US 2020/0050105 Al  98  Feb. 13, 2020  Examples of the monovalent hydrocarbon group  Rq 2  are as  exemplified above for the monovalent hydrocarbon group  Rq 1 .  Also included are fluorinated alkyl groups such as  trifluoromethyl, trifluoroethyl, 2,2,2-trifluoro-l-methyl-1- hydroxyethyl,  2,2,2-trifluoro-l-(trifluoromethyl)-1-hy› droxyethyl, aryl groups such as phenyl, tolyl, xylyl, 4-tert› butylphenyl, and naphthyl, and fluorinated aryl groups such  as  pentafluorophenyl,  4-trifluoromethylphenyl,  and  4-amino-2,3,5,6-tetrafluorophenyl. In formulae ( 4-1) and  ( 4-2), Mq+ is an onium cation. Suitable onium cations  include sulfonium, iodonium and ammonium cations, with  the sulfonium or iodonium cations being preferred.  [0155]  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.  [0156]  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.  [0157]  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.  [0158]  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. 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.  [0159]  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.  Pattern Forming Process  [0160]  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› ing, exposure, and development.  If necessary, any additional  steps may be added.  [0161]  For example, the resist composition is first applied  onto a substrate on which an integrated circuit is to be  formed (e.g., Si, SiO$_{2}$ ,  SiN, SiON, TiN, WSi, BPSG, SOG,  or organic antireflective coating) or a substrate on which a  mask circuit is to be formed ( e.g., Cr, CrO, CrON, MoSi$_{2}$ ,  or SiO$_{2}$ )  by a suitable coating technique such as spin  coating, roll coating, flow coating, dipping, spraying or  doctor coating. The coating is prebaked on a hot plate at a  temperature of 60 to 150°  C. for 10 seconds to 30 minutes,  preferably at 80 to 120°  C. for 30 seconds to 20 minutes. The  resulting resist film is generally 0.01 to 2 µm  thick.  [0162]  The resist film is then exposed to a desired pattern  of high-energy radiation such as UV, deep-UV, EB, EUV,  x-ray, soft x-ray, excimer laser light, y-ray or synchrotron  radiation. When UV, deep-UV, EUV, x-ray, soft x-ray, exci› mer laser light, y-ray or synchrotron radiation is used as the  high-energy radiation, the resist film is exposed thereto  through a mask having a desired pattern in a dose of  preferably about 1 to 200 mJ/cm 2 ,  more preferably about 10  to 100 mJ/cm 2 .  When EB is used as the high-energy radia› tion, the resist film is exposed thereto through a mask having  a desired pattern or directly in a dose of preferably about 0.1  to 100 µC/cm 2 ,  more preferably about 0.5 to 50 µC/cm 2 .  It  is appreciated that the inventive resist composition is suited  in micropatterning using KrF excimer laser, ArF excimer  laser, EB, EUV, x-ray, soft x-ray, y-ray or synchrotron  radiation, especially in micropatterning using EB or EUV.  [0163]  After the exposure, the resist film may be baked  (PEB) on a hot plate at 60 to 150°  C. for 10 seconds to 30  minutes, preferably at 80 to 120°  C. for 30 seconds to 20  minutes.  [0164]  After the exposure or PEB, in the case of positive  resist, the resist film is developed in a developer in the form  of an aqueous base solution for 3 seconds to 3 minutes,  preferably 5 seconds to 2 minutes by conventional tech› niques such as dip, puddle and spray techniques. A typical  developer is a 0.1 to 10 wt%, preferably 2 to 5 wt% aqueous  solution of tetramethylammonium hydroxide (TMAH), tet› raethylammonium hydroxide (TEAH), tetrapropylammo› nium hydroxide (TPAH), or tetrabutylammonium hydroxide  (TBAH). The resist film in the exposed area is dissolved in  the developer whereas the resist film in the unexposed area  is not dissolved. In this way, the desired positive pattern is  formed on the substrate. Inversely in the case of negative  resist, the exposed area of resist film is insolubilized and the  unexposed area is dissolved in the developer.  [0165]  In an alternative embodiment, a negative pattern  may be formed via organic solvent development using a  positive resist composition comprising a base polymer hav› ing an acid labile group. The developer used herein is  preferably selected from among 2-octanone, 2-nonanone,  2-heptanone,  3-heptanone,  4-heptanone,  2-hexanone,  3-hexanone,  diisobutyl  ketone,  methylcyclohexanone,  acetophenone, methylacetophenone, propyl acetate, butyl  acetate, isobutyl acetate, pentyl acetate, butenyl acetate,  isopentyl acetate, propyl formate, butyl formate, isobutyl  formate, pentyl formate, isopentyl formate, methyl valerate,  methyl pentenoate, methyl crotonate, ethyl crotonate,  methyl propionate, ethyl propionate, ethyl 3-ethoxypropi› onate, methyl lactate, ethyl lactate, propyl lactate, butyl  lactate, isobutyl lactate, pentyl lactate, isopentyl lactate,  methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate,  methyl benzoate, ethyl benzoate, phenyl acetate, benzyl  acetate, methyl phenylacetate, benzyl formate, phenylethyl  formate, methyl 3-phenylpropionate, benzyl propionate,  ethyl phenylacetate, and 2-phenylethyl acetate, and mixtures  thereof. 