JPH0659267A - Substrate for display device and its production - Google Patents

Abstract

PURPOSE:To substantially lower the electric resistance of transparent electrodes by allowing alloy layers consisting of indium and copper and laminated conductors consisting of copper to exist in contact with the transparent electrodes and coupling at least a part of the alloy layers to a substrate or the transparent electrodes. CONSTITUTION:This substrate consists of a glass substrate 1, ITO electrodes 2 which are subjected to fine processing, i.e., are processed to a stripe shape in the case of a simple matrix display device, photoresist 3, indium metallic layers 4, copper metallic layers 5 and the layers 6 consisting of the alloy of the indium-copper. The alloy layers 6 are coupled to the ITO electrodes 2. The indium or indium alloy has the adhesive power to the substrate 1, more specifically, the adhesive power to the ITO electrodes 2 and the glassy substrate 1. The adhesive power of the copper metal in particular is extremely poor for its noble metal characteristic. The electric resistivity is most ideally lowered by using the copper or aluminum.

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 substrate of a display device such as a liquid crystal display device.

[0002]

2. Description of the Related Art A display device such as a liquid crystal display device is an important technique as 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.

By the way, the electrode material used therefor is industrially overwhelming in view of electric resistance, controllability during production, film uniformity, light transmittance, and fine workability. , An oxide of indium-tin (so-called ITO transparent electrode) is used (see "Thin Film Handbook", edited by Japan Society for the Promotion of Science, 131st Committee, published by Ohmsha).

[0004]

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 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 or aluminum is 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, 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.

Further, this problem also applies to a ferroelectric liquid crystal display device.

In view of the above problems of the conventional liquid crystal display device, it is an object of the present invention to provide a substrate for a display device capable of substantially reducing the electric resistance of a transparent electrode and a method of manufacturing the same. It is a thing.

[0010]

According to the present invention, an alloy layer made of indium and copper and a laminated conductor made of copper are present in contact with a transparent electrode having a predetermined shape over the entire main surface of a substrate. A substrate for a display device in which at least a part of the layer is bonded to the substrate or the transparent electrode.

Further, according to the present invention, an alloy layer made of indium and aluminum and a laminated conductor made of aluminum are present in contact with a transparent electrode having a predetermined shape over the entire main surface of the substrate, and at least one of the alloy layers is provided. A part is a substrate for a display device, which is connected to a substrate or a transparent electrode.

Further, according to the present invention, a resist film patterned in a desired state is formed on a transparent electrode over the entire main surface of a substrate, and fine processing is performed by a corrosive liquid for the transparent electrode until a side-etched state is reached. Then, the exposed portion of the transparent electrode is plated with indium, and further, copper plating and indium plating are sequentially applied on the exposed portion in this order, washed and dried, and the resist film is removed, washed and dried. Then, a method for manufacturing a substrate for a display device is provided, in which a heat treatment is performed to a desired maximum temperature with a desired temperature profile.

[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. Further, especially copper metal has extremely poor adhesion due to its noble metal property.

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 also be deposited by physical means.

The electric resistance is most ideally lowered by using copper or aluminum.

Further, in the manufacturing method, it is desirable to obtain an electrode having a lower resistance by adding some processes to the fine processing of ITO (this is a conventional process).

With this, the inspection of the ITO electrode can be performed only once. The final heat treatment is for promoting the alloy reaction of a part of indium and copper and for improving the adhesive force between the substrate and the alloy.

Further, the maximum temperature should be at least the maximum temperature in a later step in manufacturing the display device.

In the above-mentioned laminated conductor, the layer of indium or indium alloy 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 aluminum should be larger than that of the layer as long as the adhesion can be satisfied.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, a simple matrix display device will be described.

(Embodiment 1) A description will be given with reference to FIG. In FIG. 1 which is a cross-sectional view of the structure of the present embodiment, 1 is a glass substrate, 2 is finely processed, that is, for a simple matrix display device, an ITO electrode processed in a stripe shape
3 is a photoresist, 4 is an indium metal layer, 5 is a copper metal layer, and 6 is a layer made of an indium-copper alloy.

