JP2861716B2 - Transparent electrode, method for manufacturing the same, and apparatus for applying the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent electrode having an ion diffusion preventing film and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, in a transparent conductive film for a transparent electrode, indium oxide (ITO) containing a small amount of tin oxide, indium oxide (IWO) containing a small amount of tungsten oxide,
Indium oxide containing a small amount of molybdenum oxide (IM
O), tin oxide (AT) with a trace amount of antimony oxide added
O), tin oxide (FTO) to which a small amount of fluorine is added, tin oxide (CTO) to which a small amount of cadmium oxide is added, zinc oxide (ZnO), and the like are used. When these transparent conductive films are formed on inexpensive soda glass or the like, alkali ions and the like diffuse from the substrate glass to the transparent conductive films, which lowers the conductivity of the transparent conductive films and causes abnormalities in the refractive index. It was a big cause. When a transparent electrode made of these transparent conductive films is used for a liquid crystal display, a transparent conductive film,
In addition, the diffusion of alkali ions into the liquid crystal cell causes cloudiness of the display, which has been a problem of hindering high definition of the display. Therefore, if high-purity silica glass containing no alkali ions or the like is used for the substrate, this has been an obstacle to reducing the cost of the liquid crystal display.

[0003] As a method of overcoming this problem, Kikai, 90,
As shown in 157-63 (1982), there is a method in which SiO ₂ is formed on inexpensive soda glass, a transparent conductive film is formed thereon, and a transparent electrode is formed. As a method of forming the SiO ₂ film for preventing the ion diffusion, a general thin film forming method can be applied, but among various film forming methods, in particular, from the viewpoint of lowering the cost of manufacturing a display, an inexpensive film forming method is used. The sol-gel method is often used.

On the other hand, an antistatic film tends to be formed on the outermost surface of a high-performance cathode ray tube, but a method of directly applying the antistatic film on the surface of the cathode ray tube has been adopted. There is no ion diffusion preventing film formed underneath. Further, an anti-reflection film is formed on the outermost surface of the high-performance CRT.

[0005]

Among the above-mentioned conventional methods for fabricating an ion diffusion preventing film, the film forming method requiring a vacuum space requires a long time to reach a vacuum, so that it takes a long time to form the film, and is inexpensive soda glass. Even if is used as a substrate, the production of the ion diffusion preventing film is costly, and as a result, it becomes an obstacle to the production of the transparent electrode at low cost. On the other hand, by using a sol-gel method that does not require a vacuum space, these problems can be solved and a large-area substrate for a transparent electrode can be manufactured. However, since an organometallic compound is mainly used as a raw material for the sol-gel method, high-temperature treatment is required to remove impurities such as organic substances contained in the raw material and to densify the thin film. However, if the ion diffusion prevention film is treated at high temperature to densify it, alkali ions contained in the soda glass are thermally diffused, so that it is difficult to produce an ion diffusion prevention film having sufficient ion diffusion prevention ability. there were. Further, since soda glass is softened by heat treatment at about 500 ° C., an ion diffusion preventing film cannot be formed at a temperature higher than 500 ° C.

The SiO ₂ film produced by the sol-gel method is 2
It is a film that absorbs near 00 nm and emits light by laser irradiation. This means that there is a structural defect in the film. For this reason, when used as an ion diffusion prevention film for preventing the intrusion of ions, not only ion diffusion through structural defects becomes a problem, but also unnecessary unnecessary defects due to structural defects occur when the produced transparent electrode is used as an optical material. The display lacks high definition due to the intense fluorescence, which is a major problem.

Further, a transparent electrode in which an ion diffusion preventing film is formed on soda glass by a sol-gel method and a transparent conductive film is further formed thereon has insufficient ion diffusion preventing ability.
A transparent electrode having high conductivity cannot be produced at low cost. Therefore, a liquid crystal display having excellent responsiveness could not be manufactured at low cost.

