JPH10297921A - Production of titanium oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing titanium oxide film at a larger film-producing rate and provide a method for producing a titanium oxide reduced in impurities from wider starting material concentration range in a treating solution. SOLUTION: An additive for advancing equilibrium of the reaction formula (NH4 )2 TiF6 +2H2 O→*TiO2 +4HF+2NH4 F (←→represents reversible reaction) to right direction is added to an aqueous solution containing ammonium titanium fluoride to prepare a treating solution comprising a supersaturation solution. The treating solution is brought into contact with a substrate to form titanium oxide film on the surface of the substrate. In this time, ammonia is added to the treating solution. Pyridine may be added thereto.

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 titanium oxide film in which a titanium oxide-containing solution is brought into contact with a substrate by utilizing a precipitation phenomenon in an aqueous solution to form a titanium oxide film on the surface of the substrate. It is about.

[0002]

2. Description of the Related Art Titanium oxide films have been used as photocatalysts and alkali elution prevention films. Conventionally, as a method of forming the above-mentioned coating on the surface of the base material, a CV
D method and PVD method are adopted, and dip coating method and spin coating method by sol-gel method are adopted in liquid phase method.

[0003] However, the CVD method and the PVD method have a problem that expensive equipment must be used, and the process cost is high because of batch processing in a vacuum.
Further, there is a problem that the method can be applied only to a substrate having a small size and relatively small irregularities. Also sol-gel
Dip coating or spin coating can form a film only on a flat base material, and there is a danger of fire and explosion due to the use of an organic solvent, and a large amount of organic matter remains in the film. Therefore, there has been a problem that high-temperature treatment is required to remove this.

[0004] On the other hand, a liquid phase deposition method in which a glass substrate is immersed in a treatment solution prepared by adding boric acid or aluminum to an aqueous solution of ammonium fluoride or titanium hydrofluoric acid and a titanium oxide film is deposited on the surface of the glass substrate is known. JP-A-59-141441, JP-A-1-93
No. 443, JP-A-3-285821, JP-A-3-285822, JP-A-4-26516, and Japanese Patent Publication No. 7-35268.
These methods do not have the above-mentioned problems and can be said to be relatively excellent as a method for forming a titanium oxide film on the surface of a substrate.

[0005]

However, the film forming rate of the titanium oxide film by the above-mentioned conventional liquid phase deposition method using ammonium titanium fluoride is about 10 to 20 nm / hour, which is an industrially sufficient film forming rate. It cannot be said that. In the above-mentioned conventional liquid phase deposition method using ammonium titanium fluoride, if the concentration of ammonium titanium fluoride in the treatment liquid is 0.3 mol / liter or more, the deposited film is not titanium oxide but NH ₄ TiOOF.
A ₃ and a mixture of TiOF _2. In addition, the adults are described in the literature (Chemistry Letters, 6 , 4).
33 (1996)), when the concentration of titanium ammonium fluoride is 0.2 mol / liter, it is reported that the obtained film is NH ₄ TiOF ₃ . From these, the concentration range of titanium ammonium fluoride in the treatment liquid which can be substantially used is from 0.05 mol / L to 0.1 mol / L.
It is as narrow as 5 mol / l. When the usable concentration range of the starting material is narrow, there is a problem that when a liquid phase deposition method is used industrially, there is a high possibility that impurities are mixed into a film to be deposited due to a concentration error at the time of processing solution preparation, and When trying to change the production conditions of the titanium oxide film in accordance with the properties required for the titanium oxide film such as film thickness and shape, a narrow range of usable concentrations of the starting material limits the degree of freedom in its design. It is not preferable.

On the other hand, the deposition rate of the titanium oxide film by the liquid phase deposition method using the conventional titanium hydrofluoric acid is 5 to 5.
Approximately 20 nm / hour, which cannot be said to be an industrially sufficient film forming speed. In the above-mentioned conventional liquid phase deposition method using titanium hydrofluoric acid, the molar concentration of the additive in the processing liquid is limited to 4 to 50 times the molar concentration of titanium hydrofluoric acid in the processing liquid. However, when trying to change the manufacturing conditions of the titanium oxide film in order to form the titanium oxide film to the required film thickness, shape, etc., when the usable concentration range of the starting material is narrow, the design is free. It is not preferable because the degree is limited.

