JP2000016812A - Production of metal oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of forming a metal oxide film having denseness and high homogeneity even on a base having low heat resistance and on the surface of a base containing an element having a bad influence on the characteristics of a film by using a sol-gel method without requiring excessive energy for improving the microstructure of the film. SOLUTION: This method for producing a metal oxide film comprises coating the surface of a base with a coating solution of a metal oxide obtained by using a metal alkoxide or a metal salt as a starting raw material to form a coating film, irradiating the coating film with ultraviolet rays at <=360 nm wavelength and heat-treating the coating film to crystallize the metal oxide. An indium alkoxide or an indium salt and a tin alkoxide or a tin salt are used as starting raw materials, an obtained coating solution of a metal oxide is a coating solution of In2O3-SnO2, a coating film obtained by coating the surface of a material to be coated with the coating solution is irradiated with ultraviolet rays at <=280 nm wavelength, metal indium and/or metal tin in the coating film is precipitated and the coating film is heat-treated to crystallize In2O3-SnO2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal oxide film on a surface of a substrate such as glass, ceramics, or plastics at a lower temperature than a conventional method. In particular, indium oxide to indium alkoxide or indium salt and tin alkoxide or tin salt as a starting material - tin oxide (In ₂ O ₃ -S
nO ₂ ; ITO) film.

[0002]

2. Description of the Related Art A functional film such as a transparent conductive ITO film or a perovskite dielectric film is formed by a sputtering method, a CVD method, or the like.
Dry process such as a dry process, a method of heating a coating film formed on the surface of a substrate by a sol-gel method using a metal alkoxide as a starting material at an appropriate temperature, and a spray decomposition method using a metal salt as a starting material. Manufactured by process.

[0003] Among the above methods, the sputtering method is the most widely used method for forming a transparent conductive ITO film, and its application to the formation of a composite oxide film having a large amount of constituent metal components has been studied. However, it is often difficult to obtain a composite oxide having a desired stoichiometric composition.
In addition, since a sputtering process is performed in a vacuum process, there is a problem that the shape and size of a substrate on which a metal oxide film is to be formed are restricted. Also,
In the CVD method, it is necessary to secure a volatile substance as a starting material, and it is difficult to control the composition ratio of each raw material. Therefore, the types of composite oxide films to which this method can be applied are limited. Problem.

On the other hand, a method of forming a metal oxide film using a sol-gel method can easily obtain a film having a desired stoichiometric ratio. However, in the sol-gel method, 500 ° C. to 700 ° C.
Heat treatment at a temperature of about ° C is required.

In the method of producing a metal oxide film using a sol-gel method, generally, the rate of hydrolysis of metal alkoxides except silicon alkoxide is very high, so that a uniform sol capable of forming a film is prepared. It is difficult. Therefore, several methods for suppressing the rate of hydrolysis of metal alkoxide have been studied.

In order to suppress the rate of hydrolysis of the metal alkoxide, for example, by making the concentration of the metal alkoxide extremely low, it is possible to form a uniform film of the coating solution. However, this method is not an effective method from an industrial point of view, since the film thickness obtained in one film forming step becomes extremely thin.

Several methods have been proposed for stabilizing metal alkoxides by adding a polydentate organic compound. For example, β-diketone is effective for forming an alumina thin film using aluminum-s-butoxide as a starting material (Academic Journal of the Ceramic Society of Japan, 97 , 396).
(1989)). In forming a titania thin film using titanium isopropoxide as a starting material, 1,3-butanediol (Toshio Koshiba, doctoral dissertation, Toyohashi University of Technology, March 1993)
Mon), diethanolamine (Academic Journal of the Ceramic Society of Japan, 97 , 183 (1989)), or β-diketone (Academic Journal of the Ceramic Society of Japan, 97 , 213)
(1989)) are reported to be effective. It has been reported that the use of diethylene glycol is effective for forming a zirconia thin film using zirconium-n-butoxide as a starting material (Ceramic Industry Association, 9).
5 , 942 (1987)). The use of β-diketones and alkanolamines has led to PbTiO ₃ and Pb (Zr, Ti)
A report that it is also effective for the synthesis of complex oxides such as O ₃ has been reported in the Journal of American Ceramics Society (Journal of American).
Ceramics Society), 74 , 140
7 (1991) and The Ceramic Society of Japan, 9
8, 745 (1990).

