US 2012/0003590 Al  14  Jan. 5, 2012  [0118]  As for specific structures of the cation moiety of  formula (ZI-3 ), please refer to cation moiety structures of the  acid generators illustrated in paragraphs 0047 and 0048 of  JP-A-2004-233661 and paragraphs 0040 to 0046 of JP-A- 2003-35948.  [0119]  The (ZI-4) group is described below.  [0120]  The (ZI-4) group is a group represented by the fol› lowing formula (ZI-4). This group is effective to suppress  outgassing.  [0130]  In the case where R 1  to R$^{13 }$contain no alcoholic  hydroxyl group, examples of R  1  to R $^{13 }$include a hydrogen  atom, a halogen atom, an alkyl group, a cycloalkyl group, an  alkenyl group, a cycloalkenyl group, analkynyl group, an aryl  group, a heterocyclic group, a cyano group, a nitro group, a  carboxy group, an alkoxy group, an aryloxy group, a silyloxy  group, a heterocyclic oxy group, an acyloxy group, a carbam› oyloxy group, an alkoxycarbonyloxy group, an aryloxycar› bonyloxy group, an amino group (including an anilino  group), an armnonio group, an acylamino group, an ami› nocarbonylamino group, an alkoxycarbonylamino group, an  aryloxycarbonylamino group, a sulfamoylamino group, an  alkyl- or aryl-sulfonylamino group, a mercapto group, an  alkylthio group, an arylthio group, a heterocyclic thio group,  a sulfamoyl group, a sulfa group, an alkyl- or aryl-sulfinyl  group, an alkyl- or aryl-sulfonyl group, an acyl group, an  aryloxycarbonyl group, an alkoxycarbonyl group, a carbam› oyl group, anaryl- or heterocyclic azo group, animido group,  a phosphino group, a phosphinyl group, a phosphinyloxy  group, a phosphinylamino group, a phosphono group, a silyl  group, a hydrazino group, a ureido group, a boronic acid  group [-B(OH)$_{2}$ ], a phosphato group [-OPO(OH) 2 ], a  sulfato group (---OSO$_{3}$H), and other known substituents.  [0131]  In the case where R 1  to R$^{13 }$contain no alcoholic  hydroxyl group, each ofR 1  to R$^{13 }$is preferably a hydrogen  atom, a halogen atom, an alkyl group, a cycloalkyl group, a  cyano group, an alkoxy group, an acyloxy group, an acy› lamino group, an aminocarbonylamino group, an alkoxycar› bonylamino group, an alkyl- or aryl-sulfonylamino group, an  alkylthio group, a sulfamoyl group, an alkyl- or aryl-sulfonyl  group, an alkoxycarbonyl group or a carbamoyl group.  [0132]  In the case where R 1  to R$^{13 }$contain no alcoholic  hydroxyl group, each ofR $^{1 }$to R $^{13 }$is more preferably a hydro› gen atom, an alkyl group, a cycloalkyl group, a halogen atom  or an alkoxy group.  [0133]  Two adjacent members out of R $^{1 }$to R $^{13 }$may com› bine with each other to form a ring structure. This ring struc› ture includes an aromatic or non-aromatic hydrocarbon ring  and a heterocyclic ring. These ring structures may further  combine to form a condensed ring.  [0134]  The (ZI-4) group preferably has a structure where at  least one ofR$^{1 }$to R$^{13 }$contains an alcoholic hydroxyl group,  more preferably a structure where at least one of R 9  to R  13  contains an alcoholic hydroxyl group.  [0135]  Z  represents, as described above, a single bond or a  divalent linking group. Examples of the divalent linking  group include an alkylene group, an arylene group, a carbonyl  group, a sulfonyl group, a carbonyloxy group, a carbony› lamino group, a sulfonylamido group, an ether bond, a thio› ether bond, an amino group, a disulfide group, an acyl group,  an alkylsulfonyl group, ----CH=CH-, an aminocarbony› lamino group and an aminosulfonylamino group.  [0136]  The divalent linking group may have a substituent.  Examples of the substituent thereof are the same as those  enumerated above for R $^{1 }$to R  13 .  [0137]  Z  is preferably a single bond, an ether bond or a  thioether more, more preferably a single bond.  [0121]  In formula (ZI-4), each ofR’ to R$^{13 }$independently  represents a hydrogen atom or a substituent, and at least one  ofR $^{1 }$to R $^{13 }$is preferably a substituent containing an alcoholic  hydroxyl group. The term "alcoholic hydroxyl group" as used  herein means a hydroxy 1 group bonded to a carbon atom of an  alkyl group.  [0122]  Z  represents a single bond or a divalent linking  group.  [0123]  zc- represents a non-nucleophilic anion, and  examples thereof are the same as those of  z- in formula  (ZI).  [0124]  In the case where R 1  to R$^{13 }$are a substituent con› taining an alcoholic hydroxyl group, each of R 1  to R 13  is  preferably a group represented by -(W-Y), wherein Y is an  alkyl group substituted with a hydroxyl group and W is a  single bond or a divalent linking group.  [0125]  Preferred examples of the alkyl group represented  byY include an ethyl group, a propyl group and an isopropyl  group. In particular, Y preferably contains a structure repre› sented by ----CH$_{2}$CH$_{2}$OH.  [0126]  The divalent linking group represented by Wis not  particularly limited but is preferably a single bond or a diva› lent group formed by substituting a single bond for an arbi› trary hydrogen atom of an alkoxy group, an acyloxy group, an  acylamino group, an alkyl- or aryl-sulfonylamino group, an  alkylthio group, an alkylsulfonyl group, an acyl group, an  alkoxycarbonyl group or a carbamoyl group, more preferably  a single bond or a divalent group formed by substituting a  single bond for an arbitrary hydrogen atom of an acyloxy  group, an alkylsulfonyl group, an acyl group or an alkoxycar› bonyl group.  [0127]  In the case where R 1  to R$^{13 }$are a substituent con› taining an alcoholic hydroxyl group, the number of carbons  contained therein is preferably from 2 to 10, more preferably  from 2 to 6, still more preferably from 2 to 4.  [0128]  The alcoholic hydroxyl group-containing substitu› ent as R 1  to R$^{13 }$may have two or more alcoholic hydroxyl  groups. The number of alcoholic hydroxyl groups in the alco- RI!  RIO  R9  RI  Rs  RylysylyR’  R$^{3}$~z~R$^{6 }$ R4  Rs  El  Zc- ZI-4  holic hydroxyl group-containing substituent as R 1  to R$^{13 }$is  from 1 to 6, preferably from 1 to 3, more preferably 1.  [0129]  The number of alcoholic hydroxyl groups contained  in the (ZI-4) group is, in total ofall ofR$^{1 }$to R 13 , from 1 to 10,  preferably from 1 to 6, more preferably from 1 to 3. 