US 8,968,979 B2  164  163  Iodonium salts which can be used herein include those  described in US 2008153030 (JP-A 2008-158339, paragraph  [0206]). Iodonium salts are salts of iodonium cations with  sulfonates, bis(substituted alkylsulfonyl)imides and tris(sub› stituted alkylsulfonyl)methides. Exemplary iodonium cat› ions are aryliodonium cations including diphenyliodinium,  bis( 4-tert-butylphenyl)iodonium,  4-tert-butoxyphenylphe- nyliodonium, and 4-methoxyphenylphenyliodonium. Exem› plary  sulfonates  include  pentafluoroethylperfluorocy› clohexanesulfonate,  2,2,2-trifluoroethanesulfonate,  pentafluoro benzenesulfonate,  4-trifluoromethy lbenzene› sulfonate, and 4-fluorobenzenesulfonate. Exemplary bis( sub- stituted alkylsulfonyl)imides include bistrifluoromethylsul› fonylimide,  bispentafluoroethylsulfonylimide,  bisheptafluoropropylsulfonylimide, and perfluoro-1,3-pro› pylenebissulfonylimide. A typical tris(substituted alkylsulfo› nyl)methide is tristrifluoromethylsulfonylmethide. Iodonium  salts based on combination of the foregoing examples are  included.  Suitable O-arylsulfonyloxime compounds and O-alkylsul› fonyloxime compounds (oxime sulfonates) include photo› acid generators in the form of glyoxime derivatives; photo› acid generators in the form of oxime sulfonates with a long  conjugated system separated by thiophene or cyclohexadi› ene; oxime sulfonates having an electron withdrawing group  such as trifluoromethyl incorporated for increased stability;  oxime sulfonates using phenylacetonitrile or substituted  acetonitrile derivatives; and bisoxime sulfonates.  Photoacid generators in the form of glyoxime derivatives  which can be used herein include those described in JP-A  2006-178317, paragraph [0131]. Suitable glyoxime deriva› tives  include  bis-O-(p-toluenesulfonyl)-a-dimethylgly› oxime, bis-O-(p-toluenesulfonyl)-a-diphenylglyoxime, bis› O-(p-toluenesulfonyl)-a-dicyclohexylglyoxime,  bis-O-(p› toluenesulfonyl)-2,3-pentanedionedioxime,  bis-O-(p- toluenesulfonyl)-2-methyl-3,4-pentanedionedioxime, bis-O- (n-butanesulfonyl)-a-dimethylglyoxime,  bis-O-(n- butanesulfonyl)-a-diphenylglyoxime,  bis-O-(n- butanesulfonyl)-a-dicyclohexylglyoxime,  bis-O-(n- butanesulfonyl)-2,3-pentanedioneglyoxime,  bis-O-(n- butanesulfonyl)-2-methyl-3,4-pentanedioneglyoxime,  bis- N-sulfonyloxyimide photoacid generators which can be  used herein include those described in U.S. Pat. No. 7,498,  126 (JP-A 2007-333933, paragraph [0074]). N-sulfonyloxy› dicarboxyimide photoacid generators include combinations  of imide skeletons with sulfonates. Exemplary imide skel› etons are succinimide, naphthalenedicarboxyimide, phthal› imide, cyclohexyldicarboxyimide, 5-norbomene-2,3-dicar- boxyimide,  and  7-oxabicyclo[2.2.1]-5-heptene-2,3- dicarboxyimide.  Exemplary  sulfonates  include  trifluoromethanesulfonate, pentafluoroethanesulfonate, hep› tafluoropropanesulfonate, nonafluorobutanesulfonate, dode› cafluorohexanesulfonate,  pentafluoroethylperfluorocy- clohexanesulfonate, heptadecafluorooctanesulfonate, 2,2,2- trifluoroethanesulfonate,  pentafluorobenzenesulfonate,  4-trifluoromethylbenzenesulfonate,  4-fluorobenzene› sulfonate, mesity lenesulfonate, 2,4, 6-triisopropy lbenzene- sulfonate, toluenesulfonate, benzenesulfonate, naphthalene› sulfonate,  camphorsulfonate,  octanesulfonate,  dodecylbenzenesulfonate,  butanesulfonate,  methane- sulfonate, 1,1-difluoro-2-naphthyl-ethanesulfonate, 1,1,2,2- tetrafluoro-2-(norbornan-2-yl)ethanesulfonate, and 1,1,2,2- tetrafluoro-2-(tetracyclo[ 4.4.0.1 2 • $^{5 }$.l 7•$^{10}$]dodec-3-en-8-yl)  ethanesulfonate.  