in which the hydrogen atom on the hydroxyl or carboxyl group is replaced by an acid labile group, as described in U.S. Pat. No. 7,771,914 (JP-A 2008-122932, paragraphs [0155]-[0178]). 

In the positive resist composition, the dissolution inhibitor is preferably added in an amount of 0 to 50 parts, more preferably 5 to 40 parts by weight per 100 parts by weight of the base polymer. 

Suitable crosslinkers which can be used herein include epoxy compounds, melamine compounds, guanamine com› pounds, glycoluril compounds and urea compounds having substituted thereon at least one group selected from among methylol, alkoxymethyl and acyloxymethyl groups, isocya› nate compounds, azide compounds, and compounds having a double bond such as an alkenyl ether group. These compounds may be used as an additive or introduced into a polymer side chain as a pendant. Hydroxy-containing com› pounds may also be used as the crosslinker. 

Of the foregoing crosslinkers, examples of suitable epoxy compounds include tris(2,3-epoxypropyl) isocyanurate, 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 65 other than the iodonium salt having formula (A) may be blended. The other quencher is typically selected from 

conventional basic compounds. Conventional basic com› pounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds with carboxyl group, nitrogen-containing compounds with sulfonyl group, nitrogen-containing compounds with hydroxyl group, nitro- gen-containing compounds with hydroxyphenyl group, alcoholic nitrogen-containing compounds, amide deriva› tives, imide derivatives, and carbamate derivatives. Also included are primary, secondary, and tertiary amine com› pounds, specifically 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 compounds having a carbamate group as described in JP 3790649. 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 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-fluo› rinated 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. 

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 other quencher is preferably added in an amount of0 to 5 parts, more preferably 0 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 0 to 20 parts, preferably 0.5 to 10 parts by weight per 100 parts by weight of the base polymer. 

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 appropri› ate amount of the acetylene alcohol blended is 0 to 5 parts by weight per 100 parts by weight of the base polymer. Process 

