JPH1129326A - Production of in2o3-sno2 precursor sol and production of in2o3-sno2 thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing an In2 O3 -SnO2 precursor sol having high concentration and uniformity to enable the formation of a uniform film containing little organic materials left in the formed gel film and provide a process for producing an In2 O3 -SnO2 thin film having high quality. SOLUTION: In the case of the hydrolysis and polymerization of a solution containing an indium alkoxide and a tin alkoxide, the addition of water to a solution containing an indium alkoxide and a tin alkoxide is carried out at <=-20 deg.C. The gel film produced by using the obtained In2 O3 -SnO2 precursor sol is irradiated with ultraviolet rays having a wavelength of <=360 nm to crystallize the gel film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indium oxide coating on a surface of glass, ceramics, plastics or the like.
Tin oxide; method of making a In ₂ O ₃ -SnO ₂ precursor sol used to form a transparent conductive thin film _{(In 2 O 3 -SnO 2 ITO} ), and, using the precursor sol In _The present invention relates to a method for producing a ₂ O ₃ —SnO ₂ thin film.

[0002]

2. Description of the Related Art In order to form a metal oxide thin film on a substrate surface using a sol-gel method, a metal alkoxide is used as a raw material, which is hydrolyzed and polymerized to form a metal oxide precursor sol. After preparing and applying the obtained sol to the surface of a substrate, forming a thin film of a metal oxide gel on the surface of the substrate, the gel film is heated at an appropriate temperature. However, in general, metal alkoxides such as indium alkoxide and tin alkoxide except silicon alkoxide have a very high hydrolysis rate,
It is difficult to prepare a homogeneous sol that can form a uniform film. Therefore, several methods for suppressing the rate of hydrolysis of metal alkoxide have been studied.

As a method of suppressing the hydrolysis rate of a metal alkoxide, for example, there is a method of extremely lowering the concentration of the metal alkoxide. In this case, a uniform sol film can be formed. However, this method is not effective from an industrial point of view because the thickness of a film obtained in one film forming step is extremely small. Further, as a method of obtaining a sol capable of forming a film by increasing the concentration of the metal alkoxide and suppressing the hydrolysis rate, a method of adding a polydentate organic compound to stabilize the metal alkoxide is known. Some have been proposed. For example, aluminum-s-
In the formation of an alumina thin film using butoxide as a starting material,
β-diketone is effective (Academic Journal of the Ceramic Society of Japan, 97, 396 (1989)), and in forming a titania thin film using titanium isopropoxide as a starting material,
1,3-butanediol is effective (Toshio Koshiba, Ph.D. dissertation, Toyohashi University of Technology, March 1993), and diethanolamine is effective (Academic Journal of the Ceramic Society of Japan, 97, 183 (1989)). Furthermore, β-diketone is effective (Academic Journal of the Ceramic Society of Japan, 9
7, 213 (1989)). Also, it has been reported that the use of diethylene glycol is effective in forming a zirconia thin film using zirconium-n-butoxide as a starting material (Ceramic Industry Association, 95, 942 (1987)). Furthermore, the use of β-diketones and alkanolamines has led to PbTiO ₃ and Pb
It has been reported that it is also effective for the synthesis of complex oxides such as (Zr, Ti) O ₃ , but it is reported in the Journal of American Ceramic Society
eric Ceramics Society),
74, 1407 (1991) and Japanese Ceramics Association Scientific Transactions, 98, 745 (1990).

Further, Physics of TinFilm, 5, p.
87 (1969), Academic Press (Acade)
mic Press) includes chloride, sulfate, nitrate,
There are reports on the hydrolysis of various inorganic salts such as ammonium salts and the production of oxide films using aqua complexes. In addition, in order to prepare a sol of In ₂ O ₃ —SnO ₂ as a composite oxide, indium nitrate and tin chloride are used in place of metal alkoxide in the Journal of the Ceramic Society of Japan, 102, 200 (1994). Shown to use.

