JPS6298506A - Formation of transparent electrode substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing a substrate having a transparent electrode film (hereinafter referred to as a transparent electrode substrate) used as a substrate for, for example, a liquid crystal display element.

"Prior Art and its Problems" It is well known that metal oxide films such as indium, mu, cadmium, tin, and antimony formed on insulating substrates such as glass and ceramics are transparent and exhibit good conductivity. There is. Therefore, this transparent conductive film is used as a transparent electrode film for, for example, liquid crystal display elements, electrochromic elements, electroluminescent elements, semiconductor elements, and the like.

In recent years, transparent electrode films such as those described above have been required to have lower sheet resistance values. For example, in the case of liquid crystal display elements, the transparent electrode film required for liquid crystal display elements for games, calculators, etc. had a sheet resistance value of just a few ohms/mouth, but it has not been applied to dot matrix panels for cars, liquid crystal televisions, etc. As the technology continues to grow, products with extremely low sheet resistance values have come to be required.

Conventionally, the transparent electrode film as described above has been produced by, for example, the vacuum four-layer method,
It was formed by methods such as sputtering, chemical spraying, screen printing, and dipping. A film such as an alignment film or an insulating film may be formed on the transparent electrode.

However, after forming a transparent electrode film, if an alignment agent such as a polyimide precursor or polyvinyl alcohol is applied and a heat treatment is performed to form an alignment film, the sheet resistance value of the transparent electrode film will decrease by about 1 compared to before the heat treatment. A problem has arisen in which the value increases by 2 to 2 times. This also applies to the formation of films other than alignment films, such as insulating films, when heat treatment is involved. Therefore, in order to obtain the desired resistance value, it is necessary to use a material that has a lower sheet resistance value by taking into account the reduction in sheet resistance value due to heat treatment, which increases the cost of the material.

OBJECT OF THE INVENTION An object of the present invention is to provide a method for forming a transparent electrode substrate that solves the problems of the prior art described above and allows a transparent electrode film with a lower sheet resistance value to be obtained.

"Structure of the Invention" The method for forming a transparent electrode substrate of the present invention involves forming a transparent electrode film on a substrate, which is made by doping indium oxide with tin oxide, and coating the electrode film with a material containing a trace amount of a reducing organic compound. It is characterized by being subjected to heat treatment.

In this way, in the present invention, a material containing a trace amount of a reducing organic compound is applied to the transparent electrode film and heat-treated, so that during the heat treatment, the reducing organic compound reduces the amount of the material in the transparent electrode film. The indium oxide is partially reduced and the carrier concentration in the transparent electrode film increases, thereby reducing the sheet resistance value of the transparent electrode film.

Next, preferred embodiments of the present invention will be explained in more detail.

As the material containing a reducing organic compound, for example, in the case of a liquid crystal display element, an alignment agent containing a reducing organic compound is used. The main ingredient of such an alignment agent is a polyimide precursor (
For example, manufactured by Toshiku Co., Ltd. under the trade name ``Trace'', Hitachi Chemical (
manufactured by Hitachi Chemical Co., Ltd., trade name rprx J), polyimide (for example, manufactured by Hitachi Chemical Co., Ltd., trade name rHIMAL 1100)
J), polyvinyl alcohol (e.g. Kurari Co., Ltd.)
manufactured by Kuraray Bobal (trade name: ``Kurare Bobal''), etc. Further, as the reducing organic compound, a quinone compound, a saccharide, an aldehyde compound, etc. are used. The content of the reducing organic compound in the material such as the alignment agent is preferably about 1 to 3% by weight. If the amount of the reducing organic compound is less than 1% by weight, the effect of the present invention will be poor, and if it exceeds 3% by weight, the state of film formation such as an alignment film will deteriorate.

Materials such as alignment films are placed on transparent electrode films formed on substrates.
For example, it is applied using a spinner, roll coating, gravure printing, or other methods. In the present invention, heat treatment is then performed, and the heat treatment conditions are, for example, 100 to 200°C for 10 to
About 80 minutes is preferable. When the heat treatment temperature is less than 100°C, it has the effect of lowering the resistance value of the transparent electrode film, but it tends to change over time, and when the heat treatment temperature exceeds 200°C, the resistance value of the transparent electrode film may increase. be. Also,
If the heat treatment time is less than 10 minutes, the effect of reducing the resistance value is small, and if it exceeds 60 minutes, the resistance value does not decrease much. The thickness of the alignment film formed on the transparent electrode film is preferably about 600 to 900, for example.

"Embodiments of the Invention" Example 1 A transparent electrode layer made of indium oxide doped with tin oxide is formed to a thickness of 400 mm on a glass substrate by a vacuum evaporation method. On this transparent electrode film, a polyimide precursor (Hitachi Chemical Co., Ltd., trade name [formerly MAL1100J) 99
% by weight and hydroquinone by 1% by weight using a spinner, and baked at 150°C for 20 minutes to obtain a thickness of 60% by weight.
0 people's orientation II was formed. In this electrode substrate, the resistance value of the transparent electrode before the formation of the alignment film was +00Ω/hole, but the initial resistance value was maintained even after the formation of the alignment film.

Example 2 A transparent electrode film forming solution is prepared by using indium trisacetylacetonate as an organic indium compound and dibutyltin acedope as an organic tin compound and dissolving them in an organic solvent of methyl ethyl ketone to which nitrocellulose is added.

A glass substrate was immersed in this transparent electrode film forming solution, and
cm/min, pre-dried at 140°C for 10 minutes, and fired at 500°C for 30 minutes. Thereafter, annealing was performed at 500° C. for 130 minutes in a mixed atmosphere of hydrogen and nitrogen. The transparent electrode film thus obtained had a sheet resistance value of 500Ω/hole.

Next, the same alignment agent as in Example 1 was applied onto the transparent electrode film using a spinner, and baked at 150° C. for 20 minutes to form an alignment film. After forming the alignment film, the sheet resistance value of the transparent electrode was measured, and a value lower than 100Ω/hole was obtained.

In this way, the effects of the present invention can be achieved by using organic indium compounds,
It has been found that this is particularly remarkable when the transparent electrode 11 is formed by coating the substrate with a transparent electrode film-forming liquid containing an organic tin compound and baking it.

"Effect of the Invention J As explained above, according to the present invention, a material containing a trace amount of a reducing organic compound is coated on a transparent electrode film and heat treatment is performed. Indium oxide in the transparent electrode film is partially reduced by the organic compound, and the carrier concentration in the transparent electrode film increases, thereby reducing the sheet resistance value of the transparent electrode film.

Claims (3)

[Claims] (1) A transparent electrode substrate characterized by forming a transparent electrode film made of indium oxide doped with tin oxide on a substrate, coating the electrode film with a material containing a trace amount of a reducing organic compound, and subjecting it to heat treatment. How to form. (2) The method for forming a transparent electrode substrate according to claim 1, wherein the material containing the reducing organic compound is an alignment agent. (3) A transparent electrode substrate according to claim 1 or 2, wherein the transparent electrode film is formed by applying a transparent electrode film forming liquid containing an organic indium compound or an organic tin compound to the substrate and baking it. How to form.