Dec.  27,  2018  48  US 2018/0373148 Al  -continued  -continued  [0089]  In formula (IA),  wa  is fluorine or a cl -C40 straight,  branched or cyclic monovalent hydrocarbon group which  may contain a heteroatom.  [0090]  Of the anions of formula (IA), an anion having the  formula (IA’) is preferred.  [0091]  In formula (IA’), R$^{106 }$is hydrogen or trifluorom› ethyl, preferably trifluoromethyl. R $^{107 }$is a C$_{1 }$-C$_{38 }$ straight,  branched or cyclic monovalent hydrocarbon group which  may contain a heteroatom. As the heteroatom, oxygen,  nitrogen, sulfur and halogen atoms are preferred, with  oxygen being most preferred. Of the monovalent hydrocar› bon groups represented by R 107 , those groups of 6 to 30  carbon atoms are preferred from the aspect of achieving a  high resolution in forming patterns of fine feature size.  Suitable monovalent hydrocarbon groups include, but are  not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobu› tyl, s-butyl, t-butyl, pentyl, neopentyl, cyclopentyl, hexyl,  cyclohexyl, 3-cyclohexenyl, heptyl, 2-ethylhexyl, nonyl,  undecyl, tridecyl, pentadecyl, heptadecyl, 1-adamantyl,  2-adamantyl, 1-adamantylmethyl, norbornyl, norbornylm› ethyl, tricyclodecanyl, tetracyclododecanyl, tetracyclodode› canylmethyl, dicyclohexylmethyl, eicosanyl, ally!, benzyl,  diphenylmethyl, tetrahydrofuryl, methoxymethyl, ethoxym› ethyl, methylthiomethyl, acetamidomethyl, trifluoroethyl,  (2-methoxyethoxy)methyl, acetoxymethyl, 2-carboxy-1-cy› clohexyl, 2-oxopropyl, 4-oxo-1-adamantyl, and 3-oxocyclo› hexyl. In these groups, one or more hydrogen atoms may be  substituted by a moiety containing a heteroatom such as  oxygen, sulfur, nitrogen or halogen, or one or more carbon  atoms may be substituted by a moiety containing a heteroa› tom such as oxygen, sulfur or nitrogen, so that the group  may contain a hydroxyl, cyano, carbonyl, ether, ester, sul› fonic acid ester, carbonate, lactone ring, sultone ring, car› boxylic anhydride or haloalkyl moiety.  [0092]  With respect to the synthesis of the sulfonium salt  having an anion of formula (IA’), reference may be made to  JP-A 2007-145797, JP-A 2008-106045, JP-A 2009-007327,  and JP-A 2009-258695. Also useful are the sulfonium salts  described in JP-A 2010-215608, JP-A 2012-041320, JP-A  2012-106986, and JP-A 2012-153644.  [0093]  Examples of the anion of formula (IA) are shown  below, but not limited thereto.  [0088]  In formulae (1-1) and (1-2), x- is an anion of the  following formula (IA), (18), (IC) or (ID).  (lD)  0  CF3  Rfd  -M-o-6-cH2-So3- I  CF3  Q  t)y 0 ,  y  /o  (lA)  (lB)  (lC) 