A # 7059 glass substrate 1 manufactured by Corning Co. having a finely processed ITO electrode 2 on its main surface was obtained.
A resist pattern 3 was formed as shown in FIG. 1A by a known photolithography method using a positive resist manufactured by Tokyo Ohka. Then it was treated with an O2 asher.

Next, indium sulfate, about 60 grams,
Indium plating 4 having a thickness of about 0.1 micron is applied on the ITO electrode 2 with a solution of about 10 grams of sodium sulfate dissolved in about 1 liter of pure water. Then wash thoroughly.

Further, with an acidic copper sulfate-based solution, a copper plating 5 having a thickness of about 2 μm was performed thereon.

The resist 3 was peeled off with an organic solvent, thoroughly washed and dried to obtain the one shown in FIG. 1 (b).

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 4 was the indium-copper alloy layer 6. Thus, FIG. 1C was obtained. The adhesion of the plating layers 5 and 6 to the ITO electrode 2 was practical.

The sheet resistance of the ITO electrode 2 was reduced by about one digit.

As usual, a polyimide film was formed on this substrate and was rubbed with rayon fibers. Two such substrates were attached so that the ITO electrodes 2 face each other and the gap was 7.0 μm, and the gap was filled with the nematic liquid crystal composition for STN. The liquid crystal display device manufactured in this manner had almost no crosstalk and the contrast was increased by about 50%.

(Embodiment 2) Description will be given with reference to FIG. In FIG. 2, which is a cross-sectional view of the configuration of the present embodiment, 7 is a glass substrate, 8 is finely processed, that is, in the case of a simple matrix display device, ITO electrodes processed in stripes,
9 is a photoresist, 10 is an indium metal layer, 11 is an aluminum metal layer, and 12 is a layer made of an indium-aluminum alloy.

A # 7059 glass substrate 7 manufactured by Corning Co. having a finely processed ITO electrode 8 on its main surface was obtained.
A resist pattern 9 was formed as shown in FIG. 2A by a known photolithography method using a negative resist manufactured by Tokyo Ohka. Then, it was treated with an O2 asher.

Next, indium sulfate, about 60 grams,
Indium plating 10 having a thickness of about 0.1 micron is applied on the ITO electrode 8 with a solution of about 10 grams of sodium sulfate dissolved in about 1 liter of pure water. Then wash well,
Dried.

Further, a commercially available non-aqueous solution aluminum plating solution was used, and an aluminum plating 11 having a thickness of about 2 μm was formed thereon.

Strip the negative resist with an organic chlorine solvent,
It was thoroughly washed and dried to obtain Fig. 2 (b).

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 10 was the indium-aluminum alloy layer 12. Thus, FIG. 2C was obtained. The adhesion of the plating layers 11 and 12 to the ITO electrode 8 was practical.

The sheet resistance of the ITO electrode 8 was lowered by about one digit.

As usual, a polyimide film was formed on this substrate and rubbed with rayon fiber. Two such substrates were bonded so that the ITO electrodes 8 faced each other and the gap was 7.0 μm, and the gap was filled with the nematic liquid crystal composition for STN. The liquid crystal display device manufactured in this manner has almost no crosstalk and a contrast of about 40%.
Rose.

(Embodiment 3) An explanation will be given with reference to FIG. In FIG. 3, which is a sectional view of the configuration of this embodiment, 13 is a glass substrate, 14 is a photoresist, 15 is an ITO electrode, 16 is a side-etched portion, 17 is a single or plural indium metal layer, and 18 is a single or plural. The copper metal layer 19 is a single or plural indium-copper alloy layer.

