Apr. 18,  2019  84  US 2019/0113844 Al  alkenyl ether group. These compounds may be used as an  additive or introduced into a polymer side chain as a  pendant. Hydroxy-containing compounds may also be used  as the crosslinker. The crosslinker may be used alone or in  admixture.  [0144]  Of the foregoing crosslinkers, examples of suitable  epoxy compounds include tris(2,3-epoxypropyl) isocyanu› rate, trimethylolmethane triglycidyl ether, trimethylolpro› pane triglycidyl 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.  [0145]  Suitable isocyanate compounds include tolylene  diisocyanate, diphenylmethane diisocyanate, hexamethyl› ene diisocyanate and cyclohexane diisocyanate. Suitable  azide compounds 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.  [0146]  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.  [0147]  In the resist composition of the invention, a  quencher other than the thiophenecarboxylic acid sulfonium  salt may be blended. The other quencher is typically selected  from conventional basic compounds. Conventional basic  compounds include primary, secondary, and tertiary ali› phatic 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- [0153]  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- [0152]  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.  [0151]  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  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.  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.  [0150]  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.  [0149]  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.  [0148]  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 or carboxylic  acid is released by salt exchange with an a-non-fluorinated  onium salt.  An  a-non-fluorinated sulfonic acid and a car› boxylic acid function as a quencher because they do not  induce deprotection reaction.  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.  Process 