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-