JP2824751B2 - Coating solution for metal oxide film formation - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating solution for forming a metal oxide film by coating and firing.
More specifically, for example, (1) a metal oxide film for the purpose of passivation to a substrate such as glass or ceramics of a liquid crystal display device, (2) a transparent conductive film of a liquid crystal display device, and (3) a semiconductor device An immersion method is used to form an insulating film to be provided on the electrodes described above, or (4) a film for the purpose of improving weather resistance, corrosion resistance, chemical resistance, optical properties, surface strength, etc. of ceramics, plastics, metals, etc. Any coating method such as spin coating, spray coating, roll coating or printing can form a metal oxide coating with high coating uniformity, and particularly roll coating which requires high viscosity and slow drying property Alternatively, the present invention relates to a coating solution for forming a metal oxide film which is effective as a coating solution for a printing method and has high storage stability. 2. Description of the Related Art Metal oxide films have recently been used in a wide variety of applications.
For example, they are used as insulating films or alignment control films for liquid crystal display elements, protective films for ceramics and metals, insulating films for semiconductor elements, and the like. In particular, in a liquid crystal display element, an electrode substrate is formed by forming a patterned transparent conductive film on an insulating substrate such as glass, forming a metal oxide film thereon, and forming an electrode substrate. A cell is formed on a pair of peripheral parts via a spacer, and a liquid crystal is sealed in the cell. The characteristics required for such a metal oxide film are that the metal oxide film has high adhesion to an insulating substrate or a transparent conductive film, and that the metal oxide film itself has no defects such as pinholes and is uniform. In recent years, since metal oxide films have been used in a wide variety of applications, it is natural that the characteristics of the above-described metal oxide films themselves must satisfy the purpose of use. It is also important to have excellent properties. Currently known methods for forming a metal oxide film include a vapor deposition method, a CVD method, and a sputtering method. However, all of these methods have problems in terms of mass productivity and cannot be said to be appropriate methods. For example, since a vacuum apparatus is used in the vapor deposition method, a uniform coating with large variations cannot be obtained, particularly when an attempt is made to form a metal oxide film on a large substrate, and the manufacturing cost is high because the apparatus is large and expensive. Lack mass productivity. In the CVD method, the substrate must be heated at the time of forming the metal oxide film, it is difficult to form a uniform film, and the apparatus is expensive, so there is a problem in mass productivity. Further, the sputtering method has almost the same defects as the vapor deposition method. [0003] As a method for improving the problems of the above method,
Coating methods have been proposed. This coating method is a method in which a coating solution for forming a metal oxide film is applied on a substrate, and then heated to form a metal oxide film on the substrate. In addition, since the process of forming a film is simple, mass productivity is extremely high. Conventionally, a coating solution for forming a metal oxide film used in a coating method includes a metal complex of β-diketone and β-diketone as a solvent.
Addition of polyethylene glycol or nitrocellulose to a solution containing an organic solvent or an inorganic solvent such as a diketone, a low-viscosity alcohol such as methanol, ethanol, and propanol; a ketone such as acetone; No. 55-149920) is known. This coating liquid can easily form a film on various substrates. However, since the coating formed by this coating liquid has a high porous property,
At the time of heat treatment after coating, undecomposed products and carbides of polyethylene glycol and nitrocellulose in the coating solution remain in the pores in the coating and hinder the formation of a uniform metal oxide film. Further, this coating solution has poor storage stability, and precipitates are generated in the coating solution when the coating solution is left for a long period of time. Conventionally, it has been difficult to obtain a coating liquid suitable for any coating method such as a dip coating method, a spin coating method, a roll coating method, and a transfer printing method. A metal oxide film formed by a coating method requiring a relatively high-viscosity coating liquid has poor uniformity and low adhesion to an insulating substrate or a transparent conductive film. On the other hand, in order to obtain a thick metal oxide film, it is effective to use a coating method such as a roll coating method and a transfer printing method using a high-viscosity coating solution. Thickeners such as organic polymers must be added. However, a coating solution containing a thickener has poor storage stability and changes over time,
There is a problem that gelation or precipitation occurs, and furthermore, the adhesion of the formed metal oxide film to the substrate surface is reduced, and peeling or clouding occurs. Accordingly, the present inventors have improved the drawbacks of the conventional coating solution for forming a metal oxide film and improved the uniformity, adhesion and film strength of the film. As a result of intensive research aimed at providing a coating solution that is free from pinholes and cissing and has excellent storage stability, (a)
