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In the present invention, the cation moiety (R $^{2}$-X-S+ (R$^{3}$)(R 4 )) in formula (a0-0-1) is preferably a cation repre- sented by a general formula (I-1), (I-2), (I-3) or (I-4) shown below. 

[Chemical Formula 7] 

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In the formulas, u represents an integerofl to 3, Rs represents an alkylene group which may have a non-aromatic substitu› ent, R 6 represents an alkyl group which may have a non› aromatic substituent, R $^{7 }$represents an alkyl group or alkoxy group which may have a non-aromatic substituent, or a hydroxy I group, R $^{8 }$represents an alky I group which may have a non-aromatic substituent, and each of R 9 a to R 9$_{c }$ indepen› dently represents an alkyl group which may have a non› aromatic substituent. 

In formula (I-1) to (I-3), u represents an integer of 1 to 3, and is most preferably 1 or 2. 

Examples of the alkylene group for Rs include the same groups as those described above for the alkylene group for R $^{92 }$in the formula ---O----C(=O)-R92 -, which was men› tioned in the description of A within the aforementioned general formula -A-[C(R11-)(R12)Jm-, and a linear or branched alkylene group is preferred. The alkylene group preferably contains 1 to 12 carbon atoms, more preferably 1 to 5 carbon atoms, still more preferably 1 to 3 carbon atoms, and most preferably 1 or 2 carbon atoms. Examples of the non-aromatic substituent which the alkylene group may have 50 55 as a substituent include the same groups as those described above for the non-aromatic substituent which the alkyl group 60 for R $^{2 }$may have. 

The alkyl group which may have a non-aromatic substitu› ent for R 6 , and the non-aromatic substituent which this alkyl group may have as a substituent are the same as the respective groups mentioned within the description ofR 2 . 

R $^{6 }$is preferably an acid-dissociable group. This improves the resolution limit. Examples of the acid-dissociable group 

include the same groups as those described below within the description for the structural unit (al), and specific examples include a tertiary alkyl ester-type acid-dissociable group and an acetal-type acid-dissociable group. 

Of these, a tertiary alkyl ester-type acid-dissociable group is preferred, and an acid-dissociable group containing an aliphatic cyclic group is particularly desirable. 

The alkyl group which may have a non-aromatic substitu› ent for R 7 , and the non-aromatic substituent which this alkyl group may have as a substituent are the same as the respective groups mentioned within the description ofR 2 . 

Examples of the alkoxy group which may have a non› aromatic substituent include groups in which -0- is bonded to an aforementioned alkyl group which may have a non-aromatic substituent, and examples of the non-aromatic substituent which this alkoxy group may have as a substituent include the same groups as those mentioned within the description ofR 2 . 

The alkyl group which may have a non-aromatic substitu› ent for R 8 , and the non-aromatic substituent which this alkyl group may have as a substituent are the same as the respective groups mentioned within the description ofR 2 . 9 

Examples of the alkyl group for R a to R $^{9$_{c }$}$include the same groups as those described above for R 2 , and the alkyl group preferably contains 5 to 15 carbon atoms. The alkyl group may be linear, branched or cyclic. It is thought that a cyclic alkyl group improves the lithography properties, and is there› fore preferred. A chain-like alkyl group, and particularly a linear alkyl group, is preferred in terms of ease of synthesis. Examples of the non-aromatic substituent which the alkyl group may have as a substituent include the same groups as those described above for the non-aromatic substituent which the alkyl group for R $^{2 }$may have. 

The structural unit (a0) of the component (Al) may be either a single type of structural unit or a combination of two or more types of structural units. 

The amount of the structural unit ( a0) within the compo› nent (Al), based on the combined total of all the structural units that constitute the component (Al), is preferably within a range from 1 to 30 mo!%, and more preferably from 5 to 20 mo!%. When this amount of the structural unit (a0) is at least 5 mo! %, the sensitivity improves. Further, when the amount is not more than 20 mo! %, satisfactory solubility within the resist solvent (a component (S) described below) can be ensured. 

In those cases where the component (Al) is a polymeric compound that exhibits increased polarity under the action of acid, the component (Al) preferably contains an acid-degrad- able group that exhibits increased polarity under the action of acid. 

The "acid-degradable group" describes a group having acid degradability which, under the action of the acid (such as the acid generated from the structural unit ( a0) upon exposure or the acid generated from an optional component (B) described below), undergoes cleavage of at least some of the bonds within the structure of the acid-degradable group. The acid-degradable group is described in more detail below, within the description of the structural unit (al). 

In those cases where the structural unit (a0) includes an acid-degradable group (such as the case where R 1 has an acid-degradable region within the structure, or the case where R 6 in the formula (I-1) is an acid-degradable group), the component (Al) may be composed solely of the structural unit (a0), or may also include a structural unit (al) containing an acid-degradable group that exhibits increased polarity under the action of acid. 

