337  US 9,411,230 B2  338  ture of 60 to 90° C., the exposure latitude (EL) and the  resolution can be remarkably enhanced.  The heating time is preferably from 30 to 300 seconds,  more preferably from 30 to 180 seconds, still more preferably  from 30 to 90 seconds.  In the pattern forming method of the present invention, the  step of forming a film on a substrate by using the composition,  the step of exposing the film, the heating step and the devel› opment step can be performed by generally known methods.  The light source used for exposure is an extreme ultraviolet  ray (EUV light) or an electron beam (EB).  The film formed using the composition of the present  invention may be subjected to immersion exposure. By this  exposure, the resolution can be more enhanced. The immer› sion medium used may be any liquid as long as it has a  refractive index higher than that of air, but pure water is  preferred.  In this case, the above-described hydrophobic resin may be  previously added to the composition, or after forming a film 20  as above, a topcoat may be provided thereon. The perfor› mance required of the topcoat, the use method thereof and the  like are described in  Ekishin Lithography no Process to  Zairyo (Process and Material of Immersion Lithography),  Chapter 7, CMC Shuppan.  25 On peeling off the topcoat after exposure, a developer may  be used or a releasing agent may be separately used. The  releasing agent is preferably a solvent less permeating the  film. From the standpoint that the peeling step can be per› formed simultaneously with the development step of the film,  the topcoat is preferably peelable with a developer.  In the present invention, the substrate on which the film is  formed is not particularly limited, and a substrate generally  used in the production process of a semiconductor such as IC,  in the production process of a liquid crystal device or a circuit  board such as thermal head or in the lithography process of  other photofabrications may be used. Examples of such a  substrate include an inorganic substrate such as silicon, SiN  and SiO$_{2}$ ,  and a coating-type inorganic substrate such as  SOG.  If desired, an organic antireflection film may be formed  between the film and the substrate.  The organic solvent-containing developer includes, for  example, a polar solvent such as ketone-based solvent, ester› based solvent, alcohol-based solvent, amide-based solvent  and ether-based solvent, and a hydrocarbon-based solvent.  Examples of the ketone-based solvent include 1-octanone,  2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone,  1-hexanone, 2-hexanone, diisobutyl ketone, cyclohexanone,  methylcyclohexanone, phenylacetone, methyl ethyl ketone,  methyl isobutyl ketone, methyl amyl ketone, acetyl acetone,  acetonyl acetone, ionone, diacetonyl alcohol, acetyl carbinol,  acetophenone, methyl naphthyl ketone, isophorone and pro› pylene carbonate.  Examples of the ester-based solvent include methyl  acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl 55  acetate, isoamyl acetate, n-pentyl acetate, propylene glycol  monomethyl ether acetate, propylene glycol monoethyl ether  acetate, ethylene glycol monoethyl ether acetate, diethylene  glycol mono butyl ether acetate, diethylene glycol monoethyl  ether acetate, ethyl-3-ethoxypropionate, 3-methoxybutyl  60  acetate, 3-methyl-3-methoxybutyl acetate, methyl formate,  ethyl formate, butyl formate, propyl formate, ethyl lactate,  butyl lactate, propyl lactate, methyl propionate, methyl  3-methoxypropionate  (MMP),  ethyl  propionate,  ethyl  3-ethoxypropionate (EEP) and propyl propionate. Among  65  these, an alkyl acetate such as methyl acetate, butyl acetate,  ethyl acetate, isopropyl acetate and amyl acetate, and an alkyl  propionate such as methyl propionate, ethyl propionate and  propyl propionate are preferred.  Examples of the alcohol-based solvent include an alcohol  such as methyl alcohol, ethyl alcohol, n-propyl alcohol, iso- propyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl  alcohol, isobutyl alcohol, n-hexyl alcohol, 4-methyl-2-pen› tanol, n-heptyl alcohol, n-octyl alcohol and n-decanol; a gly› col such as ethylene glycol, diethylene glycol and triethylene  glycol; and a glycol ether such as ethylene glycol monom- ethyl ether, propylene glycol monomethyl ether, ethylene  glycol monoethyl ether, propylene glycol monoethyl ether,  diethylene glycol monomethyl ether, triethylene glycol  monoethyl ether and methoxymethyl butanol.  Examples of the ether-based solvent include, in addition to  the glycol ether above, dioxane and tetrahydrofuran.  Examples of the amide-based solvent include N-methyl-2- pyrrolidone, N,N-dimethylacetamide, N,N-dimethylforma› mide, hexamethylphosphoric triamide and 1,3-dimethyl-2- imidazolidinone.  Examples of the hydrocarbon-based solvent include an  aromatic hydrocarbon-based solvent such as toluene and  xylene, and an aliphatic hydrocarbon-based solvent such as  pentane, hexane, octane and decane.  Two or more kinds of these solvents may be mixed and  used, or as long as sufficient performance can be exerted, the  solvent may be used by mixing it with a solvent other than  those described above and/or water. However, the percentage  of water content of the entire developer is preferably less than  10 mass%, and it is more preferred to contain substantially no  water. In other words, this developer is preferably a developer  composed of substantially only an organic solvent. Even in  this case, the developer may contain the later-described sur› factant. Also, in this case, the developer may contain unavoid- able impurities derived from the atmosphere.  The amount of the organic solvent used in the developer is  preferably from 80 to 100 mass %, more preferably from 90  to 100 mass %, still more preferably from 95 to 100 mass %,  based on the entire amount of the developer.  In particular, the organic solvent contained in the developer  is preferably at least one solvent selected from a ketone-based  solvent, an ester-based solvent, an alcohol-based solvent, an  amide-based solvent and an ether-based solvent.  The vapor pressure at 20°  C. of the organic solvent-con› taining developer is preferably 5 kPa or less, more preferably  3 kPa or less, still more preferably 2 kPa or less. By setting the  vapor pressure of the developer to 5 kPa or less, evaporation  of the developer on a substrate or in a development cup is  suppressed and the temperature uniformity in the wafer plane  is enhanced, as a result, the dimensional uniformity in the  wafer plane is improved.  Specific examples of the developer having a vapor pressure  of 5 kPa or less include a ketone-based solvent such as 1-oc› tanone, 2-octanone, 1-nonanone, 2-nonanone, 4-heptanone,  2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclo› hexanone, phenylacetone and methyl isobutyl ketone; an  ester-based solvent such as butyl acetate, amyl acetate, pro- pylene glycol monomethyl ether acetate, ethylene glycol  monoethyl ether acetate, diethylene glycol monobutyl ether  acetate, diethylene glycol monoethyl ether acetate, ethyl-3- ethoxypropionate,  3-methoxybutyl  acetate,  3-methyl-3- methoxybutyl acetate, butyl formate, propyl formate, ethyl  lactate, butyl lactate and propyl lactate; an alcohol-based  solvent such as n-propyl alcohol, isopropyl alcohol, n-butyl  alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alco› hol, n-hexyl alcohol, 4-methyl-2-pentanol, n-heptyl alcohol,  n-octyl alcohol and n-decanol; a glycol-based solvent such as  ethylene glycol, diethylene glycol and triethylene glycol; a 