171  US 9,360,753  B2  172  2.  The chemically amplified resist composition of claim  1,  wherein in addition to the recurring units (al) and (a2), the  copolymer comprises recurring units (bl), (b2) or (b3) of a  sulfonium salt having the general formula (2):  3.  The chemically amplified resist composition of claim  1,  further comprising at least one component selected from the  group consisting of an organic solvent, a dissolution inhibitor,  an acid generator, a basic compound, and a surfactant.  4.  The chemically amplified resist composition of claim  1,  wherein the metal salt is present in an amount ofO.55 to 20  parts by weight per 100 parts by weight of the polymer.  5.  The chemically amplified resist composition of claim  1,  wherein said metal salt is selected from the group consisting  of the following general formulae:  6.  A pattern forming process comprising the steps of coat› ing the chemically amplified resist composition of claim  1  onto a substrate, baking, exposing to high-energy radiation,  and developing with a developer.  7.  The process of claim  6  wherein the high-energy radiation  is EUV radiation having a wavelength of 3 to 15 nm.  8.  The process of claim  6  wherein the high-energy radiation  is an electron beam at an accelerating voltage of 1 to 150 ke  V.  *  *  *  *  *  whereinR 120 , R 124 , andR 128  eacharehydrogenormethyl,  R 121  is a single bond, phenylene, ---0-R-, or  ----C( =0)-Y  -R-,  Y is oxygen or NH, Risa straight,  branched or cyclic  C 1 -C 6  alkylene group,  C 3 -C$_{10 }$ alk- 30  enylene or phenylene group, which may contain a car› bonyl, ester, ether or hydroxyl moiety, R 122 , R 123 , R 125 ,  R 126 , R 127 , R 129 , R 130 , and R 131  are each independently  a straight, branched or cyclic C 1  -C$_{12 }$alkyl group which  may contain a carbonyl, ester or ether moiety, or a 35  CcC$_{12 }$ aryl,  C 7 -C$_{20 }$ aralkyl, or thiophenyl group which  may contain a straight, branched or cyclic C 1  -C$_{10 }$alkyl,  halogen, trifluoromethyl, cyano, nitro, hydroxyl, alkoxy,  alkoxycarbonyl or acyloxy radical, Z 1  is a single bond or  ----C(=0)-Z 3 -R 132 -, Z 2  is a single bond, methyl- 40  ene,  ethylene,  phenylene,  fluorinated  phenylene  ---O-R 132 -or----C(=0)-Z 3 -R 132 , Z 3  is oxygen or  NH, R 132  is a straight, branched or cyclic C 1 -C 6  alkylene  group, alkenylene, orphenylene group, which may con› tain a carbonyl, ester, ether or hydroxyl moiety, a pair of  45  R122 and R123, R12s and R126, R12s and R127, R126 and  R127,R129 andR130,R129 andR131,orR130 andR131 may  bond directly or via a methylene moiety or ether bond to  form a ring with the sulfur atom, R 133  is hydrogen or  trifluoromethyl,  M- is a non-nucleophilic counter ion,  bl, b2 and b3 are in the range ofOsblsO.5, Osb2sO.5,  Osb3sO.5, and Osbl+b2+b3sO.5.  50  said metal salt being present in an amount of 0.02 to 30  parts by weight per 100 parts by weight of the polymer.  wherein R  11  is each independently hydrogen, or a straight,  branched or cyclic  C  1  -C$_{20 }$ alky 1,  C 2 -C$_{20 }$ alkeny 1,  C 2 -C$_{20 }$ alkynyl, or C 6 -C 20  aryl group which may have a  hydroxyl, ether, ester, amino, amide, sulfonic acid ester,  halogen, cyano, nitro, carbonate, carbamate, thiol, sul› fide, thioketone radical or hetero-aromatic ring; R 12  is a  single bond, or a straight, branched or cyclic C 1  -C$_{20 }$ alkylene, alkenylene, alkynylene, or C 6 -C 20  arylene  group which may have a hydroxyl, ether, ester, amino,  amide, sulfonic acid ester, halogen, cyano, nitro, carbon› ate, carbamate, thiol, sulfide, thioketone radical or het› ero-aromatic ring; R 13  and R 14  each are an alkylene,  arylene, alkenylene or alkynylene group as defined for  R  12 , in which one or two hydrogen atoms are substituted  by one or two carboxyl groups.  (2)  ~  Rl21  I  R122_ 8 + -R123  M- Rl25  I  +s-R126  I  Rl27  Rl29  I  +s-R130  I  Rl31  cr’•(R  11 coo-h  Cr 3 •(R 11 coo-h  cr’•R  12 ccoo-h  (Cr $^{3}$•h(R 12 coo-Joh Cr$_{3 }$ $^{3}$•(R  11 coo-h(OH)o  (Cr $^{3}$.h(R$^{13}$Coo-)$_{6 }$ Mn 2 •(R 11 coo-)o  (Mn $^{3}$•h(R 12 (COO-)o)$_{3 }$ Fe 2 •R 12 (COO-)o  Fe $^{3}$.R $^{13}$(coo-h  ca 2 •(R 11 coo-)o  Fe $^{3}$•(R  $_{l }$1 coo-h  Fe 2 •(R 11 coo-)o  Co 2 •R 12 (COO-h  Ni 2 •R  12 ccoo-h  (Zn•) 2 R 12 (COO-)2  (Ag.JoR 12 ccoo-h  cd 2 •R 12 ccoo-h  Sn 2 •R 12 (coo-) 2  Sn 4 •R 14 (COO-) 4  (Sb$^{3}$.h(R  12 ccoo-J  2)3  Ni 2 •cR 11 coo-h  zn•R 11 coo› Ag•R11coo› cd 2 •cR 11 coo-h  sn 2 •(R 11 coo-) 2  Sn 4 •(R  12 (COO-)o)o  Sb $^{3}$.(R  11 coo-)$_{3 }$ Sb $^{3}$.R$^{13}$(coo-)$_{3 }$ Hf’•R 14 (coo-J 4  Hf’•(R  12 ccoo-hJ2 