The present invention has been made in view of the above points, and provides a method for producing a titanium oxide film at a higher film formation rate. It is an object of the present invention to provide a method for producing a titanium oxide coating film having a small amount.

[0008]

According to a first aspect of the present invention, there is provided a method for producing a titanium oxide film, comprising the steps of (NH ₄ ) ₂ TiF ₆ + 2H ₂ O in an aqueous solution containing ammonium titanium fluoride.
An additive for promoting the equilibrium of ⇔TiO ₂ + 4HF + 2NH ₄ F (⇔ represents a reversible reaction) to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide, and this treatment solution is brought into contact with the substrate. Then, when the titanium oxide film is formed on the surface of the substrate, the treatment liquid contains ammonia.

Further, according to the present invention, (NH ₄ ) ₂ is contained in an aqueous solution containing ammonium titanium fluoride.
An additive for promoting the equilibrium of TiF ₆ + 2H ₂ O⇔TiO ₂ + 4HF + 2NH ₄ F to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide. A process for producing a titanium oxide film, characterized in that the treatment solution contains pyridine when forming a titanium oxide film on the surface of the material.

[0010] Further, according to a third aspect of the present invention, there is provided an aqueous solution containing titanium hydrofluoric acid in an aqueous solution containing H ₂ TiF ₆ + 2H.
_An additive that promotes the equilibrium of 2O⇔TiO ₂ + 6HF to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide, and this treatment solution is brought into contact with the substrate to oxidize the surface of the substrate. This is a method for producing a titanium oxide film, wherein the treatment liquid contains ammonia when forming a titanium film.

[0011] The invention according to claim 4 of the present invention is characterized in that H ₂ TiF ₆ + 2H is contained in an aqueous solution containing titanium hydrofluoric acid.
_An additive that promotes the equilibrium of 2O⇔TiO ₂ + 6HF to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide, and this treatment solution is brought into contact with the substrate to oxidize the surface of the substrate. This is a method for producing a titanium oxide film, wherein the treatment liquid contains pyridine when forming a titanium film.

[0012]

Embodiments of the present invention will be described below. First, the first and second aspects of the present invention will be described. It is desirable that the concentration of titanium ammonium fluoride in the treatment liquid is less than 0.5 mol / liter. In order to set the concentration of the processing solution to a higher concentration, the concentration of titanium ammonium fluoride before mixing with an additive such as boric acid or aluminum must be set to 0.5 mol / liter or more. Dissolving ammonium titanium fluoride in water at this concentration takes a very long time or does not dissolve, which is not preferable for work. Although the lower limit of the concentration of titanium ammonium fluoride is not particularly set, it is 0.08 m in order to obtain a sufficient film forming speed.
It is preferably higher than ol / liter.

If the amount of the additive such as boric acid or aluminum used in the treatment liquid is too small, the titanium oxide may not precipitate on the surface of the substrate, and if the amount is too large, the titanium oxide precipitates in the aqueous solution. There is a possibility that a product may be generated and a titanium oxide film having a uniform thickness may not be formed. Therefore, when boric acid is used as an additive, the concentration of boric acid in the processing solution is 0.01 mol / liter to 1.0 m
It is preferable to add an aqueous solution of boric acid to an aqueous solution of titanium ammonium fluoride so as to be ol / liter.

The inventions according to the first and second aspects are characterized in that ammonia or pyridine is added to the treatment solution. The preferable addition amount of ammonia and pyridine depends on the concentration of other starting materials in the processing solution, and is particularly strongly affected by the concentration of ammonium titanium fluoride. However, regardless of the concentration of the other starting materials, when the pH of the processing solution becomes 5.8 or more, a titanium oxide film is hardly formed on the surface of the substrate, and the precipitate formation reaction is preferentially performed in the processing solution. It is not preferable because it occurs. Although the lower limit of the pH is not particularly set, the pH of the aqueous solution of titanium ammonium fluoride is about 3.8. Further, when ammonia and pyridine are added to the treatment liquid, the pH of the treatment liquid increases, so that the substantial lower limit of the pH of the treatment liquid is about 3.8.