[0005]

However, as described above, according to the method of stabilizing a metal alkoxide such as an indium alkoxide or a tin alkoxide by adding a polydentate compound to suppress the rate of hydrolysis of the metal alkoxide. Although a homogeneous film-forming sol can be easily prepared, many organic substances having a high boiling point and being difficult to decompose coexist in the sol or gel film. As a result, it is necessary to heat-treat the gel film at a high temperature of about 500 ° C. in order to remove the organic substances. In addition, since many organic substances remain in the gel film, the heat treatment of the gel film greatly reduces the weight of the film. In other words, many pores are generated in the film by removing organic substances from the gel film, and the obtained In ₂
It causes a defect of a metal oxide thin film such as an O ₃ —SnO ₂ thin film. On the other hand, in order to remove the pores in the film, extra energy is required for densification of the thin film. In order to obtain an In ₂ O ₃ —SnO ₂ thin film having desired characteristics, usually, 600 nm is used. It is necessary to fire at a temperature of not less than ° C.

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

The present invention has been made in view of the above circumstances, and can prepare a homogeneous In ₂ O ₃ —SnO ₂ precursor sol capable of forming a uniform film. Also, to provide a method capable of producing an In ₂ O ₃ —SnO ₂ precursor sol having a small amount of an organic substance remaining in a sol or a gel film after film formation, and In ₂ O ₃ −
When the film is formed using the SnO ₂ precursor sol, the amount of the organic substance remaining in the gel film is small. Therefore, it is not necessary to perform the heat treatment of the gel film at a high temperature for removing the organic substance, and there is no bubble. A method capable of forming a homogeneous In ₂ O ₃ —SnO ₂ thin film and capable of manufacturing an In ₂ O ₃ —SnO ₂ thin film without requiring extra energy for densification of the thin film. The purpose is to provide.

[0008]

The invention according to claim 1 is
In a method for producing an In ₂ O ₃ —SnO ₂ precursor sol by hydrolyzing and polymerizing a solution containing indium alkoxide and tin alkoxide, the addition of water to the solution containing indium alkoxide and tin alkoxide is -2.
The process is performed at a temperature of 0 ° C. or less.

According to a second aspect of the present invention, there is provided the production method according to the first aspect, wherein In ₂ is used without using a polydentate compound.
It is characterized by producing an O ₃ —SnO ₂ precursor sol.

According to a third aspect of the present invention, in the method of the first or second aspect, the addition of water to the solution containing indium alkoxide and tin alkoxide is -5.
The process is performed in a temperature range of 0 ° C to -80 ° C.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor device according to any one of the first to third aspects.
In ₂ O ₃ —SnO _{2 was} prepared using an n ₂ O ₃ —SnO ₂ precursor sol.
A method for producing a thin film, comprising applying an In ₂ O ₃ —SnO ₂ precursor sol to a surface of a substrate, and applying an In ₂ O ₃ —
After forming a thin film of SnO ₂ gel, the thin film is irradiated with ultraviolet light having a wavelength of 360 nm or less to crystallize the In ₂ O ₃ —SnO ₂ gel forming the thin film, thereby improving conductivity. And forming an In ₂ O ₃ —SnO ₂ thin film on the substrate surface.

According to the manufacturing method of the first aspect,
Since the addition of water to the solution containing the indium alkoxide and the tin alkoxide is performed at a low temperature of −20 ° C. or less, the rate of hydrolysis and polymerization of the indium alkoxide and the tin alkoxide is suppressed, so that a uniform film can be formed. can be prepared is homogeneous In ₂ O ₃ -SnO ₂ precursor sol. And since it is not necessary to use a polydentate compound as in the production method of the invention according to claim 2, when a film is formed using the obtained In ₂ O ₃ —SnO ₂ precursor sol, The amount of organic matter remaining in the gel film is small. It is more preferable that the addition of water to the solution containing indium alkoxide and tin alkoxide is performed at a temperature in the range of -50 ° C to -80 ° C as in the production method according to the third aspect of the present invention.