It contains at least one element selected from an element forming a complex with a β-diketone, a salt of the element and a hydrolyzate of an alkoxide, (b) β-diketone, and (c) a specific aprotic polar solvent. A coating solution for forming a metal oxide film, and a coating solution for forming a metal oxide film containing a metal complex of β-diketone and a specific aprotic polar solvent,
The inventors have found that not only the coating properties but also the storage stability of the coating solution are excellent, and based on this finding, the present invention has been completed. SUMMARY OF THE INVENTION The gist of the present invention is to provide β
Metal complex of diketone, N, N-dimethylformamide, N, N-dimethylacetamide, acetonitrile, dimethylsulfoxide, N, N, N ′, N′-tetraethylsulfamide, hexamethylphosphoric triamide, N-methyl Morpholone, N-methylpyrrole, N-
Ethylpyrrole, N-methyl- △ 3-pyrroline, N-methylpiperidine, N-ethylpiperidine, N, N-dimethylpiperazine, N-methylimidazole, N-methyl-4-piperidone, N-methyl-2-piperidone, N-
Methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyltetrahydro-2 (1
H) -Pyrimidinone is a coating solution for forming a metal oxide film comprising at least one aprotic polar solvent selected from the group consisting of: Hereinafter, the present invention will be described in more detail. (Elements forming a complex with β-diketone) Group Ib elements of the periodic table such as copper; Periodic elements of the group IIa of the periodic table such as beryllium, magnesium, calcium, strontium and barium; and periods of zinc and cadmium. Group IIb element of the table, lanthanum, cerium, scandium,
Group IIIa element of the periodic table such as yttrium, Group IIIb element of the periodic table such as aluminum, gallium, indium and thallium; Group IVa element of the periodic table such as titanium, zirconium and hafnium; silicon, germanium, tin and lead Group IVb element of the periodic table, such as vanadium, niobium, tantalum, etc.
Group Vb elements of the periodic table such as antimony and bismuth; and VI of the periodic table such as chromium, molybdenum and tungsten
Group VIa element such as selenium and tellurium, Group VIb element such as manganese and rhenium, Group VIIa element such as manganese and rhenium, and Periodic table VIII such as iron, cobalt and nickel
Group elements can be mentioned, and salts and alkoxide hydrolysates of these elements can also be used. (Salts of Elements) As salts of these elements,
Inorganic salts such as hydrochloride, nitrate and sulfate, organic salts such as acetate and octylate, β-diketone complex such as acetylacetone complex, biscyclopentadienyl complex and the like can be mentioned. (Hydrolysates of alkoxides) As hydrolysates of alkoxides of these elements, compounds of the periodic table I
Group b, Group IIa, Group IIb, Group IIIa, Group II
Ib, IVa, IVb, Va, Vb
, VIa, VIb, VIIa, VII
Examples include hydrolyzates of alkoxide compounds of at least one element belonging to any of Group I elements. For example, when an alkoxide of silicon is shown as an example, tetraalkoxysilane, monoalkyltrialkoxysilane, monoaryltrialkoxysilane Hydrolysates such as alkoxysilanes, and specific examples thereof include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, monomethyltrimethoxysilane, monomethyltriethoxysilane, monomethyltripropoxysilane, and monomethyltributoxysilane. And hydrolysates such as monoethyltrimethoxysilane, monoethyltriethoxysilane, monophenyltrimethoxysilane, and monophenyltriethoxysilane. In order to hydrolyze these alkoxides, an inorganic acid such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, or the like, or an organic acid such as monochloroacetic acid, monofluoroacetic acid, or organic sulfonic acid, is used as a catalyst. For convenient use, metal alkoxide and β
-A solution obtained by hydrolysis using a solution obtained by adding the catalyst to the diketone and the aprotic polar solvent described above may be used as the coating solution. Hydrolysis products of these alkoxides alone,
Also, a mixture of two or more kinds can be used. The above-mentioned elements, salts thereof and hydrolysates of alkoxides can be used alone or in combination of two or more. (Β-diketone) The β-diketone used in the present invention includes acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone, benzoyltrifluoroacetone, dibenzoylmethane, acetoacetate methyl ester, and acetoacetate ethyl ester. And acetoacetic acid butyl ester. The above β-diketone can be used alone or
A mixture of more than one species can be used. (Metal Complex of β-Diketone) The metal complex of β-diketone used in the present invention is a metal complex comprising the above element and the above β-diketone. It can be obtained by reacting the above element, a salt of the element (excluding the metal complex of β-diketone) or a hydrolyzate of alkoxide with β-diketone. (Aprotic polar solvent) The aprotic polar solvent used in the present invention includes N, N-dimethylformamide, N, N-dimethylacetamide, acetonitrile, dimethylsulfoxide, N, N, N ', N '
-Tetraethylsulfamide, hexamethylphosphoric triamide, N-methylmorpholone, N-methylpyrrole,
N-ethylpyrrole, N-methyl-Δ3-pyrroline, N
-Methylpiperidine, N-ethylpiperidine, N, N-
Dimethylpiperazine, N-methylimidazole, N-methyl-4-piperidone, N-methyl-2-piperidone,
N-methyl-2-pyrrolidone, 1,3-dimethyl-2-
Imidazolidinone, 1,3-dimethyltetrahydro-2
Examples thereof include (1H) -pyrimidinone, and these may be used alone or as a mixture of two or more. (Preparation method of coating liquid) The coating liquid of the present invention comprises (1) at least one selected from (a) an element which forms a complex with β-diketone, a salt of the element and a hydrolyzate of an alkoxide. One kind is (b) β-diketone and (c)
(2) a method of dissolving a metal complex of β-diketone in a mixed solution of β-diketone and the aprotic polar solvent,
Or (3) a method in which a metal complex of β-diketone is dissolved in the aprotic polar solvent described above. (Blending ratio) In the coating solution of the present invention, the respective blending ratios of the components (a), (b) and (c) are as follows.