Physics of Chin Film (P
physics of Tin Film), 5 , p87
(1969), Academic Press (Academi)
cPress) reports a method of hydrolyzing various inorganic salts such as chlorides, sulfates, nitrates, and ammonium salts and a method of producing an oxide film using an aqua complex. Furthermore, The Ceramics Society of Japan, 102 , 200
(1994) describes In ₂ O ₃ —S as a composite oxide.
It has been shown to use indium nitrate and tin chloride instead of metal alkoxide for the preparation of nO ₂ sol.

[0009]

In the above-mentioned sol-gel method, heat treatment at a temperature of about 500 ° C. to 700 ° C., which is usually performed, is required to crystallize a metal oxide. Therefore, a metal oxide film could not be formed on a substrate having low heat resistance such as plastics. In addition, in the case of a substrate containing a large amount of an element such as Na, it is very difficult to form a high-quality metal oxide film due to diffusion of the Na component into the film by heat treatment at several hundred degrees Celsius.

According to the method of suppressing the rate of hydrolysis of metal alkoxide by adding a polydentate compound as described above, a homogeneous coating solution can be easily prepared. Many organic matter will remain in it. As a result, it is necessary to heat-treat the coating film at a high temperature of about 500 ° C. to remove the residue.
Further, since many organic substances remain in the coating film, heat treatment of the coating film greatly reduces the weight of the film. In other words, many pores are generated in the film due to the removal of the organic matter from the coating film, which is likely to be a defect. Extra energy is required to improve the microstructure of the film.

The method using a metal salt as described above is basically a thermal decomposition method, and causes many problems in the film quality after the heat treatment.

The present invention has been made in view of the above circumstances, and when a metal oxide film is formed on the surface of a substrate using a sol-gel method, removal of residues from the coating film is performed. It is not necessary to perform heat treatment of the coating film at a high temperature for the purpose. On a substrate having low heat resistance or on a surface of a substrate containing many elements that adversely affect the film characteristics such as Na, a good fine structure and excellent It is an object of the present invention to provide a method for manufacturing a metal oxide film capable of forming a metal oxide film having characteristics at a lower temperature.

[0013]

The invention according to claim 1 is
A metal oxide coating solution obtained using a metal alkoxide or a metal salt as a starting material is applied to the surface of an object to be coated to form a coating film, and the coating film is irradiated with ultraviolet light having a wavelength of 360 nm or less. The present invention is characterized in that a crystallized metal oxide film is manufactured by heat-treating the coating film to crystallize the metal oxide.

According to a second aspect of the present invention, in the production method of the first aspect, an indium alkoxide or an indium salt and a tin alkoxide or a tin salt are used as starting materials, and the obtained metal oxide coating solution is In ₂ O ₃ -Sn
O ₂ is the coating liquid, its wavelength coating liquid to a coating film formed by coating the surface of the coating object is irradiated with ultraviolet light at 280nm or less, metallic indium and / or metal in the coating film after precipitation of the tin, the in ₂ O ₃ -SnO ₂ and heat treated coating film is characterized by crystallization.

According to the method of the present invention, the wavelength of the coating film is set to 360 nm before the coating film is subjected to the heat treatment.
By irradiating the following ultraviolet light, removal of residues in the coating film and densification of the film advance in advance, and thus deterioration of the film structure due to heat treatment until crystallization of the metal oxide is reduced. This is effective for crystallization at a low temperature. Therefore,
The heat treatment temperature at the time of crystallizing the metal oxide by heat treatment of the coating film can be reduced.

According to the method of the second aspect of the invention, In
₂ O ₃ when the wavelength against -SnO ₂ was irradiated to the following ultraviolet light 280nm, the metal indium and / or tin metal is deposited on the coating film. By heating the coating film metal indium and / or tin metal was deposited, it becomes possible to significantly reduce the crystallization temperature of the In ₂ O ₃ -SnO _2.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

In the method for producing a metal oxide film according to the present invention, starting from a metal alkoxide or a metal salt, water is added to a solution containing the alkoxide or the salt to cause hydrolysis and polymerization reactions. By
A coating solution (precursor sol) is prepared, and the coating solution is applied to the surface of a substrate or the like to form a coating film. Crystallize the oxide.