A Corning # 7059 glass substrate 13 having ITO electrodes 15 on the entire main surface was obtained. As shown in FIG. 3A, the resist pattern 14 is formed by a known photolithography method using a positive resist manufactured by Tokyo Ohka.
Got

Next, it is dipped in a hydroiodic acid solution at about 43 ° C., and the ITO electrode 15 is over-etched, that is, side-etched with respect to the resist pattern 14 as shown in FIG. 3B. Side-etched about 4 microns. After this, it was washed well.

Next, as in Example 1, an indium metal film 17 of about 0.1 micron was deposited on the side wall of the ITO electrode 15 in the side-etched portion. Wash more thoroughly.

Further, as in Example 1, copper metal 18 of 1 micron or more was deposited on the indium metal layer 17. Wash more thoroughly.

This indium and copper plating is repeated if necessary. In this example, indium 17 and copper 1
8. Indium 17 plating was repeated. Thus, Figure 3
(C) was obtained.

The resist 14 is peeled off with an organic solvent, thoroughly washed and dried.

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 17 was the indium-copper alloy layer 19. Thus, FIG. 3 (d) was obtained. The adhesion of the plating layers 18 and 19 to the ITO electrode 15 was practical.

The sheet resistance of the ITO electrode 15 was lowered by about one digit.

As usual, a polyimide film was formed on this substrate and rubbed with rayon fibers. Two such substrates were attached so that the ITO electrodes 15 face each other and the gap was 7.0 μm, and the gap was filled with the nematic liquid crystal composition for STN. The liquid crystal display device manufactured in this way is
There is almost no crosstalk and the contrast is about 30.
%Rose.

This manufacturing method can also be applied to a method of manufacturing one in which at least a part of an alloy layer of aluminum and indium is bonded to a substrate.

The present invention can also be applied to other liquid crystal display devices, or other display devices such as EL display devices.

[0050]

As is apparent from the above description,
INDUSTRIAL APPLICABILITY The present invention can provide a substrate for a display device that can substantially reduce the electric resistance of a transparent electrode and a method for manufacturing the same, and greatly contributes to the industry.

[Brief description of drawings]

FIG. 1 is a sectional process drawing for explaining one embodiment of a display device substrate of the present invention.

FIG. 2 is a sectional process drawing for explaining another embodiment of the display device substrate of the present invention.

FIG. 3 is a cross-sectional process diagram of a method for manufacturing a display device substrate of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 ITO electrode 3 processed into a stripe shape 3 Photoresist 4 Indium metal layer 5 Copper metal layer 6 Layer consisting of indium-copper alloy 7 Glass substrate 8 ITO electrode processed into a stripe shape 9 Photoresist 10 Indium metal Layer 11 Aluminum metal layer 12 Layer composed of indium-aluminum alloy 13 Glass substrate 14 Photoresist 15 ITO transparent electrode 16 Side etched part 17 Single or plural indium metal layers 18 Single or plural copper metal layers 19 Single or plural indium − Copper alloy layer

Claims (3)

[Claims] 1. An alloy layer made of indium and copper and a laminated conductor made of copper are formed in contact with a transparent electrode having a predetermined shape formed on a substrate, and at least a part of the alloy layer is formed on the substrate or A substrate for a display device, which is formed by combining with a transparent electrode. 2. An alloy layer made of indium and aluminum, which is in contact with a transparent electrode having a predetermined shape formed on a substrate,
A display device substrate, wherein a laminated conductor made of aluminum is formed, and at least a part of the alloy layer is bonded to the substrate or the transparent electrode. 3. A resist film patterned in a desired state is formed on a transparent electrode formed on a substrate, and the transparent electrode is finely processed by a corrosive solution of the transparent electrode until it is in a side-etched state. Then, the exposed portion of the transparent electrode is subjected to indium plating, and further, copper plating and indium plating are sequentially performed thereon in this order, washed and dried, and the resist film is removed, washed and dried. The method for manufacturing a substrate for a display device according to claim 1, further comprising heat-treating with a desired temperature profile to a desired maximum temperature.