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[0094] The acid generator may be a compound having a plurality of structures represented by Formula (ZI). For example, the acid generator may be a compound having a structure in which at least one of R$_{20}$ i, ... , or R$_{203 }$ of the compound represented by Formula (ZI) is bonded to at least one of R$_{201}$ , ... , or R $_{203 }$of another compound represented by Formula (ZI) via a single bond or a linking group. 

[0095] Examples of the organic group ofR$_{201}$, R 202 , and R$_{203 }$include an aryl group (preferably having 6 to 15 carbon atoms), a linear or branched alkyl group (preferably having 1 to 10 carbon atoms), and a cycloalkyl group (preferably having 3 to 15 carbon atoms) 

[0096] It is preferable that at least one of R$_{201 }$ R$_{202}$, or R$_{203 }$ an aryl group, and it is more preferable that $^{0}$all of the three are acyl groups. In addition to a phenyl group and a naphthyl group, as the aryl group, a heteroaryl group such as an indole residue, a pyrrole residue is also possible. 

[0097] An aryl group, an alkyl group, and a cycloalkyl group as R$_{201}$ , R 202 , and R 203 each may further have a substituent. Examples the substituent include a halogen atom such as a nitro group and a fluorine atom, a carboxy group, a hydroxyl group, an amino group, a cyano group, an alkoxy group (preferably having 1 to 15 carbon atoms), a cycloalkyl group (preferably having 3 to 15 carbon atoms), an aryl group (preferably having 6 to 14 carbon atoms), an alkoxycarbonyl group (preferably having 2 to 7 carbon atoms), an acyl group (preferably having 2 to 12 carbon atoms), and an alkoxycarbonyloxy group (preferably having 2 to 7 carbon atoms), and the present invention is not limited to these. 

[0098] Two selected from R$_{20}$ i, R$_{202}$, and R 203 may be bonded to each other via a single bond or a linking group. Examples of the linking group include an alkylene group (preferably having 1 to 3 carbon atoms), -0-, -S-, -CO- and but the present invention is not limited to these. 

[0099] Examples of the preferable structure in a case where at least one ofR$_{201}$, R 202 , or R $_{203 }$is not an aryl group include cation structures such as compounds disclosed in paragraphs 0046 and 0047 of JP2004-233661A and para› graphs 0040 to 0046 of JP2003-035948A, compounds exemplified as Formulae (I-1) to (I-70) in US2003/ 0224288Al, and compounds exemplified as Formulae (IA- 1) to (IA-54) and Formulae (IB-1) to (IB-24) in US2003/ 0077540Al. 

[0100] Preferable examples of the cation represented by Formula (ZI) include cations represented by Formula (ZI-3) or (ZI-4) described below. First, a cation represented by Formula (ZI-3) is described. 

<img src='content_image/926013.jpg'>

[0101] In Formula (ZI-3), 

[0102] R$_{1 }$represents an alkyl group, a cycloalkyl group, an alkoxy group, a cycloalkoxy group, an aryl group, and an alkenyl group, 

[0103] R$_{2 }$ and R$_{3 }$ each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, and an aryl group, and R$_{2 }$ and R$_{3 }$ may be linked to each other to form a ring, 

(ZI-3) 

[0104] R$_{1 }$ and R$_{2 }$ may be linked to each other to form a ring, and 

[0105] Rx and RY each independently represent an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, a 2-oxoalkyl group, a 2-oxocycloalkyl group, an alkoxycar› bonylalkyl group, and an alkoxycarbonyl cycloalkyl group, Rx and RY may be linked to each other to form a ring, and this ring structure may include an oxygen atom, a nitrogen atom, a sulfur atom, a ketone group, an ether bond, an ester bond, or an amide bond. 

[0106] The alkyl group in R$_{1 }$ is preferably a linear and branched alkyl group having 1 to 20 carbon atoms and may have an oxygen atom, a sulfur atom, or a nitrogen atom in an alkyl chain. Specific examples thereof include a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, an n-dodecylgroup, an n-tetradecyl group, and an n-octadecyl group, and a branched chain alkyl group such as an isopropyl group, an isobutyl group, a t-butyl group, a neopentyl group, and a 2-ethylhexyl group. The alkyl group of R$_{1 }$ may have a substituent, and examples of the alkyl group having a substituent include a cyanomethyl group, a 2,2,2-trifluoro› ethyl group, a methoxycarbonylmethyl group, and an ethoxycarbonylmethyl group. 

[0107] The cycloalkyl group as R$_{1 }$ is preferably a cycloalkyl group having 3 to 20 carbon atoms and may have an oxygen atom, or a sulfur atom in the ring. Specific examples thereof include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a norbomyl group, and an adamantyl group. The cycloalkyl group of R$_{1 }$ may have a substituent, and examples of the substituent include an alkyl group and an alkoxy group. 

[0108] The alkoxy group as R$_{1}$is preferably an alkoxy group having 1 to 20 carbon atoms. Specific examples thereof include a methoxy group, an ethoxy group, an isopropyloxy group, a t-butyloxy group, a t-amyloxy group, and an n-butyloxy group. The alkoxy group ofR$_{1 }$ may have a substituent, and examples of the substituent include an alkyl group and a cycloalkyl group. 

[0109] The cycloalkoxy group as R$_{1 }$ is preferably a cycloalkoxy group having 3 to 20 carbon atoms, and examples thereof include a cyclohexyloxy group, a norbor› nyloxy group, and an adamantyloxy group. The cycloalkoxy group of R$_{1 }$ may have a substituent, and examples of the substituent include an alkyl group and a cycloalkyl group. 

[0110] The aryl group as R$_{1 }$ is preferably an aryl group having 6 to 14 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and a biphenyl group. The aryl group of R$_{1 }$ may have a substituent, and preferable examples of the substituent include an alkyl group, a cycloalkyl group, an alkoxy group, a cycloalkoxy group, an aryloxy group, an alkylthio group, and an arylthio group. In a case where the substituent is an alkyl group, a cycloalkyl group, an alkoxy group, or a cycloalkoxy group, examples thereof include the same groups as the alkyl group, the cycloalkyl group, the alkoxy group, and the cycloalkoxy group described above as R$_{1}$ . 

[0111] Examples of the alkenyl group as R$_{1 }$include a vinyl group and an ally! group. 

[0112] R$_{2 }$ and R$_{3 }$ represent a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group, and R$_{2 }$ and R$_{3 }$ may be linked to each other to form a ring. It is preferable that at least one of R$_{2 }$ or R$_{3 }$ represents an alkyl group, a 