The metal oxide film to which the manufacturing method according to the present invention can be applied is not limited as long as a metal oxide coating solution can be obtained using a metal alkoxide or a metal salt as a starting material. However, there is no particular limitation. For example, metal oxide films manufactured by the method according to the present invention include titania, zirconia, vanadium oxide, niobium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, nickel oxide, zinc oxide, manganese oxide, cobalt oxide, and oxide oxide. Iron, copper oxide, indium oxide,
For example, tin oxide. Further, the manufacturing method according to the present invention,
The present invention is also applicable to the formation of a perovskite-type composite oxide film represented by the chemical formula ABO ₃ . In the chemical formula, A is Ba,
S is Sr or Pb, B is Ti, Zr, Ge or Sn, a combination of these elements, or A is Li, Na or K;
Is V, Nb or Ta, and is a combination of these elements. The chemical formula A (B _1/3 , C
_2/3 ) A metal oxide having a complex perovskite structure represented by O ₃ , wherein A is Ba, Sr, Pb
Or B, B is Mg, Mn, Co, Ni or Zn, and C is V, Nb or Ta, and a combination of these elements. Further, the present invention can be applied to a transparent conductive film in which the metal oxide film is an In ₂ O ₃ —SnO ₂ film or an Al ₂ O ₃ —ZnO film. In particular, I
The manufacturing method according to the present invention is effective for a dielectric film such as an n ₂ O ₃ —SnO ₂ film or a composite oxide having a perovskite structure.

Examples of usable metal alkoxides or metal salts include alkali metal elements, alkaline earth metal elements and Group 3B elements from the second period to the sixth period of the periodic table, and those of the third period of the periodic table. One metal alkoxide or metal salt, or two or more metal alkoxides, or an element selected from the group consisting of Group 4B elements and Group 5B elements up to the sixth period, transition metal elements, and lanthanoid elements Any combination of metal salts may be used, and there is no particular limitation. Also, a complex alkoxide obtained by a reaction between two or more metal alkoxides of the above element, or a compound alkoxide obtained by a reaction of one or more metal alkoxides with one or more metal salts. Or a complex alkoxide. Furthermore, these can be used in combination.

For the reaction between two or more metal alkoxides
The composite alkoxide obtained from
Or an alkaline earth metal alkoxide and a transition metal
Complex alkoxide obtained by reaction with lucoxide
Or as a complex salt obtained by a combination of Group 3B elements
Complex alkoxides are used. For example, BaTi (O
R)₆, SrTi (OR)₆, BaZr (OR)₆, S
rZr (OR)₆, LiNb (OR)₆, LiTa (O
R)₆, And combinations thereof, LiVO (O
R)₄, MgAl₂(OR)₈and so on. Also, (R
O)₃SiOAl (OR ')₂, (RO)₃SiOTi
(OR ')₃, (RO)₃SiOZr (OR ') ₃,
(RO)₃SiOB (OR ')₂, (RO)₃SiON
b (OR ')₄, (RO)₃SiOTa (OR ')₄What
Any reaction product with silicon alkoxide or its condensation polymer
Used. Here, R and R 'represent an alkyl group.
You. The carbon number of the alkoxyl group of the metal alkoxide is particularly
Although not limited, the concentration of oxides contained and the ease of desorption of organic substances
Now, from the point of easy availability, the carbon number is 1 to 4
Is preferred. In addition, one or more metal
Reaction of coxide with one or more metal salts
The resulting complex alkoxides include chloride, nitric acid
Metal salts such as salts, sulfates, acetates, formates and oxalates
Compounds obtained by the reaction of
It is.

The metal oxide film finally obtained is In
₂O₃-SnO₂Taking the case of a membrane as an example, the starting material
The indium alkoxide is
Toxide, indium ethoxide, indium propoxy
Sid and indium butoxide are used. Also,
Tin alkoxides include tin methoxide, tin ethoxy
, Tin propoxide and tin butoxide are used.
In addition, the inclusion of indium alkoxide and tin alkoxide
Although the proportion is not particularly limited, the lower resistance In ₂O₃
-SnO₂In order to obtain a film, In₂O₃-SnO₂of
SnO at home₂Contains only 1% to 20% by weight
It is preferable that the ratio be as follows.

