JPH1112745A - Production of thin indium oxide-selenium oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thin transparent conductive In2 O3 -SnO2 film even on a base material with inferior heat resistance, such as plastics, by irradiating a gel film capable of crystallization by means of heating treatment at specific temp. with ultraviolet rays of specific wavelength in order to crystallize the gel film. SOLUTION: Indium alkoxide and tin alkoxide are used as starting materials, and a solution containing these alkoxides in hydrolyzed and an In2 O3 -SnO2 sol is prepared. This sol is applied to the surface of a base martial and a gel film is formed on the surface of the base material and then crystallized, by which a thin In2 O3 -SnO2 film with electric conductivity is formed on the surface of the base material. To crystallize the gel gilm, the gel film capable of crystallization by heating treatment at <=300 deg.C is irradiated with ultraviolet rays of <=360 nm wavelength. It is preferable to irradiate the gel film with ultraviolet rays under the reduced pressure of <=500 Torr, and irradiation in a nonoxidizing atmosphere or in an oxidizing atmosphere is also suited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention, glass, ceramics, further oxidation to the surface of the substrate, such as plastic having poor heat resistance indium - tin oxide (In ₂ O ₃ -SnO
In ₂ O for forming a transparent conductive thin film _2, ITO)
_{The present} invention relates to a method for producing a _3- SnO ₂ thin film.

[0002]

_2. Description of the Related Art Conventionally, in order to form an In ₂ O ₃ —SnO ₂ thin film on a substrate, for example, the Journal of the Ceramic Society of Japan (Journal)
of Ceramic Society of
Japan) 102 [2], 200-205 (199
As described in 4), a metal salt such as indium nitrate and tin chloride In ₂ O ₃ -SnO ₂ sol was prepared as a raw material, by coating the sol on the substrate, the gel film on the substrate surface Is formed, the gel film is heat-treated at a temperature of 550 ° C. to crystallize the In ₂ O ₃ —SnO ₂ gel. Also, the In ₂ O ₃ —SnO ₂ thin film is
It can also be formed by a sol-gel method using indium alkoxide (In alkoxide) and tin alkoxide (Sn alkoxide) as a starting material. In this case, an In ₂ O ₃ —SnO ₂ gel film was formed on the substrate surface. Thereafter, the gel film is crystallized by heat treatment at a temperature of 500 ° C. or higher. Thus, conventionally, sol-
In the In ₂ O ₃ -SnO ₂ gel film formed by a gel method is crystallized, it was necessary heat treatment at a high temperature.

[0003]

However, the sol
In the method of forming an In ₂ O ₃ —SnO ₂ thin film by a gel method, in order to crystallize the In ₂ O ₃ —SnO ₂ and to impart conductivity to the thin film, conventionally, a gel film is formed by 500 times.
It was essential to heat and bake at a high temperature of not less than ℃. For this reason, depending on the conventional method, the conductive I.S.
it was not possible to form a n ₂ O ₃ -SnO ₂ thin film.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is to form a conductive In ₂ O ₃ —SnO ₂ thin film on a substrate having low heat resistance such as plastics. It is an object of the present invention to provide a method for producing an In ₂ O ₃ —SnO ₂ thin film that can be used.

[0005]

The invention according to claim 1 is
A sol obtained by hydrolyzing and polymerizing a solution containing indium alkoxide and tin alkoxide is applied to the surface of the substrate, and after forming a gel film on the surface of the substrate, the gel film is crystallized to have conductivity. in in ₂ O ₃ -SnO ₂ method for producing a thin film formed in ₂ O ₃ -SnO ₂ thin film substrate surface, in order to crystallize the gel film, 30
The method is characterized in that a gel film that can be crystallized by heat treatment at a temperature of 0 ° C. or less is irradiated with ultraviolet light having a wavelength of 360 nm or less.

According to a second aspect of the present invention, in the method according to the first aspect, the gel film is irradiated with ultraviolet light under a reduced pressure of 500 Torr or less.

According to a third aspect of the present invention, in the manufacturing method of the first aspect, the gel film is irradiated with ultraviolet light in a non-oxidizing atmosphere.

According to a fourth aspect of the present invention, in the manufacturing method of the first aspect, the gel film is irradiated with ultraviolet light in an oxidizing atmosphere.

According to a fifth aspect of the present invention, in the manufacturing method according to any one of the first to fourth aspects, the gel film and / or the substrate is heated to a temperature of 80 ° C. or more with respect to the gel film. It is characterized by irradiating ultraviolet light.