According to the manufacturing method of the fourth aspect of the present invention,
A homogeneous In ₂ O ₃ -SnO ₂ precursor sol obtained by the production method according to any one of claims 1 to 3 is applied to the surface of a substrate to form a thin film of In ₂ O ₃ -SnO ₂ gel. Therefore, the amount of residual organic matter in the gel film is small.
For this reason, it is not necessary to heat-treat the gel film at a high temperature for removing organic substances. In addition, by crystallizing the In ₂ O ₃ —SnO ₂ gel, the foam has few bubbles, and is homogeneous, transparent, and conductive. In ₂ O ₃ -SnO ₂ thin film is obtained.

In general, depending on the sol-gel method,
It is very difficult to obtain an In ₂ O ₃ —SnO ₂ thin film having a resistance value of 10 ₋₃ Ωcm or less. This is because, when a thin film having a resistance of 10 ₋₃ Ωcm or less is to be obtained, migration (atom transfer) of an impurity element from the substrate during heat treatment becomes a problem. Substrates containing such materials cannot be used, but ordinary sol-
This is because the gel method requires a heat treatment temperature of 600 ° C. or higher for crystallization of the gel film, and the heat treatment at such a high temperature hinders the migration of impurity elements from the substrate. On the other hand, in the manufacturing method of the invention according to claim 4, after the In ₂ O ₃ —SnO ₂ precursor sol is applied to the surface of the substrate to form a gel film, the wavelength of the gel film is 360 nm or less. Irradiation with ultraviolet light crystallizes the gel film. Therefore, since it is not necessary to perform heat treatment at a high temperature for crystallization of the gel film,
Migration of the impurity element from the substrate does not pose a problem. Therefore, according to the method of the present invention, 10
An In ₂ O ₃ —SnO ₂ thin film having a resistance value of ₋₃ Ωcm or less can be obtained. In addition, the low-temperature crystallization of the gel film allows I
An n ₂ O ₃ -SnO ₂ thin film can also be formed. Low-temperature crystallization here means that the In ₂ O ₃ —SnO ₂ crystal phase can be confirmed by X-ray diffraction in a heat treatment at a temperature of 300 ° C. or lower. The mechanism of crystallization of the gel film by irradiation with ultraviolet light is not clear, but the wavelength is 360 n.
m or less of ultraviolet light is absorbed by indium and tin metal, and furthermore by functional groups of organic substances such as acid amide remaining in the gel film, and is converted into energy for densification and crystallization of In ₂ O ₃ —SnO _2. It is considered to be converted.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In ₂ O ₃ -SnO _{2 according} to the present invention
In the method for producing a precursor sol, indium alkoxide and tin alkoxide are used as starting materials, and water is added to a solution containing these alkoxides at a temperature of −20 ° C. or less,
Indium alkoxide and tin alkoxide are hydrolyzed and polymerized.

The indium alkoxide and tin alkoxide that can be used are not particularly limited. However, those having 1 to 4 carbon atoms in the alkoxyl group in view of the concentration of the oxide contained, the ease of desorption of organic substances, and the availability. Is preferred. For example, as indium alkoxide, indium methoxide, indium ethoxide, indium propoxide and indium butoxide are used, and among these, tri-i-propoxyindium, tri-s-butoxyindium, tri-t-butoxyindium and the like are used. Is preferably used. As the tin alkoxide, tin methoxide, tin ethoxide, tin propoxide and tin butoxide are used.
i-propoxy tin, tetra-n-butoxy tin, tetra-s-
Butoxy tin, tetra-t-butoxy tin and the like are preferably used. As the indium alkoxide and the tin alkoxide, one kind may be used, or two or more kinds may be used in combination. The content ratio of the indium alkoxide and the tin alkoxide is not particularly limited, but the lower resistance I
In order to obtain an n ₂ O ₃ -SnO ₂ conductive film, In ₂ O _3-
It is preferable that the ratio as SnO ₂ is contained by 1 wt% to 20 wt% of SnO _2.

