Composition for forming metal oxide film

0001The present invention relates to a composition for forming a metal oxide film.

0002With the miniaturization of semiconductor devices and the like, the processing size using a multilayer resist process is being miniaturized in order to obtain a higher degree of integration. In this multilayer resist process, an inorganic film is formed using an inorganic material, and then a resist composition is further applied to form a resist film which is an organic film having an etching selectivity different from that of the inorganic film, and then a mask pattern is obtained by exposure. Is transferred and developed with a developing solution to obtain a resist pattern. Subsequently, this resist pattern is transferred to the inorganic film by dry etching, and finally the pattern of the resist underlayer film is transferred to the substrate to be processed by dry etching to obtain a substrate having a desired pattern (Japanese Patent Laid-Open No. 2001). -Refer to JP-A-284209, JP-A-2010-85912 and JP-A-2008-39811).

0003Further, as one of the miniaturization techniques, a metal oxide film may be formed between the inorganic film and the resist film in the above-mentioned multilayer resist process. At this time, the conventional composition for forming a metal oxide film can be uniformly applied on the surface of a base material having a certain degree of hydrophilicity, but is uniform on the surface having a hydrophobic surface in which an inorganic film is formed on the base material. There is a problem that it cannot be applied to.

0004Under such circumstances, it is desired to develop a composition for forming a metal oxide film having good uniform coating property on various substrates.

<p num="0005"><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-284209</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2010-85912</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 2008-39811</text></patcit></p>

<p num="0006"> The present invention has been made based on the above circumstances, and an object of the present invention is to provide a composition for forming a metal oxide film having good uniform coating properties on various substrates.</p>

<p num="0007"> The invention made to solve the above problems is [A] At least one metal element (a) selected from the group consisting of metal elements having atomic numbers 23 to 78, and^-OO^-、^-OS^-、^-OO-SO₂-O^-、^-O-SO₂-OO-SO₂-O^-as well as^-OC (= O)-OO^-A compound containing at least one ligand (b) selected from the group consisting of (hereinafter, also referred to as "[A] compound"), [B] Surfactants, as well [C] Solvent It is a composition for forming a metal oxide film containing.</p><p num="0008"> The composition for forming a metal oxide film of the present invention may have good uniform coating property on various substrates by containing [A] compound, [B] surfactant, and [C] solvent. it can.</p><p num="0009"> The metal element (a) is preferably at least one metal element selected from the group consisting of zirconium, molybdenum, hafnium and tungsten. By making the metal element (a) the above-mentioned specific element, the uniform coating property of the metal oxide film forming composition can be further improved.</p><p num="0010"> [A] Compound At least one selected from the group consisting of a single metal of the metal element (a), a metal oxo acid, a metal oxo acid salt, a metal oxide, a metal hydroxide, a metal alkoxide, a metal halide and a metal oxyhalide. At least one compound selected from the group consisting of hydrogen peroxide, thiohydrogen peroxide, persulfate, peroxodisulfuric acid and percarbonate. It is preferably a reaction product with.</p><p num="0011"> The metal element (a) and the ligand (b) can be easily contained in the [A] compound by forming the reaction product of the metal element (a) of the specific embodiment and the specific compound.</p><p num="0012"> [B] The surfactant is preferably a nonionic surfactant. [B] By using a nonionic surfactant as the surfactant, the uniform coating property of the metal oxide film forming composition can be further improved.</p><p num="0013"> [B] The content of the surfactant is preferably 0.01% by mass or more and 10% by mass or less. [B] By setting the content of the surfactant in the above-mentioned specific range, the uniform coating property of the metal oxide film forming composition can be further improved.</p><p num="0014"> The [C] solvent preferably contains 80% by mass or more of an organic solvent. By using the solvent [C] as a solvent containing an organic solvent, the uniform coating property of the metal oxide film forming composition can be further improved.</p><p num="0015"> The composition for forming a metal oxide film is suitable for a multilayer resist process. As described above, the composition for forming a metal oxide film has good uniform coating property on various substrates, and therefore, when it is applied on an inorganic film having hydrophobicity in a multilayer resist process, it is used. Can also be preferably used.</p>

<p num="0016"> As described above, the present invention can provide a composition for forming a metal oxide film having good uniform coating properties on various substrates. Therefore, the composition for forming a metal oxide film can be suitably used for forming a resist pattern in a lithography process, which is expected to be further miniaturized in the future.</p>

0017&lt;Composition for forming a metal oxide film&gt; The composition for forming a metal oxide film of the present invention contains [A] compound, [B] surfactant and [C] solvent. In addition, the composition for forming a metal oxide film may contain other optional components as long as the effects of the present invention are not impaired. Hereinafter, each component will be described in detail.

