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salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxy› imide, and oxime-O-sulfonate acid generators. Suitable PAGs are as exemplified in U.S. Pat. No. 7,537,880 (JP-A 2008-111103, paragraphs [0122]-[0142]). 

[0112] Also sulfonium salts having the formula (1-1) and iodonium salts having the formula (1-2) are useful PAGs. 

[0113] In formulae (1-1) and (1-2), R$^{101 }$to R$^{105 }$are each independently a C$_{1 }$-C$_{20 }$ monovalent hydrocarbon group which may contain a heteroatom. Any two of R 101 , R $^{102 }$and R $^{103 }$may bond together to form a ring with the sulfur atom to which they are attached. The monovalent hydrocarbon group may be straight, branched or cyclic, and examples thereof are as exemplified above for R $^{21 }$to R $^{28 }$in formulae (dl) to (d3). 

[0114] Examples of the cation of the sulfonium salt having formula (1-1) are shown below, but not limited thereto. 

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-continued 