The temperature at which water is added to the solution containing the indium alkoxide and the tin alkoxide depends on the stability of the alkoxide, and may be a temperature of -20 ° C. or less. Depending on the type, it is more preferable to add water to the alkoxide in a temperature range of -50C to -80C. By adding water at a low temperature such as −20 ° C. or lower, the indium alkoxide and the tin alkoxide have a high concentration without adding a polydentate compound to the indium alkoxide and the tin alkoxide to stabilize the alkoxide. , A hydrolysis / polymerization reaction can be carried out, and a high-concentration In ₂ O ₃ —SnO ₂ precursor sol containing no unnecessary organic substances such as a polydentate compound can be obtained. As a result, the In ₂ O ₃ —Sn
When an O ₂ precursor sol is used, a gel film having a small content of organic substances can be easily obtained, and when the organic substances are desorbed from the gel by heat treatment or the like, the fine structure of the obtained thin film is destroyed or remains. The amount of porosity can be reduced.

The solvent used may be a single solvent or a mixed solvent as long as the alkoxide raw material and the water used for hydrolysis are each soluble and do not solidify at the temperature at which the water is added. There is no particular limitation. For example, a combination of a polar solvent and a non-polar solvent may be used. From the viscosity in the temperature range where water is added, the ease of removal, etc.,
Methanol, ethanol and propanol, which are alcohols having 1 to 3 carbon atoms, are particularly preferred.

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. On the contrary, according to the method of the present invention, it is also possible to prepare an In ₂ O ₃ —SnO ₂ precursor sol without using a polydentate compound. On the other hand, acid amides and the like represented by RCONR ′ (R and R ′ are hydrogen or alkyl groups) having a plurality of coordinable functional groups do not form a bond by substitution with an alkoxyl group, and therefore, do not form at the temperature of water addition. If it does not coagulate and can be easily removed by volatilization, it can be used without any problem.

The amount of water to be added cannot be specified because it depends on the type of each alkoxyl group in the indium alkoxide and the tin alkoxide and the mixing ratio of the indium alkoxide and the tin alkoxide. Further, the optimum stable pH value of the sol differs depending on the type of the alkoxyl group and the mixing ratio of the indium alkoxide and the tin alkoxide. Therefore, an acid or a base is appropriately used as a catalyst. The catalyst used is not particularly limited,
In order to obtain a high-purity material, a compound containing no metal component is preferable. For example, as the acid, hydrochloric acid, nitric acid, sulfuric acid,
Mineral acids such as 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.

In ₂ obtained by the above-described manufacturing method
By coating the O ₃ —SnO ₂ precursor sol on the substrate to be formed into a film, a thin film of In ₂ O ₃ —SnO ₂ gel is formed on the surface of the substrate. As a coating method, a generally practiced method such as dip coating, spin coating, and flow coating can be used. And In ₂ O ₃
-SnO to ₂ gel thin, heat treatment, such as light irradiation, such as ultraviolet light, by performing a process in accordance with the purpose, an In ₂ O ₃ -SnO ₂ thin film having conductivity.

When the thin film of In ₂ O ₃ —SnO ₂ gel is irradiated with ultraviolet light having a wavelength of 360 nm or less to crystallize the gel film, the heat treatment at a high temperature is not performed. In ₂ O ₃ —SnO having desired conductivity
_Two thin films are obtained. As a light source of ultraviolet light,
There is no particular limitation as long as it can irradiate ultraviolet light having a wavelength of 360 nm or less.
Low pressure mercury lamp, excimer lamp, ArF excimer laser, KrF excimer laser, synchrotron radiation, Y
An AG laser quadruple wave or the like is used, and particularly preferably, a low-pressure mercury lamp, an excimer lamp, or the like having a shorter peak wavelength.
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.

By irradiating the gel film formed on the substrate surface with ultraviolet light having a wavelength of 360 nm or less to crystallize the gel film, the surface of a substrate or the like containing a large amount of an alkali element or the like is also reduced. can form a in ₂ O ₃ -SnO ₂ thin film resistance value, and because also allows formation of in ₂ O ₃ -SnO ₂ thin film to low heat resistance substrate such as a plastic, preferably However, when an In ₂ O ₃ —SnO ₂ thin film is formed on a substrate where migration of impurity elements does not cause a problem even when heat-treated at a high temperature or a substrate having high heat resistance, the gel film is heated and crystallized. It can also be done.