In the production method according to the first aspect of the present invention, indium alkoxide and tin alkoxide are hydrolyzed and
The sol obtained by polymerization is applied to the surface of the substrate to form a gel film, and then the gel film is irradiated with ultraviolet light having a wavelength of 360 nm or less, whereby the gel film is crystallized and becomes a conductive film. Is imparted. At this time, the gel film formed on the surface of the base must be capable of being crystallized by a heat treatment at a temperature of 300 ° C. or less. Therefore, it is not necessary to perform a heat treatment at a high temperature of 500 ° C. or more as in the related art for crystallization of the gel film, so that In ₂ O _{3 is formed} on a substrate having low heat resistance such as plastics.
Formation of -SnO ₂ thin film also becomes possible. The mechanism of crystallization of the gel film by irradiation with ultraviolet light is not clear, but the ultraviolet light is absorbed by the gel film, the rearrangement of atoms proceeds by the energy, and In ₂ O ₃ —SnO ₂ is crystallized. It is thought that it becomes.

In the manufacturing method according to the second aspect of the present invention, when the gel film is crystallized by irradiating the gel film with ultraviolet light,
The pressure is reduced to 500 Torr or less. Here, the present inventor has found that removing residual hydroxyl groups in the gel film requires In ₂ O ₃ −
It has been found that it is effective for crystallization of SnO ₂ and for expressing conductivity of a thin film. When the crystallization of the gel film is performed under a reduced pressure of 500 Torr or less as in this manufacturing method, residual hydroxyl groups in the gel film are efficiently removed. Therefore, it is easy to produce a transparent conductive In ₂ O ₃ —SnO ₂ thin film.

[0012] In the manufacturing method of the invention according to claim 3, when the gel film is crystallized by irradiating the gel film with ultraviolet light,
The gel film is placed in a non-oxidizing atmosphere. Therefore, In ₂
The introduction of oxygen vacancies into the O ₃ —SnO ₂ thin film makes In ₂ O ₃
-The resistance of the SnO ₂ thin film can be reduced.

In the manufacturing method of the invention according to claim 4, when the gel film is crystallized by irradiating the gel film with ultraviolet light,
The gel film is placed in an oxidizing atmosphere. Thereby, the residual organic matter in the gel film is efficiently removed. Therefore, it is not necessary to heat the gel film at a high temperature in order to remove the organic substances from the gel film, and the treatment at a relatively low temperature becomes possible. Further, according to this manufacturing method, the residual hydroxyl groups in the gel film are efficiently removed, thereby facilitating the production of a transparent conductive In ₂ O ₃ —SnO ₂ thin film.

In the manufacturing method of the invention according to claim 5, when the gel film is irradiated with ultraviolet light to crystallize the gel film,
The gel film and / or substrate is heated to a temperature of 80 ° C. or higher. This makes it possible to efficiently remove the residual hydroxyl groups in the gel film, and to make the transparent conductive In ₂ O ₃ —Sn
The production of the O ₂ thin film becomes easy. Further, by heating, it is possible to efficiently remove the residual organic matter in the gel film.

[0015]

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

In the production method according to the present invention, first, an indium alkoxide and a tin alkoxide are used as starting materials, and a solution containing these alkoxides is hydrolyzed to prepare an In ₂ O ₃ —SnO ₂ sol. The indium alkoxide and the tin alkoxide are not particularly limited, but those each having an alkoxyl group having 1 to 5 carbon atoms are preferably used. For example, as indium alkoxide, indium methoxide, indium ethoxide, indium propoxide, indium butoxide and indium pentoxide are used. Also,
As tin alkoxide, tin methoxide, tin ethoxide, tin propoxide, tin butoxide and tin pentoxide are 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 indium alkoxide and tin alkoxide in the alkoxide is adjusted according to the ratio of indium alkoxide / tin alkoxide to indium oxide and tin oxide in In ₂ O ₃ —SnO ₂ to be obtained. For example, the range is 97/3 to 80/20.

