content_image/904110.jpg content_image/904108.jpg content_image/904109.jpg
wherein R’a, R:11’1, R:11’ 2 , R’c1, R’c 2 and R’c3 are each inde› pendently fluorine or a C$_{1 }$-C$_{40 }$ monovalent hydrocarbon group which may contain a heteroatom, or a pair ofR:11’$^{1 }$and R:11’ 2 , or R’c1 and R’c$^{2 }$may bond together to form a ring with the carbon atom to which they are attached and any inter› vening atoms, R’d is a monovalent hydrocarbon group which may contain a heteroatom, 

<img src='content_image/904110.jpg'>

wherein R 201 and R 202 are each independently a C$_{1}$-C$_{30 }$ monovalent hydrocarbon group which may contain a het› eroatom, R$^{203 }$is a C$_{1 }$-C$_{30 }$divalent hydrocarbon group which may contain a heteroatom, any two of R 201 , R $^{202 }$and R 203 may bond together to form a ring with the sulfur atom to which they are attached, LA is a single bond, ether bond or a C$_{1 }$-C$_{20 }$ divalent hydrocarbon group which may contain a heteroatom, xa, X 6 , xc and Xd are each independently hydrogen, fluorine or trifluoromethyl, at least one ofXa, X 6 , xc and Xd being fluorine or trifluoromethyl. 

13. The resist composition of claim 7, further comprising a compound having the formula (5) or (6): 

<img src='content_image/904108.jpg'>

<img src='content_image/904109.jpg'>

wherein Rq is hydrogen or a monovalent hydrocarbon group which may contain a heteroatom, exclusive of the group wherein hydrogen bonded to the carbon atom at a-position relative to the sulfa group is substituted by fluorine or fluoroalkyl, Rq 2 is hydrogen or a monovalent hydrocarbon group which may contain a heteroatom, and Mq+ is an onium cation. 

14. The resist composition of claim 7, further comprising an amine compound. 

15. The resist composition of claim 7, further comprising a surfactant which is insoluble or substantially insoluble in 

water and soluble in alkaline developer, and/or a surfactant which is insoluble or substantially insoluble in water and alkaline developer. 

16. A pattern forming process comprising the steps of applying the resist composition of claim 7 onto a substrate to form a resist film, exposing a selected region of the resist film to KrF excimer laser, ArF excimer laser, EB or EUV, and developing the exposed resist film in a developer. 

17. The pattern forming process of claim 16 wherein the developing step uses an alkaline aqueous solution as the developer, thereby forming a positive pattern in which an exposed region of the resist film is dissolved away and an unexposed region of the resist film is not dissolved. 

18. The pattern forming process of claim 16 wherein the developing step uses an organic solvent as the developer, thereby forming a negative pattern in which an unexposed region of the resist film is dissolved away and an exposed region of the resist film is not dissolved. 

19. The pattern forming process of claim 18 wherein the organic solvent is at least one solvent selected from the group consisting of 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pen› tenoate, methyl crotonate, ethyl crotonate, methyl propi› onate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxy› isobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phe› nylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate. 

20. The process of claim 16 wherein the exposure step is carried out by immersion lithography while a liquid having a refractive index of at least 1.0 is held between the resist film and a projection lens. 

21. The process of claim 20, further comprising the step of coating a protective film on the resist film prior to the exposure step, wherein immersion lithography is carried out while the liquid is held between the protective film and the projection lens. 

* * * * * 