The above reaction rate and the properties and film thickness of the deposited film are affected by the concentrations of ammonium ammonium fluoride, boric acid, ammonia, and pyridine and the reaction temperature. It is preferable to set Next, the third and fourth aspects of the present invention will be described. Titanium hydrofluoric acid in the treatment liquid can be used at an arbitrary concentration, but is preferably 0.05 mol / liter to 0.30 mol / liter from the viewpoints of the formation speed of the titanium oxide coating film and workability.

If the amount of the additive such as boric acid or aluminum used in the treatment liquid is too small, the titanium oxide may not precipitate on the surface of the base material. If the amount is too large, the precipitate of the titanium oxide may be formed in the aqueous solution. In some cases, a titanium oxide film having a uniform thickness may not be formed. Therefore, when boric acid is used as an additive, the concentration of boric acid in the processing solution is from 0.01 mol / l to 1.0 mol / l.
It is preferable to add an aqueous solution of boric acid to an aqueous solution of titanium ammonium fluoride so that the volume becomes 1 liter.

The third and fourth aspects of the present invention are characterized in that ammonia or pyridine is added to the treatment solution. The preferable addition amount of ammonia and pyridine depends on the concentration of other starting materials in the processing solution, and is particularly strongly affected by the concentration of titanium hydrofluoric acid. However, regardless of the concentration of the other starting materials, when the pH of the processing solution becomes 5.8 or more, a titanium oxide film is hardly formed on the surface of the substrate, and the precipitate formation reaction is preferentially performed in the processing solution. It is not preferable because it occurs. Although the lower limit of the pH is not particularly set, the pH of the aqueous solution of titanium hydrofluoric acid is about 1.2, and when ammonia and pyridine are added to the processing solution, the pH of the processing solution increases. The lower limit of the pH is about 1.2.

The above reaction rate and the properties and thickness of the deposited film are affected by the concentrations of titanium hydrofluoric acid, boric acid, ammonia, and pyridine and the reaction temperature. It is preferable to set within. The substrate of the present invention may be any substrate that does not react with or hardly reacts with the treatment liquid, and for example, glass can be used. The substrate may be in any shape as long as it can come into contact with the treatment liquid, and may be in any shape such as a thread, plate, pot, or a surface having irregularities.

Next, the film forming step of claims 1 to 4 will be described. First, ammonia or pyridine is added to an aqueous solution of titanium ammonium fluoride or an aqueous solution of titanium hydrofluoric acid, and after stirring, additives such as boric acid and aluminum are added. When adding ammonia or pyridine here, a sudden addition may cause precipitation,
When adding ammonia or pyridine, it is preferable to add gradually. If an additive such as boric acid or aluminum is added before the addition of ammonia or pyridine, precipitation of titanium oxide proceeds during the addition of ammonia or pyridine, and it is difficult to control the thickness of titanium oxide. Therefore, it is preferable to add the additive after adding ammonia or pyridine.

Next, the base material is immersed in a treatment solution placed in a reaction vessel of an appropriate size and left for a predetermined time to form a titanium oxide film having a predetermined thickness on the surface of the base material. Can be. At this time, the temperature of the treatment liquid is preferably 25 ° C. or more and less than 100 ° C. The temperature of the processing solution is 2
If the temperature is lower than 5 ° C., it takes a long time to obtain a titanium oxide film having a predetermined film thickness, and the productivity may be reduced. If the temperature of the treatment liquid is 100 ° C. or higher, the treatment liquid may be boiled and a uniform deposition of a titanium oxide film may be hindered.

When a titanium oxide film is formed by using the above-described method, the film formation rate of the titanium oxide film by the conventional liquid phase deposition method using ammonium titanium fluoride is 10 times.
About 30 nm / hour, but 80 nm / hour.
hour or more, and the deposition rate of a titanium oxide film by a conventional liquid phase deposition method using titanium hydrofluoric acid is 5
About 20 nm / hour, but 60 nm / hour.
hour or more, and the film formation rate of titanium oxide is twice or more as compared with the conventional method.