Using indium alkoxide and tin alkoxide as starting materials, In ₂ O ₃ −
In a method of manufacturing a SnO ₂ thin film, In ₂ O ₃ —S
The stability and film formability of the nO ₂ precursor sol are very important. In general, in order to improve the stability of the sol, increasing the degree of polymerization of the alkoxide (in the sol-forming stage,
MOM (metal-
An inorganic polymer having an oxygen-metal) bond is produced, or a method of adding a polydentate compound is effective.
However, since the stability of indium alkoxide and tin alkoxide in water is very low, it has been very difficult to obtain a homogeneous sol by the conventional method. on the other hand,
A stable sol can be easily obtained by adding a polydentate compound.However, the sol and the gel contain a large amount of residual organic substances, and during the final mineralization, the gel is removed from the gel. It is necessary to remove residual organic matter. With the removal of the residual organic matter, the microstructure is deteriorated due to the destruction of the microstructure in the thin film and the generation of pores. In order to improve the microstructure, heat treatment or the like requires more energy than necessary. On the other hand, according to the method of the present invention described above, the hydrolysis / polymerization reaction of indium alkoxide and tin alkoxide after addition of water can be suppressed without adding an extra polydentate compound. ,
It is possible to obtain a high concentration stable In ₂ O ₃ —SnO ₂ precursor sol. Then, the amount of residual organic matter in the obtained gel is small, and the target functional material can be obtained by low-energy post-treatment.

[0025]

Next, a more specific embodiment of the present invention will be described. The [In ₂ O ₃ -SnO ₂ Preparation of the precursor sol] <Examples 1-16> and indium alkoxide and tin alkoxide, an In ₂ O _3, and a solid concentration of SnO ₂ is 1
The solution was added to ethanol so as to be 5% by weight to prepare a mixed solution of indium alkoxide and tin alkoxide. When added to the mixed solution of alkoxide,
A mixed solution of distilled water and ethanol was prepared such that the solid concentration of n ₂ O ₃ and SnO ₂ was 10% by weight. After cooling the alkoxide mixed solution and the distilled water-ethanol mixed solution to a predetermined temperature in a refrigerant, the two solutions were mixed, and then the solution was returned to room temperature. Thereby, homogeneous In ₂ O ₃
-SnO ₂ (ITO) to obtain a precursor sol. Table 1 summarizes the mixing ratios and the synthesis conditions. In Table 1, the column of "amount" of "water" indicates the molar ratio of _{H 2 O / (In + Sn} ), "pH" of the "water" was adjusted by hydrochloric acid (HCl). Further, “〇” in the column of “sol state” in Table 1 indicates that a transparent homogeneous sol was prepared.

[0026]

[Table 1]

Comparative Example 1 Tri-t-butoxyindium and tetra-s-butoxytin were mixed with an oxide having a solid concentration of 5%.
The mixture was added to 2-butanol so as to be a weight% to prepare a mixed solution of alkoxide. Also, a 1N hydrochloric acid-2-butanol mixed solution (H) was added so that when added to the mixed solution of the alkoxide, the solid content concentration of the oxide was 2.5% by weight.
The molar ratio of ₂ O / (In + Sn) was 0.6), and the mixture was added to a mixed solution of alkoxide at room temperature.
From the place where water (1N hydrochloric acid-2-butanol mixture) was added, local turbidity and gelation occurred locally, and a homogeneous sol could not be obtained. The mixing ratio and the synthesis conditions at this time are also shown in Table 2, together with Comparative Examples 2 and 3 described later. In Table 2, in the column of “addition amount” of “water”, H ₂ O /
It shows the molar ratio of (In + Sn), and the “p” of “water”
"H" was adjusted with hydrochloric acid (HCl). Further, “〇” in the column of “sol state” in Table 2 indicates that a transparent homogeneous sol was prepared.

