US 9,869,931 B2  178  177  4-cyclohexylcarbonyloxy-2,3,5,6-tetrafluorophenyl,  4-adamantylcarbonyloxy-2,3 ,5, 6-tetrafluoropheny 1,  4-phenylcarbonyloxy-2,3,5,6-tetrafluorophenyl,  4-cy› clohexylsulfonyl-2,3,5,6-tetrafluorophenyl, and 4-phe› nylsulfonyl-2,3,5,6-tetrafluorophenyl,  R 15 ,  R 16 ,  R 17 ,  R 18 , and  R 19  are each independently  fluorine, trifluoromethyl, pentafluoroethyl, trifluoro› ethyl, octafluorobutyl, or nonafluorobutyl,  R $^{15 }$and  R 16  may bond together to form a ring,  R 20 ,  R 21 ,  R 22 , and  R $^{23 }$are each independently fluorine or  trifluoromethyl, each of p, q, r and s is an integer of 1  to 5.  12.  A pattern forming process comprising the steps of  coating the resist composition of claim  11  onto a substrate,  baking, exposing the resulting resist film to high-energy  radiation, and developing with a developer.  13.  A pattern forming process comprising the steps of  coating a resist composition onto a substrate, baking, expos› ing the resulting resist film to high-energy radiation, and  developing with a developer;  wherein the resist composition comprises recurring units  of acid labile group-substituted (meth)acrylic acid,  styrenecarboxylic acid or vinylnaphthalenecarboxylic  acid and/or recurring units having an acid labile group- substituted phenolic hydroxyl group, and an acid gen› erator, or a copolymer comprising recurring units of  acid labile group-substituted (meth)acrylic acid, styren› ecarboxylic acid or vinylnaphthalenecarboxylic acid  and/or recurring units having an acid labile group- substituted phenolic hydroxyl group and recurring units  having an acid generator, and  said resist composition further comprises a complex of a  metal with an acid, the metal being selected from the  group consisting of cerium, copper, zinc, iron, indium,  yttrium, ytterbium, tin, thulium, scandium, nickel, neo› dymium, hafnium, zirconium, titanium, lanthanum, sil› ver, barium, holmium, terbium, lutetium, europium,  dysprosium, gadolinium, rubidium, strontium, and  cesium, and the acid being selected from the group  consisting of an alkylsulfonic acid, arylsulfonic acid,  alkylsulfonimidic acid, alkylsulfonemethide acid, and  tetraphenylboric acid each of which has at least one  fluorine atom;  wherein in the step of exposing the resist film to high› energy radiation, the surface of the substrate under› neath the resist film is electrically charged positive.  14.  A pattern forming process comprising the steps of  coating the resist composition of claim  13  onto a substrate,  baking, exposing the resulting resist film to high-energy  radiation, and developing with a developer.  * * * * *  wherein R  $^{11 }$is fluorine or an organic group selected from  the group consisting of trifluoromethyl, pentafluoro- ethyl, trifluoroethyl, octafluorobutyl, nonafluorobutyl,  2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2,4-di› fluorophenyl, 2,3-difluorophenyl, 3,4-difluorophenyl,  3,5-difluorophenyl, 2,4,5-trifluorophenyl, 2,3,4-trifluo› rophenyl, 2,3,4,5-tetrafluorophenyl, 2,3,5,6-tetrafluo- rophenyl,  2,3,4,5,6-pentafluorophenyl,  2-trifluorom› ethylphenyl,  3-trifluoromethylphenyl,  4-trifluoromethylphenyl,  2,4-di(trifluoromethyl)phe› nyl, 4-hydroxy-2,3,5,6-tetrafluorophenyl, 4-methoxy- 2,3,5,6-tetrafluorophenyl, 4-acetoxy-2,3,5,6-tetrafluo› rophenyl,  4-pivaloyloxy-2,3,5,6-tetrafluorophenyl, 