[0022]

The present invention will be described below in detail with reference to examples. (Example 1) The vertical length is 76 mm and the horizontal length is 26 m
A soda lime glass having a thickness of 1.1 mm and a thickness of 1.1 mm was sufficiently washed and dried to obtain a base material of a sample. On the other hand, the density is 0.4m
ol / liter of titanium ammonium fluoride aqueous solution
Five milliliters were prepared. While stirring the aqueous solution of titanium ammonium fluoride, 5 ml of an aqueous ammonia solution having a concentration of 1.0 mol / liter was gradually added dropwise over 5 minutes. Next, water is added to the aqueous solution of titanium ammonium fluoride containing ammore to dilute the solution to 70 ml, and 30 ml of an aqueous solution of boric acid having a concentration of 1.0 mol / l is mixed to prepare about 100 ml of a treatment solution. did. The concentration of ammonium titanium fluoride in this treatment liquid was 0.1 mol / l, the concentration of ammonia was 0.05 mol / l, and the concentration of boric acid was 0.3 mol / l.

The substrate was immersed while maintaining the treatment liquid at 35 ° C. At this time, the substrate was immersed up to the lower part of 50 mm, and the upper part of 26 mm was kept out of contact with the processing liquid. After a lapse of 30 minutes, the substrate was pulled up, washed with water, and then dried to obtain a titanium oxide film having a thickness of about 120 nm on the surface of the substrate. The film forming speed of the titanium oxide film was 240 nm / hour.

Example 2 25 ml of an aqueous solution of titanium ammonium fluoride having a concentration of 0.4 mol / l was prepared. While stirring the aqueous solution of titanium ammonium fluoride, 5 ml of an aqueous solution of pyridine having a concentration of 1.0 mol / liter was gradually added dropwise over 5 minutes. Water is added to this pyridine-containing aqueous solution of ammonium ammonium fluoride to dilute it to 70 ml, and a boric acid aqueous solution 30 having a concentration of 1.0 mol / l is added.
Milliliters were mixed to prepare about 100 milliliters of a treatment solution. The concentration of ammonium titanium fluoride in this treatment liquid was 0.1 mol / l, the concentration of pyridine was 0.05 mol / l, and the concentration of boric acid was 0.3 mol / l.

The same substrate as in Example 1 was immersed while maintaining this treatment solution at 35 ° C. At this time, the lower 50mm of the substrate
And the upper 26 mm portion was kept out of contact with the processing solution. After a lapse of 30 minutes, the substrate was pulled up, washed with water, and dried to obtain a titanium oxide film having a thickness of about 90 nm on the surface of the substrate. The film forming speed of this titanium oxide is 180 nm / ho.
was ur.

(Comparative Example 1) 25 ml of an aqueous solution of titanium ammonium fluoride having a concentration of 0.4 mol / l was prepared. Water was added to this aqueous solution of titanium ammonium fluoride to dilute to 70 ml, and 30 ml of an aqueous solution of boric acid having a concentration of 1.0 mol / l was mixed to prepare about 100 ml of a treatment solution. The concentration of ammonium titanium fluoride in this treatment liquid was 0.1 mol / liter, and the concentration of boric acid was 0.3
mol / liter.

The same substrate as in Example 1 was immersed while maintaining this treatment liquid at 35 ° C. At this time, the lower 50mm of the substrate
And the upper 26 mm portion was kept out of contact with the processing solution. After a lapse of 30 minutes, the substrate was pulled up, washed with water, and then dried. As a result, no film was observed on the surface of the substrate.

[0028]

[Table 1]

Example 3 50 ml of an aqueous solution of titanium ammonium fluoride having a concentration of 0.4 mol / l was prepared. While stirring the aqueous solution of titanium ammonium fluoride, 10 ml of an aqueous solution of ammonia having a concentration of 1.0 mol / liter was gradually added dropwise over 5 minutes. Water was added to this aqueous ammonium ammonium fluoride solution containing anmoa to dilute it to 70 ml, and a boric acid aqueous solution 3 having a concentration of 1.0 mol / l was added.
0 ml was mixed to prepare about 100 ml of a treatment solution. The concentration of ammonium titanium fluoride in this treatment liquid was 0.2 mol / l, the concentration of ammonia was 0.1 mol / l, and the concentration of boric acid was 0.3 mol / l.
mol / liter.