As the solvent for dissolving the alkoxide,
Alcohols such as methanol, ethanol, propanol and butanol, alkoxy alcohols such as 2-methoxyethanol and 2-ethoxyethanol, organic acid esters such as ethyl acetate, acetonitrile, ketones such as acetone and methyl ethyl ketone, tetrahydrafuran (THF) And cycloethers such as dioxane, N,
Acid amides such as N-dimethylformamide (DMF),
Hydrocarbons, aromatics, and the like are used, and DMF is preferably used without any particular limitation. In addition, In ₂ O ₃ -Sn
Although the method for preparing the O ₂ sol is not particularly limited, for example, 0.05 mol times to 2 mol times of water of the alkoxide is used for hydrolysis of the solution containing the alkoxide, and more preferably 0.5 mol times to 1.5 molar times water is used.
For the hydrolysis, an acid catalyst and / or a base catalyst may be used. Preferably, a mineral acid such as hydrochloric acid or an organic acid such as acetic acid is used. By using a combination of the alkoxide, the solvent, the catalyst, and the like as described above, a precursor sol from which a gel that can be crystallized by a heat treatment at a temperature of 300 ° C. or lower is obtained is prepared.

When an In ₂ O ₃ —SnO ₂ sol is prepared by hydrolysis of a solution containing an alkoxide, the sol is applied to the surface of a substrate and dried to form a gel film on the substrate surface. The method of applying the sol is not particularly limited, and a commonly used dip coating method, spin coating method, flow coating method, spray coating method, or the like is used. At this time, the gel film formed on the substrate surface can be crystallized when heat-treated at a temperature of 300 ° C. or less.

When a gel film is formed on the substrate surface, the gel film is irradiated with ultraviolet light having a wavelength of 360 nm or less. High-pressure mercury lamps, low-pressure mercury lamps, excimer lamps, ArF excimer lasers, K
An rF excimer laser, synchrotron radiation, or the like is used, and particularly preferably, a low-pressure mercury lamp having a shorter peak wavelength, an excimer lamp, an ArF excimer laser, Kr
An F excimer laser or synchrotron radiation is used. It is also possible to use two or more of these light sources in combination. Then, by irradiating the gel film with ultraviolet light,
The In ₂ O ₃ —SnO ₂ forming the gel film is crystallized, the thin film is given conductivity, and the In ₂ O ₃
Transparent conductive thin film of -SnO ₂ is formed.

Further, when irradiating the gel film with ultraviolet light, the pressure may be reduced, for example, to 500 Torr or less. By causing the gel film to be crystallized under reduced pressure by irradiation with ultraviolet light, the residual hydroxyl groups in the gel film are efficiently removed, and the transparent conductive In ₂ O ₃ —Sn
The production of the O ₂ thin film becomes easy. In addition, In ₂ O ₃ -SnO ₂
For the purpose of lowering the resistance of the In ₂ O ₃ —SnO ₂ thin film by introducing oxygen defects into the thin film, the gel film may be irradiated with ultraviolet light in a non-oxidizing atmosphere. On the other hand, the irradiation of the gel film with ultraviolet light may be performed in an oxidizing atmosphere. In this case, residual organic substances in the gel film are efficiently removed, and residual hydroxyl groups in the gel film are efficiently removed. Further, transparent conductive In ₂ by efficient removal of residual hydroxyl groups in the gel film.
For the purpose of facilitating the preparation of the O ₃ —SnO ₂ thin film and efficiently removing the residual organic substances in the gel film, the gel film and / or the substrate is heated to a temperature of 80 ° C. or higher and the gel film is irradiated with ultraviolet light. May be applied to crystallize the gel film. In addition, by irradiating the gel film with ultraviolet light in the presence of an aqueous aerosol (H ₂ O),
Resulting In ₂ O ₃ -SnO ₂ thin film physical properties it is also possible to control.

[0021]

Next, an embodiment to which the present invention is specifically applied will be described.

Example 1 Formation of Gel Film Tri-t-butoxyindium and tetra-s-butoxytin were dissolved in DMF such that the molar ratio of the mixture was 90:10, and then the solution was dissolved. When added to In ₂ O ₃ and SnO ₂
1N hydrochloric acid-DMF so that the solid concentration of
Mixture ((In + Sn) / H 2 O molar ratio of 1) were prepared and added to its hydrochloride -DMF liquid mixture solution of an alkoxide. Thereby, a homogeneous In ₂ O ₃ —SnO ₂ precursor sol was obtained. The obtained In ₂ O ₃ —SnO ₂ precursor sol was applied on a Corning 7059 substrate by spin coating to form a gel film on the substrate. When the obtained gel film was subjected to a heat treatment at a temperature of 270 ° C. for one hour in the air, as shown in FIG.
A crystal phase of ₂ O ₃ —SnO ₂ was confirmed.

