tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylol propane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tet› ravinyl ether, sorbitol pentavinyl ether, and trimethylol propane trivinyl ether. 

[0157] In the negative resist composition, the crosslinker is preferably added in an amount of 0 to 50 parts, more preferably 1 to 40 parts by weight per 100 parts by weight of the base polymer. 

[0158] In the resist composition of the invention, a quencher other than the inventive iodized aromatic N-car› bonylsulfonamide salt may be blended. The other quencher is typically selected from conventional basic compounds. Conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing com› pounds with carboxyl group, nitrogen-containing com› pounds with sulfonyl group, nitrogen-containing com› pounds with hydroxyl group, nitrogen-containing compounds with hydroxyphenyl group, alcoholic nitrogen› containing compounds, amide derivatives, imide deriva› tives, and carbamate derivatives. Also included are primary, secondary, and tertiary amine compounds, specifically amine compounds having a hydroxyl group, ether bond, ester bond, lactone ring, cyano group, or sulfonic acid ester bond as described in JP-A 2008-111103, paragraphs [0146]› [0164], and compounds having a carbamate group as described in JP 3 790649. Addition of a basic compound may be effective for further suppressing the diffusion rate of acid in the resist film or correcting the pattern profile. 

[0159] Onium salts such as sulfonium salts, iodonium salts and ammonium salts of sulfonic acids which are not fluo› rinated at a-position as described in U.S. Pat. No. 8,795,942 (JP-A 2008-158339) and similar onium salts of carboxylic acid may also be used as the other quencher. While an a-fluorinated sulfonic acid, imide acid, and methide acid are necessary to deprotect the acid labile group of carboxylic acid ester, an a-non-fluorinated sulfonic acid and a carbox› ylic acid are released by salt exchange with an a-non› fluorinated onium salt. An a-non-fluorinated sulfonic acid and a carboxylic acid function as a quencher because they do not induce deprotection reaction. 

[0160] 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. 

[0161] 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. 

[0162] 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. 

[0163] Pattern Forming Process 

[0164] 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 applying the resist composition to form a resist film on a substrate, exposing the resist film to high-energy radiation, and developing the exposed resist film in a developer. If necessary, any addi› tional steps may be added. 

[0165] 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, M0Si$_{2}$ , 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 0.1 to 2 µm thick. 

[0166] The resist film is then exposed to a desired pattern of high-energy radiation such as UV, deep-UV, EB, EUV of wavelength 3 to 15 nm, x-ray, soft x-ray, excimer laser light, y-ray or synchrotron radiation. When UV, deep-UV, EUV, x-ray, soft x-ray, excimer 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 500 mJ/cm 2 , more preferably about 10 to 200 mJ/cm 2 . When EB is used as the high-energy radiation, the resist film is exposed thereto through a mask having a desired pattern or directly in a dose of preferably about 0.1 to 500 µC/cm 2 , more preferably about 0.5 to 200 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. 

[0167] After the exposure, the resist film may be baked (PEB) on a hot plate or in an oven at 30 to 150° C. for 10 seconds to 30 minutes, preferably at 50 to 120° C. for 30 seconds to 20 minutes. 

[0168] 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. 

[0169] 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, 

