JP2001072415A - Production of tin oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fixed sheet resistance value without causing a foreign matter and a defect in a film by coating a tin oxide film formed on a substrate with a coating agent containing one kind of ion selected from Li+, Na+ and K+ and heat-treating the coated substrate to raise the sheet resistance value. SOLUTION: A tin oxide film 2 is formed through a barrier film 3 (SiCxOy film) on a substrate 4 (soda-lime glass, etc.), and is coated with a coating agent 1 (preferably an aqueous solution of NaOH) containing one kind of ion selected from Li+, Na+ and K+ in about 10 nm to 10 μm thickness. Then the coated substrate is heat-treated at about 100-1,000 deg.C, preferably <= about 800 deg.C and the monovalent ion is difftused into the tin oxide film so that a free electron carrier existing in the tin oxide film is trapped, the concentration of the free electron carrier is reduced to raise the sheet resistance value of the tin oxide film to about 10-100 ω/square..Consequently a tin oxide film of various kinds of qualities is obtained in excellent productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a tin oxide film.

[0002]

2. Description of the Related Art As a method for controlling the resistance value of a tin oxide film, it is general to control the thickness, the amount of dopant in the film, the substrate temperature during film formation, and the like. However, in order to obtain a tin oxide film having a certain resistance value by these control methods, it was necessary to search and set parameters for each type of tin oxide film. In addition, in the case of performing high-mix low-volume production in a continuous production facility, the production conditions must be changed each time, which has been a cause of deterioration in productivity.

Therefore, there has been a demand for a method capable of freely controlling the resistance value after film formation. As a method of controlling the resistance value after the film formation, there is a method of changing the resistance value by heat treatment after the film formation, but the control range of the resistance value is limited to a narrow range. In addition, an oxide (JP-A-9-6940) is contained in the tin oxide film.
5) and voids (Japanese Unexamined Patent Publication No. 9-69403) may be used to increase the resistance. However, in these methods, foreign substances or defects are formed in the tin oxide film itself, which impairs the film quality. In addition, there was a possibility that the film characteristics would change.

[0004]

An object of the present invention is to provide a method for producing a tin oxide film which can obtain a tin oxide film having a desired sheet resistance by a simple method without causing foreign substances or defects in the film. The purpose is to provide.

[0005]

According to the present invention, a tin oxide film is formed on a substrate, and then a coating agent containing one type of ion selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ is applied. Then, a heat treatment is performed to obtain a tin oxide film having an increased sheet resistance value.

A tin oxide film is coated with a coating agent containing one kind of ion selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ (hereinafter simply referred to as monovalent ion), and then heat-treated to obtain a tin oxide film. Monovalent ions diffuse into it. Due to the diffusion of the monovalent ions, free electron carriers existing in the tin oxide film are trapped, the free electron carrier concentration decreases, and the sheet resistance value of the tin oxide film increases accordingly.

By controlling the diffusion amount of monovalent ions (for example, controlling the amount of application, the composition of the coating agent, the type of monovalent ions, the concentration, the pH value, etc.), foreign substances and tin oxide are contained in the tin oxide film. The sheet resistance can be increased in a wide range without causing defects and without impairing the film quality, and a tin oxide film having a desired sheet resistance can be obtained.

As the tin oxide film used in the present invention, F
Alternatively, a tin oxide film to which Sb is added may be used. The tin oxide film is formed by a wet method (for example, a thermal decomposition method, a sol-gel method, or the like) or a dry method (for example, a CVD method, a sputtering method, or the like). The thickness (geometric thickness) of the tin oxide film is appropriately selected as needed, but from the viewpoint of productivity, the thickness is 10 nm to 10 nm.
A range of 1 μm is preferred.

The substrate used in the present invention is preferably a transparent substrate utilizing the transparency of the tin oxide film, particularly a glass substrate. For example, non-alkali glass, alkali-containing glass (such as soda lime glass) having a surface coated with a barrier film (hereinafter simply referred to as a barrier film) for preventing diffusion of an alkali component in the glass, and the like can be used.

The coating agent used in the present invention is NaOH
An aqueous solution, an aqueous KOH solution, an aqueous solution of Na ₂ CO _{3, an} aqueous solution of K ₂ CO _{3, an} aqueous solution of sodium alginate, and the like are given. From the viewpoint of wettability, an aqueous solution of NaOH or KOH having high alkalinity is preferred. In particular, N
An aqueous aOH solution is preferred.

As a method of applying the coating agent, a dipping method,
Screen printing, flexographic printing, spraying and the like can be mentioned. The application amount of the coating agent (the film thickness of the coating film formed after application) is from 10 nm to 1
It is preferably 0 μm.

The heating temperature of the heat treatment in the present invention is preferably 100 ° C. or higher. If the temperature is lower than 100 ° C., the diffusion rate is low, and the productivity is poor. The upper limit temperature is not particularly limited, and can be up to a temperature that the substrate can withstand. Practically, it is preferable to carry out at a temperature of 1000 ° C. or lower, particularly 800 ° C. or lower. The atmosphere of the heat treatment is not particularly limited, and the heat treatment is performed in an air atmosphere or the like.

