Feb.4,2021  106  US 2021/0033970 Al  thereof, hexamethoxyethyl melamine, hexaacyloxymethyl  melamine, hexamethylol melamine compounds having 1 to  6 methylol groups acyloxymethylated and mixtures thereof.  Examples of the guanamine compound include tetrameth› ylol guanamine, tetramethoxymethyl guanamine, tetrameth› ylol guanamine compounds having 1 to 4 methylol groups  methoxymethylated and mixtures thereof, tetramethoxy› ethyl guanamine, tetraacyloxyguanamine, tetramethylol  guanamine compounds having 1 to 4 methylol groups acy› loxymethylated and mixtures thereof. Examples of the gly› coluril compound include tetramethylol glycoluril, tetram› ethoxyglycoluril,  tetramethoxymethyl  glycoluril,  tetramethylol glycoluril compounds having 1 to 4 methylol  groups methoxymethylated and mixtures thereof, tetrameth› ylol glycoluril compounds having 1 to 4 methylol groups  acyloxymethylated and mixtures thereof. Examples of the  urea compound include tetramethylol urea, tetramethoxym› ethyl urea, tetramethylol urea compounds having 1 to 4  methylol groups methoxymethylated and mixtures thereof,  and tetramethoxyethyl urea.  [0147]  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.  [0148]  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. The crosslinker may be used alone or  in admixture.  [0149]  In the resist composition of the invention, a  quencher other than the ammonium salt compound having  formula (A) 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, heterocy› clic 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  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 carbam› ate 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.  [0150]  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  [0155]  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.  [0154]  To the resist composition, a water repellency  improver may also be added for improving the water repel› lency on surface of a resist film as spin coated. The water  repellency improver may be used in the topcoatless immer› sion 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 composition should be  soluble in the alkaline developer and organic solvent devel› oper. The water repellency improver of specific structure  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.  [0153]  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.  [0152]  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.  [0151]  The iodized aromatic ring-containing ammonium  salt has an outstanding acid diffusion suppressing effect in  the exposed region as well as in the unexposed region. In the  exposed region, an iodized or brominated carboxylic acid is  detached from an amine compound having an iodized aro› matic ring bonded thereto and dissolved in the alkaline  developer while forming a salt with the alkaline developer.  This prevents any drop of dissolution rate in the over› exposed region. Using the iodized aromatic ring-containing  ammonium salt in combination with the quencher in the  form of a sulfonium salt or iodonium salt, the desired  properties including low acid diffusion and high contrast are  achieved in a good balance.  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. Since the quencher in the  form of a sulfonium salt or iodonium salt is photo-decom› posable, the quencher function is reduced in the exposed  region whereas acid activity is improved. This results in an  improved contrast. 