The same substrate as in Example 1 was immersed while maintaining this treatment liquid at 35 ° C. At this time, the lower 50mm of the substrate
And the upper 26 mm portion was kept out of contact with the processing solution. After a lapse of 90 minutes, the substrate was pulled up, washed with water, and then dried to obtain a titanium oxide film having a thickness of about 140 nm on the surface of the substrate. The film formation rate of this titanium oxide is 93 nm / hou.
r. .

Example 4 50 ml of an aqueous solution of titanium ammonium fluoride having a concentration of 0.4 mol / l was prepared. While stirring the aqueous solution of titanium ammonium fluoride, 10 ml of an aqueous solution of pyridine having a concentration of 1.0 mol / liter was gradually added dropwise over 5 minutes. Water is added to this pyridine-containing aqueous solution of ammonium ammonium fluoride to dilute it to 70 ml, and a boric acid aqueous solution 30 having a concentration of 1.0 mol / l is added.
Milliliters were mixed to prepare about 100 milliliters of a treatment solution. The concentration of ammonium titanium fluoride in this treatment liquid was 0.2 mol / l, the concentration of pyridine was 0.1 mol / l, and the concentration of boric acid was 0.3 mol / l.

The same substrate as in Example 1 was immersed while maintaining this treatment solution at 35 ° C. At this time, the lower 50mm of the substrate
And the upper 26 mm portion was kept out of contact with the processing solution. After a lapse of 90 minutes, the substrate was pulled up, washed with water, and then dried, whereby a titanium oxide film having a thickness of about 130 nm was obtained on the surface of the substrate. The film forming speed of this titanium oxide film is 87 nm / h.
it was our.

(Comparative Example 2) 37.5 ml of an aqueous solution of titanium ammonium fluoride having a concentration of 0.4 mol / l was prepared. Water was added to this aqueous solution of titanium ammonium fluoride to dilute to 70 ml, and 30 ml of an aqueous solution of boric acid having a concentration of 1.0 mol / l was mixed to prepare about 100 ml of a treatment solution. The concentration of ammonium titanium fluoride in this treatment liquid was 0.2 mol / liter, and the concentration of boric acid was 0.1 mol / L.
It was 3 mol / liter.

The same substrate as in Example 1 was immersed while maintaining this treatment liquid at 35 ° C. At this time, the lower 50mm of the substrate
And the upper 26 mm portion was kept out of contact with the processing solution. After a lapse of 90 minutes, the substrate was pulled up, washed with water, and dried. As a result, no film was observed on the surface of the substrate. In the experiment in which the reaction time was further extended, after 10 hours, white NH ₄ was added to the surface of the substrate.
Precipitation of TiOF ₃ crystals was confirmed.

[0035]

[Table 2]

Example 5 20 ml of an aqueous solution of titanium hydrofluoric acid having a concentration of 1.0 mol / l was prepared. While stirring this titanium hydrofluoric acid aqueous solution,
Ammonia aqueous solution 30 with a concentration of 1.0 mol / liter 30
Milliliter was slowly added dropwise over 5 minutes. Water was added to the aqueous solution of titanium hydrofluoric acid containing anmoa to dilute it to 70 ml, and the concentration was adjusted to 1.0 ml.
About 100 ml of a treatment liquid was prepared by mixing 30 ml of an aqueous solution of boric acid of mol / liter. The concentration of titanium hydrofluoric acid in this treatment liquid was 0.2 mol /
Liter, the concentration of ammonia was 0.3 mol / l, and the concentration of boric acid was 0.3 mol / l.

The same substrate as in Example 1 was immersed while maintaining this treatment liquid at 35 ° C. At this time, the lower 50mm of the substrate
And the upper 26 mm portion was kept out of contact with the processing solution. After elapse of 120 minutes, the substrate is pulled up, washed with water, and then dried,
A titanium oxide film having a thickness of about 90 nm was obtained on the surface of the substrate. The film forming speed of this titanium oxide film is 45 nm / h.
it was our.