On the other hand, at present, no ion diffusion preventing film is formed between the surface of the cathode ray tube and the antistatic film in the cathode ray tube. However, considering the future performance of the cathode ray tube, improvement of the conductivity of the antistatic film is an essential condition, and it is expected that a problem in manufacturing a liquid crystal display will immediately become a problem in manufacturing a cathode ray tube.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has been made in view of the above circumstances. A transparent electrode on the prevention film, wherein the diffusion amount of alkali ions from the glass substrate to the transparent conductive film is 2% or less as compared with the case where the transparent conductive film is formed by directly contacting the glass substrate. It is.
The thickness of the ion diffusion preventing film is set to 2000 ° or less. As a material for the ion diffusion preventing film, a metal oxide, for example, SiO ₂ can be used, but two or more kinds of composite oxides can also be used. Further, it is assumed that the number of defects in the ion diffusion preventing film is 10 ¹⁰ to 10 ¹⁴ / cm ³ . When the ultraviolet absorption spectrum of the ion diffusion preventing film is measured,
The absorption at 190 nm is smaller than the absorption at 50 nm.
This ion diffusion preventing film has M (OR) n [where M: metal, R: alkyl group, and n: integer] on at least a part of the glass surface by a sol-gel method. And forming a coating film of the metal alkoxide solution represented by the formula (1), and curing the coating film by irradiation with ultraviolet rays. When the coating film is cured by irradiation with ultraviolet light and heat treatment, a film with sufficient adhesion to the substrate can be obtained. In this case, the irradiation of ultraviolet light is 100
It is desirable to carry out in an atmosphere of not more than ℃. As a method for forming the transparent conductive film, a general film forming method such as a sputtering method, a vacuum evaporation method, an ion plating method, a CVD method, and a sol-gel method can be used. Further, a display device such as a liquid crystal display can be manufactured using the transparent electrode having the ion diffusion preventing film. Further, the above-mentioned ion diffusion preventing film can be formed on the glass face of a cathode ray tube containing alkali ions, and a high-performance cathode ray tube having a film having an antistatic function thereon can be manufactured. Further, a cathode ray tube having an anti-reflection function can be manufactured by making the surface of the film having an anti-static function uneven. If a surface protective film is further provided thereon, a cathode ray tube having excellent durability can be manufactured. Produce irregularities on the surface of this protective film,
A high-definition CRT having an anti-reflection function can also be manufactured.

[0010]

In the present invention, M (OR) n [where M is a metal, R is an alkyl group, and n is an integer. And forming a coating film of the metal alkoxide solution represented by the formula (1), and curing the coating film by irradiating ultraviolet rays at a lower temperature than before. By performing light irradiation, heat treatment conventionally performed is not required, so that thermal diffusion of ions to the ion diffusion preventing film does not occur. When a heat treatment at 100 ° C. or lower is performed while irradiating light, a material having excellent adhesion of the ion diffusion preventing film to the soda glass substrate can be obtained.

By the above method, diffusion of alkali ions into the transparent conductive film and the display main body is prevented. Alkali ions in the transparent conductive film trap electrons, resulting in a decrease in conductivity. However, this method can provide a transparent electrode having high conductivity, and can further reduce the amount of impurities in the transparent conductive film. Therefore, a change in the refractive index, which is important as an optical material, can be suppressed. It is sufficient that the thickness of the ion diffusion preventing film is 2000 ° or less. Further, an oxide such as SiO ₂ can be applied as a material of the ion diffusion prevention film, the composition may be changed depending on the surrounding conditions, and a transparent electrode having an antireflection function by controlling the refractive index may be used. it can. When SiO ₂ produced by this method was used as an ion diffusion preventing film, the number of defects in the SiO ₂ film was measured by an electron spin resonance method.
Since ¹⁰ to ¹⁰¹⁴ pieces / cm ^3, not fluoresce with visible light irradiation. In the ultraviolet absorption spectrum, 20
The absence of absorption near 0 nm also indicates that the number of defects in the film is very small. For this reason, the transparent electrode provided with the ion diffusion preventing film does not show any fluorescence upon irradiation with visible light due to a defect in the ion diffusion preventing film. Can be obtained.
Note that as a method for forming the transparent conductive film, a general film forming method such as a sputtering method, a vacuum evaporation method, an ion plating method, a CVD method, and a sol-gel method can be used. Also in the production of this transparent conductive film, the substrate temperature may be low by using a sol-gel method in which the film curing process is performed by light irradiation.