[0028]

[Table 2]

<Comparative Example 2> Tri-t-butoxyindium and tetra-s-butoxytin were mixed with an oxide having a solid content of 5%.
% By weight of N, N-dimethylformamide (D
MF) to prepare a mixed solution of metal alkoxide. In addition, when added to the mixed solution of the alkoxide, the solid content concentration of the metal oxide is set to 2.5% by weight.
A mixed solution of N hydrochloric acid and DMF (the molar ratio of H ₂ O / (In + Sn) was 0.6) was prepared, and the mixed solution was added to the mixed solution of the metal alkoxide. As in Comparative Example 1, a portion where water was added was locally clouded and gelled, and a homogeneous sol could not be obtained.

Comparative Example 3 Tri-t-butoxyindium and tetra-s-butoxytin were mixed with an oxide having a solid concentration of 5%.
The mixture was added to 2-butanol so as to be a weight% to prepare a mixed solution of metal alkoxide. Further, when added to the mixed solution of the alkoxide, the solid concentration of the oxide is 2.5%.
A 1N hydrochloric acid-2-butanol mixed solution (the molar ratio of H ₂ O / (In + Sn) was 1) was prepared so as to be in a weight%.
After adding equimolar acetylacetone to the mixed solution of indium alkoxide and tin alkoxide, a 1N hydrochloric acid-2-butanol mixed solution was added to the mixed solution of alkoxide at room temperature. When the solid content concentration of the oxide was up to 2.5% by weight, a homogeneous solution was obtained, but when the oxide concentration was 3% by weight or more, it became partially cloudy.

As is clear from the above results, according to the production method of the present invention, the In ₂ O ₃ -SnO ₂ concentration can be reduced to 10% by weight without adding an extra organic substance such as a polydentate compound. % Of a homogeneous transparent sol is obtained. On the other hand, in the conventional method, it is possible to prepare a partially stable sol by adding a polydentate compound. However, compared with the sol obtained by the method according to the present invention, the oxidation of the sol is improved. Substance concentration is very low.

[Thinning and Physical Properties of Thin Film] The In ₂ O ₃ —SnO ₂ sol obtained in each of the above embodiments was diluted so that the oxide concentration was 5% by weight, and the diluted sol was diluted. Was spin-coated at 1,000 rpm to form a film on a silica substrate. As a result, a gel film having a homogeneous appearance was obtained. After the obtained gel film was subjected to a heat treatment, the thickness and resistance of the In ₂ O ₃ —SnO ₂ thin film were measured and evaluated. The film thickness was measured using a step meter. The resistance value was determined as a sheet resistance by a four-terminal method (for measurement, Mitsubishi Chemical Corporation, Loresta MP, MC
PT-350 was used). For comparison, the sol obtained in Comparative Example 3 was formed by the same method. Table 3 summarizes the properties of the obtained films.

[0033]

[Table 3]

The I manufactured by the method according to the present invention
n ₂ O ₃ -SnO ₂ thin film, thick film thickness compared to that of Comparative Example, and the sheet resistance is reduced, also tend to be specific resistance value decreases. This is presumably because the film formed by the method according to the present invention has a small amount of residual organic components, so that defects such as pores inside the film are reduced.

