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(12) A pattern forming method comprising steps of expos› ing and developing the resist film described in (11) above. 

(13) A resin (P) comprising: 

(A) a repeating unit having an ionic structure moiety and being capable of decomposing upon irradiation with an 5 actinic ray or radiation to generate an acid; 

(B) a repeating unit containing a group capable of decom› posing by the action of an acid to produce an alkali-soluble group, and 

(C) a repeating unit represented by the following formula (VI): 

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wherein 

each ofR$_{01}$, R$_{02 }$and R$_{03 }$independently represents a hydro› gen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group, or R$_{03 }$may rep- resent an alkylene group and combine with Ar $_{1 }$to form a 5- or 6-membered ring, 

Ar$_{1 }$ represents an aromatic ring group, and n represents an integer of 1 to 4, 

wherein 

the ionic structure moiety of the repeating unit (A) is a structure capable of producing an acid anion on the resin side chain upon irradiation with an actinic ray or radiation and the counter cation is represented by the following formula (Ia): 

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wherein 

each of R$_{1}$a to R$_{13}$ a independently represents a hydrogen atom or a monovalent substituent and may combine together to form a ring, and 

Z represents a single bond or a divalent linking group. 

In the present invention, the following embodiments are also preferred. 

(14) The actinic ray-sensitive or radiation-sensitive resin composition as described in any one of (1) to (10) above, 60 wherein 

in formula (Ia), at least one ofR$_{1}$a to R$_{13}$ a is a monovalent substituent containing an alcoholic hydroxyl group. 

(15) The actinic ray-sensitive or radiation-sensitive resin composition as described in (14) above, wherein 

in formula (Ia), at least one ofR$_{9}$ a to R$_{13}$ a is a monovalent substituent containing an alcoholic hydroxyl group. 

(16) The resist film as described in (11) above, wherein in formula (Ia), at least one ofR$_{9}$ a to R$_{13}$ a is a monovalent substituent containing an alcoholic hydroxyl group. 

(17) The actinic ray-sensitive or radiation-sensitive resin composition as described in any one of (1) to (10) and (14) above, wherein 

in formula (Ia), each ofR$_{1}$a to R$_{10}$ a, R$_{12}$ a and R$_{13}$ a repre› sents a hydrogen atom and Rua is a monovalent substituent. 

(18) The resist film as described in (11) above, wherein in formula (Ia), each ofR$_{1}$a to R$_{10}$ a, R$_{12}$ a and R$_{13}$ a repre› sents a hydrogen atom and Rua is a monovalent substituent. 

## DETAILED DESCRIPTION OF THE INVENTION 

The present invention is described in detail below. Incidentally, in the context of the present invention, when a group ( atomic group) is denoted without specifying whether substituted or unsubstituted, the group includes both a group having no substituent and a group having a substituent. For example, an "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). 

In the present invention, the term "actinic ray" or "radia› tion" indicates, for example, a bright line spectrum of a mer› cury lamp, a far ultraviolet ray typified by an excimer laser, an extreme-ultraviolet ray (EUV light), an X-ray or an electron beam. Also, in the present invention, the "light" means an actinic ray or radiation. Furthermore, in the present invention, unless otherwise indicated, the "exposure" includes not only exposure to a mercury lamp, a far ultraviolet ray typified by excimer laser, an X-ray, EUV light or the like but also lithog› raphy with a particle beam such as electron beam and ion beam. 

The actinic ray-sensitive or radiation-sensitive resin com› position (preferably positive resist composition) of the present invention contains a resin (P). [1] Resin (P) 

The resin (P) contained in the actinic ray-sensitive or radia- tion-sensitive resin composition is a resin containing (A) a repeating unit having an ionic structure moiety capable of producing an acid anion on the side chain upon irradiation with an actinic ray or radiation, where the cation of the ionic structure moiety has a structure represented by formula (Ia). 

That is, the ionic structure moiety contained in the repeat› ing unit (A) has anion and cation, where the cation repre› sented by formula (Ia) is capable of decomposing upon irra› diation with an actinic ray or radiation to produce an acid anion on the side chain of the repeating unit. 

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