When a transparent electrode provided with the above-mentioned ion diffusion preventing film is applied to a display device such as a liquid crystal display, it greatly contributes to cost reduction, which is a major goal in manufacturing a liquid crystal display. In addition, ion diffusion into the display body can be suppressed, and problems such as cloudiness of the display can be solved. In manufacturing a display, it is desirable that a film used for a cell has high transmittance and does not emit light by light irradiation.
The film of the present invention satisfies this condition.

On the other hand, at present, no ion diffusion preventing film is formed between the surface of the cathode ray tube and the antistatic film in the cathode ray tube. However, considering the future performance of the cathode ray tube, improvement of the conductivity of the antistatic film is an essential condition, and it is expected that a problem in manufacturing a liquid crystal display will immediately become a problem in manufacturing a cathode ray tube. When the ion diffusion preventing film of the present invention is formed on the surface of a cathode ray tube and an antistatic film is formed thereon, ion diffusion into the antistatic film can be prevented, and the antistatic film having high conductivity is provided. A high-performance cathode ray tube can be manufactured.

Further, if the surface of the film having an antistatic function is provided with irregularities to add an antireflection function, a higher performance cathode ray tube can be manufactured. When a surface protective film is formed on the antistatic film, a cathode ray tube with excellent durability can be manufactured. Furthermore, if the surface of the protective film has irregularities and has a function of preventing reflection, a high-definition CRT is obtained.

[0015]

【Example】

(Example 1) Tetraethoxysilane (TEOS), water,
Ethanol (ETOH) and nitric acid in a molar ratio of 1: 12: 4
The raw materials were mixed at a ratio of 5: 0.25. By reacting TEOS, which is a metal alkoxide, with water, a metal cluster compound containing Si—O—Si is generated in the solution. This solution was formed into a film on soda glass. Spin coating, dipping,
One of the spray coating methods was used. When the produced film was irradiated with a 100 mW argon gas laser, it emitted fluorescence. When the ultraviolet absorption spectrum was measured,
Absorption was observed at around 00 nm. From these results,
However, it can be seen that the film contains defects in the film formed. When the ESR spectrum of this thin film was measured, 10 ¹⁶ defects / cm ³ were observed. The thin film was irradiated with 210 nm light for 10 minutes. Fabricated Si
The thickness of the O ₂ thin film was about 1000 °. The film cured by irradiation with ultraviolet light did not emit fluorescence even when irradiated with a 100 mW argon gas laser. Also, when the ultraviolet absorption spectrum was measured, no absorption around 200 nm was observed. Furthermore, when the ESR spectrum was measured,
The number of defects was 10 ¹⁰ / cm ³ or less. Further, in this film hardening step, no heat treatment was performed, so that the soda glass used for the substrate did not soften. ITO was formed on soda glass provided with the ion diffusion preventing film. Examples of the method for producing ITO include a sputtering method, a vacuum deposition method, a CVD method, an ion plating method, a spray method,
A sol-gel method or the like was used. In the same manner as described above, an ion diffusion preventing film is formed on soda glass by a sol-gel method in which the film is cured by heat treatment at 500 ° C.
Table 1 shows a comparison of the electrical conductivity between when the TO film was formed and when the TO method was used.

[0016]

[Table 1]

By using this method, a transparent electrode having high conductivity could be produced even when soda glass was used. In addition, ITO formed by sputtering on soda glass provided with an ion diffusion preventing film formed by a sol-gel method in which the film is cured by heat treatment
FIG. 1 shows the transmittance of a transparent electrode made of ITO and a transparent electrode made of ITO formed by sputtering on a soda glass provided with an ion diffusion preventing film formed by a sol-gel method in which the film is cured by light irradiation of the present method. . Reference numeral 1 denotes a film prepared by this method, and reference numeral 2 denotes a film prepared by heat treatment to form an ion diffusion preventing film. As can be seen from this figure, the transparent electrode produced by this method has very low alkali ion diffusion, and therefore has excellent light transmittance.