Sulfonyldiazomethane compounds which can be used  herein include those described in U.S. Pat. No. 7,498,126  (JP-A 2007-333933, paragraph [0073]). Exemplary sulfonyl› diazomethane compounds include bissulfonyldiazomethane  compounds and sulfonylcarbonyldiazomethane compounds  such as bis( ethylsulfonyl)diazomethane, bis(l-methylpro- py lsulfony l)diazomethane, bis(2-methy lpropy lsulfony I )dia› zomethane,  bis( 1, 1-dimethylethy lsulfony I )diazomethane,  bis(cyclohexylsulfonyl)diazomethane, bis(perfluoroisopro› pylsulfonyl)diazomethane,  bis(phenylsulfonyl)diaz› omethane, bis( 4-methylphenylsulfonyl)diazomethane, bis(2,  4-dimethylphenylsulfonyl)diazomethane,  bis( 4- acetyloxyphenylsulfonyl)diazomethane,  bis( 4- methanesulfonyloxyphenylsulfonyl)diazomethane, bis( 4-( 4- toluenesulfonyloxy)phenylsulfonyl)diazomethane,  bis(2- naphthylsulfonyl )diazomethane,  4-methylphenylsulfonylbenzoyldiazomethane, tert-butylcar› bonyl-4-methylphenylsulfonyldiazomethane, 2-naphthylsul› fony lbenzoy ldiazomethane,  4-methy lpheny lsulfony 1-2- naphthoyldiazomethane,  methylsulfonylbenzoyldiazomethane, and tert-butoxycarbo› ny 1-4-methy lphenylsulfony ldiazomethane.  4-n-butoxynaphthyl-1-thiacyclopentanium, and 2-n-butox› ynaphthyl-1-thiacyclopentanium.  Exemplary  sulfonates  include  trifluoromethanesulfonate,  pentafluoroethane› sulfonate, heptafluoropropanesulfonate, nonafluoro butane› sulfonate, tridecafluorohexanesulfonate, perfluoro( 4-ethyl- cyclohexane )sulfonate, heptadecafluorooctanesulfonate, 2,2,  2-trifluoroethanesulfonate,  pentafluorobenzenesulfonate,  4-(trifluoromethyl)benzenesulfonate,  4-fluorobenzene› sulfonate, mesitylenesulfonate, 2,4,6-triisopropylbenzene› sulfonate, toluenesulfonate, benzenesulfonate, 4-(p-toluene- sulfonyloxy)benzenesulfonate,  6-(p-toluenesulfonyloxy)  naphthalene-2-sulfonate,  4-(p-toluenesulfonyloxy)  naphthalene-1-sulfonate,  5-(p-toluenesulfonyloxy)  naphthalene-1-sulfonate,  8-(p-toluenesulfonyloxy)  naphthalene-1-sulfonate,  naphthalenesulfonate,  camphorsulfonate,  octanesulfonate,  dodecy lbenzene› sulfonate, butanesulfonate, methanesulfonate, 1, l-difluoro- 2-naphthylethanesulfonate,  1, 1,2,2-tetrafluoro-2-(norbor› nan-2-yl)ethanesulfonate,  1, 1,2,2-tetrafluoro-2-(tetracyclo  [ 6.2.1.1 3 • $^{6 }$.02 • $^{7}$]dodec-3-en-8-yl)ethanesulfonate,  2-benzoy loxy-1, 1,3 ,3 ,3-pentafluoropropanesulfonate, 1, 1,3,  3 ,3-pentafluoro-2-( 4-pheny lbenzoy loxy )propanesulfonate,  1, 1,3 ,3 ,3-pentafluoro-2-pivaloy loxypropanesulfonate, 2-cy› clohexanecarbony loxy-1, 1,3 ,3 ,3-pentafluoropropane- sulfonate,  1, 1,3,3,3-pentafluoro-2-furoyloxypropane- sulfonate,  2-naphthoy loxy-1, 1,3 ,3 ,3- pentafluoropropanesulfonate, 2-( 4-tert-buty lbenzoy loxy )-1,  1,3,3,3-pentafluoropropanesulfonate,  2-(1- adamantanecarbony loxy )-1, 1,3 ,3 ,3- pentafluoropropanesulfonate,  2-acety loxy-1, 1,3 ,3 ,3- 1, 1,3 ,3 ,3-pentafluoro-2- 1, 1,3,3,3-pentafluoro-2- 1,1-difluoro-2- pentafluoropropanesulfonate,  hydroxypropanesulfonate,  tosyloxypropanesulfonate,  tosyloxyethanesulfonate,  adamantanemethoxycarbonyldifluoromethanesulfonate,  1-(3-hydroxymethyladamantane )methoxycarbonyldifluo› romethanesulfonate,  methoxycarbonyldifluo› romethanesulfonate, l-(hexahydro-2-oxo-3,5-methano-2H› cyclopenta[b ]furan-6-yloxy-carbonyl)  difluoromethanesulfonate,  and  4-oxo-1- adamanty loxycarbony ldifluoromethanesulfonate.  Exemplary bis(substituted alkylsulfonyl)imides include bis  ( trifluoromethy lsulfony l)imide,  bis(pentafluoroethy lsulfo- ny l)imide, bis(heptafluoropropylsulfonyl)imide, and per› fluoro(l ,3-propylenebissulfonyl)imide.  A  typical  tris  (substituted  alkylsulfonyl)methide  is  tris  (trifluoromethylsulfonyl)methide. Sulfonium salts based on  combination of the foregoing examples are included. 