Aug. 8, 2019  7  US 2019/0243238 Al  [0057]  Z  represents a phosphorus atom, a boron atom, or  an antimony atom. A represents a halogen atom (preferably  a fluorine atom).  [0058]  P represents a phosphorus atom, F represents a  fluorine atom, B represents a boron atom, and Ga represents  a gallium atom.  [0059]  S represents a sulfur atom, 0 represents an oxygen  atom, C represents a carbon atom, and N represents a  nitrogen atom.  [0060]  Rf is preferably an alkyl group having 80 mo!% or  more of its hydrogen atom substituted with fluorine atom,  and the alkyl group having 1 to 8 carbon atoms is preferable.  The alkyl group made into Rf by fluorine substitution can  include a linear alkyl group (methyl, ethyl, propyl, butyl,  pentyl, octyl and the like), a branched alkyl group (isopro› pyl, isobutyl, s-butyl, t-butyl and the like), a cycloalkyl  group (cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and  the like) and the like. In Rf, the ratio of the hydrogen atom  of the alkyl group being substituted with fluorine atom is  preferably 80 mo! % or more, more preferably 90% or more,  and especially preferably 100%, based on the molar number  of the hydrogen atom contained in the original alkyl group.  [0061]  When the ratio of substitution by fluorine atom is  in such preferable range, the light responsiveness of the  sulfonium salt becomes further favorable. The especially  preferable Rf can include CF3-, CF$_{3}$CF 2 -, (CF$_{3}$ $^{)}$2 CF-,  CF$_{3}$CF 2 CF 2 -, CF$_{3}$CF 2 CF 2 CF 2 -, (CF$_{3}$ $^{)}$2 CFCF 2 -, CF$_{3}$CF 2  (CF$_{3}$)CF- and (CF$_{3}$ ) $_{3}$C-. Rf contained by the number of"b"  are independent from each other, and thus they can be the  same or different from each other.  [0062]  R 4  represents a phenyl group having a part of  hydrogen atoms being substituted with at least one halogen  atom or electron withdrawing group. The halogen atom can  include a fluorine atom, a chlorine atom, a bromine atom and  the like. The electron withdrawing group can include a  trifluoromethyl group, a nitro group, a cyano group and the  like. Among these, a phenyl group having one hydrogen  atom substituted with a fluorine atom or a trifluoromethyl  group is preferable. R 4  contained by the number of "c" are  independent from each other, and thus they can be the same  or different from each other.  [0063]  R $^{5 }$represents an alkyl group having 1 to 20 carbon  atoms, a perfluoroalkyl group having 1 to 20 carbon atoms,  or an aryl group having 6 to 20 carbon atoms. The alkyl  group and the perfluoroalkyl group can be either linear,  branched, or cyclic group, and the aryl group can be a  non-substituted group or can have a substituent group.  [0064]  "a" represents an integer of 4 to 6. "b" represents  an integer of 1 to 5, preferably 2 to 4, and especially  preferably 2 or 3. "c" represents an integer of 1 to 4,  preferably 4.  [0065]  The anion represented by  ZAa  - can include anions  represented by SbF6-, PF$_{6}$ -, and BF 4 -.  [0066]  The anion represented by (Rf)$_{6}$PF c$_{6}$ _ 6 )- can include  anions represented by (CF$_{3}$CF 2 ) 2 PF $_{4}$-, (CF$_{3}$CF 2 )$_{3}$PF$_{3 }$-,  ((CF$_{3}$ ) 2 CF) 2 PF $_{4}$-, ((CF 3 ) 2 CF)$_{3}$PF$_{3 }$-, (CF$_{3}$CF 2 CF 2 ) 2 PF  4 -,  (CF$_{3}$CF 2 CF 2 )$_{3}$PF$_{3 }$-, ((CF 3 ) 2 CFCF 2 ) 2 PF $_{4}$ -, ((CF 3 ) 2 CFCF 2 )  $_{3}$PF$_{3}$ -, (CF $_{3}$CF 2 CF 2 CF 2 ) 2 PF$_{4}$ - and (CF$_{3}$CF 2 CF 2 CF 2 )$_{3}$PF$_{3}$-.  Among these, anions represented by ((CF$_{3}$ ) 2 CF 2 )$_{3}$PF$_{3 }$-,  (CF$_{3}$CF 2 CF 2 )$_{3}$PF$_{3 }$-,  (CF$_{3}$ $^{)}$2 CF)$_{3}$PF$_{3 }$ -,  (CF$_{3}$ $^{)}$2 CF) 2 PF  4 -,  (CF$_{3}$ ) 2 CFCF 2 )$_{3}$PF$_{3}$ - and ((CF$_{3}$ ) 2 CFCF 2 ) 2 PF $_{4}$ - are prefer› able.  [0067]  amon  The anion represented by R $^{4}$cBAc$_{4}$ -c)- can include  represented  by  (C$_{6}$F $_{5}$ ) $_{4}$B-,  (CF$_{3}$ ) 2 C$_{6}$H$_{3}$ ) $_{4}$B-,  [0075]  Here, when  R 5 a  has a substituent group, the number  of carbon atom including the number of carbon atom of such  substituent group is preferably 1 to 200, more preferably 1  to 100, further preferably 1 to 30, and especially preferably  3 to 30. Further, it is preferable that  R 5 a  has a substituent  group. That is, at least one of the hydrogen atoms ofR$^{56 }$and  R $^{5}$c is preferably substituted by the substituent group.  [0076]  The substituent group which can be included in  R 5 a  can include a hydroxy group, a carboxy group, an alkoxy  group, an acyl group, an alkoxycarbonyl group, an aryl  group, an aryloxy group, a phosphino group, an alkylthio  [0074]  Here, in the afore-mentioned formula (a2), "m" is  0 or an integer of 1 to 10. When "m" is 0,  R 5 a  includes the  hydroxyl group, and when "m" is 1 or higher, at least either  one of R 56  and R$^{5}$c includes the hydroxyl group. "m" is  preferably O to 5, more preferably O to 3.  [0073]  R $^{5}$c is either one of a divalent group selected  independently from each other, from a linear, branched, or  cyclic divalent aliphatic hydrocarbon group; a divalent aro› matic hydrocarbon group; and a divalent aliphatic hetero› cyclic group or a divalent aromatic heterocyclic group  having at least one structure in its skeleton, the structure  being selected from a group consisting of ---0-, -CO-,  -COO-, ---OCO-,  ---O-CO---0-,  -NHCO-,  ----CONH-,  -NH-CO---0-,  ---0-CO-NH-,  -NH-, -N=, -S-, and -SO 2 -.  [0072]  Here, L is either one of a group selected indepen› dently from each other, from a direct bond; or from the  group consisting of -0-, -CO-, -COO-, ---OCO-,  ---O-CO---0-, -NHCO-, ----CONH-, -NH-CO› O-, -O----CO-NH-, -NH-, -S-, and ----CO-O› CH2-CO---O-.  [0071]  In formula (a2), R$^{56 }$is either one of a monovalent  group selected from a linear, branched, or cyclic monovalent  aliphatic hydrocarbon group; a monovalent aromatic hydro› carbon group; and a monovalent aliphatic heterocyclic group  or a monovalent aromatic heterocyclic group having in its  skeleton at least one structure selected from the group  consisting of -0-, -CO-, -COO-, ---OCO-,  ---O-CO---0-, -NHCO-, ----CONH-, -NH-CO› O-, ---0-CO-NH-, -NH-, -N=, -S-, -SO-,  and-SO 2 -.  [0070]  In formula (al),  R 5 a  represents a monovalent  organic group having 1 to 20 carbon atoms, which can have  a substituent group. As the organic group, a group repre› sented by the following formula having 1 to 20 carbon atoms  can be preferably mentioned.  Rsb_(L-Rsc)n- (a2)  (al)  [0069]  The anion represented by R$^{5}$SO$_{3 }$ - can include  those described in WO 2011/093139. As a radiation-sensi› tive acid generator, a sulfonic acid derivative having an  anion structure represented by the following formula (al) is  preferable, however, the present invention is not limited to  these.  [0068]  The anion represented by R $^{4}$cGaAc$_{4}$ -c)- can include  anion  represented  by  (C$_{6}$F$_{5}$ ) $_{4}$Ga,  (CF$_{3}$ ) 2 C$_{6}$H$_{3}$ ) $_{4}$Ga,  (CF $_{3}$C$_{6}$H$_{4}$ ) $_{4}$Ga, (C$_{6}$F $_{5}$ $^{)}$2 GaF  2 , C$_{6}$F $_{5}$GaF $_{3 }$ and (C$_{6}$H$_{3}$F  2 )$_{4}$Ga-.  Among these, anion represented by (C$_{6}$F$_{5}$)$_{4}$Ga- and ((CF$_{3}$)  2 C$_{6}$H$_{3}$ ) $_{4}$Ga- are preferable.  (CF$_{3}$C$_{6}$H$_{4}$ ) $_{4}$B-, (C$_{6}$F $_{5}$ $^{)}$2 BF 2  -, C$_{6}$F $_{5}$BF$_{3 }$ - and (C$_{6}$H$_{3}$F 2 )$_{4}$ B-.  Among these, anion represented by (C$_{6}$F$_{5}$ ) $_{4}$B- and ((CF$_{3}$ )  2 C$_{6}$H$_{3}$ ) $_{4}$B- are preferable. 