Example 2 A raw material solution was prepared by mixing TEOS, water, ETOH, and nitric acid at a molar ratio of 1: 12: 45: 0.25. This solution was formed into a film on soda glass. The thin film was heat-treated at 80 ° C. while being irradiated with 210 nm light for 10 minutes. By heat treatment,
The adhesion between the glass substrate and the ion diffusion preventing film was improved.
The thickness of the produced SiO ₂ thin film was about 900 °.
The film cured by irradiating ultraviolet rays did not emit fluorescence even when heat treatment was performed at the same time or irradiation with an argon gas laser of 100 mW. Also, when the ultraviolet absorption spectrum was measured, no absorption around 200 nm was observed. When the ESR spectrum was further measured, the number of defects was 10 ¹⁰ /
cm ³ or less. In this film curing step, the heat treatment temperature was lower than the softening temperature of the glass, so that the soda glass used for the substrate did not soften. ITO was produced on soda glass provided with the ion diffusion preventing film. In this way, a transparent electrode having high conductivity was able to be produced even with soda glass.

Example 3 A liquid crystal display was manufactured using the transparent electrode of the above example. FIG. 2 shows a cross-sectional view of the manufactured display. In FIG. 2, 3 is soda glass, 4 is a transparent conductive film, 5 is an inorganic insulating film, 6 is an alignment film,
7 is a sealing material, 8 is a liquid crystal layer, 9 is a display surface, and 10 is an ion diffusion preventing film. In addition, when the amount of sodium ions in a liquid crystal cell using a transparent electrode in which a transparent conductive film was directly formed on soda glass was examined by atomic absorption spectrometry, it was found to be 1.2.
A liquid crystal cell having an ion diffusion preventing film obtained by performing a heat treatment at 500 ° C. without light irradiation for film curing using the same raw material as in the present method at 9 to 1.77 × 10 ⁻² mol / cm ² . Diffusion of 1.15 to 1.35 × 10 ⁻³ mol / cm ² was observed. However, when the ion diffusion preventing film according to the present invention was used, 10 ⁻⁴ was observed.
Only about mol / cm ² diffused.

The liquid crystal cell produced by this method has no diffusion of alkali ions into the cell, does not deteriorate the display characteristics such as white turbidity, and has sufficient conductivity. It could be manufactured at cost.

Example 4 A raw material solution was prepared by mixing TEOS, water, ETOH, and nitric acid at a molar ratio of 1: 12: 45: 0.25. This solution was used to form an ion diffusion preventing film on the face of the cathode ray tube. As a film forming method, any of spin coating, dipping, and spray coating was possible. On this thin film, 210 nm light is applied for 10 minutes.
Heat treatment was performed at 80 ° C. while irradiating for 10 minutes. The heat treatment improved the adhesion between the glass substrate and the ion diffusion preventing film. Like the ion diffusion prevention film of the above embodiment,
This ion diffusion preventing film did not emit fluorescence even when irradiated with visible light. An acetylacetone solution of indium nitrate and tin chloride was formed on the ion diffusion preventing film by a spray coating method. 160 ° C while irradiating this with ultraviolet light
To cure the film, thereby forming an antistatic film. The conductivity of this conductive film was 10 ⁸ Ω / □. In this way, a conductive film having irregularities on the surface was produced, and a film capable of irregularly reflecting the external light of the cathode ray tube, preventing the reflection on the surface which would cause a problem in the visual quality of the cathode ray tube, and preventing the surface of the cathode ray tube from being charged was produced.

Example 5 A raw material solution was prepared by mixing TEOS, water, ETOH, and nitric acid at a molar ratio of 1: 12: 45: 0.25. This solution was used to form an ion diffusion preventing film on the face of the cathode ray tube. On this thin film, 210n
Heat treatment was performed at 80 ° C. while irradiating with m light for 10 minutes.
Like the ion diffusion preventing film of the above example, the ion diffusion preventing film did not emit fluorescence even when irradiated with visible light.
An acetylacetone solution of indium nitrate and tin chloride was formed on the ion diffusion preventing film. As a film forming method, any of spin coating, dipping, and spray coating was possible. This was heat-treated at 160 ° C. while being irradiated with ultraviolet light to cure the film, thereby forming an antistatic film.
The conductivity of this conductive film was 10 ⁸ Ω / □, and TEOS, water, ETOH, and nitric acid were mixed at a molar ratio of 1: 12: 45: 0.25 on this antistatic film. A film of the raw material solution was formed by a spray coating method. The thin film was heat-treated at 80 ° C. while being irradiated with 210 nm light for 10 minutes. FIG. 3 shows a cross-sectional view of the produced CRT. In FIG. 3, reference numeral 11 denotes a cathode ray tube outer wall, 12 denotes an antireflection film, 13 denotes an antistatic film, and 14 denotes an ion diffusion preventing film. In this way, an SiO ₂ protective film having irregularities on the surface is formed to protect the surface of the cathode ray tube, to diffusely reflect external light, to prevent the reflection of the surface which causes a problem in the visual quality of the cathode ray tube, and to prevent the surface of the cathode ray tube from being charged. A film was produced.

