Feb.4,2021  65  US 2021/0033969 Al  TI  HXRI04  so - R $^{105}$~0  CFi  3  (3A’)  [0071]  In formula (3A’), R$^{104 }$is hydrogen or trifluorom› ethyl, preferably trifluoromethyl.  [0072]  R  105  is a C$_{1 }$-C$_{38 }$ hydrocarbyl group which may  contain a heteroatom. Suitable heteroatoms include oxygen,  nitrogen, sulfur and halogen, with oxygen being preferred.  Of the hydrocarbyl groups, those of 6 to 30 carbon atoms are  preferred because a high resolution is available in fine  pattern formation. Suitable hydrocarbyl groups include alkyl  groups such as methyl, ethyl, propyl, isopropyl, butyl,  isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, hep› tyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, hep› tadecyl, icosanyl; cyclic saturated hydrocarbyl groups such  as  cyclopentyl, cyclohexyl,  1-adamantyl, 2-adamantyl,  1-adamantylmethyl, norbomyl, norbornylmethyl, tricyclo› decanyl, tetracyclododecanyl, tetracyclododecanyhnethyl,  dicyclohexylmethyl;  unsaturated  aliphatic  hydrocarbyl  groups such as ally! and 3-cyclohexenyl; aryl groups such as  phenyl, 1-naphthyl, 2-naphthyl; and aralkyl groups such as  benzyl and diphenylmethyl. In these groups, some or all of  the hydrogen atoms may be substituted by a moiety con› taining a heteroatom such as oxygen, sulfur, nitrogen or  halogen, or some carbon may be replaced by a moiety  containing a heteroatom such as oxygen, sulfur or nitrogen,  so that the group may contain a hydroxyl, cyano, carbonyl,  ether, ester, sulfonic acid ester, carbonate, lactone ring,  sultone ring, carboxylic anhydride or haloalkyl moiety.  Examples of the heteroatom-containing hydrocarbyl group  include tetrahydrofuryl,  methoxymethyl,  ethoxymethyl,  methylthiomethyl,  acetamidomethyl,  trifluoroethyl,  (2-methoxyethoxy )methy I, acetoxymethy I, 2-carboxy-1-cy› clohexy l, 2-oxopropyl, 4-oxo-1-adamantyl, and 3-oxocyclo› hexyl.  [0073]  With respect to the synthesis of the sulfonium salt  having an anion of formula (3A’), reference is 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.  [0074]  Examples of the anion having formula (3A) are  shown below, but not limited thereto.  0  #  -continued  0  0  0  /’-.... ,....,s03- 0  C  F2  /’-.... ,....,s03- 0  C  F2  0  /’-.... ,....,s03- 0  C  F2  TI  ~  ,....,so 3 -~ 0  ~  ,....,s0 3 - ~o  C  O  C  F2  F2  0  ~  ,....,s03- 0  C  F2  0  ~  ,....,s03- 0  C  F2  0  ~  ,....,s03- 0  C  F2  0  0 