Examples of the monovalent hydrocarbon group Rq 2 are as exemplified above for the monovalent hydrocarbon group Rq 1 . Also included are fluorinated alkyl groups such as trifluoromethyl, trifluoroethyl, 2,2,2-trifluoro-l-methyl-1- hydroxyethyl, 2,2,2-trifluoro-l-(trifluoromethyl)-1-hy› droxyethyl, aryl groups such as phenyl, tolyl, xylyl, 4-tert› butylphenyl, and naphthyl, and fluorinated aryl groups such as pentafluorophenyl, 4-trifluoromethylphenyl, and 4-amino-2,3,5,6-tetrafluorophenyl. In formulae ( 4-1) and ( 4-2), Mq+ is an onium cation. Suitable onium cations include sulfonium, iodonium and ammonium cations, with the sulfonium or iodonium cations being preferred. 

[0155] Also useful are quenchers of polymer type as described in U.S. Pat. No. 7,598,016 (JP-A 2008-239918). The polymeric quencher segregates at the resist surface after coating and thus enhances the rectangularity of resist pat› tern. When a protective film is applied as is often the case in the immersion lithography, the polymeric quencher is also effective for preventing a film thickness loss of resist pattern or rounding of pattern top. 

[0156] The other quencher is preferably added in an amount of 0 to 5 parts, more preferably 0 to 4 parts by weight per 100 parts by weight of the base polymer. The other quencher may be used alone or in admixture. 

[0157] To the resist composition, a polymeric additive or water repellency improver may also be added for improving the water repellency on surface of a resist film as spin coated. 

[0158] The water repellency improver may be used in the topcoatless immersion lithography. Suitable water repel› lency improvers include polymers having a fluoroalkyl group and polymers having a specific structure with a 1,1,1,3,3,3-hexafluoro-2-propanol residue and are described in JP-A 2007-297590 and JP-A 2008-111103, for example. The water repellency improver to be added to the resist composition should be soluble in the organic solvent as the developer. The water repellency improver of specific struc› ture with a 1,1,1,3,3,3-hexafluoro-2-propanol residue is well soluble in the developer. A polymer having an amino group or amine salt copolymerized as recurring units may serve as the water repellent additive and is effective for preventing evaporation of acid during PEB, thus preventing any hole pattern opening failure after development. The water repel› lency improver may be used alone or in admixture. An appropriate amount of the water repellency improver is 0 to 20 parts, more preferably 0.5 to 10 parts by weight per 100 parts by weight of the base polymer. 

[0159] Also, an acetylene alcohol may be blended in the resist composition. Suitable acetylene alcohols are described in JP-A 2008-122932, paragraphs [0179]-[0182]. An appro› priate amount of the acetylene alcohol blended is Oto 5 parts by weight per 100 parts by weight of the base polymer. 

## Pattern Forming Process 

[0160] The resist composition is used in the fabrication of various integrated circuits. Pattern formation using the resist composition may be performed by well-known lithography processes. The process generally involves coating, prebak› ing, exposure, and development. If necessary, any additional steps may be added. 

[0161] For example, the resist composition is first applied onto a substrate on which an integrated circuit is to be formed (e.g., Si, SiO$_{2}$ , SiN, SiON, TiN, WSi, BPSG, SOG, or organic antireflective coating) or a substrate on which a 

mask circuit is to be formed ( e.g., Cr, CrO, CrON, MoSi$_{2}$ , or SiO$_{2}$ ) by a suitable coating technique such as spin coating, roll coating, flow coating, dipping, spraying or doctor coating. The coating is prebaked on a hot plate at a temperature of 60 to 150° C. for 10 seconds to 30 minutes, preferably at 80 to 120° C. for 30 seconds to 20 minutes. The resulting resist film is generally 0.01 to 2 µm thick. 

[0162] The resist film is then exposed to a desired pattern of high-energy radiation such as UV, deep-UV, EB, EUV, x-ray, soft x-ray, excimer laser light, y-ray or synchrotron radiation. When UV, deep-UV, EUV, x-ray, soft x-ray, exci› mer laser light, y-ray or synchrotron radiation is used as the high-energy radiation, the resist film is exposed thereto through a mask having a desired pattern in a dose of preferably about 1 to 200 mJ/cm 2 , more preferably about 10 to 100 mJ/cm 2 . When EB is used as the high-energy radia› tion, the resist film is exposed thereto through a mask having a desired pattern or directly in a dose of preferably about 0.1 to 100 µC/cm 2 , more preferably about 0.5 to 50 µC/cm 2 . It is appreciated that the inventive resist composition is suited in micropatterning using KrF excimer laser, ArF excimer laser, EB, EUV, x-ray, soft x-ray, y-ray or synchrotron radiation, especially in micropatterning using EB or EUV. 

[0163] After the exposure, the resist film may be baked (PEB) on a hot plate at 60 to 150° C. for 10 seconds to 30 minutes, preferably at 80 to 120° C. for 30 seconds to 20 minutes. 

[0164] After the exposure or PEB, in the case of positive resist, the resist film is developed in a developer in the form of an aqueous base solution for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes by conventional tech› niques such as dip, puddle and spray techniques. A typical developer is a 0.1 to 10 wt%, preferably 2 to 5 wt% aqueous solution of tetramethylammonium hydroxide (TMAH), tet› raethylammonium hydroxide (TEAH), tetrapropylammo› nium hydroxide (TPAH), or tetrabutylammonium hydroxide (TBAH). The resist film in the exposed area is dissolved in the developer whereas the resist film in the unexposed area is not dissolved. In this way, the desired positive pattern is formed on the substrate. Inversely in the case of negative resist, the exposed area of resist film is insolubilized and the unexposed area is dissolved in the developer. 

[0165] In an alternative embodiment, a negative pattern may be formed via organic solvent development using a positive resist composition comprising a base polymer hav› ing an acid labile group. The developer used herein is preferably selected from among 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 pentenoate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropi› onate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate, and mixtures thereof. 

