JPH10144208A - Formation of electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture in a simplified process, and to prevent silver (Ag) from diffusing into a glass base in a burning process. SOLUTION: In a first process, a surface forming at least an electrode is polished in a glass base 1. In a second process, an electrode 31 is formed of conductive material containing Ag. The electrode is manufactured through the procedure including the first and second process. Furthermore, a transparent conductive film 4 composed mostly of indium oxide or tin oxide is configured between the glass base 1 and the electrode 31 formed of the conductive material containing Ag. By polishing the surface of the glass base 1 in the first process, colloid formation is restrained in the glass produced in burning of the material to prevent discoloration of the glass base 1 and to improve insulation between the electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to electrodes in a plasma display panel (PDP), a field emission display (FED), a liquid crystal display (LCD), a fluorescent display, a hybrid integrated circuit, and the like. The present invention relates to a method for forming an electrode on a glass substrate as a component.

[0002]

Conventionally, it has been studied to use inexpensive and highly productive Ag for the electrodes and wirings in the above-described display devices and integrated circuits. However, the use of Ag has its own problems, and in this regard, a typical display device such as PD
This will be described below using P as an example.

In general, a PDP has a structure in which a pair of electrodes arranged regularly on two opposing glass substrates are provided, and a gas mainly containing an inert gas such as Ne or Xe is sealed between them. . Then, a voltage is applied between these electrodes, and a discharge is generated in minute cells around the electrodes, so that each cell emits light and display is performed. In order to display information, regularly arranged cells are selectively discharged to emit light. In this PDP,
There are two types, a direct current type (DC type) in which the electrodes are exposed to the discharge space, and an alternating current type (AC type) in which the electrodes are covered with an insulating layer.
Further, both are classified into a refresh driving method and a memory driving method according to the difference in display function and driving method.

FIG. 1 shows a configuration example of an AC type PDP. This figure shows the front plate and the back plate separated from each other. As shown in the figure, two glass substrates 1 and 2 are arranged in parallel and opposed to each other, and both become the back plate. The cell barriers 3 provided on the glass substrate 2 in parallel to each other are held at regular intervals. On the back side of the glass substrate 1 serving as a front plate, a composite electrode 6 composed of a sustain electrode 4 which is a transparent electrode and a bus electrode 5 which is a metal electrode is formed in parallel with each other. Is formed, and a protective layer 8 (MgO layer) is further formed thereon.
Are formed. On the other hand, on the front side of the glass substrate 2 serving as the back plate, address electrodes 9 are formed between the cell barriers 3 so as to be orthogonal to the composite electrode 6 and parallel to each other. The phosphor 10 is provided so as to cover the cell bottom. The AC type PDP is of a surface discharge type, and has a structure in which an AC voltage is applied between composite electrodes on a front panel to discharge by an electric field leaking into a space. In this case, since the alternating current is applied, the direction of the electric field changes according to the frequency. Then, the phosphor 10 emits light by the ultraviolet light generated by the discharge, so that an observer can visually recognize the light transmitted through the front plate.

The composite electrode 6 on the front panel of the AC type PDP has a bus electrode 5 formed on the sustain electrode 4 in order to reduce the resistance since the sustain electrode 4 alone has a high resistance and cannot be used as an electrode. It is. The material of the sustain electrode 4 may be ITO, SnO ₂ , ZnO, or the like. However, ITO is usually used because of ease of film formation and patterning. On the other hand, the bus electrode 5 is formed of a metal material. When the bus electrode 5 is formed of a single metal thin film, a low resistivity material such as Cu or Al
The use of is considered. However, when Cu is used, adhesion to ITO, which is a base layer of the bus electrode 5, is poor, and
As a result of the subsequent baking process when the dielectric layer 7 is formed, there is a problem that the resistance value increases due to thermal oxidation of the material. Further, even when Al is used, there is a problem that the material is thermally oxidized and the surface is roughened (hillocks) due to the subsequent baking treatment. Therefore, the bus electrode 5 is not generally formed of a single metal thin film, but is generally formed of a combination of different metal materials such as Cr / Cu / Cr and Cr / Al / Cr. In this case, the lower Cr functions as an adhesion layer with the sustain electrode 4 serving as a base layer, and the upper Cr functions as an antioxidant layer for Cu and Al. Further, not only the AC-type PDP but also the DC-type PDP has the same laminated structure and material as those of the bus electrode for the same reason. However, adopting such a laminated structure does not cause the problem of a single metal layer, but requires three thin film forming techniques such as sputtering and vapor deposition and etching to form a bus electrode, and the process is complicated. Therefore, there is a problem that it takes time and lacks processing ability.

