JPH06148661A - Production of substrate for display device - Google Patents

Abstract

PURPOSE:To provide the method for improving a display grade. CONSTITUTION:ITO 2 is finely worked by hydriodic acid and a substrate is heated to shrink a photoresist 3; further, the exposed parts of the ITO 2 from the resist 3 are washed by the ozone generated when the resist is irradiated with UV rays. An indium electroplating 4 is then formed on the ITO by a soln. prepd. by dissolving indium sulfate and sodium sulfate in pure water. The substrate is then washed thoroughly and the electroplating of copper 5 is executed thereon by a soln. of an acidic copper sulfate system. A gold layer 6 is further formed thereon by an electroless plating liquid of gold. The resist 3 is peeled by an org. solvent and the substrate is washed and dried. The substrate is thereafter heat-treated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a display device substrate such as a liquid crystal display device. In particular, it relates to further lowering the resistance of the electrodes.

[0002]

2. Description of the Related Art A display device such as a liquid crystal display device is an essential technology for a man-machine interface. Particularly, recently, in computer terminals and the like, liquid crystal display devices have become indispensable also from the viewpoint of downsizing.

From the viewpoint of electric resistance, controllability during production, film uniformity, light transmittance, fine workability, etc., industrially,
Overwhelmingly, indium-tin oxide (so-called ITO)
Is used.

The technical contents are "Thin Film Handbook",
Detailed information on Ohmsha, edited by the 131st Committee of Japan Society for the Promotion of Science.

[0005]

Recently, in liquid crystal display devices used for computer terminals and the like, the demand for high-quality display has become a reality. In these liquid crystal display devices, simple mode liquid crystal display devices such as STN are mainly used. In these liquid crystal display devices, the display quality is deteriorated due to a crosstalk phenomenon or the like in the display, but it is unavoidably used at present.

This phenomenon is caused by the fact that the electric resistance value of the transparent electrode (ITO) is not sufficiently low and therefore the CR time constant is large. With the current technology, the specific electric resistivity of ITO has been achieved only up to about 2 × 10 −4 Ωcm. By the way, the resistivity of gold, copper, and aluminum is 2
It is about 10 −6 Ωcm.

However, gold, copper and aluminum are replaced with ITO.
A substrate in which wiring is formed in contact with the substrate (so-called auxiliary electrode) has been developed, but in this case, the lack of adhesion strength to ITO or the substrate becomes a problem.

Further, it is required to reduce the cost of forming the auxiliary electrode as much as possible. For example, the method using the photolithography method and the vapor deposition process is reliable, but the cost is high, and it cannot be considered as a method generally used.

This problem also applies to the ferroelectric liquid crystal display device.

[0010]

In order to solve the above-mentioned problems, the present invention forms a resist film patterned in a desired state on a transparent electrode over the entire main surface of a substrate, Fine processing with a corrosive liquid for the transparent electrode, washing, then shrinking the resist film, cleaning the exposed part of the transparent electrode with ozone or oxygen plasma, indium electroplating on the exposed part of the transparent electrode, , A copper single-layer electric field plating, a gold single-layer electric field plating, or a two-layer plating of copper electric field plating and gold electric field or electroless plating, in this order, and washing,
The present invention provides a method of manufacturing a substrate for a display device in which the resist film is dried, the resist film is removed, washed, and dried, and then heat-treated at a desired temperature profile to a desired maximum temperature.

Further, according to the present invention, a resist film patterned in a desired state is formed on the transparent electrode over the entire main surface of the substrate, finely processed with a corrosive liquid for the transparent electrode, and washed. Shrink the resist film to, the exposed portion of the transparent electrode is cleaned with ozone or oxygen plasma, nickel electric field or electroless plating is applied to the exposed portion of the transparent electrode, further, copper single-layer electric field plating or, Gold single-layer electric field or electroless plating or two-layer plating of copper electric field plating and gold electric field or electroless plating is applied in this order, washed and dried, and the resist film is removed, washed and dried, and then heat treated. A method of manufacturing such a substrate for a display device will be clarified.

It is desirable that the patterned resist film is shrunk by a thermal effect, or the resist film is shrunk by irradiating ozone or oxygen plasma.