0018&lt;[A] Compound&gt; The compound [A] is composed of at least one metal element (a) selected from the group consisting of metal elements having atomic numbers 23 to 78, and^-OO^-、^-OS^-、^-OO-SO₂-O^-、^-O-SO₂-OO-SO₂-O^-as well as^-OC (= O)-OO^-It is a compound containing at least one ligand (b) selected from the group consisting of. In addition, 2 or more types of [A] compounds may be used in combination.

0019As a ligand, in addition to the ligand (b), for example Carboxylic acid ions such as acetate ion and propionic acid ion; Β-diketonate ions such as acetylacetoneate ion, methylacetylacetoneate ion, benzoylacetonate ion; Alcolate ions such as methylate ion and ethylate ion; Phenolate ions such as phenolate ions and methylphenolate ions; F^-, Cl^-, Br^-, I^-Halide anions such as; O^2-, NO₃^-, CN^-, ClO₄^-, HSO₄^-, H₂PO₄^-, BF₄^-, PF₆^-, SbF₆^-, Aliphatic sulfonate anion, aromatic sulfonate anion, fluorinated alkane sulfonate anion; Nitrogen-containing neutral ligands such as ammonia methylamine, dimethylamine, trimethylamine, ethylenediamine, diethylenetriamine, and pyridine; Examples thereof include phosphorus-containing neutral ligands such as trimethylphosphine, triethylphosphine, triphenylphosphine, and triphenylphosphine.

0020The metal element (a) is preferably at least one metal element selected from the group consisting of zirconium, molybdenum, hafnium and tungsten. By making the metal element (a) the above-mentioned specific element, the uniform coating property of the metal oxide film forming composition can be further improved.

0021The compound [A] is selected from the group consisting of elemental metal of metal element (a), metal oxoacid, metal oxoacid, metal oxide, metal hydroxide, metal alkoxide, metal halide and metal oxyhalide. It is preferably a reaction product of at least one compound and at least one compound selected from the group consisting of hydrogen peroxide, thiohydrogenide, persulfate, peroxodisulfuric acid and percarbonate. The metal element (a) and the ligand (b) can be easily contained in the [A] compound by forming the reaction product of the metal element (a) of the specific embodiment and the specific compound.

0022The content of the compound [A] is preferably 0.05% by mass or more and 20% by mass or less with respect to 100% by mass of the composition for forming a metal oxide film. By setting the content of the compound [A] to the above-mentioned specific range, the uniform coating property of the metal oxide film forming composition can be further improved.

0023&lt;[A] Compound synthesis method&gt; The method for synthesizing the compound [A] will be described by taking as an example a case where tungsten, which is preferable as the metal element (a), is used and reacted with hydrogen peroxide.

0024First, a commercially available tungstic acid salt is dissolved in ion-exchanged water or the like, contacted with a proton-type cation exchange resin, and ion-exchanged to obtain an aqueous solution of tungstic acid.

0025Examples of the tungstate include ammonium metatungstate, ammonium paratungstate, sodium tungstate, potassium tungstate, calcium tungstate and the like. Of these, ammonium metatungstate is preferable because the obtained aqueous solution of tungstic acid has high stability.

0026The concentration of the tungstate aqueous solution is not particularly limited as long as it has a saturated solubility or less, but is usually 0.01 mol / L or more and 2.0 mol / L or less, preferably 0.1 mol / L or more and 1.0 mol / L or less, and 0.2 mol. More preferably, it is / L or more and 0.5 mol / L or less.

0027The cation exchange resin is not particularly limited as long as it can exchange cations of tungstic acid salt with protons, but a strong acid type is preferable. As a contact method between the tungstate aqueous solution and the cation exchange resin, a column method widely used in industry is preferable. The temperature of the aqueous tungstate solution during ion exchange is preferably 0 ° C or higher and 70 ° C or lower, and more preferably 5 ° C or higher and 50 ° C or lower.

0028The space velocity in ion exchange is not particularly limited as long as the cation of tungstate is sufficiently exchanged for protons.