According to the method of the present invention, the sheet resistance of the substrate provided with the tin oxide film after the application of the coating agent and the heat treatment is from 1 to 1.
000Ω / □, particularly preferably 10-100Ω / □. Further, the sheet resistance value of the substrate with the tin oxide film after the application of the coating agent and the heat treatment is increased in a range of 1.01 to 50 times the sheet resistance value of the substrate with the tin oxide film before the treatment. It is particularly preferable that the temperature rises in the range of 1.01 to 5 times.

The tin oxide film obtained according to the present invention can be used for various purposes such as a conductive film for electric heating of a reach indoor, a conductive film used for an electrode of a touch panel, and a conductive film used for an electrode of a solar cell. Used.

[0015]

EXAMPLE 1 FIG. 1 is a schematic sectional view showing a state where a coating agent is applied to a tin oxide film on a substrate. In FIG. 1, a barrier film 3 is formed between a base 4 and a tin oxide film 2, and a coating material 1 is applied on the tin oxide film 2. In this example, a soda lime glass substrate was used as the base 4, and a SiC _x O _y film was formed as the barrier film 3 with a thickness of 100 nm by the CVD method. The formation of the tin oxide film 2 was performed by a CVD method. The thickness was 300 nm. The sheet resistance value of the substrate provided with the tin oxide film prepared as described above is 23 Ω / □.
Met.

As the coating agent, NaOH aqueous solutions of various concentrations were used. The application of the coating agent was performed by a dipping method so that the thickness of the coating film was about 50 nm. After the application, the coating was dried in air at 120 ° C. for 10 minutes. Next, the heat treatment after the application was performed at 560 ° C. for 2 minutes in the air, and then performed at 740 ° C. for 2 minutes in the air. Thereafter, it was washed with water. The sheet resistance (Ω / □) of the substrate with the tin oxide film after washing with water was measured. Table 1 shows the results. No foreign matter or defect occurred at any concentration.

Example 2 Example 1 was repeated except that aqueous Na ₂ CO ₃ solutions of various concentrations were used in place of the aqueous NaOH solution in Example 1.
The sheet resistance (Ω / □) of the finally obtained substrate with a tin oxide film was measured in the same manner. Table 1 shows the results
Shown in No foreign matter or defect occurred at any concentration.

Example 3 The barrier film in Example 1 was made of SiO ₂
The sheet resistance (Ω / □) was obtained in the same manner as in Example 1, except that the film was changed to a film.
Was measured. Table 1 shows the results. No foreign matter or defect occurred at any concentration. The SiO ₂ film was formed with a thickness of 100 nm by the CVD method.

Example 4 Example 1 was repeated except that aqueous Na ₂ CO ₃ solutions of various concentrations were used instead of the aqueous NaOH solution in Example 3.
The sheet resistance (Ω / □) of the finally obtained substrate with a tin oxide film was measured in the same manner. Table 1 shows the results
Shown in No foreign matter or defect occurred at any concentration.

[0020]

[Table 1]

Example 5 A substrate with a tin oxide film was prepared in the same manner as in Example 1. In this example, instead of the coating agent used in Example 1, an aqueous solution containing sodium alginate aqueous solution at a concentration of 5 wt% and NaOH at a concentration shown in Table 2 (viscosity of about 40,000 cP) was used as the coating agent. .
The thickness of the coating film was about 1 μm. In this example, the coating agent was applied on the tin oxide film in a pattern by a screen printing method so that there were portions where the coating agent was applied and portions where the coating agent was not applied.

After the application, the coating was dried at 120 ° C. for 10 minutes in the air. Next, the heat treatment after the application was performed at 560 ° C. for 2 minutes in the air, and then performed at 740 ° C. for 2 minutes in the air. Thereafter, it was washed with water. The sheet resistance value (Ω / □) was measured for the portion of the substrate with the tin oxide film after washing with water where the coating agent was applied and the portion where the coating agent was not applied. Table 2 shows the results. In addition, when the presence or absence of foreign matter or defect was confirmed in the portion where the coating agent was applied, no foreign matter or defect was found.

[0023]

[Table 2]

[0024]

According to the present invention, the sheet resistance value can be increased in a wide range without changing the film quality of the formed tin oxide film (without generating foreign substances and defects).
A tin oxide film having a desired sheet resistance value can be obtained by a simple method. Therefore, the present invention is preferably used when a small amount of tin oxide film is produced in many kinds, for example, by setting a desired sheet resistance value by a method of the present invention for a tin oxide film formed in a continuous production facility, Various types of tin oxide films can be obtained with high productivity. Further, according to the present invention, the sheet resistance value of the tin oxide film can be locally increased.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a state where a coating agent is applied to a tin oxide film on a base.

[Explanation of symbols]

 1: coating agent 2: tin oxide film 3: barrier film 4: base

Claims (1)

[Claims] A tin oxide film is formed on a substrate.
a tin oxide film having a sheet resistance increased by applying a coating agent containing one type of ion selected from the group consisting of i ⁺ , Na ^+, and K ⁺ , and then performing a heat treatment. Manufacturing method.