US 2020/0209747 Al  72  Jul. 2, 2020  [0156]  R$^{402 }$is a single bond or a C$_{1 }$-C$_{20 }$divalent linking  group in case ofr=l, and a C$_{1}$-C$_{20 }$tri- or tetravalent linking  group in case of r=2 or 3. The linking group may contain  oxygen, sulfur or nitrogen.  [0157]  R11  to  R11 $^{4 }$are each independently hydrogen, fluo› rine or trifluoromethyl, at least one thereof being fluorine or  trifluoromethyl. Also  R11 $^{1 }$and  R11 2 ,  taken together, may form  a carbonyl group. Most preferably both  R11 1  and  R11 2  are  fluorine.  [0158]  R 403 , R 404 , R 405 , R $^{406 }$and R$^{407 }$are each indepen› dently a C$_{1 }$-C$_{20 }$monovalent hydrocarbon group which may  contain a heteroatom. Any two ofR 403 , R $^{404 }$and R$^{405 }$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 include  C$_{1 }$-C$_{12 }$alkyl groups, C$_{2}$ -C$_{12 }$alkenyl groups, C$_{2}$ -C$_{12 }$alkynyl  groups,  CcC$_{20 }$ aryl groups, and C$_{7}$ -C$_{12 }$ aralkyl groups. In  these groups, some or all hydrogen may be substituted by  hydroxyl, carboxyl, halogen, cyano, amide, nitro, mercapto,  sultone, sulfone, or sulfonium salt-containing moiety, or  some carbon may be replaced by an ether bond, ester bond,  carbonyl, carbonate or sulfonic acid ester bond.  [0159]  The subscript r is an integer of  1  to 3. The subscript  sis an integer of  1  to 5, and tis an integer ofO to 3, meeting  lss+ts5. Preferably, sis an integer of  1  to 3, more preferably  2 or 3, and t is an integer of O to 2.  [0160]  The cation moiety in the sulfonium salt having  formula (3-1) is as exemplified above for the cation moiety  in the sulfonium salt having formula  (1-1  ). The cation  moiety in the iodonium salt having formula (3-2) is as  exemplified above for the cation moiety in the iodonium salt  having formula (1-2).  [0161]  Examples of the anion moiety in the onium salts  having formulae (3-1) and (3-2) are given below, but not  limited thereto. Herein X is as defined above.  X  6-<_t  F2C-S03- X  ~:-(  F2C-S03- X-o--<:_t  F2C-S03- -continued  X  Q-<-{’  OH  F2C-S03- X~:-(  F2C-S03- X  H,N~:-(  F2C-S03-