As the metal salt, acetate, oxalate, nitrate, chloride and the like are used.

The solvent to be used may be a single solvent or a mixed solvent, as long as the raw materials such as metal alkoxide and metal salt and water used for hydrolysis are respectively soluble, and are not particularly limited. For example, a combination of a polar solvent and a non-polar solvent may be used. Methanol, ethanol and propanol, which are alcohols having 1 to 3 carbon atoms, are particularly preferred from the viewpoint of viscosity in the temperature range in which water is added, ease of removal, and the like. Also, 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 1-methyl-2-propanol, 1-ethyl-
Alkoxy alcohols such as 2-propanol can also be used.

In order to facilitate the elimination of the solvent after gelation, it is preferable to reduce the amount of the polydentate compound directly bonded to the alkoxide as much as possible. An acid amide represented by RCONR '(R, R' is hydrogen or an alkyl group) having a plurality of coordinable functional groups does not form a bond due to substitution with an alkoxyl group, and thus solidifies at the temperature at which water is added. If it is easy to remove by volatilization, it can be used without any problem. Further, an organic substance such as β-diketone, which is effective for improving the solubility and the stability of the coating solution, may be appropriately added.

The amount of water to be added depends on the type of alkoxyl group in the metal alkoxide, the mixing ratio of the metal alkoxide,
It cannot be specified because it differs depending on the type of the metal salt. An acid or a base is appropriately used in combination as a catalyst. The catalyst to be used is not particularly limited, but in order to obtain a high-purity material, a compound containing no metal component is preferable. For example, as the acid, mineral acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid, and organic acids such as carbonic acid, boric acid, formic acid, acetic acid, and oxalic acid are used. As the base, ammonia,
Amines and the like are used.

The metal oxide coating solution obtained by the above-described production method is applied to a substrate on which a film is to be formed, thereby forming a coating film on the surface of the substrate. As a coating method, a generally practiced method such as dip coating, spin coating, flow coating, and bar coating can be used.

Next, a wavelength of 36 was applied to the obtained coating film.
Irradiation with ultraviolet light of 0 nm or less is performed. Irradiation light wavelength is 3
When the thickness is 60 nm or more, the decomposition of the residue in the coating film does not progress so much, which is not preferable. After the application film is irradiated with ultraviolet light, the application film is subjected to a heat treatment at a relatively low temperature. The heat treatment temperature varies depending on the type of the target metal oxide film. However, by previously irradiating the coating film with ultraviolet light having a wavelength of 360 nm or less, residues in the coating film are reduced, and As the densification progresses, the crystallization temperature of the metal oxide decreases, and the quality of the metal oxide film improves. Through the above steps, the desired functional film is formed on the surface of the base.

The wavelength of the ultraviolet light source is 360 nm.
There is no particular limitation as long as it can irradiate the following ultraviolet light, for example, a high-pressure mercury lamp, a low-pressure mercury lamp,
Excimer lamp, ArF excimer laser, KrF excimer laser, XeCl excimer laser, XeF excimer laser, synchrotron radiation, YAG laser fourth harmonic, Y
An AG laser third harmonic is used, and particularly preferably, a low-pressure mercury lamp, an excimer lamp, or the like having a shorter peak wavelength is used.
An ArF excimer laser, a KrF excimer laser, synchrotron radiation, or a fourth harmonic of a YAG laser is used. It is also possible to use two or more of these light sources in combination.

The method according to the invention is particularly suitable for In ₂ O _3-
This is effective when forming a SnO ₂ film. In this case, it is preferable to irradiate an In ₂ O ₃ -SnO ₂ coating film with ultraviolet light having a wavelength of 280 nm or less. Irradiation of ultraviolet light in this wavelength range generates reduced metal indium and / or metal tin in the coating film. By heat-treating the coating film on which metal indium and / or metal tin has been deposited, the crystallization temperature of the ITO phase will be significantly reduced.

[0031]

Next, a more specific embodiment of the present invention will be described.