Further, the In ₂ obtained in Example 8 described above was used.
When the gel film obtained by forming the O ₃ —SnO ₂ sol by the same method as described above is fired at various temperatures, the film of the In ₂ O ₃ —SnO ₂ thin film with respect to the change in the firing temperature is obtained. The change in thickness was examined. For comparison, the relationship between the firing temperature of the gel film and the thickness of the obtained In ₂ O ₃ —SnO ₂ thin film was also determined for the In ₂ O ₃ —SnO ₂ sol obtained in Comparative Example 3 described above. Examined. The result is shown in FIG. In FIG. 1, a curve I represents the In ₂ O ₃ − obtained in Example 8.
The curve II for the gel film obtained by forming the SnO ₂ sol was the In ₂ O ₃ -SnO ₂ obtained in Comparative Example 3.
Each of the gel films obtained by forming the sol is shown. As shown in FIG. 1, In ₂ obtained in Example 8
In a gel film obtained by forming an O ₃ —SnO ₂ sol, the shrinkage ratio due to baking is about 40%, while Comparative Example 3
In the gel film obtained by forming the In ₂ O ₃ —SnO ₂ sol obtained in the above, shrinkage of about 65% was recognized by firing, and the In ₂ O ₃ —SnO ₂ obtained by the method according to the present invention was observed. _Two
The thin film is more suitable for the In ₂ O ₃ —Sn obtained by the conventional method.
It can be seen that the film thickness is larger than that of the O ₂ thin film.

Further, the In ₂ obtained in Example 5 described above was used.
The O ₃ —SnO ₂ sol was diluted so that the oxide concentration became 5% by weight, and the diluted sol was formed into a film by dip coating, and the same evaluation as above was performed. By baking the obtained gel film at 400 ° C., an In ₂ O ₃ —SnO ₂ thin film having a thickness of 85 nm and a sheet resistance of 2.6 × 10 ³ Ω / □ was obtained. Further, the In ₂ O ₃ —SnO ₂ obtained in Example 5 was used.
Sol, oxide concentration is diluted to 1% by weight, it was deposited by flow coating the diluted sol on a glass plate of 50mm square, without problem homogeneous In ₂ O ₃ -Sn
An O ₂ gel film was obtained. By baking the obtained gel film at 400 ° C., a film thickness of 65 nm and a sheet resistance of 3.6 ×
An In ₂ O ₃ -SnO ₂ thin film of 10 ³ Ω / □ was obtained.

[Ultraviolet irradiation] <Embodiment 17> In ₂ O ₃ —SnO _{2 of} Embodiment 5 described above.
A gel film formed on a silica substrate using a precursor sol,
ArF excimer laser light (193 nm, 15 mJ / cm
² ) was irradiated for 100 shots. As a result, as shown in FIG. 2, the thin film X-ray diffraction showed In ₂ O ₃ —SnO ₂ (IT
Crystallization of the O) phase was confirmed, and the obtained crystalline ITO thin film had a specific resistance of 2.3 × 10 ₋₃ Ωcm and a transmittance of 90% for light having a wavelength of 520 nm.

Example 18 In _{2 of} Example 5 described above was used.
The gel film formed on the silica substrate using the O ₃ —SnO ₂ precursor sol was applied to a low-pressure mercury lamp (254 nm, 10 mW /
cm ² ) for 1 hour at room temperature.
rF excimer laser light (193 nm, 15 mJ / c
m ² ) was irradiated for 100 shots. As a result, the crystalline I having a diffraction pattern similar to that of Example 17 described above was obtained.
A TO thin film is obtained, and the ITO thin film has a specific resistance of 2.1.
The transmittance was 95% for light having a wavelength of 520 nm at × 10 ₋₃ Ωcm. As described above, by performing the pretreatment using the low-pressure mercury lamp, a conductive ITO thin film having a better transmittance than that of Example 17 was obtained.

<Embodiment 19> In _{2 of} Embodiment 5 described above.
The gel film formed on the silica substrate using the O ₃ —SnO ₂ precursor sol is applied to the fourth harmonic (266 nm, 10 nm) of the YAG laser.
(mJ / cm ² ) at room temperature for 100 shots. As a result, a diffraction peak corresponding to the (222) plane of In ₂ O ₃ was observed, and crystallization of ITO was confirmed.

Example 20 In _{2 of} Example 5 described above was used.
A gel film formed by coating an O ₃ —SnO ₂ precursor sol on PET was irradiated with ultraviolet light under the same conditions as in Example 17. As a result, a diffraction peak corresponding to the (222) plane of In ₂ O ₃ was observed, and the sheet resistance value of the ITO thin film was 1.2.
× 10 ⁴ Ω / □.