0029Next, a peroxotungstic acid aqueous solution as the [A] compound is obtained by adding a hydrogen peroxide solution to the tungstic acid aqueous solution and reacting it.

0030The reaction temperature is usually 5 ° C to 70 ° C, preferably 10 ° C to 50 ° C. Below 5 ° C, the reaction may be inadequate, and above 70 ° C, hydrogen peroxide may decompose. The reaction time is usually 0.1 hour to 3 hours, preferably 0.5 hour to 2 hours. The reaction is preferably accompanied by stirring.

0031The amount of hydrogen peroxide added is usually 0.5 mol to 15 mol, preferably 1 mol to 10 mol, relative to 1 mol of tungsten. If the amount of hydrogen peroxide added is less than 0.5 mol, the reaction may be insufficient. In addition, there is no difference in the effect even if it is added in excess of 15 mol.

0032After the reaction, it is preferable to remove the hydrogen peroxide remaining in the solution. Examples of the method for removing hydrogen peroxide include a method of decomposing and removing hydrogen peroxide by heating at 90 ° C to 100 ° C for 1 to 3 hours.

0033&lt;[B] Surfactant&gt; [B] Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants and the like. In addition, 2 or more types of [B] surfactants may be used in combination.

0034Examples of nonionic surfactants include Acetylene group-containing surfactant; Polyoxyethylene (POE) octyl ether, POE (2-ethyl-hexyl) ether, POE lauryl ether, POE myristyl ether, POE cetyl ether, POE stearyl ether, POE oleyl ether, POE isostearyl ether, POE behenyl ether, POE cetyl POE alkyl ethers such as stearyl diether; POE polyoxypropylene alkyl ether type such as POE / polyoxypropylene (POP) butyl ether, POE / POP lauryl ether, POE / POP cetyl ether, POE / POP glycol; POE aryl ethers such as POE octylphenyl ether, POE nonylphenyl ether, POE chlorophenyl ether, POE naphthyl ether; POE hardened castor oil ether, POE castor oil ether; Other POE higher alcohol ethers such as POE lanolin alcohol ether, POE phytosterol; POE glycerin fatty acid esters such as POE glyceryl monostearate, POE glyceryl oleate; POE sorbitan fatty acid esters such as POE sorbitan monolaurate, POE sorbitan monostearate, POE sorbitan tristearate, POE sorbitan monoisostearate; POE sorbitol fatty acid esters such as POE sorbitol hexastearate, POE sorbitol tetrastearate, POE sorbitol tetraoleate, POE sorbitol monolaurate; Polyethylene glycol fatty acid esters such as polyethylene glycol monolauric acid, polyethylene glycol monostearic acid, polyethylene glycol monooleic acid, polyethylene glycol distearic acid, polyethylene glycol dioleic acid, polyethylene glycol diisostearic acid; Ether ester type such as polyethylene glycol lanolin fatty acid ester; Glycerin fatty acid esters such as glyceryl monostearate, self-emulsifying glyceryl monostearate, glyceryl monohydroxystearate, glyceryl distearate; Diglyceryl monostearate, diglyceryl monooleate, diglyceryl dioleate, diglyceryl monoisostearate, tetraglyceryl monostearate, tetraglyceryl tristearate, tetraglyceryl pentastearate, hexaglyceryl monolaurate, hexamonomyristate Polyglycerin fatty acid esters such as glyceryl, decaglyceryl distearate, decaglyceryl diisostearate; Sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate, sorbitan monoisostearate; Ethylene glycol fatty acid esters such as ethylene glycol monolaurate and ethylene glycol distearate; Propylene glycol fatty acid esters such as propylene glycol monostearate and self-emulsifying propylene glycol monostearate; Pentaerythritol fatty acid esters such as pentaerythritol monostearate and pentaerythritol monooleate; Sugar derivatives such as maltitol hydroxy fatty acid ether, alkylated polysaccharides, alkyl (poly) glucosides, sugar esters; Alkyl glyceryl ethers such as α-monoisostearyl glyceryl ether; Organic acid monoglycerides such as acetyl-monoglyceride, lactic acid monoglyceride, citric acid monoglyceride; Palm oil fatty acid monoethanolamide, lauroyl monoethanolamide, myristoyl monoethanolamide, lauroyl diethanolamide, palm oil fatty acid diethanolamide, lauroyl isopropanol amide, myristoyl isopropanol amide, palm oil fatty acid isopropanol amide, POE lauroyl monoethanolamide, palm oil fatty acid Fatty acid alkanolamides such as methylmonoethanolamide and coconut oil fatty acid methyldiethanolamide; POE alkylamines such as POE laurylamine, POE stearylamine; Examples thereof include amine oxides such as lauryldimethylamine oxide, cocodimethylamine oxide, and cocoamide propyldimethylamine oxide.