Example 2 Crystallization of Gel Film (1) The In ₂ O ₃ —SnO ₂ gel film obtained in Example 1 was
ArF excimer laser (193 nm) at 20 mJ / cm ₂
Was irradiated for 100 shots. Thereby, as shown in FIG. 2, crystallization of the In ₂ O ₃ —SnO ₂ phase was confirmed by thin film X-ray diffraction, and a transparent I ₂ O ₃ —SnO ₂ phase having a specific resistance of 9.4 × 10 ₋₃ Ωcm was obtained.
n ₂ O ₃ -SnO ₂ thin film was obtained.

Example 3 Crystallization of Gel Film (2) The In ₂ O ₃ —SnO ₂ gel film obtained in Example 1 was
ArF excimer laser (193n) under reduced pressure of 7 Torr
m) was irradiated at 100 mJ / cm ₂ for 100 shots. As a result, the In ₂ O ₃ —SnO ₂ phase was crystallized, and a transparent In ₂ O ₃ —SnO ₂ thin film having a specific resistance of 1.9 × 10 ₋₃ Ωcm was obtained. FT-I of the obtained In ₂ O ₃ —SnO ₂ thin film
When the R spectrum was measured, as shown in FIG. 3, the In ₂ O ₃ —SnO ₂ thin film was irradiated with an ArF excimer laser at atmospheric pressure and the In ₂ O ₃ —SnO _{2 of} the above Example 2 was irradiated.
It was found that the amount of residual hydroxyl groups was smaller than that of the thin film. 3. In FIG. 3, the spectrum curve A shows the In ₂ O ₃ − of Example 2.
For the SnO ₂ thin film, the spectrum curve B is for the In ₂ O ₃ —SnO ₂ thin film of Example 3.
When the hole measurement of the obtained In ₂ O ₃ —SnO ₂ thin film was performed, the carrier density was 1 × 10 ₁₉ / cm.
_{At 3} , the mobility was 8.0 cm ₂ / SV.

Example 4 Crystallization of Gel Film (3) The In ₂ O ₃ —SnO ₂ gel film obtained in Example 1 was
An ArF excimer laser (193 nm) was irradiated at 100 mJ / cm ₂ for 100 shots in a nitrogen atmosphere (non-oxidizing atmosphere). Thereby, the In ₂ O ₃ —SnO ₂ phase is crystallized,
Transparent In ₂ O ₃ —SnO having a specific resistance of 9.2 × 10 ₋₃ Ωcm
_Two thin films were obtained.

Example 5 Crystallization of Gel Film (4) The In ₂ O ₃ —SnO ₂ gel film obtained in Example 1 was
An ArF excimer laser (193 nm) was irradiated at 100 mJ / cm ₂ for 100 shots in a hydrogen atmosphere (non-oxidizing atmosphere). Thereby, the In ₂ O ₃ —SnO ₂ phase is crystallized,
Transparent In ₂ O ₃ —SnO having a specific resistance of 8.9 × 10 ₋₃ Ωcm
_Two thin films were obtained.

From the results of Examples 4 and 5, laser irradiation in a non-oxidizing atmosphere such as nitrogen or hydrogen improves the carrier density and mobility of the obtained In ₂ O ₃ —SnO ₂ thin film, It was found that this contributed to increasing the conductivity of the ₂ O ₃ —SnO ₂ thin film.

Example 6 Crystallization of Gel Film (5) The In ₂ O ₃ —SnO ₂ gel film obtained in Example 1 was
An ArF excimer laser (193 nm) was irradiated for 100 shots at 20 mJ / cm ₂ in an oxygen atmosphere. Thereby, the In ₂ O ₃ —SnO ₂ phase is crystallized, and the specific resistance value is 4.8.
A transparent In ₂ O ₃ —SnO ₂ thin film of × 10 _-3 Ωcm was obtained. When obtained was measured FT-IR spectrum of an In ₂ O ₃ -SnO ₂ thin film, as shown in the spectrum curve C in FIG. 3, the In ₂ O ₃ -SnO ₂ thin film, an In ₂ of Example 3 O ₃ -SnO ₂ thin film (spectral curves of FIG. 3 B
In the same manner as in Example 1), a decrease in residual hydroxyl groups was confirmed.