Example 1 An alkoxide solution was prepared by adding pentaethoxy niobium to 2-ethoxyethanol so that the final oxide concentration was 2.5% by weight. Next, using a hydrochloric acid catalyst (HCl / Nb = 0.15), the alkoxide solution was hydrolyzed with 5 moles of water,
An Nb ₂ O ₅ coating solution was obtained. The obtained coating solution was applied once on the surface of a silicon substrate using a spin coater under the conditions of a rotation speed of 500 rpm for 5 seconds and a rotation speed of 2,000 rpm for 15 seconds to form a film on the substrate. The obtained coating film was dried at a temperature of 110 ° C. for 30 minutes, whereby a coating film without cracks was obtained. Subsequently, using a low-pressure mercury lamp (10 mW / cm ² ) on the obtained coating film,
Irradiated with ultraviolet light for 5 hours.

The coating film before and after the irradiation of the ultraviolet light by the low-pressure mercury lamp is peeled off from the surface of the substrate, respectively.
-The difference between the two coated films was evaluated by measuring DTA. As a result, in the unirradiated coating film (Comparative Example 1), as shown in FIG. 2, an exothermic peak accompanied by a weight loss of nearly 30% was observed at a temperature around 300 ° C., but after irradiation with ultraviolet light, As shown in FIG. 1, this exothermic peak becomes smaller,
The weight loss was also reduced to 10% or less. In addition, the shrinkage ratios of the film thicknesses of the two coating films were greatly different, and were about 60% and 30% before and after the irradiation of the ultraviolet light, respectively.

Example 2 Tetraisopropoxytitanium was added so that the final oxide concentration was 2.5% by weight.
-An alkoxide solution was prepared by addition in ethoxyethanol. Next, a hydrochloric acid catalyst (HCl / Ti = 0.2)
Was used to hydrolyze the alkoxide solution with 5 moles of water to obtain a TiO ₂ coating solution. The obtained coating solution was applied once on the surface of a silica glass substrate using a spin coater under the conditions of a rotation speed of 500 rpm for 5 seconds and a rotation speed of 2,000 rpm for 15 seconds to form a film on the substrate. The obtained coating film was dried at a temperature of 110 ° C. for 30 minutes, whereby a coating film without cracks was obtained. Subsequently, the obtained coating film was irradiated with ultraviolet light for 5 hours using a low-pressure mercury lamp (10 mW / cm ² ).

The coating film before and after irradiation with ultraviolet light by a low-pressure mercury lamp is peeled off from the surface of the substrate, respectively.
-The difference between the two coated films was evaluated by measuring DTA. As a result, in the unirradiated coating film (Comparative Example 2), as shown in FIG.
%, But after irradiation with ultraviolet light, as shown in FIG. 3, the exothermic peak almost disappeared, and near the temperature of 340 ° C., the residual hydroxyl group due to crystallization was reduced. Only about 10% weight loss due to elimination was observed.

As described above, by irradiating the coating film with ultraviolet light from a low-pressure mercury lamp, the amount of residues in the coating film can be significantly reduced, and improvement in film quality can be expected. it can.

Example 3 A mixed solution was prepared by adding stoichiometric ratios of barium metal and tetraisopropoxytitanium to 2-methoxyethanol so that the final oxide concentration was 2.5% by weight. With 0.1 M HCl (H ₂ O / Ti =
Hydrolysis was performed in 1) to obtain a BaTiO ₃ coating solution. Using a spin coater, the obtained coating solution was applied at a rotation speed of 500 rpm for 5 seconds and at a rotation speed of 2,000 rpm for 15 seconds.
Pt / Ti / SiO ₂ / Si substrate (each 1
(00 nm, 30 nm, 100 nm) once and formed on the substrate. The obtained coating film was dried at a temperature of 110 ° C. for 30 minutes, whereby a coating film without cracks was obtained. Subsequently, the obtained coating film was irradiated with ultraviolet light for 5 hours using a low-pressure mercury lamp (10 mW / cm ² ).

The coating films before and after the irradiation of ultraviolet light by the low-pressure mercury lamp are respectively peeled from the surface of the substrate, and TG
-Measurement of DTA yielded the same results as in Examples 1 and 2 above. Ba
The crystallization temperature of TiO ₃ was examined by an X-ray diffraction method. As a result, crystallization of BaTiO ₃ at a temperature of 300 ° C. to 400 ° C. was confirmed in the coating film after irradiation with ultraviolet light. On the other hand, in the unirradiated coating film (Comparative Example 3), a heat treatment at a temperature of 600 ° C. or higher was required for crystallization of BaTiO ₃ .