Example 6 20 ml of an aqueous solution of titanium hydrofluoric acid having a concentration of 1.0 mol / l was prepared. While stirring this titanium hydrofluoric acid aqueous solution,
20 ml of a pyridine aqueous solution having a concentration of 1.0 mol / l was gradually added dropwise over 5 minutes. Water was added to the aqueous solution of titanium hydrofluoric acid containing pyridine to dilute the solution to 70 ml, and the concentration was 1.0 m
ol / liter of an aqueous solution of boric acid (30 ml) was mixed to prepare about 100 ml of a treatment solution. The concentration of titanium ammonium fluoride in this treatment liquid is 0.2 mol
l / liter and the concentration of pyridine is 0.2 mol /
And the concentration of boric acid was 0.3 mol / l.

The same substrate as in Example 1 was immersed while maintaining this treatment liquid at 35 ° C. At this time, the lower 50mm of the substrate
And the upper 26 mm portion was kept out of contact with the processing solution. After elapse of 120 minutes, the substrate is pulled up, washed with water, and then dried,
A titanium oxide film having a thickness of about 80 nm was obtained on the surface of the substrate. The film forming speed of this titanium oxide film is 40 nm / h.
it was our.

(Comparative Example 3) 20 ml of an aqueous solution of titanium hydrofluoric acid having a concentration of 1.0 mol / l was prepared. Water is added to this titanium hydrofluoric acid aqueous solution to form a 70
Dilute to a milliliter and make the concentration 1.0 mol
Per liter of boric acid aqueous solution 30 ml,
About 100 milliliters of the treatment liquid was prepared. The concentration of ammonium ammonium fluoride in this treatment solution was 0.2 mol /
And the concentration of boric acid was 0.3 mol / l.

The same substrate as in Example 1 was immersed while maintaining this treatment solution at 35 ° C. At this time, the lower 50mm of the substrate
And the upper 26 mm portion was kept out of contact with the processing solution. After a lapse of 120 minutes, the substrate was pulled up, washed with water, and dried, and no film was observed on the surface of the substrate.

[0042]

[Table 3]

As can be seen from Table 1, the processing solution to which the concentration of ammonium titanium fluoride in the processing solution was set to 0.1 mol / liter and only boric acid was added so that the concentration in the processing solution became 0.3 mol / liter. In the case of Comparative Example 1 used, formation of a titanium oxide film was not observed after a dipping time of 30 minutes, but in Example 1 in which ammonia was added so that the concentration in the treatment liquid became 0.05 mol / L. In this case, a film of titanium oxide was formed at a film formation rate of 240 nm / hour, and the concentration of pyridine in the treatment solution was 0.1%.
In the case of Example 2 which was added at a concentration of 05 mol / liter, a film of titanium oxide was formed at a film forming speed of 180 nm / hour.

Further, as can be seen from Table 2, the treatment liquid was prepared by setting the concentration of ammonium titanium fluoride in the treatment liquid to 0.2 mol / liter and adding only boric acid so that the concentration in the treatment liquid became 0.3 mol / liter. In the case of Comparative Example 2 in which immersion time was 90 minutes, no film formation was observed, and when immersion time passed for 10 hours or more, film formation was observed. However, the component of the film was NH ₄ TiOOF.
While was _3, Example 3 in which the concentration in the treatment solution of ammonia was added to a 0.1 mol / liter
In this method, a film of titanium oxide is formed at a film forming speed of 93 nm / hour, and the concentration of pyridine is 0.1 m in the processing solution.
In the case of Example 4 which was added so as to be ol / liter, a film of titanium oxide was formed at a film forming speed of 87 nm / hour.

As can be seen from Table 3, the concentration of titanium hydrofluoric acid in the treatment liquid was 0.2 mol / liter,
In the case of Example 3 using the treatment solution in which only boric acid was added so that the concentration in the treatment solution was 0.3 mol / liter, no film formation was observed when the immersion time was 120 minutes, but ammonia was used. 0.3mol concentration in processing solution
In Example 5, the titanium oxide film was formed at a film formation rate of 45 nm / hour, and pyridine was added so that the concentration in the treatment liquid was 0.2 mol / L. In the case of 6, the film forming speed is 4
A coating of titanium oxide was formed at 0 nm / hour.