0035Examples of anionic surfactants include Sulphonic acid-type surfactants such as polyarylalkane sulfonate, dialkyl sulfosuccinate, dialkyl sulfosuccinic acid, alkylbenzene sulfonic acid, α-olefin sulfonic acid, POE alkylphenyl ether sulfonic acid, POE alkyl ether sulfosuccinic acid half ester; Polyacrylic acid, polymethacrylic acid, polymaleic acid, copolymer of maleic acid and olefin, copolymer of acrylic acid and itaconic acid, copolymer of methacrylic acid and itaconic acid, maleic acid and styrene , Copolymers of acrylic acid and methacrylic acid, copolymers of acrylic acid and acrylic acid methyl ester, copolymers of acrylic acid and vinyl acetate, copolymers of acrylic acid and maleic acid Carboxylic acid type surfactants such as those; POE alkyl ether sulfate ester, POE alkylphenyl ether sulfate ester, POE benzyl phenyl ether sulfate ester, POE styrylphenyl ether sulfate ester, POE styrylphenyl ether polymer sulfate ester, POE polyoxypropylene block polymer sulfate ester, sulfated olefin Such as sulfate ester type surfactants and the like can be mentioned.

0036Examples of cationic surfactants include Lauryl trimethyl ammonium chloride, myristyl trimethyl ammonium chloride, palmityl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, oleyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, coconut oil alkyl trimethyl ammonium chloride, beef alkyl trimethyl ammonium chloride, stearyl Monoalkyl quaternary ammonium salts such as trimethylammonium bromide, coconut oil alkyltrimethylammonium bromide, cetyltrimethylammonium methylsulfate; Dialkyl quaternary ammonium salts such as dioctyldimethylammonium chloride, dilauryldimethylammonium chloride, distearyldimethylammonium chloride; Lanoline fatty acids Aminopropyl ethyldimethylammonium ethyl sulfate, lauroylaminoethylmethyldiethylammonium methylsulfate and other acylaminoalkyl quaternary ammonium salts; Alkylethenoxy quaternary ammonium salts such as dipalmitylpolyethenoxyethylammonium chloride, distearylpolyethenoxymethylammonium chloride; Alkyl isoquinolinium salts such as lauryl isoquinolinium chloride; Benzalkonium salts such as lauryldimethylbenzylammonium chloride, stearyldimethylbenzylammonium chloride; Benzyldimethyl {2- [2- (p-1,1,3,3, -tetramethylbutylphenoxy) ethoxy] ethyl} benzethonium salts such as ammonium chloride; Pyridine salts such as cetylpyridinium chloride; Imidazolenium salt; Acylbasic amino acid alkyl ester salts such as N-cocoyl arginine ethyl ester pyrrolidone carboxylate, N-lauroyl lysine ethyl ethyl ester hydrochloride; Primary amine salts such as laurylamine hydrochloride; Secondary amine salts such as dilaurylamine acetate; Tertiary amine salts; Fatty acid amide guanidinium salt; Examples thereof include alkyltrialkylene glycolammonium salts such as lauryltriethylene glycolammonium hydroxide.

0037[B] As the surfactant, a nonionic surfactant is preferable. [B] By using a nonionic surfactant as the surfactant, the uniform coating property of the metal oxide film forming composition can be further improved.

0038[B] The content of the surfactant is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, based on 100% by mass of the composition for forming a metal oxide film. .. [B] By setting the content of the surfactant in the above-mentioned specific range, the uniform coating property of the metal oxide film forming composition can be further improved.

0039&lt;[C] Solvent&gt; The solvent [C] is not particularly limited, but a solvent that uniformly dissolves or disperses each component and does not react with each component is used. Pure water is preferable as such a [C] solvent. Further, the [C] solvent preferably contains 80% by mass or more of an organic solvent.

0040Examples of the organic solvent include alcohols, ethers, aromatic hydrocarbons, ketones, other esters and the like. Two or more of these organic solvents may be used in combination.