Example 4 Diethoxylead, tetraisopropoxytitanium, and tetra-n-butoxyzirconium (Zr / Ti = 52/48) in stoichiometric ratio were added to 2-methoxyethanol and then mixed. The solution was heated at a temperature of 80 ° C. for 2 hours to obtain an alkoxide mixed solution. Next, the mixed solution was adjusted to 0.1 M HCl (H ₂ O / Pb = 1) so that the final oxide concentration was 2.5% by weight.
To obtain a PZT (Pb (Zr, Ti) O ₃ ) coating solution. Using a spin coater, the obtained coating solution was rotated at 500 rpm for 5 seconds and 3,000 rpm.
Pt / Ti / SiO ₂ /
It was applied once on the surface of a Si substrate (100 nm, 30 nm, and 100 nm, respectively) and formed on the substrate. The obtained coating film was dried at a temperature of 110 ° C. for 30 minutes, whereby a coating film without cracks was obtained. Further, the above coating operation was repeated four times so that the thickness of the coating film was 0.4 μm. Subsequently, a low-pressure mercury lamp (1
(0 mW / cm ² ) and irradiated with ultraviolet light for 5 hours.

The coating film before and after the irradiation of the ultraviolet light by the low-pressure mercury lamp was peeled off from the surface of the substrate, and TG
-Measurement of DTA yielded the same results as in Examples 1 and 2 above. Further, the coating films before and after the irradiation of the ultraviolet light were respectively fired at various temperatures by a rapid temperature raising method. As a result, in the coating film after the irradiation with ultraviolet light, no defects such as cracks were found in the film, and a single-phase perovskite phase PZT film was obtained by firing at a temperature of 600 ° C. On the other hand, in the unirradiated coating film (Comparative Example 4), cracks were observed at any firing temperature, and a uniform PZT film could not be obtained.

Example 5 Tri-t-butoxyindium and tetra-s-butoxytin (In / Sn = 90/1)
0) was added to a mixed solution of 2-butanol and dimethylformamide, and acetylacetone in an equimolar amount to indium was added to the solution. Further, a 1N hydrochloric acid-2-butanol mixed solution (H) was added such that the solid content concentration of the metal oxide was 5% by weight when added to the alkoxide solution.
_{A 2} O / In molar ratio of 0.6) was prepared, and the mixture was added to a mixed solution of metal alkoxide at room temperature, and an ITO coating solution was obtained by hydrolysis. The obtained coating solution was applied once on the surface of a silica substrate using a spin coater under the conditions of a rotation speed of 500 rpm for 5 seconds and a rotation speed of 2,000 rpm for 15 seconds, to form a film on the substrate. The obtained coating film was dried at a temperature of 110 ° C. for 30 minutes, whereby a coating film without cracks was obtained. Subsequently, using a low-pressure mercury lamp (10 mW / cm ² ) on the obtained coating film,
Irradiated with ultraviolet light for 5 hours. Irradiation of ultraviolet light from a low-pressure mercury lamp produced metal indium in the coating film, and the film turned black. FIG. 5 shows an X-ray diffraction pattern of the obtained film.

The coating films before and after the irradiation of ultraviolet light by the low-pressure mercury lamp were each subjected to heat treatment at various temperatures for 1 hour. As a result, as shown in FIG. 6, crystallization of the ITO phase was confirmed by heat treatment at a temperature of 200 ° C. for one hour, as shown in FIG. The X-ray diffraction pattern shown in FIG.
This is for the ITO film when heat treatment is performed at temperatures of 250C, 250C, 300C and 400C, respectively.
On the other hand, in the unirradiated coating film (Comparative Example 5), as shown in FIG. 7, in order to crystallize ITO, a heat treatment at a temperature of 350 ° C. for 1 hour or more was required. The X-ray diffraction pattern shown in FIG.
This is for the ITO film when heat treatment is performed at temperatures of 0 ° C. and 350 ° C., respectively.

