169  US 9,250,518 B2  170  -continued  wherein R  1  is hydrogen, or a straight, branched or cyclic  C$_{1 }$-C$_{30 }$ alkyl,  CcC$_{30 }$ aryl, C$_{7}$-C$_{30 }$ aralkyl, C$_{2}$-C$_{30 }$ alkenyl,  C$_{2}$ -C$_{10 }$alkenyl, or C$_{4}$ -C$_{12 }$heterocyclic-bearing group, or a  combination of such groups, which group may contain a  hydroxyl, mercapto, carboxyl, ether, thio ether, ester, sulfonic  acid ester, sulfonyl, lactone ring, carbonyl, cyano, nitro, halo- gen, trifluoromethyl, amide, imide, sulfonamide, carbonate,  sulfide, -N=CR---0-, -N=CR-S-, or  N-O› N=moiety, or R $^{1 }$may be an acid labile group; R is hydrogen,  mercapto, hydroxyl or C$_{1 }$-C$_{3 }$ alkyl, or may bond with the  nitrogen atom in formula (1) to form a ring; R $^{2 }$and R$^{3 }$each are  hydrogen, a straight or branched C$_{1 }$-C$_{4 }$ alkyl group or C$_{2}$-C$_{4 }$ alkenyl group, or R$^{2 }$andR$^{3 }$may bond together to form a ring  with the carbon atom to which they are attached; R 4 ,  Rs and  R  6  are each independently a straight, branched or cyclic  C$_{1 }$-C$_{12 }$alkyl, alkenyl, oxoalkyl or oxoalkenyl group,  CcC$_{20 }$ aryl, C$_{7}$ -C$_{12 }$aralkyl or aryloxoalkyl group, in which at least  one hydrogen atom may be substituted by an ether, ester,  carbonyl, carbonate, hydroxyl, carboxyl, halogen, cyano,  amide, nitro, sultone, sulfonic acid ester, sulfone moiety, or  sulfonium salt-containing substituent, R 4  and Rs may bond  together to form a ring with the sulfur atom to which they are  attached; R$^{7 }$and R $^{8 }$each are a C$_{6}$-C$_{20 }$aryl group which may  contain a straight, branched or cyclic C$_{1 }$-C$_{10 }$alkyl or alkoxy  moiety, and mis an integer of 2 to 8.  13.  The resist composition of claim  12  wherein the base  polymer further comprises recurring units (al) derived from  (meth)acrylate, styrenecarboxylic acid or vinylnaphthalen› ecarboxylic acid having an acid labile group substituted  thereon, or recurring units (a2) derived from hydroxystyrene  having an acid labile group substituted thereon, as repre› sented by the general formula (2):  14.  A process for forming a pattern comprising the steps of  applying a resist composition onto a substrate, baking to form  a resist film, exposing the resist film to ArF excimer laser  radiation of 193 nm wavelength or KrF excimer laser radia- tion of 248 nm wavelength, and developing the exposed film  with a developer,  wherein R  1  is hydrogen, or a straight, branched or cyclic  C$_{1 }$-C$_{30 }$ alkyl,  CcC$_{30 }$ aryl, C$_{7}$ -C$_{30 }$ aralkyl, C$_{2}$ -C$_{30 }$ alkenyl,  C$_{2}$-C$_{10 }$ alkenyl, or C$_{4}$ -C$_{12 }$heterocyclic-bearing group, or a  combination of such groups, which group may contain a  hydroxyl, mercapto, carboxyl, ether, thio ether, ester, sulfonic  acid ester, sulfonyl, lactone ring, carbonyl, cyano, nitro, halo› gen, trifluoromethyl, amide, imide, sulfonamide, carbonate,  sulfide, -N=CR---0-, -N=CR-S-, or  N-O› N=moiety, or R $^{1 }$may be an acid labile group; R is hydrogen,  mercapto, hydroxyl or C$_{1 }$-C$_{3 }$ alkyl, or may bond with the  nitrogen atom in formula (1) to form a ring; R $^{2 }$and R$^{3 }$each are  hydrogen, a straight or branched C$_{1 }$-C$_{4 }$ alkyl group or C$_{2}$-C$_{4 }$ alkenyl group, or R$^{2 }$andR$^{3 }$may bond together to form a ring  with the carbon atom to which they are attached; R 4 ,  Rs and  R  6  are each independently a straight, branched or cyclic  C$_{1 }$-C$_{12 }$alkyl, alkenyl, oxoalkyl or oxoalkenyl group, C$_{6}$-C$_{20 }$ aryl, C$_{7}$ -C$_{12 }$aralkyl or aryloxoalkyl group, in which at least  one hydrogen atom may be substituted by an ether, ester,  carbonyl, carbonate, hydroxyl, carboxyl, halogen, cyano,  amide, nitro, sultone, sulfonic acid ester, sulfone moiety, or  sulfonium salt-containing substituent, R 4  and Rs may bond  together to form a ring with the sulfur atom to which they are  attached; R$^{7 }$and R$^{8 }$each are a  CcC$_{20 }$ aryl group which may  contain a straight, branched or cyclic C$_{1 }$-C$_{10 }$alkyl or alkoxy  moiety, and m is an integer of 2 to 8.  15.  A process for forming a pattern comprising the steps of  applying a resist composition onto a substrate, baking to form  a resist film, exposing the resist film to electron beam or  extreme ultraviolet radiation of 3 to 15 nm wavelength, and  developing the exposed film with a developer,  wherein the resist composition comprises a base polymer  and a sulfonium salt having the general formula (1 )-1 or  a iodonium salt having the general formula (1)-2,  wherein the resist composition comprises a base polymer  and a sulfonium salt having the general formula (1 )-1 or  a iodonium salt having the general formula (1)-2,  wherein R 9  and R  11  are each independently hydrogen or  methyl, Xis a single bond, a C$_{1 }$-C$_{12 }$linking group hav› ing an ester moiety or lactone ring, phenylene group or  naphthylene group, Y is a single bond or ester group, and  R $^{10 }$and R $^{12 }$are each independently an acid labile group.  (1)-2  ( 2 (1)-1  (1)-2  (1)-1 