[0013]

First, indium or an indium alloy has a good adhesive force to the substrate, specifically, ITO and the adhesive force to the glass substrate surface. This phenomenon has been verified with glass solder and the like. Also, copper and gold, in particular, have extremely poor adhesion due to their noble metal properties. IT
Nickel is another example of O and a metal having a strong adhesion to the surface of the glass substrate. As is chrome,
The difficulty of plating technology is unusual (though of course there is chrome plating technology).

Indium can be electroplated using an aqueous solution. Since indium is deposited, it is not necessary to use a physical deposition method. The physical precipitation method requires expensive equipment such as a vapor deposition machine and a sputtering apparatus. Of course, indium metal can be deposited by a physical method such as vapor deposition. Nickel is the metal that is most easily plated, and electroplating and selective plating on ITO are also possible.

The electric resistance is most ideally lowered by using copper or gold. Also, in terms of process, ITO
Microfabrication (this is a conventional process)
It is desirable to obtain a lower resistance electrode by adding a few processes to the above. This is the following proposal. That is, a resist film patterned in a desired state is formed on the ITO over the entire main surface of the substrate, and the IT
Fine processing with an O corrosive liquid, washing, shrinking the resist film to bring exposed areas of ITO, and then applying indium plating or nickel plating to the exposed areas of ITO, and further, No copper plating or gold plating,
Wash, dry, remove resist film, wash, dry,
This is followed by heat treatment with a desired temperature profile. In the case of copper plating, it is also desirable to perform electroless gold plating on the surface of plated copper from the viewpoint of corrosion resistance.
The final heat treatment is aimed at increasing the adhesion to the substrate and, when indium plating is performed, forming indium alloy with copper or gold to improve heat resistance.

With this, the inspection of the ITO electrode can be performed only once. The final heat treatment also has the meaning of promoting the alloy reaction of a part of the underlying metal indium and copper or gold, and improving the adhesive force between the substrate and the alloy. Even when the base metal is nickel, this can improve the adhesive strength.

In the above-mentioned laminated conductor, the layer of indium, indium alloy or nickel contributes only to the adhesion to the substrate and is not effective for reducing the electric resistance. Therefore, the volume of the layer made of copper or gold should be larger than that of the layer if the adhesion is satisfactory.

[0018]

EXAMPLES Examples of the present invention will be described below. Here, a simple matrix display device will be described. However, this embodiment basically also applies to an EL display device and the like.

(Example 1) (FIG. 1) will be described.
In the cross-sectional configuration diagram (FIG. 1), 1 is a glass substrate, 2 is ITO, 3 is a photoresist, 4 is an indium metal layer,
Reference numeral 5 is a copper layer, 6 is a gold layer on the surface of the copper layer, and 7 is a layer made of an indium-copper alloy.

A Corning # 7059 glass substrate 1 having ITO on the entire main surface was obtained. Using a positive resist, OFPR manufactured by Tokyo Ohka Co., Ltd., a resist pattern 3 was formed by a known photolithography method as shown in FIG. Then, it was treated with an O2 asher. Further, ITO was finely processed with hydroiodic acid by a known method (FIG. 1) (a).

Next, the substrate was heated to about 150 ° C. or higher to shrink the photoresist. Further, the exposed part of the ITO from the resist was washed with ozone generated by irradiation with ultraviolet rays (FIG. 1) (b).

About 60 grams of indium sulphate and about 10 grams of sodium sulphate were dissolved in about 1 liter of pure water and indium electroplated to a thickness of about 0.1 micron on ITO. Next, wash thoroughly. Further, with an acidic copper sulfate-based solution, copper electroplating with a thickness of about 2 μm was performed thereon. Further, a commercially available gold electroless plating solution was used to form a gold layer of about 0.2 μm thereon (FIG. 1) (c).

The resist was peeled off with an organic solvent, thoroughly washed and dried to obtain (d) in FIG.

Thereafter, the temperature is gradually raised to about 150 ° C.,
Finally, the temperature was raised to about 260 ° C. and the substrate was heat-treated. At this time, it was revealed by Auger electron analysis that the indium metal layer was an indium-copper alloy layer. Thus, (FIG. 1) (e) was obtained. these,
The adhesion of the plating layer to ITO was practical.