As means for solving such a problem, for example, as disclosed in Japanese Patent Application No. 8-11468,
A method of patterning a thick film printing paste into an electrode shape by a screen printing method or a photolithography method is effective. In consideration of the conductivity, heat resistance and cost required for the bus electrode, a conductor paste containing Ag is suitable as the thick film printing paste. However, when a conductor paste containing Ag is used, this conductor paste is
If baked at a temperature of not less than ° C., Ag diffuses into the glass through the sustain electrode, and the glass substrate exhibits a so-called amber color. Therefore, there is a problem that it cannot be used particularly for the front plate facing the observer. Further, even in the case of the back plate, there is a problem that the insulating property between the electrodes is reduced due to the presence of conductive Ag particles between the electrodes. It is described that the coloration of the glass substrate is caused by the fact that Sn existing on the surface of the glass substrate acts as a reducing agent and Ag colloid particles are formed in the glass substrate. The reaction formula in that case is as follows. 2Ag ⁺ + Sn ²⁺ → 2Ag + Sn ⁴⁺

Although the problem in the case of using the Ag electrode with the PDP as an example has been described above, the same problem occurs in other display devices and integrated circuits when Ag is used for the electrode and the wiring. It can happen.

The present invention has been made in view of the above-mentioned problems, and has as its object to be able to be manufactured in a simple process, and to diffuse Ag into a glass substrate in a firing process. It is an object of the present invention to provide a method for forming an electrode that does not need to be used.

[0009]

In order to achieve the above object, an electrode forming method according to the present invention comprises a first step of polishing at least a surface of a glass substrate on which an electrode is to be formed, and a step of using a conductive material containing Ag. And a second step of forming an electrode. Further, a transparent conductive film containing indium oxide or tin oxide as a main component is formed between the glass substrate and an electrode formed of a conductive material containing Ag.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be applied to a display device or an integrated circuit in which an electrode needs to be formed on a glass substrate such as a PDP, but here, an AC type PDP shown in FIG. Embodiments will be described by describing examples of the address electrodes on the face plate and the composite electrodes on the front plate.

(Embodiment 1) A soda lime glass formed by a float method was used for a glass substrate 2 serving as a back plate. In the float method, Sn is injected into glass as an impurity in order to form a glass flat plate on liquid Sn. Generally, the glass surface on the side in contact with Sn is called a bottom surface, and the surface on the opposite side is called a top surface. The bottom surface has a larger Sn content. First, as shown in FIG. 2A, the surface of a glass substrate 2 serving as a back plate was polished using a polishing machine G. The thickness of the polishing is desirably greater than the thickness of the top surface since Sn is injected at least on the order of several μm from the glass surface. Substantially, when the polishing is performed at 5 to 10 μm, Sn reaches a level at which almost no detection is possible.

Chemical polishing may be performed instead of physical polishing as described above. Incidentally, when a glass substrate was etched using an etching solution having the following composition, the etching rate of glass in this solution was about 0.5 μm /
Minutes. Therefore, to remove 5 to 10 μm by the chemical polishing method, the treatment may be performed for 10 to 20 minutes. Hydrogen peroxide 10 wt% 1 hydrogen ammonium difluoride 4 wt% Water 86 wt%

Next, a metal electrode is formed of a conductive material containing Ag on the substrate whose surface has been polished. For example, as shown in FIG.
1 (Ag printing paste, “D590” manufactured by ESL) was applied in a pattern to the shape of the address electrode 9. In the figure, reference numeral 22 denotes a screen plate, and 23 denotes a squeegee. Then 170 ° C
The conductor material 21 is dried at 580 ° C. for 30 minutes.
By baking for 0 minutes, a metal electrode 24 was formed as shown in FIG. In this embodiment, the line width of the metal electrode is 80.
μm.