~ 60% by weight, (b) component is 1% ~ 60% by weight,
The component (c) is 10 to 80% by weight, preferably the component (a) is 1 to 50% by weight, the component (b) is 1 to 50% by weight, and the component (c) is 10 to 80% by weight. % By weight to 70
% By weight. Also, instead of the components (a) and (b), β
(2) and (3) using a metal complex of a diketone
In the case of the method (1), the metal complex of β-diketone is preferably 1 to 60% by weight, and the component (C) is preferably 40 to 99% by weight. (Organic Solvent) An organic solvent may be added to the coating solution of the present invention in order to improve coating properties. As the organic solvent, the following general formulas R-OH, HO-R-OH, HO-R-O-R, HO-R-O-R-OH, HO-R-O-OR-O-R, R- An organic solvent represented by OR-OR-OR (wherein R independently represents an alkyl group, an alkylene group, an aryl group, an arylene group or a benzyl group) is preferably used. , Methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, octylene glycol, diethylene glycol, dipropylene glycol, dihexylene glycol, ethylene glycol Monomethyl ether, ethylene glycol monoethyl ether, ethyl Glycol monobutyl ether, ethylene glycol monopropyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol Methyl ethyl diether, ethylene glycol dibutyl ether, ethylene glycol dipropyl ether, ethylene glycol diphenyl ether, ethylene glycol dibenzyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether, methyl carbite , Ethyl carbitol, butyl carbitol, phenyl carbitol, benzyl carbitol, dimethyl carbitol, diethyl carbitol, dibutyl carbitol, diphenyl carbitol, dibenzyl carbitol, methyl ethyl carbitol, dipropylene glycol dimethyl ether, dipropylene glycol Examples thereof include propylene glycol diethyl ether and dipropylene glycol dibutyl ether. These organic solvents may be used alone or as a mixture of two or more. In this case, the amount of the organic solvent added is
The content is preferably 80% by weight or less, more preferably 30% by weight, based on the mixed solution of the metal complex of the components (a), (b) and (c) or the β-diketone and the aprotic polar solvent.
Preferably it is in the range of 70% by weight. If it exceeds this range, the adhesion of the coating film decreases, the film strength decreases,
It is not preferable because it leads to a decrease in coating properties and the like. (Coating Method and Metal Oxide Film Forming Method) The coating solution of the present invention is applied to a substrate obtained by sintering a powder of plastic, glass, ceramics, metal nitride, metal carbonate, or the like, a metal, a semiconductor substrate, or the like. By heating, a metal oxide film having excellent adhesion and uniformity can be formed on the substrate. As a coating means in this case, any of a dipping and pulling method, a spray method, a spin coating method, a brush coating method, a roll coating method, and a printing method can be used. Examples of the heating means include hot plate heating, hot air heating, burner heating, infrared heating, laser heating, and high frequency heating. The heating temperature is preferably 100 ° C. or higher, and more preferably 300 ° C. or higher, in order to form a chemically stable film. However, it is limited by the material and the like of the substrate. It is necessary to make a choice. EXAMPLES The present invention will be described below with reference to examples. In the following, parts represent parts by weight. Example 1 After washing a 1.1 mm thick soda glass substrate, the substrate was immersed in a coating solution comprising the following components, and then 10 cm / mi
Coating was performed by raising n at a constant speed. Ethyl acetoacetate aluminum diisopropylate 15 parts Acetylacetone 3 parts N-methyl-2-pyrrolidone 25 parts Then put in a hot air circulating drier at 140 ° C for 15 minutes, transfer to electric furnace and calcine at 500 ° C for 60 minutes And 80
A nm thick Al2 O3 coating was obtained. The coating was transparent, no clear pinholes were observed, the uniformity was high, and the adhesion and coating strength were good. The coating solution was homogeneous without any change in components even after storage at room temperature for 12 months. Further, a coating test was carried out in the same manner as described above using the coating liquid after 12 months, but no significant difference was observed in the formed film from the evaluation 12 months ago. Example 2 After cleaning a metal aluminum substrate having a thickness of 1.0 mm, a coating liquid comprising the following components was used.