As described above, according to the method of the present invention, it is possible to prepare an In ₂ O ₃ —SnO ₂ precursor sol having a high oxide concentration, and to form an In ₂ O ₃ —SnO ₂ thin film. , A thick coating film can be easily obtained as compared with the conventional method. In addition, the crystallization temperature is lowered because the amount of residual organic matter in the gel is small. When the gel film is crystallized by irradiating ultraviolet light, a crystalline In ₂ O ₃ —SnO ₂ thin film can be obtained without performing heat treatment, and a plastic film having poor heat resistance can be obtained. crystalline in ₂ O ₃ forming the conductive thin film -SnO ₂ on the substrate also becomes possible.

[0042]

According to the manufacturing method of each of the first to third aspects of the present invention, the high-concentration, uniform, and high-concentration homogeneous gel film is formed in the gel film after the film formation. An In ₂ O ₃ —SnO ₂ precursor sol having a small amount of remaining organic substances is obtained. And the obtained precursor sol is In ₂ O ₃ —Sn
It is most suitable for forming an O ₂ thin film, and a high quality In ₂ O ₃ —SnO ₂ thin film can be obtained from this precursor sol.

Further, according to the manufacturing method of the present invention, when the In ₂ O ₃ —SnO ₂ precursor sol is gelled, the amount of organic matter remaining in the gel is small, so that the organic matter can be removed. it is not necessary to perform heat treatment of in ₂ O ₃ -SnO ₂ gels at high temperatures in order, also, a homogeneous bubble free in ₂ O ₃
It can be formed -SnO ₂ thin film. Further, the obtained In ₂ O ₃ —SnO ₂ thin film does not require extra energy for densification. According to the manufacturing method of the present invention, a high-quality In ₂ O ₃ —SnO ₂ thin film can be obtained. Further, according to the manufacturing method of the present invention, In is deposited on a substrate having low heat resistance such as plastics.
_{A 2} O ₃ —SnO ₂ thin film can also be formed.

[Brief description of the drawings]

[1] In ₂ O ₃ -SnO ₂ In ₂ of the sol obtained by the calcination of the calcination temperature and the gel film of the gel film obtained by forming a
O ₃ is a diagram showing the relationship between the thickness of -SnO ₂ thin film.

FIG. 2 shows an In ₂ O ₃ —SnO ₂ sol formed by irradiating ArF excimer laser light on a gel film obtained by forming an InF.
It is a view showing a thin-film X-ray diffraction pattern of the ₂ O ₃ -SnO ₂ thin film.

Claims (4)

[Claims] A solution containing an indium alkoxide and a tin alkoxide is hydrolyzed and polymerized to form In ₂ O ₃ —S
a process for preparing nO ₂ precursor sol of In ₂ O ₃ -SnO ₂ precursor sol and performs addition of water to the solution containing the indium alkoxide and tin alkoxide at -20 ° C. below the temperature Production method. 2. The method according to claim 1, wherein the compound is In ₂ O ₃ without using a polydentate compound.
-SnO ₂ precursor sol is prepared according to claim 1, wherein In ₂
O ₃ -SnO ₂ method for manufacturing a precursor sol. 3. The In ₂ O _{3 according to} claim 1 or 2, wherein the water is added to the solution containing the indium alkoxide and the tin alkoxide in a temperature range of -50 ° C to -80 ° C.
-SnO ₂ method for manufacturing a precursor sol. 4. An In ₂ O ₃ -SnO ₂ precursor sol obtained by the production method according to any one of claims 1 to 3 is applied to the surface of a substrate, and the In ₂ O ₃ −
After forming a thin film of SnO ₂ gel, the thin film is irradiated with ultraviolet light having a wavelength of 360 nm or less to crystallize the In ₂ O ₃ —SnO ₂ gel forming the thin film, thereby improving conductivity. in ₂ O ₃ -SnO ₂ manufacturing method of a thin film and forming the in ₂ O ₃ -SnO ₂ thin film substrate surface with.