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equal to 1, B is an integer of 2 to 25, and C is an integer of 0 to 10. Preferably, Bis an integer of 4 to 20, and C is O or 1. Note that the above structural formula does not prescribe the arrangement of respective constituent units while they may be arranged either blockwise or randomly. For the preparation of surfactants in the form of partially fluorinated oxetane ring-opened polymers, reference should be made to U.S. Pat. No. 5,650,483, for example. 

[0102] The surfactant which is insoluble or substantially insoluble in water and soluble in alkaline developer is useful when ArF immersion lithography is applied to the resist composition in the absence of a resist protective film. In this embodiment, the surfactant has a propensity to segregate on the resist film surface for achieving a function of minimizing water penetration or leaching. The surfactant is also effective for preventing water-soluble components from being leached out of the resist film for minimizing any damage to the exposure tool. The surfactant becomes solubilized dur› ing alkaline development following exposure and PEB, and thus forms few or no foreign particles which become defects. The preferred surfactant is a polymeric surfactant which is insoluble or substantially insoluble in water, but soluble in alkaline developer, also referred to as "hydropho› bic resin" in this sense, and especially which is water repellent and enhances water slippage. 

[0103] Suitable polymeric surfactants include those con› taining recurring units of at least one type selected from the formulae (IA) to (IE). 

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[0104] Herein, RA is hydrogen, fluorine, methyl or trifluo› romethyl. W 1 is ----CH$_{2}$-, ----CH$_{2}$CH$_{2}$ - or ---0-, or two separate -H. Rs 1 is each independently hydrogen or a C$_{1 }$-C$_{10 }$monovalent hydrocarbon group. Rs 2 is a single bond or a C$_{1 }$-C$_{5 }$ straight or branched divalent hydrocarbon group. Rs 3 is each independently hydrogen, a C$_{1 }$-C$_{15 }$ monovalent hydrocarbon or fluorinated hydrocarbon group, or an acid labile group. When Rs 3 is a monovalent hydrocarbon or fluorinated hydrocarbon group, an ether bond (-0-) or carbonyl moiety (----C(=O)-) may intervene in a carbon› carbon bond. R5 4 is a C$_{1}$-C$_{20 }$ (u+l)-valent hydrocarbon or fluorinated hydrocarbon group, and u is an integer of 1 to 3. R5 5 is each independently hydrogen or a group having the formula. 

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wherein Rsa is a C$_{1 }$-C$_{20 }$fluorinated hydrocarbon group. Rs 6 is a C-Cis monovalent hydrocarbon or fluorinated hydrocar› bon group in which an ether bond (---0-) or carbonyl moiety (----C(=O)-) may intervene in a ca-carbon bond. [0105] The monovalent hydrocarbon group represented by Rs $^{1 }$may be straight, branched or cyclic and examples thereof include methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, adamantyl, and norbornyl. Inter alia, C$_{1 }$-C$_{6 }$ hydro› carbon groups are preferred. 2 

[0106] The divalent hydrocarbon group represented by R5 may be straight, branched or cyclic and examples thereof include methylene, ethylene, propylene, butylene, and pen› tylene. 

[0107] The monovalent hydrocarbon group represented by Rs 3 or Rs$^{6 }$may be straight, branched or cyclic and examples thereof include alkyl, alkenyl, and alkynyl groups, with the alkyl groups being preferred. Suitable alkyl groups include those exemplified for the monovalent hydrocarbon group represented by Rs $^{1 }$as well as n-undecyl, n-dodecyl, tridecyl, tetradecyl, and pentadecyl. Examples of the monovalent fluorinated hydrocarbon group represented by Rs 3 or Rs 6 include the foregoing monovalent hydrocarbon groups in which some or all carbon-bonded hydrogen atoms are sub› stituted by fluorine atoms. In these groups, an ether bond 

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