0041Examples of alcohols include methanol, ethanol, benzyl alcohol, 2-phenylethyl alcohol, 3-phenyl-1-propanol and the like.

0042Examples of ethers include cyclic ethers, glycol ethers, ethylene glycol alkyl ether acetates, diethylene glycol alkyl ethers, propylene glycol monoalkyl ethers, propylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ether propionates and the like.

0043Examples of the cyclic ether include tetrahydrofuran and the like.

0044Examples of the glycol ether include ethylene glycol monomethyl ether and ethylene glycol monoethyl ether.

0045Examples of the ethylene glycol alkyl ether acetate include methyl cellosolve acetate, ethyl cellosolve acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoethyl ether acetate and the like.

0046Examples of the diethylene glycol alkyl ether include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether and the like.

0047Examples of the propylene glycol monoalkyl ether include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether.

0048Examples of the propylene glycol monoalkyl ether acetate include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, and propylene glycol monobutyl ether acetate.

0049Examples of the propylene glycol monoalkyl ether propionate include propylene monoglycol methyl ether propionate, propylene glycol monoethyl ether propionate, propylene glycol monopropyl ether propionate, and propylene glycol monobutyl ether propionate. ..

0050Examples of aromatic hydrocarbons include toluene, xylene and the like.

0051Examples of the ketones include methyl ethyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone and the like.

0052Other esters include, for example, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, hydroxy. Methyl acetate, ethyl hydroxyacetate, butyl hydroxyacetate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 3-hydroxypropionate, ethyl 3-hydroxypropionate, propyl 3-hydroxypropionate, butyl 3-hydroxypropionate , 2-Hydroxy-3-methylbutanoate, methyl methoxyacetate, ethyl methoxyacetate, propyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate, propyl ethoxyacetate, butyl ethoxyacetate, methyl propoxyacetate, ethyl propionate , Propoxyacetate propyl, propoxyacetate butyl, butoxyacetate methyl, butoxyacetate ethyl, butoxyacetate propyl, butoxyacetate butyl, 2-methoxypropionate methyl, 2-methoxypropionate ethyl, 2-methoxypropionate propyl, 2-methoxypropion Butyl acid, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate, propyl 2-ethoxypropionate, butyl 2-ethoxypropionate, methyl 2-butoxypropionate, ethyl 2-butoxypropionate, 2-butoxypropionate Propyl, butyl 2-butoxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate , Propyl 3-ethoxypropionate, butyl 3-ethoxypropionate, methyl 3-propoxypropionate, ethyl 3-propoxypropionate, propyl 3-propoxypropionate, butyl 3-propoxypropionate, methyl 3-butoxypropionate, Ethyl 3-butoxypropionate, 3-butoxypropionate proExamples include pills, butyl 3-butoxypropionate and the like.

0053&lt;Other optional ingredients&gt; In addition to the [A] compound, [B] surfactant and [C] solvent, the composition for forming a metal oxide film may contain other adhesive aids, storage stabilizers, etc. as long as the desired effects are not impaired. May contain any component of. Two or more of these other optional components may be used in combination. Hereinafter, each component will be described in detail.

0054[Adhesive aid] The adhesion aid is a component capable of further improving the adhesiveness between the metal oxide film formed from the metal oxide film forming composition and the substrate or the inorganic film. Examples of the adhesion aid include a functional silane coupling agent having a reactive functional group such as a carboxyl group, a (meth) acryloyl group, a vinyl group, an isocyanate group, and an oxylanyl group. Specifically, trimethoxysilyl benzoic acid, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, β -(3,4-Epoxycyclohexyl) ethyltrimethoxysilane and the like can be mentioned.

0055[Preservation stabilizer] Examples of the storage stabilizer include sulfur, quinones, hydroquinones, polyoxy compounds, amines, nitronitroso compounds and the like. Specific examples thereof include 4-methoxyphenol and N-nitroso-N-phenylhydroxylamine aluminum.

0056&lt;Method of preparing composition for forming metal oxide film&gt; In the composition for forming a metal oxide film of the present invention, in addition to the [A] compound and the [B] surfactant, other optional components are added to the [C] solvent in a predetermined ratio as long as the desired effect is not impaired. It is prepared by mixing with.