Example 6 Indium hydroxide was added to a mixed solution of acetic acid and acetic anhydride, and the solution was refluxed for 24 hours. Then, the solution was filtered to obtain indium acetate.
The obtained indium acetate is dispersed in 1-propanol, and equimolar amounts of diethanolamine and tetra-t-butoxytin are added to the solution, so that the final oxide concentration becomes 5% by weight. After the solution was prepared, the solution was refluxed for 1 hour to obtain a transparent ITO. Using a spin coater, the obtained coating solution was
once on the surface of the silica substrate under the conditions of 5 seconds at a rotation speed of rpm and 15 seconds at a rotation speed of 2,000 rpm,
A film was formed on a substrate. The obtained coating film was dried at a temperature of 110 ° C. for 30 minutes, whereby a coating film without cracks was obtained. Subsequently, a low-pressure mercury lamp (1
(0 mW / cm ² ) and irradiated with ultraviolet light for 5 hours.
Irradiation of ultraviolet light from the low-pressure mercury lamp produced metal indium in the coating film and blackened the film in the same manner as in Example 5 described above.

The coating films before and after the irradiation of the ultraviolet light by the low-pressure mercury lamp were each subjected to a heat treatment at various temperatures for 1 hour. As a result, as shown in FIG.
In the coating film after the irradiation of the ultraviolet light, crystallization of the ITO phase was confirmed by heat treatment at a temperature of 200 ° C. for 1 hour. The X-ray diffraction pattern shown in FIG.
This is for the ITO film when heat treatment is performed at temperatures of 250C, 250C, 300C and 400C, respectively.
On the other hand, in the unirradiated coating film (Comparative Example 6), as shown in FIG. 9, a heat treatment at a temperature of 300 ° C. for 1 hour or more was required for crystallization of ITO. The X-ray diffraction pattern shown in FIG.
This is for the ITO film when heat treatment is performed at temperatures of 0 ° C. and 400 ° C., respectively.

Example 7 Indium nitrate anhydride and tetra-t-butoxytin were added to 2-ethoxyethanol, and the mixture was stirred at room temperature for 20 hours to obtain a clear solution. . After the obtained solution was filtered, the solution (coating solution) was separated using a spin coater.
The coating was performed once on the surface of the silica substrate under the conditions of a rotation speed of 00 rpm for 5 seconds and a rotation speed of 2,000 rpm for 15 seconds, and a film was formed on the substrate. The obtained coating film was dried at a temperature of 110 ° C. for 30 minutes, whereby a coating film without cracks was obtained. Subsequently, the obtained coating film was irradiated with ultraviolet light for 20 minutes using a low-pressure mercury lamp (10 mW / cm ² ). Irradiation of ultraviolet light from the low-pressure mercury lamp produced metal indium in the coating film and blackened the film in the same manner as in Example 5 described above.

Further, the coating films before and after the irradiation of the ultraviolet light by the low-pressure mercury lamp were respectively subjected to heat treatment at various temperatures for 1 hour. As a result, in the coating film after the irradiation with the ultraviolet light, as shown in FIG. 10, crystallization of the ITO phase was confirmed by performing the heat treatment at a temperature of 200 ° C. for 1 hour. The X-ray diffraction pattern shown in FIG.
This is for the ITO film when subjected to heat treatment at temperatures of ° C and 250 ° C, respectively. On the other hand, in the unirradiated coating film (Comparative Example 7), as shown in FIG. 11, a heat treatment at a temperature of 300 ° C. for 1 hour or more was required for crystallization of ITO. The X-ray diffraction pattern shown in FIG. 11 shows 200 ° C., 250 ° C., 300 ° C., and 400 ° C. from below.
This is for the ITO film after each heat treatment at a temperature of ° C.

As shown in the above embodiments, according to the method of the present invention, it is possible to form a metal oxide film having a smaller amount of residue in the film than the conventional method.
By a heat treatment at a lower temperature, a dense crystalline metal oxide film having excellent film quality can be obtained. In particular, in the production of an ITO film, a crystalline ITO film can be obtained by a heat treatment at a temperature of 200 ° C. or less, and a crystalline conductive ITO film can be formed on a plastic substrate having poor heat resistance. It becomes possible to form a film.

