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trimethylolmethane triglycidyl ether, trimethylolpropane tri› glycidyl ether, and triethylolethane triglycidyl ether. Examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, hexamethylol melamine compounds having 1 to 6 methylol groups methoxymethylated and mixtures thereof, hexamethoxy› ethyl melamine, hexaacyloxymethyl melamine, hexameth› ylol melamine compounds having 1 to 6 methylol groups acyloxymethylated and mixtures thereof. Examples of the guanamine compound include tetramethylol guanamine, tetramethoxymethyl guanamine, tetramethylol guanamine compounds having 1 to 4 methylol groups methoxymethyl› ated and mixtures thereof, tetramethoxyethyl guanamine, tetraacyloxyguanamine, tetramethylol guanamine com› pounds having 1 to 4 methylol groups acyloxymethylated and mixtures thereof. Examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxyglycoluril, tetramethoxymethyl glycoluril, tetramethylol glycoluril compounds having 1 to 4 methylol groups methoxymethyl› ated and mixtures thereof, tetramethylol glycoluril com- pounds having 1 to 4 methylol groups acyloxymethylated and mixtures thereof. Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, tetramethylol urea compounds having 1 to 4 methylol groups methoxymethylated and mixtures thereof, and tetramethoxyethyl urea. 

Suitable isocyanate compounds include tolylene diisocya› nate, diphenylmethane diisocyanate, hexamethylene diiso› cyanate and cyclohexane diisocyanate. Suitable azide com- pounds include 1,1’-biphenyl-4,4’-bisazide, 4,4’- methylidenebisazide, and 4,4’-oxybisazide. Examples of the alkenyl ether group-containing compound include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2- propanediol divinyl ether, 1,4-butanediol divinyl ether, 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. 

In the negative resist composition, the crosslinker is preferably added in an amount of 0.1 to 50 parts, more preferably 1 to 40 parts by weight per 100 parts by weight of the base polymer. 

In the resist composition of the invention, a quencher may be blended. The quencher is typically selected from con› ventional basic compounds. Conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitro› gen-containing compounds with carboxyl group, nitrogen- containing compounds with sulfonyl group, nitrogen-con› taining compounds with hydroxyl group, nitrogen› containing compounds with hydroxyphenyl group, alcoholic nitrogen-containing compounds, amide derivatives, imide derivatives, and carbamate derivatives. Also included are primary, secondary, and tertiary amine compounds, specifi› cally amine compounds having a hydroxyl, ether, ester, lactone ring, cyano, or sulfonic acid ester group as described in JP-A 2008-111103, paragraphs [0146]-[0164], and com› pounds 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. 

Onium salts such as sulfonium salts, iodonium salts and ammonium salts of sulfonic acids which are not fluorinated 65 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 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 carboxylic 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. 

Also a carboxylic acid onium salt having the formula (1) is useful as the quencher. 

In formula (1 ), R 101 is a C$_{1 }$-C$_{40 }$ straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom. MA+ is an onium ion such as a sulfonium or iodonium ion. Suitable sulfonium ions are as exemplified above as the cation moiety in the sulfonium salt having formula (1-1 ). Suitable iodonium ions are as exemplified above as the cation moiety in the iodonium salt having formula (1-2). 

Preferably the anion moiety in the carboxylic acid onium salt has the formula (2). 

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In formula (2), R 102 and R 103 are each independently hydrogen, fluorine or trifluoromethyl. R 14 is hydrogen, hydroxyl, a C$_{1 }$-C$_{35 }$ straight, branched or cyclic monovalent hydrocarbon group which may contain a heteroatom, or a substituted or unsubstituted C$_{6}$-C$_{30 }$aryl group. 

Also useful are quenchers of polymer type as described in U.S. Pat. No. 7,598,016 (JP-A2008-239918). The polymeric quencher segregates at the resist surface after coating and thus enhances the rectangularity of resist pattern. When a protective film is applied as is often the case in the immer› sion lithography, the polymeric quencher is also effective for preventing a film thickness loss of resist pattern or rounding of pattern top. 

The quencher is preferably added in an amount of O to 5 parts, more preferably O to 4 parts by weight per 100 parts by weight of the base polymer. 

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. The water repellency improver may be used in the topcoat› less immersion lithography. Suitable water repellency 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 compo- sition 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. An appropriate amount of the water repellency improver is O to 20 parts, preferably 0.5 to 10 parts by weight per 100 parts by weight of the base polymer. 

(2) 

