inhibition of any acid diffusion. It is optional for the heterocyclic group to have aromaticity. As the heterocycle having aromaticity, there can be mentioned, for example, a furan ring, a thio› phene ring, a benzofuran ring, a benzothiophene ring, a dibenzofuran ring, a dibenzothiophene ring or a pyridine ring. As the heterocycle having no aromaticity, there can be mentioned, for example, a tetrahydropyran ring, a lactone ring or a decahydroisoquinoline ring. It is especially pre› ferred for the heterocycle in the heterocyclic group to be a furan ring, a thiophene ring, a pyridine ring or a decahy- droisoquinoline ring. As examples of the lactone rings, there can be mentioned those set forth above by way of example in connection with RA and RB in general formula (N-1). 

A substituent may be introduced in the above cyclic organic group. As the substituent, there can be mentioned, for example, an alkyl group, a cycloalkyl group, an aryl group, a hydroxyl group, an alkoxy group, an ester group, an amido group, a urethane group, a ureido group, a thioether group, a sulfonamido group or a sulfonic ester group. The alkyl group may be in the form of a linear or branched chain. It is preferred for the alkyl group to have 1 to 12 carbon atoms. The cycloalkyl group may be monocyclic or poly› cyclic. It is preferred for the cycloalkyl group to have 3 to 12 carbon atoms. The aryl group preferably has 6 to 14 carbon atoms. 

In the formula, x is preferably 1 to 8, more preferably 1 to 4 and most preferably 1; y is preferably O to 4, more preferably O; and z is preferably O to 8, more preferably O to 4. 

Also, the nonnucleophilic anion is preferably expressed by, for example, general formula (LD2) below. 

In general formula (LD2), Xf, Ri, R$_{2}$ , L, Cy, x, y and z are 55 as defined above in connection with general formula (LDl). Rf is a group containing a fluorine atom. 

As the group containing a fluorine atom represented by Rf, there can be mentioned, for example, an alkyl group containing at least one fluorine atom, a cycloalkyl group containing at least one fluorine atom or an aryl group containing at least one fluorine atom. 

These alkyl group, cycloalkyl group and aryl group may be substituted with a fluorine atom, or may be substituted with another substituent containing a fluorine atom. When Rf is a cycloalkyl group containing at least one fluorine atom or an aryl group containing at least one fluorine atom, the 

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(LD2) 

other substituent containing a fluorine atom can be, for example, an alkyl group substituted with at least one fluorine atom. Further, these alkyl group, cycloalkyl group and aryl 

group may further be substituted with a substituent contain› ing no fluorine atom. As this substituent, there can be mentioned, for example, any of those mentioned above with respect to Cy wherein no fluorine atom is contained. 

As the alkyl group containing at least one fluorine atom represented by Rf, there can be mentioned, for example, any of those mentioned hereinbefore as the alkyl group substi› tuted with at least one fluorine atom, represented by Xf. As the cycloalkyl group containing at least one fluorine atom represented by Rf, there can be mentioned, for example, a perfluorocyclopentyl group or a perfluorocyclohexyl group. As the aryl group containing at least one fluorine atom represented by Rf, there can be mentioned, for example, a perfluorophenyl group. 

As a preferred form of the anion moiety of compound (A), there can be mentioned any of structures to be set forth hereinafter as examples of preferred anion structures of photoacid generator (B), other than the above structures of general formulae (LDl) and (LD2). 

In compound (A), the fluorine content expressed by (sum of the masses of all fluorine atoms contained in the com› pound)/(sum of the masses of all atoms contained in the compound) is preferably 0.30 or less, more preferably 0.25 or less, further more preferably 0.20 or less, still further preferably 0.15 or less and most preferably 0.10 or less. 

Nonlimiting specific examples of compounds (A) are shown below. 

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