US 10,323,113 B2  146  145  -continued  -continued  wherein R  1  is hydrogen, hydroxy, carboxy, nitro, cyano,  fluorine, chlorine, bromine, amino group, or a straight,  branched or cyclic, C$_{1 }$-C$_{20 }$ alkyl, C$_{1 }$-C$_{20 }$ alkoxy,  C$_{2}$-C$_{20 }$alkoxycarbonyl, C$_{2}$-C$_{20 }$acyloxy or C$_{1}$-C$_{4 }$ alkyl- sulfonyloxy group, which may contain fluorine, chlo› rine, bromine, hydroxy, amino or alkoxy moiety, or  -NR’----C(=0)-R $^{8 }$or-NR$^{7}$-C(=0)---0-R8 ,  R 7  is hydrogen, or a straight, branched or cyclic C$_{1 }$-C$_{6 }$ alkyl group which may contain halogen, hydroxy,  alkoxy, acyl or acyloxy moiety, R 8  is a straight,  branched or cyclic, C$_{1 }$-C$_{16 }$ alkyl or C$_{2}$-C$_{16 }$ alkenyl  group, or  CcC$_{12 }$ aryl group, which may contain halo› gen, hydroxy, alkoxy, acyl or acyloxy moiety,  X 1  is a single bond or a C$_{1}$-C$_{20 }$ divalent linking group  when p=l, or a C$_{1}$-C$_{20 }$ tri- or tetravalent linking  group when p=2 or 3, the linking group optionally  containing an oxygen, sulfur or nitrogen atom,  Rf$^{1 }$to Rf4 are each independently hydrogen, fluorine or 30  trifluoromethyl, at least one of Rf 1  to Rf4 being  fluorine or trifluoromethyl, or Rf 1  and Rf 2 , taken  together, may form a carbonyl group,  R 2 , R 3 , R 4 , R 5  and R$^{6 }$are each independently a C$_{1}$-C$_{12 }$ straight, branched or cyclic alkyl group which may  contain an oxo moiety, C$_{2}$ -C$_{12 }$straight, branched or  cyclic alkenyl group which may contain an oxo  moiety, C$_{2}$-C$_{12 }$ straight, branched or cyclic alkynyl  group,  CcC$_{20 }$ aryl group, C$_{7}$-C$_{12 }$ aralkyl group or  C$_{7}$ -C$_{12 }$ aryloxyalkyl group, in which at least one  hydrogen may be substituted by a hydroxy, carboxy,  halogen, cyano, amide, nitro, sultone, sulfone or  sulfonium salt-containing moiety, or in which an  ether, ester, carbonyl, carbonate or sulfonic acid ester  moiety may intervene between carbon atoms, or R 2  and R 3  may bond together to form a ring with the  sulfur atom to which they are attached,  m is an integer of  1  to 5, n is an integer of  O  to 3, and  p is an integer of  1  to 3.  3.  The resist composition of claim  1  wherein the base  polymer comprises recurring units having the formula (al)  or recurring units having the formula (a2):  2.  The resist composition of claim  1,  further comprising  an organic solvent.  wherein  RA  is each independently hydrogen or methyl, Y 1  is a single bond,  C$_{1 }$-C$_{12 }$ linking group containing ester  group or lactone ring, phenylene group or naphthylene  group, Y 2  is a single bond or ester group, and R $^{12 }$each  are an acid labile group, R $^{13 }$is fluorine, trifluoromethyl,  cyano, a C$_{1 }$-C$_{6 }$ straight, branched or cyclic alkyl or  alkoxy group, or a C$_{2}$ -C$_{7 }$ straight, branched or cyclic  acyl, acyloxy or alkoxycarbonyl group, R$^{14 }$is a single  bond or C$_{1 }$-C$_{6 }$ straight or branched alkylene group in  which at least one carbon atom may be substituted by  an ether or ester moiety, q is  1  or 2, and r is an integer  of Oto  4.  4.  The resist composition of claim  3,  further comprising  a dissolution inhibitor.  5.  The resist composition of claim  3  which is a chemically  amplified positive resist composition.  6.  The resist composition of claim  1  wherein the base  polymer is free of an acid labile group.  7.  The resist composition of claim  6,  further comprising  a crosslinker.  8.  The resist composition of claim  6  which is a chemically  amplified negative resist composition.  9.  The resist composition of claim  1,  further comprising  a surfactant.  10.  The resist composition of claim  1  wherein the base  polymer further comprises recurring units of at least one  type selected from the formulae  (fl) to (f3):  (fl)  (f2)  (fJ)  (al)  (A-2)  (a2)  {fi  y2  ’-.. Rl4  r]_Rl3  (OR12)q  R37  I  +s-R3s  I  R39  R34  I  +s-R35  I  R36 