When the present method is applied to a color cathode ray tube, compared to the case where the film is cured by heat treatment, no generation of fluorescence due to irradiation with visible light is observed, and a cathode ray tube having high definition and excellent antistatic ability is produced. I was able to.

[0024]

According to the present invention, a decrease in conductivity and transmittance due to diffusion of alkali ions from soda glass to the transparent conductive film and the display cell can be greatly suppressed. Therefore, if this is applied to an ion diffusion preventing film such as a liquid crystal display and a cathode ray tube, a high performance liquid crystal display and a cathode ray tube can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing the transmittance of a transparent electrode produced by the present method and the transmittance of a transparent electrode obtained by heat-treating a film of an ion diffusion preventing film by heat treatment.

FIG. 2 is a cross-sectional view of a display manufactured by the present method.

FIG. 3 is a cross-sectional view of a cathode ray tube manufactured by the present method.

[Explanation of symbols]

1 ... transmittance of a transparent electrode prepared by curing the ion diffusion preventing film by heat treatment 2 ... transmittance of a transparent electrode prepared by curing the ion diffusion preventing film by light irradiation 3 ... soda glass, 4 ... transparent conductive Film, 5: inorganic insulating film, 6: alignment film, 7: liquid crystal layer, 8: sealing material, 9: display surface, 10 ...
Ion diffusion prevention film CRT, 11 ... CRT outer wall,
12: anti-reflection film, 13: anti-static film, 14: ion diffusion preventing film.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Satoru Ogiwara 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (56) References JP-A-58-26408 (JP, A) JP-A-62-158136 (JP, A) JP-A-61-118946 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C03C 15/00-23/00

Claims (8)

(57) [Claims] 1. A method according to claim 1, wherein M (OR) n [where M: metal, R: alkyl group,
n: Indicates an integer. A coating process of forming a coating film of a metal alkoxide solution represented by the formula: and a curing process of curing the coating film by ultraviolet irradiation.
A method for manufacturing a transparent electrode, comprising forming an anti-diffusion film and forming a transparent conductive film thereon . 2. The method according to claim 1 , wherein the ultraviolet light irradiation is performed at 100 ° C.
A method for producing a transparent electrode, wherein the method is performed in the following atmosphere. 3. At least a part of the glass surface is coated with M (OR) n [M: metal, R: alkyl group,
n: Indicates an integer. A coating step of forming a coating film of a metal alkoxide solution represented by the formula: and a curing step of curing the coating film by irradiating ultraviolet rays after heat treatment to form an ion diffusion preventing film.
A method for producing a transparent electrode, wherein a transparent conductive film is formed on the transparent electrode. 4. The method according to claim 3 , wherein the ultraviolet light irradiation is performed at 100 ° C.
A method for producing a transparent electrode, wherein the method is performed in the following atmosphere. 5. A method for producing a transparent electrode, wherein the heat treatment according to claim 3 is performed in an atmosphere at 100 ° C. or lower. 6. At least a part of the glass surface is coated with M (OR) n [M: metal, R: alkyl group,
n: Indicates an integer. A coating step of forming a coating film of a metal alkoxide solution represented by, that to form an ion diffusion preventing film by curing step of curing by heat treatment simultaneously with the ultraviolet radiation to the coating film
A method for manufacturing a transparent electrode on which a transparent conductive film is formed . 7. The method according to claim 6 , wherein the ultraviolet light irradiation is performed at 100 ° C.
A method for producing a transparent electrode, wherein the method is performed in the following atmosphere. 8. A method for producing a transparent electrode, wherein the heat treatment according to claim 6 is performed in an atmosphere at 100 ° C. or lower.