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[0167] In formula (3B), W1’ 1 and W1’ 2 are each indepen› dently fluorine or a C$_{1 }$-C$_{40 }$monovalent hydrocarbon group which may contain a heteroatom. The monovalent hydro› carbon groups may be straight, branched or cyclic, and examples thereof are as exemplified above for R 112 . Pref› erably W1’ 1 and W1’ 2 each are fluorine or a straight C$_{1 }$-C$_{4 }$ fluorinated alkyl group. A pair of W1’ 1 and W1’ 2 may bond together to form a ring with the linkage (-CF$_{2}$-SO$_{2}$ - 

N--SO$_{2}$----CF $_{2}$-) to which they are attached, and prefer› ably the pair is a fluorinated ethylene or fluorinated propyl› ene group. 

[0168] In formula (3C), Rf’cl, wc 2 and Wc3 are each inde› pendently fluorine or a C$_{1 }$-C$_{40 }$ monovalent hydrocarbon group which may contain a heteroatom. The monovalent hydrocarbon groups may be straight, branched or cyclic, and examples thereof are as exemplified above for R 112 . Pref› erably wc1, wc 2 and Wc3 each are fluorine or a straight cl -C4 fluorinated alkyl group. A pair of wc1 and wc 2 may bond together to form a ring with the linkage (--CF 2 - SO2-c--SO 2 -CF 2 -) to which they are attached, and preferably the pair is a fluorinated ethylene or fluorinated propylene group. 

[0169] In formula (3D), wd is a Cl-C40 monovalent hydro› carbon group which may contain a heteroatom. The mon› ovalent hydrocarbon groups may be straight, branched or cyclic, and examples thereof are as exemplified above for R112_ 

[0170] With respect to the synthesis of the sulfonium salt having an anion of formula (3D), reference is made to JP-A 2010-215608 and JP-A 2014-133723. 

[0171] Examples of the anion having formula (3D) are shown below, but not limited thereto. 

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