The method for forming the metal electrode 24 need not be a screen printing method. For example, after a film of a conductive material (Ag printing paste, “D590” manufactured by ESL) is formed on the entire surface of the substrate after the surface polishing, a photoresist (“OFPR80” manufactured by Tokyo Ohka Kogyo Co., Ltd.) is formed on the conductive material film.
0 "), a metal layer 24 could be formed by a method of forming a mask layer having the shape of the address electrode 9 and etching unnecessary portions in 30 wt% HNO ₃ . Alternatively, a photoresist (“OFPR800” manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied to the entire surface of the substrate after the surface polishing, and UV exposure is performed in the shape of the address electrode 9 to remove the photoresist in the shape of the address electrode 9. After forming a concave portion in the photoresist film, a conductive material (Ag printing paste, “D590” manufactured by ESL) is filled in the concave portion.
After drying the conductor material for 0 minutes, the photoresist was stripped with a 1 wt% NaOH aqueous solution, and the conductor material was baked at 580 ° C. for 10 minutes, whereby the metal electrode 24 could be formed. Further, a) Ag powder,
The metal electrode 24 can be obtained by using a photosensitive Ag paste consisting of b) an acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in a side chain, c) a photoreactive compound, and d) a photopolymerization initiator. Could be formed. in this case,
A photosensitive Ag paste is applied to the entire surface of the substrate after the surface polishing, dried at 100 ° C. for 20 minutes, exposed to UV light, and then developed by spraying a 0.2 wt% NaCO ₃ aqueous solution to address. After patterning into the shape of the electrode 9, the paste was baked at 580 ° C. for 10 minutes to form the metal electrode 24.

When the metal electrode 24 is formed by any of the above methods, the reaction between Sn and Ag is suppressed because Sn does not exist on the glass surface, and the glass substrate does not discolor even after the baking treatment. Therefore, the insulation between the electrodes was also good, and the reliability of the electrode operation was improved.

After the address electrodes 9 are formed on the glass substrate 2 serving as the back plate as described above, an insulating paste ("Noritake Co., Ltd."
P-7948 ”) was laminated eight times and then fired at 580 ° C. for 10 minutes to form barrier ribs 3 having a width of 70 μm and a height of 140 μm. After the barrier ribs 3 are formed, R
The phosphor of each color of GB was filled to complete the back plate. When a panel lighting test was actually performed, the same driving voltage and panel luminance were obtained as compared with a conventional panel in which the glass substrate surface was not polished. However, there was no discoloration of the glass substrate due to the formation of Ag colloid. The insulation between them has improved.

Example 2 The same soda lime glass as that used for the back plate was used for the front plate. First, as in Example 1, as shown in FIG. 3A, the surface of the glass substrate 1 serving as the front plate was polished using a polishing machine. The removal of Sn present on the glass substrate by polishing is the same as in the first embodiment.

Subsequently, as shown in FIG. 3B, a sustain electrode 4 was formed of a transparent conductive film having a predetermined shape on the glass substrate 1 whose surface was polished. Specifically, after forming a film of ITO having a thickness of 0.15 μm as a transparent conductive film on a glass substrate by a sputtering method, and then forming an etching mask with a photoresist (“OFPR800” manufactured by Tokyo Ohka Kogyo Co., Ltd.) on the ITO film, , Water, hydrochloric acid, nitric acid 1: 1
The ITO film was etched in a solution mixed at a ratio of 0.08, the photoresist was peeled off, the substrate was washed with water, and dried to form the sustain electrode 4 having a line width of 188 μm.

