Feb.28,2019  74  US 2019/0064665 Al  wherein  RA  is hydrogen, fluorine, methyl or trifluorom› ethyl,  zA  is a single bond, phenylene group, naphthyl› ene group or (backbone)-C(=O)---0-Z’-, Z’ is a  straight, branched or cyclic C$_{1 }$-C$_{10 }$ alkylene group  which may contain a hydroxyl moiety, ether bond, ester  bond or lactone ring, or phenylene group or naphthyl› ene group,  XA  is an acid labile group, and  yA  is  hydrogen or a polar group having at least one structure  selected from the group consisting of hydroxyl, cyano,  carbonyl, carboxyl, ether bond, ester bond, sulfonic  acid ester bond, carbonate bond, lactone ring, sultone  ring and carboxylic anhydride.  wherein  R: 1 \  R:11’1, R:11’ 2 , R’c1, R’c 2  and R’c3 are each  independently fluorine or a straight, branched or cyclic  C$_{1 }$-C$_{40 }$ monovalent hydrocarbon group which may  contain a heteroatom, or a pair ofR:11’$^{1 }$and R:11’ 2 , or R’c1  and R’c 2  may bond together to form a ring with the  carbon atom to which they are attached and any inter› vening atoms,  R’d  is a straight, branched or cyclic  C$_{1 }$-C$_{40 }$ monovalent hydrocarbon group which may  contain a heteroatom,  wherein R 121 , R 122  and R 123  are each independently a  straight, branched or cyclic C$_{1 }$-C$_{20 }$alkyl group, Lis a  single bond, ether bond, or a straight, branched or  cyclic C$_{1 }$-C$_{20 }$ divalent hydrocarbon group which may  contain a heteroatom, X1, X 2 , X 3  and X 4  are each  independently hydrogen, fluorine or trifluoromethyl, at  least one of X1, X 2 , X 3  and X 4  is fluorine or trifluo› romethyl, pl and p2 are each independently an integer  of 0 to 5, and p3 is an integer of Oto 4.  wherein R  101 , R  102  and R  103  are each independently a  straight, branched or cyclic C$_{1 }$-C$_{20 }$monovalent hydro› carbon group which may contain a heteroatom, any two  ofR  101 , R  $^{102 }$and R $^{103 }$may bond together to form a ring  with the sulfur atom to which they are attached, and  x› is an anion selected from the formulae (4A) to (4D):  wherein R$^{151 }$and R$^{152 }$are each independently hydrogen  or a straight, branched or cyclic C$_{1 }$-C$_{40 }$ monovalent  hydrocarbon group which may contain a heteroatom,  exclusive of hydrocarbon groups in which the hydrogen  atom in bond with the carbon atom at a-position  relative to the sulfa group is replaced by a fluorine atom  or fluoroalkyl moiety, and  M+ is an onium cation.  11.  The resist composition of claim  6,  further comprising  an onium salt having the formula (6) or (7):  10.  The resist composition of claim  9  wherein the other  photoacid generator has the formula ( 4) or (5):  9.  The resist composition of claim  6,  further comprising  a photoacid generator other than the photoacid generator  comprising the sulfonium compound of formula  (I).  8.  The resist composition of claim  6,  further comprising  an organic solvent.  -continued  (4C)  (4D)  (5)  (4)  Rfi>l -CF2-S02  ’  N- Rfi’2  -cF $_{2}$-so(  (4B)  (A)  i/  ’j==o  $^{0 }$\ $_{yA }$ (b)  (6)  (7)  (4A) 