The sheet resistance of the ITO electrode was reduced by about one digit. As usual, a polyimide film was formed on this substrate and was rubbed with rayon fibers.
The two substrates are placed so that the ITO films face each other.
The two were bonded so that the gap was 7.0 μm, and this gap was filled with the nematic liquid crystal composition for STN. Almost no crosstalk and contrast of about 50%
Rose.

(Embodiment 2) (FIG. 2) will be described.
In the configuration cross-sectional view (FIG. 2), 8 is a glass substrate, 9 is ITO, 10 is a photoresist, 11 is a nickel metal layer, and 12 is a gold layer.

Corning # with ITO 9 on the main surface
The 7059 glass substrate 8 was obtained. Using a positive resist made by Tokyo Ohka, with a well-known photolithography method,
(FIG. 2) A resist pattern 10 was formed as shown in FIG. Then, it was treated with an O2 asher. Next, the ITO was finely processed with a commercially available salt iron solution to obtain (a) in FIG.

Next, the substrate is dried with an etcher for about 20 minutes.
Min, expose to oxygen plasma. Thus, the edges of the resist generally have the effect of substantially shrinking the photoresist due to the faster decomposition of the resist material by the oxygen plasma. That is, an exposed portion of the clean ITO is obtained (FIG. 2) (b).

Next, using a commercially available chemical, nickel electroplating of about 0.5 micron was selectively performed only on the exposed portion. At this time, control of the deposition rate is very important in order to prevent film peeling of the nickel layer. Furthermore, a gold layer of about 1.5 μm is obtained by gold electroplating solution (FIG. 2).
(C).

The resist was stripped with an organic chlorine-based solvent, thoroughly washed, and dried to obtain (FIG. 2) (d).

After that, the substrate was heat-treated at about 100.degree.
The adhesion of the plating layer to ITO was practically useable.

The sheet resistance of the ITO electrode was reduced by about one digit. As usual, a polyimide film was formed on this substrate and was rubbed with rayon fibers.
The two substrates are placed so that the ITO films face each other.
The two were bonded so that the gap was 7.0 μm, and this gap was filled with the nematic liquid crystal composition for STN. Almost no crosstalk and contrast of about 40%
Rose.

[0033]

As described above, the present invention provides an effective method for improving the display quality of a display device and greatly contributes to the industry.

[Brief description of drawings]

FIG. 1 is a structural cross-sectional view for explaining an embodiment of the present invention.

FIG. 2 is a configuration cross-sectional view for explaining an embodiment of the present invention.

[Explanation of symbols]

 1 Glass Substrate 2 ITO 3 Photoresist 4 Indium Metal Layer 5 Copper Layer 6 Gold Layer on Copper Surface 7 Layer Made of Indium-Copper Alloy 8 Glass Substrate 9 ITO 10 Photoresist 11 Nickel Metal Layer 12 Gold Layer

Claims (4)

[Claims] 1. A resist film patterned in a desired state is formed on a transparent electrode over the entire main surface of a substrate, finely processed by a corrosive liquid for the transparent electrode, and washed, and then the resist is formed. The film is shrunk, the exposed part of the transparent electrode is cleaned with ozone or oxygen plasma, indium electrolytic plating is applied to the exposed part of the transparent electrode, and further, copper single-layer electrolytic plating or gold single-layer electrolytic plating is applied on this. A substrate for a display device, characterized in that two-layer plating of copper electric field plating and gold electric field or electroless plating is applied in this order, washed and dried, the resist film is removed, washed and dried, and then heat-treated. Manufacturing method. 2. A resist film patterned in a desired state is formed on a transparent electrode over the entire main surface of a substrate, finely processed with a corrosive liquid for the transparent electrode, washed, and then the resist is formed. The film is shrunk, the exposed part of the transparent electrode is cleaned with ozone or oxygen plasma, and the exposed part of the transparent electrode is subjected to nickel electric field or electroless plating, and further, copper single layer electric field plating or gold single layer is formed on this. Characteristic of performing electric field or electroless plating or two-layer electroplating of copper electric field plating and gold electric field or electroless plating in this order, washing and drying, removing the resist film, washing and drying, and then performing heat treatment And manufacturing method of substrate for display device. 3. The method for manufacturing a substrate for a display device according to claim 1, wherein the patterned resist film is contracted by a thermal effect. 4. The method for manufacturing a substrate for a display device according to claim 1, wherein the patterned resist film is irradiated with ozone or oxygen plasma to shrink the resist film.