0057When the composition for forming a metal oxide film is prepared in a solution state, the solid content concentration (components other than the [C] solvent in the composition solution) depends on the purpose of use, the value of the desired film thickness, and the like. It can be set to any concentration (for example, about 0.05% by mass to 25% by mass).

0058&lt;About the multilayer resist process&gt; The multilayer resist process is, for example, (1) A process of forming an inorganic film on a substrate to be processed using a composition for forming an inorganic film. (2) A step of forming a metal oxide film on the inorganic film using the composition for forming a metal oxide film. (3) A step of forming a resist film on the metal oxide film using the resist composition. (4) A step of exposing the resist film by irradiating radiation through a photomask. (5) The step of developing the exposed resist film to form a resist pattern, and (6) A step of forming a pattern on a substrate to be processed by one or a plurality of dry etchings using the resist pattern as a mask. Have. Hereinafter, each step will be described in detail.

0059The metal oxide film forming composition can form a pattern on the substrate to be processed even in a process that does not have the above step (3). The metal oxide film formed from the composition for forming a metal oxide film has a pattern because the exposed portion is cured and is not dissolved by the developing solution, while the unexposed portion is dissolved in the developing solution. Can be formed.

0060[Process (1)] In this step, an inorganic film forming composition is used to form an inorganic film on a substrate to be processed. Examples of the substrate to be processed include conventionally known substrates such as silicon wafers and wafers coated with aluminum. Examples of the composition for forming an inorganic film include conventionally known compositions disclosed in Japanese Patent Application Laid-Open No. 6-12452 and Japanese Patent Application Laid-Open No. 59-93448.

0061As a method for forming the inorganic film, the composition for forming an inorganic film is applied to the surface of the substrate to be processed, and if necessary, heat treatment is performed to form the inorganic film. Examples of the coating method include a spin coating method, a roll coating method, a dip method and the like. The heating temperature is usually 150 ° C to 500 ° C, preferably 180 ° C to 350 ° C. The heating time is usually 30 seconds to 1,200 seconds, preferably 45 seconds to 600 seconds. The film thickness of the inorganic film is usually about 5 nm to 50 nm.

0062[Process (2)] In this step, the metal oxide film forming composition is used to form a metal oxide film on the inorganic film. As a method for forming the metal oxide film, the same method as the above-mentioned method for forming an inorganic film can be applied.

0063[Process (3) ~ (5)] In steps (3) to (5), the resist composition is applied onto the metal oxide film, exposed, heated and developed to form a resist pattern. Examples of the resist composition include a positive or negative chemically amplified resist composition containing a photoacid generator, a positive resist composition composed of an alkali-soluble resin and a quinonediazide-based photosensitizer, an alkali-soluble resin and a cross-linking agent. Examples thereof include a negative resist composition comprising. In the pattern forming method of the present invention, a commercially available resist composition can also be used as such a resist composition. As a method of applying the resist composition, it can be applied by a conventional method such as a spin coating method. When applying the resist composition, the amount of the resist composition to be applied is adjusted so that the obtained resist coating film has a desired film thickness.

0064The resist coating film is formed by prebaking the coating film formed by applying the resist composition to volatilize the solvent in the coating film (that is, the solvent contained in the resist composition). Can be done. The prebake temperature is appropriately adjusted according to the type of resist composition used and the like, but is preferably 30 ° C to 200 ° C, more preferably 50 ° C to 150 ° C. The heating time is usually 30 seconds to 200 seconds, preferably 45 seconds to 120 seconds. In addition, another coating film may be further provided on the surface of this resist film. The film thickness of the resist film is usually 1 nm to 500 nm, preferably 10 nm to 300 nm.

0065Next, the obtained resist coating film is selectively irradiated with radiation through a photomask to expose the resist coating film. The radiation is appropriately selected from visible light, ultraviolet rays, far ultraviolet rays, X-rays, electron beams, γ-rays, molecular rays, ion beams, etc., depending on the type of acid generator used in the resist composition. However, it is preferably far ultraviolet light, and KrF excimer laser light (248 nm), ArF excimer laser light (193 nm), F.₂Excimer laser light (wavelength 157 nm), Kr₂Excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm), and extreme ultraviolet light (wavelength 13 nm, etc.) are more preferable. Moreover, the immersion exposure method can also be adopted. The immersion upper layer film may be formed on the resist film by using the immersion upper layer film forming composition.

