US 2020/0050105 Al  65  Feb. 13, 2020  -continued  [0123]  Of the foregoing PAGs, those having an anion of  formula (IA’) or (ID) are especially preferred because of  reduced acid diffusion and high solubility in the resist  solvent. Also those having an anion of formula (2’) are  especially preferred because of extremely reduced acid  diffusion.  [0124]  Also a sulfonium or iodonium salt having an  iodized or brominated aromatic ring-containing anion may  be used as the PAG. Suitable are sulfonium and iodonium  salts having the formulae (3-1) and (3-2).  (3-2)  [0125]  In formulae (3-1) and (3-2), X 1  is iodine or bro› mine, and may be the same or different when s is 2 or more.  [0126]  L  1  is a single bond, ether bond, ester bond, or a  C 1  -C 6  alkanediyl group which may contain an ether bond or  ester bond. The alkanediyl group may be straight, branched  or cyclic.  [0127]  R 401  is a hydroxyl group, carboxyl group, fluorine,  chlorine, bromine, amino group, or a  C 1  -C$_{20 }$ alkyl,  C 1  -C$_{20 }$ alkoxy,  C 2 -C 20  alkoxycarbonyl,  C 2 -C 20  acyloxy or  C 1  -C$_{20 }$ alkylsulfonyloxy group, which may contain fluorine, chlo› rine, bromine, hydroxyl, amino or C 1  -C$_{10 }$alkoxy moiety, or  -NR401A ----C(=O)-R-NR401A ----C(O)-O-R401B’  wherein R 401 A is hydrogen, or a C 1  -C 6  alkyl group which  may contain halogen, hydroxy,  C 1  -C 6  alkoxy,  C 2 -C 6  acyl or  C 2 -C 6  acyloxy moiety, R 401 B is a  C 1 -C 16  alkyl,  C 2 -C 16  alkenyl or  CcC$_{12 }$ aryl group, which may contain halogen,  hydroxy,  C 1  -C 6  alkoxy,  C 2 -C 6  acyl or  C 2 -C 6  acyloxy moiety.  [0128]  The foregoing alkyl, alkoxy, alkoxycarbonyl, acy› loxy, acyl and alkenyl groups may be straight, branched or  cyclic. When t is 2 or more, groups R 401  may be the same  or different.  Of these,  R 401  is  preferably hydroxyl,  -NR401A----C(=O)-R401B’  -NR401A _C(=O)-O- R401B, fluorine, chlorine, bromine, methyl or methoxy.  402  [0129]  R is a single bond or a C 1  -C$_{20 }$ divalent linking  group when r= 1, or a C 1  -C$_{20 }$tri- or tetravalent linking group  when r=2 or 3, the linking group optionally containing an  oxygen, sulfur or nitrogen atom.  1  [0131]  R , R , R , R and R 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,  C 2 -C 12  alkenyl,  C 2 -C 12  alkynyl,  C 6 -C 20  aryl,  and C 7 -C$_{12 }$ aralkyl groups. In these groups, some or all of  the hydrogen atoms may be substituted by hydroxyl, car› boxyl, halogen, cyano, amide, nitro, mercapto, sultone,  sulfone, or sulfonium salt-containing moieties, and some  carbon may be replaced by an ether bond, ester bond,  carbonyl moiety, carbonate moiety or sulfonic acid ester  bond.  rine or trifluoromethyl, at least one of Rf 1  to R:t4 is fluorine  or trifluoromethyl, or Rf 1  and Rf2, taken together, may form  a carbonyl group. Preferably, both Rf $^{3 }$and  R:t4  are fluorine.  403 404 405 406  407  [0132]  In formulae (3-1) and (3-2), r is an integer of 1 to  3, sis an integer of 1 to 5, and tis an integer of Oto 3, and  lss+ts5. Preferably, sis an integer of 1 to 3, more preferably  2 or 3, and t is an integer of O to 2.  [0133]  Examples of the cation in the sulfonium salt having  formula (3-1) include those exemplified above as the cation  in the sulfonium salt having formula (1-1). Examples of the  cation in the iodonium salt having formula (3-2) include  those exemplified above as the cation in the iodonium salt  having formula (1-2).  [0134]  Examples of the anion in the onium salts having  formulae (3-1) and (3-2) are shown below, but not limited  thereto. Herein X 1  is as defined above.  (3-1)  R403  I  +s-R404  I  R4os  ~:-t  F2C-S03- X’-O--<_t  F2C-S03-