As a material of the transparent conductive film, an SnO ₂ (tinnesa) film or the like can be used in addition to ITO. SnO
_{2 When a} (tinnesa) film is used, first, a mask layer is formed on the glass
A film was formed by the VD method, and subsequently, the mask layer was peeled off to perform patterning. The thickness of the transparent conductive film is I
Both the TO and SnO ₂ (tinnesa) films are 0.05-0.
It is about 4 μm.

Since the transparent electrode alone has a high resistance and cannot be used as an electrode, as shown in FIG. 3C, a metal electrode 31 serving as a bus electrode is formed on the transparent electrode to reduce the resistance.
Was formed to form the composite electrode 6. The metal electrode 31 is formed of a conductive material containing Ag.
Both screen printing and other methods were possible. The line width of the metal electrode 31 was 64 μm.

In this embodiment, after the patterning of the sustain electrode 4 as the first layer is completed, the metal electrode 3 as the second layer is formed.
Although No. 1 was formed, it was also possible to pattern the sustain electrode 4 as the first layer after forming the second layer. That is, in this case, after a transparent conductive film is formed on one surface of the glass substrate 1, a second layer is formed by the same method as described above, and a photoresist (“OFPR80” manufactured by Tokyo Ohka Kogyo Co., Ltd.) is formed.
0 ”), after forming an etching mask layer in the shape of the sustain electrode 4, unnecessary portions of the transparent conductive film were etched. Also in this example, a composite electrode 6 having the same configuration as that of the above-described example could be formed.

After the composite electrode 6 is formed on the glass substrate 1 serving as the front plate as described above, a dielectric paste ("PLS-3232" manufactured by NEC Corporation) is formed by a screen printing method.
And baked at 560 ° C. for 10 minutes to form a dielectric layer 6. Ag diffusion into the glass substrate was also suppressed by this baking treatment. Next, MgO is formed on the dielectric layer 6 by a vacuum evaporation method.
Layers were formed to complete the front panel. Further, the panel was completed by gas sealing together with a back plate formed by a conventional method. When a panel lighting test was actually performed, similar driving voltage and panel luminance were obtained as compared with a conventional panel in which bus electrodes were composed of Cr / Cu / Cr.
Further, as compared with the case where a metal electrode was formed of a conductive material containing Ag on a glass substrate which was not surface-polished, there was no discoloration of the glass substrate and the image display was good.

In the above description, electrodes of a surface discharge type AC PDP are taken as an example.
Even when various PDP electrodes such as DP are formed,
Furthermore, the same effects as in the present embodiment can be obtained even when electrodes and wirings in other display devices and integrated circuits are formed.

[0024]

As described above, according to the present invention, when an electrode is formed on a glass substrate, a conductive material containing Ag, which is a material which is inexpensive and excellent in productivity, is used. By polishing the glass substrate surface in the process,
It is possible to suppress the formation of Ag colloid in the glass which is generated when the present material is fired, to eliminate the discoloration of the glass substrate, and to improve the insulation between the electrodes.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing an example of a configuration of an AC type plasma display panel in a state where a front plate and a back plate are separated from each other.

FIG. 2 is a process diagram illustrating an example of a method for forming an electrode according to the present invention.

FIG. 3 is a process chart for explaining another example of the method for forming an electrode according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front plate 2 Back plate 3 Barrier rib 4 Sustain electrode 5 Bus electrode 6 Composite electrode 7 Dielectric layer 8 Protective layer (MgO layer) 9 Address electrode 10 Fluorescent layer 21 Conductor material 22 Screen plate 23 Squeegee 24 Metal electrode 31 Metal electrode

Claims (2)

[Claims] 1. A method for forming an electrode, comprising: a first step of polishing at least a surface of a glass substrate on which an electrode is to be formed; and a second step of forming an electrode using a conductive material containing Ag. 2. A first step of polishing at least a surface of a glass substrate on which an electrode is to be formed, a second step of forming a transparent conductive film containing indium oxide or tin oxide as a main component, and containing Ag. Forming an electrode from a conductive material.