[0048]

According to the manufacturing method of the first aspect of the present invention, when a metal oxide film is formed on the surface of a substrate using a sol-gel method, a high temperature is used to remove residues from the coating film. The need for heat treatment of the coating film is eliminated, so that a metal oxide film having a good fine structure can be formed at a low temperature, and extra energy is required to improve the fine structure of the film. Nor.

According to the manufacturing method of the second aspect,
In₂O₃-SnO₂The crystallization temperature of
For gentle heating with lower energy
More on substrates with low heat resistance such as plastics
Many elements that adversely affect conductivity, such as Na and Na
The surface of the substrate including₂O ₃
-SnO₂It becomes possible to form a film.

[Brief description of the drawings]

FIG. 1 is a graph showing T of an Nb ₂ O ₅ coating film after irradiation with ultraviolet light obtained by performing the manufacturing method according to Example 1.
It is a G-DTA curve.

FIG. 2 is a comparative example with respect to the embodiment shown in FIG. 1,
TG-DT for Nb ₂ O ₅ coating film not irradiated with ultraviolet light
It is an A curve.

FIG. 3 is a diagram showing a state in which the manufacturing method according to the second embodiment is performed.
The obtained TiO after irradiation with ultraviolet light ₂TG for coating film
-It is a DTA curve.

FIG. 4 is a comparative example for the embodiment shown in FIG. 3,
TG-DTA for TiO ₂ coating film not irradiated with ultraviolet light
It is a curve.

FIG. 5 is a view showing an X-ray diffraction pattern of an In ₂ O ₃ —SnO ₂ coating film after irradiation with ultraviolet light obtained by performing the manufacturing method according to Example 5.

FIG. 6 is a diagram showing a heating change of an X-ray diffraction pattern of an In ₂ O ₃ —SnO ₂ film obtained by performing the manufacturing method according to Example 5.

FIG. 7 is a comparative example for the embodiment shown in FIG. 6,
It is a diagram showing a heating change in X-ray diffraction pattern of the _{In 2 O} 3 -SnO 2 layer of ultraviolet light unirradiated.

FIG. 8 is a view showing a heating change of an X-ray diffraction pattern of an In ₂ O ₃ —SnO ₂ film obtained by performing the manufacturing method according to Example 6.

9 is a comparative example with respect to the embodiment shown in FIG. 8,
It is a diagram showing a heating change in X-ray diffraction pattern of the _{In 2 O} 3 -SnO 2 layer of ultraviolet light unirradiated.

FIG. 10 is a view showing a heating change of an X-ray diffraction pattern of an In ₂ O ₃ —SnO ₂ film obtained by performing the manufacturing method according to Example 7.

11 is a comparative example with respect to the example shown in FIG. 10 and is a view showing a heating change of an X-ray diffraction pattern of an In ₂ O ₃ —SnO ₂ film not irradiated with ultraviolet light.

[Procedure amendment]

[Submission date] July 8, 1998 (1998.7.8)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

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FIG. 6

[Procedure amendment 2]

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[Correction target item name] Fig. 7

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FIG. 7

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 8

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FIG. 8

[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] Fig. 9

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FIG. 9

[Procedure amendment 5]

[Document name to be amended] Drawing

[Correction target item name] FIG.

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FIG. 10

[Procedure amendment 6]

[Document name to be amended] Drawing

[Correction target item name] FIG.

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FIG. 11

Claims (2)

[Claims] A metal oxide coating solution obtained from a metal alkoxide or a metal salt as a starting material is applied to the surface of an object to be coated to form a coating film.
A method for producing a metal oxide film, comprising irradiating ultraviolet light having a wavelength of 60 nm or less, and then heating the applied film to crystallize the metal oxide. 2. An indium alkoxide or an indium salt and a tin alkoxide or a tin salt are used as starting materials, and the obtained metal oxide coating solution is In ₂ O ₃ —Sn.
O ₂ is the coating liquid, its wavelength coating liquid to a coating film formed by coating the surface of the coating object is irradiated with ultraviolet light at 280nm or less, metallic indium and / or metal in the coating film after precipitation of the tin, method for producing a metal oxide film according to claim 1, wherein crystallizing the in ₂ O ₃ -SnO ₂ and heating the coating film.