Aug. 27, 2020  152  US 2020/0272048 Al  ether acetate; and lactones such as y-butyrolactone, which  may be used alone or in admixture.  [0145]  The organic solvent is preferably added in an  amount of 100 to 10,000 parts, and more preferably 200 to  8,000 parts by weight per 100 parts by weight of the base  polymer.  [0146]  Other Components  [0147]  With the foregoing components, other components  such as a surfactant, dissolution inhibitor, and crosslinker  may be blended in any desired combination to formulate a  chemically amplified positive or negative resist composi› tion. This positive or negative resist composition has a very  high sensitivity in that the dissolution rate in developer of  the base polymer in exposed areas is accelerated by catalytic  reaction. In addition, the resist film has a high dissolution  contrast, resolution, exposure latitude, and process adapt› ability, and provides a good pattern profile after exposure,  and minimal proximity bias because of restrained acid  diffusion. By virtue of these advantages, the composition is  fully useful in commercial application and suited as a  pattern-forming material for the fabrication of VLSis.  [0148]  Exemplary surfactants are described in JP-A 2008- 111103, paragraphs [0165]-[0166]. Inclusion of a surfactant  may improve or control the coating characteristics of the  resist composition. While the surfactant may be used alone  or in admixture, it is preferably added in an amount of  0.0001 to 10 parts by weight per 100 parts by weight of the  base polymer.  [0149]  In the case of positive resist compositions, inclu› sion of a dissolution inhibitor may lead to an increased  difference in dissolution rate between exposed and unex› posed areas and a further improvement in resolution. The  dissolution inhibitor which can be used herein is a com› pound having at least two phenolic hydroxyl groups on the  molecule, in which an average of from Oto 100 mo! % of all  the hydrogen atoms on the phenolic hydroxyl groups are  replaced by acid labile groups or a compound having at least  one carboxyl group on the molecule, in which an average of  50 to 100 mo!% of all the hydrogen atoms on the carboxyl  groups are replaced by acid labile groups, both the com› pounds having a molecular weight of 100 to 1,000, and  preferably 150 to 800. Typical are bisphenol A, trisphenol,  phenolphthalein,  cresol novolac, naphthalenecarboxylic  acid, adamantanecarboxylic acid, and cholic acid derivatives  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]).  [0150]  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. The dissolution inhibitor may be  used alone or in admixture.  [0151]  In the case of negative resist compositions, a nega› tive pattern may be formed by adding a crosslinker to reduce  the dissolution rate of a resist film in exposed area. Suitable  crosslinkers which can be used herein include epoxy com› pounds, melamine compounds, guanamine compounds, gly› coluril compounds and urea compounds having substituted  thereon at least one group selected from among methylol,  alkoxymethyl and acyloxymiethyl groups, isocyanate com› pounds, 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  [0155]  In the resist composition of the invention, a  quencher other than the inventive cyclic ammonium 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 to compounds with carboxyl  group, nitrogen-containing compotmds 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  [0154]  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.  [0153]  Suitable isocyanate compounds inchlude 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.  [0152]  Of the foregoing crosslinkers, examples of the  epoxy compound 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 guammnine  compounds having 1 to 4 methylol groups methoxymethyl› ated and mixtures thereof, tetramethoxyethyl guanamine,  tetraacyloxyguamnnine,  tetramethylol  guanamine  com› pounds having 1 to 4 methylol groups acyloxymethylated  and mixtures thereof. Examples of the glycoluril compound  include tetramethylol glycoluril, tetramethoxyglycoluril,  tetramethoxymethyl glycohluril, 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.  chain as a pendant. Hydroxy-containing compounds may  also be used as the crosslinker. The crosslinker may be used  alone or in admixture. 