Feb. 18,2021  88  US 2021/0048748 Al  monomethyl ether acetate (PGMEA), propylene glycol  monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl  acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropi› onate, tert-butyl acetate, tert-butyl propionate, and propyl› ene glycol mono-tert-butyl ether acetate; and lactones such  as y-butyrolactone, which may be used alone or in admix› ture.  [0140]  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.  [0141]  Other Components  [0142]  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.  [0143]  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.  [0144]  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]).  [0145]  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.  [0146]  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 include epoxy compounds, melamine com› pounds, guanamine compounds, glycoluril compounds and  urea compounds having substituted thereon at least one  [0139]  An organic solvent may be added to the resist  composition. The organic solvent used herein is not particu› larly limited as long as the foregoing and other components  are soluble therein. Examples of the organic solvent are  described in JP-A 2008-111103, paragraphs [0144]-[0145]  (U.S. Pat. No. 7,537,880). Exemplary solvents include  ketones such as cyclohexanone, cyclopentanone, methyl-2- n-pentyl  ketone  and  2-heptanone;  alcohols  such as  3-methoxybutanol,  3-methyl-3-methoxybutanol,  l-methoxy-2-propanol, l-ethoxy-2-propanol, and diacetone  alcohol (DAA); ethers such as propylene glycol monom› ethyl ether (PGME), ethylene glycol monomethyl ether,  propylene glycol monoethyl ether, ethylene glycol mono› ethyl ether, propylene glycol dimethyl ether, and diethylene  glycol dimethyl ether; esters such as propylene glycol  [0138]  Organic Solvent  [0137]  When used, the acid generator of addition type is  preferably added in an amount of 0.1 to 50 parts, and more  preferably 1 to 40 parts by weight per 100 parts by weight  of the base polymer. When the base polymer includes  recurring units  (f)  and/or the acid generator of addition type  is added, the resist composition functions as a chemically  amplified resist composition.  -continued  0  ;j  0  ____r<O_z_~F3  0~  ’  ~S03- 0  Q)--o-<:t:o, 