66  US 8,114,570 B2  65  Herein R$^{325 }$is a C$_{6}$-C$_{20 }$aryl group or C$_{4}$ -C$_{20 }$hetero-aromatic  group, in which some or all hydrogen atoms may be replaced  by halogen atoms, straight, branched or cyclic C$_{1 }$-C$_{20 }$alkyl  groups,  CcC$_{20 }$ aryl groups, C$_{7}$ -C$_{20 }$aralkyl groups, C$_{1 }$-C$_{10 }$ alkoxy groups, C$_{1 }$-C$_{10 }$ acyloxy groups or C$_{1 }$-C$_{10 }$ alkylthio  groups. R$^{326 }$is CO$_{2}$R 327 , OR $^{328 }$or cyano group. R$^{327 }$is a  C$_{1 }$-C$_{10 }$alkyl group, in which some methylene groups may be  replaced by oxygen atoms. R$^{328 }$is a C$_{1 }$-C$_{10 }$ alkyl or acyl  group, in which some methylene groups may be replaced by  oxygen atoms. R$^{329 }$is a single bond, methylene, ethylene,  sulfur atom or---O(CH$_{2}$CH$_{2}$O)h-group whereinh is 0, 1, 2,  3 or 4. R 330  is hydrogen, methyl, ethyl or phenyl. T is a  nitrogen atom or CR 331 . U is a nitrogen atom or CR 332 . V is  a nitrogen atom or CR 333 . R 331 , R $^{332 }$and R$^{333 }$are each inde› pendently hydrogen, methyl or phenyl. Alternatively, a pairof  R$^{331 }$andR$^{332 }$or a pairofR$^{332 }$and R$^{333 }$may bond together to  form a C$_{6}$-C$_{20 }$aromatic ring or C$_{2}$-C$_{20 }$hetero-aromatic ring  with the carbon atoms to which they are attached.  Further included are amine compounds of 7-oxanorbor› nane-2-carboxylic ester structure, represented by the general  formula (Am-15).  Herein R$^{334 }$is hydrogen or a straight, branched or cyclic  C$_{1 }$-C$_{10 }$alkyl group. R$^{335 }$and R$^{336 }$are each independently a  C$_{1 }$-C$_{20 }$ alkyl group, C$_{6}$-C$_{20 }$ aryl group or C$_{7}$-C$_{20 }$ aralkyl  group, which may contain one or more polar functional  groups selected from among ether, carbonyl, ester, alcohol,  sulfide, nitrile, amine, imine, and amide and in which some  hydrogen atoms may be replaced by halogen atoms. R$^{335 }$and  R 336 , taken together, may form a C $_{2}$-C$_{20 }$heterocyclic or het› ero-aromatic ring with the nitrogen atom to which they are  attached.  The quenchers may be used alone or in admixture of two or  more. The quencher is preferably formulated in an amount of  0.001 to 2 parts, and especially 0.01 to 1 part by weight, per  100 parts by weight of the base resin. Less than 0.001 phr of  the quencher may achieve no addition effect whereas more  than 2 phr may lead to too low a sensitivity.  ComponentE  In one preferred embodiment, the resist composition fur› ther contains (E) an auxiliary photoacid generator other than  the photoacid generator of formula (la).  It may be any com› pound capable of generating an acid upon exposure to high› energy radiation such as UV, deep UV, electron beam, EUV,  x-ray, excimer laser beam, gamma-ray or synchrotron radia- tion. Suitable auxiliary photoacid generators include sulfo› nium salts, iodonium salts, sulfonyldiazomethane, N-sulfo› nyloxydicarboxyimide,  O-arylsulfonyloxime  and  O-alkylsulfonyloxime photoacid generators. Exemplary aux- iliary photoacid generators are given below while they may be  used alone or in admixture of two or more.  Sulfonium salts are salts of sulfonium cations with sul› fonates, bis(substituted alkylsulfonyl)imides and tris(substi› tuted alkylsulfonyl)methides. Exemplary sulfonium cations  include triphenylsulfonium, ( 4-tert-butoxyphenyl)diphenyl› sulfonium, bis( 4-tert-butoxyphenyl)phenylsulfonium, tris( 4- tert-butoxyphenyl )sulfonium,  (3-tert-butoxypheny l)diphe› ny lsulfonium, bis(3-tert-butoxyphenyl)phenylsulfonium, tris  (3-tert-butoxypheny l)sulfonium, (3 ,4-di-tert-butoxyphenyl)  dipheny lsulfonium,  bis(3 ,4-di-tert-butoxyphenyl)  pheny lsulfonium,  tris(3 ,4-di-tert-butoxyphenyl )sulfonium,  diphenyl( 4-thiophenoxyphenyl)sulfonium,  ( 4-tert-butoxy› carbony lmethy loxypheny I )dipheny lsulfonium,  tris( 4-tert› butoxycarbony lmethy loxyphenyl )sulfonium, ( 4-tert-butox- yphenyl)bis( 4-dimethylaminophenyl)sulfonium,  tris( 4- dimethylaminophenyl)sulfonium,  4-methylphenyldiphenylsulfonium, 4-tert-butylphenylsulfo› nium, bis( 4-methylphenyl)phenylsulfonium, bis( 4-tert-bu› ty !phenyl )pheny lsulfonium, tris( 4-methy !phenyl )sulfonium,  tris( 4-tert-butylphenyl)sulfonium, tris(phenylmethyl)sulfo› nium, 2-naphthyldiphenylsulfonium, dimethyl(2-naphthyl)  sulfonium, 4-hydroxyphenyldimethylsulfonium, 4-methox› yphenyldimethylsulfonium,  trimethylsulfonium,  2-oxocyclohexy lcyclohexy lmethy lsulfonium,  trinaphthyl- sulfonium, tribenzylsulfonium, diphenylmethylsulfonium,  dimethylphenylsulfonium, 2-oxopropylthiacyclopentanium,  2-oxobuty lthiacyclopentanium, 2-oxo-3 ,3-dimethy lbuty lthi› acyclopentanium, 2-oxo-2-phenylethylthiacyclopentanium,  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, mesity lenesulfonate, 2,4, 6-triisopropy lbenzene› 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-pivaloyloxypropanesulfonate, 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,  pentafluoropropanesulfonate,  hydroxypropanesulfonate,  tosyloxypropanesulfonate,  tosyloxyethanesulfonate,  2-acetyloxy-l, 1,3,3,3- 1, 1,3,3,3-pentafluoro-2- 1, 1,3,3,3-pentafluoro-2- 1, l-difluoro-2- (Arn-13)  R330  R325  o,  /’-....  A  ’y’  ’-..../  ’N ~V  II  \  /  O  T=u  (Arn-14)  -continued  (Arn-15) 