Example 7 Crystallization of Gel Film (6) The In ₂ O ₃ —SnO ₂ gel film obtained in Example 1 was
ArF excimer laser (193) in the presence of aqueous aerosol
nm) at 20 mJ / cm ₂ for 100 shots. As a result, the In ₂ O ₃ -SnO ₂ phase was crystallized, and a transparent In ₂ O ₃ -SnO ₂ thin film having a specific resistance of 8.4 × 10 ₋₃ Ωcm was obtained.

[0030]

According to the manufacturing method of the first aspect of the present invention, the I.S.
n ₂ O ₃ can form a transparent conductive thin film -SnO _2.

In the manufacturing method according to the second aspect of the present invention, the residual hydroxyl groups in the gel film are efficiently removed, and as a result, it becomes easy to produce a transparent conductive In ₂ O ₃ —SnO ₂ thin film.

In the manufacturing method according to the third aspect of the present invention,
The introduction of oxygen vacancies into the ₂ O ₃ —SnO ₂ thin film allows In ₂ O 3
_The resistance of the _3- SnO ₂ thin film can be reduced.

In the manufacturing method according to the fourth aspect of the present invention, the organic matter remaining in the gel film is efficiently removed. As a result, it is necessary to heat the gel film at a high temperature in order to remove the organic matter from the gel film. And processing at a relatively low temperature becomes possible. Further, in this manufacturing method, the residual hydroxyl groups in the gel film are efficiently removed, and as a result, the transparent conductive In ₂ O ₃
Preparation of -SnO ₂ thin film is facilitated.

According to the manufacturing method of the fifth aspect of the present invention, it is possible to efficiently remove the residual hydroxyl groups in the gel film, and it is easy to produce a transparent conductive In ₂ O ₃ —SnO ₂ thin film. Further, according to this manufacturing method, it is possible to efficiently remove the residual organic matter in the gel film.

[Brief description of the drawings]

FIG. 1 is a diagram showing a thin-film X-ray diffraction pattern after a gel film used in a manufacturing method according to the present invention is subjected to a heat treatment.

FIG. 2 shows In obtained by the manufacturing method according to the present invention.
It is a view showing a thin-film X-ray diffraction pattern of the ₂ O ₃ -SnO ₂ thin film.

FIG. 3 shows In obtained by the manufacturing method according to the present invention.
It is a diagram showing the FT-IR spectrum of the ₂ O ₃ -SnO ₂ thin film.

[Explanation of symbols]

A At the atmospheric pressure, ArF was applied to the In ₂ O ₃ -SnO ₂ gel film.
In ₂ O ₃ —SnO ₂ obtained by excimer laser irradiation
It is a spectrum curve of a thin film. In B vacuo to In ₂ O ₃ -SnO ₂ gel film is a spectral curve of In ₂ O ₃ -SnO ₂ thin film obtained by irradiation with ArF excimer laser. C In the oxygen atmosphere, the In ₂ O ₃ -SnO ₂ gel film
In ₂ O ₃ —Sn obtained by irradiating rF excimer laser
O ₂ is a spectral curve of a thin film.

Claims (5)

[Claims] 1. A sol obtained by hydrolyzing and polymerizing a solution containing indium alkoxide and tin alkoxide is applied to the surface of a substrate to form a gel film on the surface of the substrate, and then the gel film is crystallized. , Conductive In ₂
In ₂ O ₃ —Sn for forming O ₃ —SnO ₂ thin film on substrate surface
In the method for producing an O ₂ thin film, in order to crystallize the gel film, ultraviolet light having a wavelength of 360 nm or less is applied to a gel film that can be crystallized by a heat treatment at a temperature of 300 ° C. or less. in ₂ O ₃ -SnO ₂ method of manufacturing a thin film, characterized in that. Wherein wherein the ultraviolet light to a gel film in the following reduced pressure 500Torr is irradiated to claim 1, wherein the In ₂
O ₃ -SnO ₂ method of manufacturing a thin film. 3. The In ₂ O ₃ —SnO _{2 according} to claim 1, wherein the gel film is irradiated with ultraviolet light in a non-oxidizing atmosphere.
Manufacturing method of thin film. 4. The method for producing an In ₂ O ₃ —SnO ₂ thin film according to claim 1, wherein the gel film is irradiated with ultraviolet light in an oxidizing atmosphere. 5. The In ₂ O _{3 according to} claim 1, wherein the gel film and / or the substrate is heated to a temperature of 80 ° C. or higher and the gel film is irradiated with ultraviolet light. -SnO ₂ method of manufacturing a thin film.