0066After exposure, post-baking is performed to improve the resolution, pattern profile, developability, etc. of the resist film. The post-bake temperature is appropriately adjusted according to the type of resist composition used and the like, but the pre-bake temperature is preferably 180 ° C. or lower, more preferably 150 ° C. or lower. The heating time is usually 30 seconds to 200 seconds, preferably 45 seconds to 120 seconds.

0067After post-baking, the resist coating film is developed to form a resist pattern. The developing solution used for development can be appropriately selected depending on the type of resist composition used, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n. -Propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo [5.4] Alkaline aqueous solutions such as .0] -7-undecene and 1,5-diazabicyclo [4.3.0] -5-nonen can be mentioned. Further, these alkaline aqueous solutions may be those to which an appropriate amount of a water-soluble organic solvent, for example, alcohols such as methanol or ethanol, or a surfactant is added.

0068[Process (6)] In this step, a pattern is formed on the substrate to be processed by one or a plurality of dry etchings using the resist pattern as a mask. Dry etching can be performed using a known dry etching apparatus. The source gas for dry etching depends on the elemental composition of the object to be etched, but O₂, CO, CO₂Gas containing oxygen atoms such as He, N₂, Ar and other inert gases, Cl₂, BCl₄Chlorine gas, CHF, etc.₃, CF₄Fluorine gas, H, etc.₂, NH₃Gas etc. can be used. In addition, these gases can also be mixed and used.

<p num="0069"> Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limited to this Example.</p><p num="0070">&lt;Preparation of composition for forming metal oxide film&gt; [Example 1] Ammonium paratungate (manufactured by Nippon Inorganic Chemical Industry, WO)₃(90.8% by mass in conversion) 8.58 g was dissolved in 112.1 g of ion-exchanged water to prepare an aqueous ammonium paratungate solution. 200 cm on a column with an inner diameter of 30 mm³Was filled with a proton-type cation exchange resin (Amberlite 200CT, manufactured by Rohm and Haas). Approximately 10 cm of the prepared ammonium metatungstate aqueous solution was applied to the above cation exchange resin.³/ Minute ~ 20cm³Pass through at a rate of / minute, and start recovery when the pH after elution becomes acidic. After the supply of the ammonium paratungate aqueous solution is completed, further ion-exchanged water is supplied, and the eluate returns to neutral again. At that point, the collection was completed. Further, the concentration of tungstic acid in the aqueous solution was adjusted to 4% by mass. The recovered tungstic acid aqueous solution was about 200 g. To 100 g of the obtained eluate, 10 g (31% by mass) of hydrogen peroxide solution was added, and the mixture was stirred at room temperature for 1 hour. The solution was then heated to 95 ° C and stirred for 1.5 hours. After cooling to room temperature, pure water as the solvent of [C] was added to the transparent solution of the compound [A] to obtain a peroxytungstic acid solution. To 100 g of this peroxytungstic acid solution, 1 g of a nonionic acetylene group-containing surfactant (manufactured by Nisshin Chemical Co., Ltd., Surfinol 465) as a [B] surfactant was added to prepare a composition for forming a metal oxide film.</p><p num="0071">[Comparative example 1] A composition for forming a metal oxide film was prepared in the same manner as in Example 1 except that it did not contain a surfactant.</p><p num="0072">&lt;Uniform coating property&gt; Each of the prepared composition for forming a metal oxide film was applied to a 5 cm square silicon wafer (base A) and a 5 cm square silicon wafer coated with a polydimethylsiloxane resin (base B), and the uniform coatability was evaluated. As a coating method, about 1 cc of each metal oxide film forming composition was dropped onto the substrates A and B, and then the substrate was rotated at 1,000 rpm with a spin coater (manufactured by Mikasa, MS-A100). The uniform coating property after coating was visually confirmed. When the coating film was uniformly formed, it was judged that the uniform coating property was good, and when the coating film was not uniformly formed, it was judged that the uniform coating property was poor.</p><p num="0073"> As a result, the composition for forming a metal oxide film of Example 1 had good uniform coating properties on both the substrates A and B. On the other hand, the composition for forming a metal oxide film of Comparative Example 1 had good uniform coating property on the substrate A, but poor uniform coating property on the substrate B.</p>

0074The present invention can provide a composition for forming a metal oxide film having good uniform coating properties on various substrates. Therefore, the composition for forming a metal oxide film can be suitably used for forming a resist pattern in a lithography process, which is expected to be further miniaturized in the future.