[0046]

As described above, according to the first aspect of the present invention, (NH ₄ ) ₂ TiF ₆ + 2H ₂ O⇔TiO ₂ + 4HF + is contained in an aqueous solution containing ammonium titanium fluoride.
An additive for promoting the equilibrium of 2NH ₄ F to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide, and this treatment solution is brought into contact with the substrate to form a titanium oxide film on the surface of the substrate. In the formation, since this processing solution contains ammonia, it is possible to manufacture a titanium oxide film at a higher film formation rate, and further, from a wider range of the starting material concentration in the processing solution, it is possible to reduce the amount of impurities. This makes it possible to produce a titanium oxide film.

Further, according to the invention of claim 2 of the present invention, (NH ₄ ) ₂ is contained in an aqueous solution containing ammonium titanium fluoride.
An additive for promoting the equilibrium of TiF ₆ + 2H ₂ O⇔TiO ₂ + 4HF + 2NH ₄ F to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide. In forming a titanium oxide film on the surface of the material, the processing solution contains pyridine, so that it is possible to produce a titanium oxide film at a higher film formation rate, and furthermore, the starting solution in a wider processing solution can be obtained. From the substance concentration range, it becomes possible to produce a titanium oxide film with few impurities.

Further, the invention according to claim 3 of the present invention is characterized in that H ₂ TiF ₆ + 2H is contained in an aqueous solution containing titanium hydrofluoric acid.
_An additive that promotes the equilibrium of 2O⇔TiO ₂ + 6HF to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide, and this treatment solution is brought into contact with the substrate to oxidize the surface of the substrate. In forming the titanium film, since this processing solution contains ammonia, it is possible to produce a titanium oxide film at a higher film forming rate, and further, from a wider range of starting material concentration in the processing solution, This makes it possible to produce a titanium oxide film with few impurities.

Further, the invention according to claim 4 of the present invention is characterized in that H ₂ TiF ₆ + 2H is contained in an aqueous solution containing titanium hydrofluoric acid.
_An additive that promotes the equilibrium of 2O⇔TiO ₂ + 6HF to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide, and this treatment solution is brought into contact with the substrate to oxidize the surface of the substrate. In forming a titanium film, this processing solution contains pyridine, which makes it possible to produce a titanium oxide film at a higher film formation rate, and furthermore, a wider range of starting material concentration in the processing solution. Therefore, it is possible to produce a titanium oxide film with few impurities.

Claims (4)

[Claims] 1. An aqueous solution containing titanium ammonium fluoride (NH ₄ ) ₂ TiF ₆ + 2H ₂ O⇔TiO ₂ + 4H
Add an additive that advances the equilibrium of F + 2NH ₄ F to the right,
A processing solution prepared as a supersaturated solution of titanium oxide is prepared, and the processing solution is contacted with the substrate to form a titanium oxide film on the surface of the substrate, and the processing solution contains ammonia. Of producing a titanium oxide film. 2. An aqueous solution containing titanium ammonium fluoride (NH ₄ ) ₂ TiF ₆ + 2H ₂ O⇔TiO ₂ + 4H
Add an additive that advances the equilibrium of F + 2NH ₄ F to the right,
A processing solution prepared as a supersaturated solution of titanium oxide is prepared, and the processing solution is contacted with the substrate to form a titanium oxide film on the surface of the substrate, and the processing solution contains pyridine. Of producing a titanium oxide film. 3. An aqueous solution containing titanium hydrofluoric acid containing H
_An additive for promoting the equilibrium of ₂ TiF ₆ + 2H ₂ O⇔TiO ₂ + 6HF to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide, and the treatment solution is brought into contact with a substrate,
In forming a titanium oxide film on the surface of the substrate,
A method for producing a titanium oxide film, wherein the treatment liquid contains ammonia. 4. An aqueous solution containing titanium hydrofluoric acid containing H
_An additive for promoting the equilibrium of ₂ TiF ₆ + 2H ₂ O⇔TiO ₂ + 6HF to the right is added to prepare a treatment solution as a supersaturated solution of titanium oxide, and the treatment solution is brought into contact with a substrate,
In forming a titanium oxide film on the surface of the substrate,
A method for producing a titanium oxide film, wherein the treatment liquid contains pyridine.