Coated by roll coat. Iron (III) acetylacetonate 25 parts Hexamethylphosphoric acid triamide 20 parts Ethyl alcohol 5 parts Drying is performed immediately after roll coating in a hot air circulating drier at 140 ° C for 15 minutes, and then transferred to an electric furnace at 300 ° C. 6
By baking for 0 minutes, a Fe2O3 film having a thickness of 56 nm was formed. The coating had no obvious pinholes or cissing, and had good adhesion and coating strength. The coating solution was homogeneous without any change in components even after storage at room temperature for 12 months. Further, the same coating test as described above was performed using the coating solution after 12 months.
There were no significant differences from the assessments made months ago. Example 3 After cleaning a 1.0 mm-thick ceramic substrate, a coating solution comprising the following components was used.
Spin coating was performed at 00 rpm. Dibutyltin diacetate 5 parts Acetoacetic acid ethyl ester 1.9 parts Tin (II) trifluoroacetylacetonate 12 parts Dimethyl sulfoxide 60 parts Propylene glycol 40 parts Ethyl alcohol 20 parts After spin coating, 100 ° C in a hot air circulating drier. After drying for 10 minutes, UV light was applied for 3 minutes with a 30 W low-pressure mercury lamp.
After irradiating for 0 minute, it was transferred into an electric furnace and baked at 700 ° C. for 60 minutes to form a SnO film having a thickness of 68 nm. The coating had a sheet resistance of 8.3 kΩ / □, no apparent pinholes or cissing, etc., and good adhesion and coating strength. The coating solution was homogeneous without any change in components even after storage at room temperature for 12 months. Furthermore, this 12
A coating test similar to that described above was performed using the coating solution after a lapse of months, but the formed film did not show any significant difference from the evaluation 12 months ago. Comparative Example 1 On a 5-inch silicon wafer, the following components were mixed with 7 parts of pure water and 0.1% of phosphoric acid as a catalyst.
Using a coating solution consisting of one part, 3000 rpm
m and spin coating was performed. 40 parts of tetraethoxysilane 30 parts of N-methyl-2-pyrrolidone 60 parts of ethylene glycol monoethyl ether Subsequently, after drying on a hot plate at 200 ° C. for 10 minutes,
Transfer into an electric furnace and bake at 800 ° C for 30 minutes, 135n
An m-thick PSG coating was formed. The coating had good uniformity and good adhesion and coating strength. However, at room temperature
After storage for a week, the coating solution exhibited a milky white gel, and was not used as a coating solution. [Comparative Example 2] A 1.1 mm thick soda glass substrate was washed and then immersed in a coating solution comprising the following components.
The coating was performed by pulling up at a constant speed of cm / min. Triisopropoxyaluminum 10 parts Isopropyl alcohol 60 parts Dimethylformamide 20 parts After pulling up the soda glass substrate, it was dried in a hot air circulating drier at 100 ° C for 10 minutes. The coating film became cloudy and cloudy on the entire surface. Admitted. In this coating solution, precipitation of a white precipitate was observed in about 2 weeks at room temperature. Effect of the Invention The coating solution for forming a metal oxide film of the present invention has excellent storage stability, good uniformity of coating, good adhesion, and good coating strength, and does not generate pinholes or cissing. A metal oxide film having excellent characteristics can be provided. Further, according to the present invention, it is possible to provide a substrate or the like on which a film is formed with good mass productivity, and to exert great industrial advantages.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-55-149920 (JP, A) JP-A-60-49509 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09D 185/00 C09D 1/00

Claims (1)

(57) [Claims] β-diketone metal complex, N, N-dimethylformamide, N, N-dimethylacetamide, acetonitrile, dimethylsulfoxide, N, N, N ′, N ′
-Tetraethylsulfamide, hexamethylphosphoric triamide, N-methylmorpholone, N-methylpyrrole,
N-ethylpyrrole, N-methyl- △ 3-pyrroline, N
-Methylpiperidine, N-ethylpiperidine, N, N-
Dimethylpiperazine, N-methylimidazole, N-methyl-4-piperidone, N-methyl-2-piperidone,
N-methyl-2-pyrrolidone, 1,3-dimethyl-2-
Imidazolidinone, 1,3-dimethyltetrahydro-2
A coating solution for forming a metal oxide film, comprising at least one kind of aprotic polar solvent selected from (1H) -pyrimidinone.