JP2000011884A - Gas discharge type display device and wiring board used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-reliability gas discharge type display device by realizing an electrode structure that can prevent the increase in wiring resistance and a fatal disconnection failure due to oxidation or reaction and can remarkably improve the connection reliability of an external terminal part. SOLUTION: In this display device, a conductor pattern constituting a bus electrode 4 is formed directly on a glass substrate 2 in advance, thereafter, a display electrode 3 formed from a transparent ITO(indium-tin oxide) conductive film is so formed to cover the entire conductor pattern, and additionally, a lower layer conductor pattern of the conductor pattern having a three-layer structure covered with the display electrode is formed wider than the width of the patterns over it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas discharge type display device such as a plasma display panel and a wiring substrate used for the same, and more particularly to an electrode structure formed on a front substrate in the gas discharge type display device.

[0002]

2. Description of the Related Art A gas discharge type display device such as a plasma display performs display by self-emission, so that the display is wide and the display is easy to see. In addition, it has features such as being able to manufacture a thin type and realizing a large screen, and has begun to be applied to a display device of an information terminal device and a high-definition TV receiver. Plasma displays are broadly classified into DC-driven and AC-driven types. In the case of AC-driven types, the brightness is high due to the memory effect of the dielectric layer covering the electrodes, and the reliability is enhanced by forming a protective layer. Has been obtained, and has been applied as a display monitor.

FIG. 4 is a sectional structural view showing an assembly structure of a general display panel device in the prior art. Here, the back plate 1 is shown rotated 90 degrees for easy viewing of the drawing.

The front plate (front substrate) 21 is a glass substrate 2
On top of this, ITO (Indium Tin Oxide) or tin oxide (SnO)
₂ ) a display electrode 3 made of a transparent conductive material such as, a bus electrode 4 made of a low-resistance material, a dielectric layer 5 made of a transparent material, and a protective layer 6 made of magnesium oxide (MgO) on the surface. It has a structure. Similarly, the back plate (back substrate) 22 is formed on the glass substrate 1 by the address electrodes 7, the protective layer 8, the barrier ribs (partitions) 9 for forming discharge spaces and cells, and further emitting light in the discharge space region. It has a configuration in which a phosphor layer 10 serving as a medium is formed. The space 11 formed between the front plate 21 and the back plate 22 and separated by the barrier ribs 9 constitutes a discharge cell.

In this display panel device, an AC voltage is applied between a pair of display electrodes 3 provided on a front plate 21 and a voltage is applied between the address electrodes 7 provided on the back plate 22 and the display electrodes 3. By doing so, a main discharge is generated in an arbitrary discharge cell. Then, the fluorescent layer 10 emits light by the ultraviolet light generated by the main discharge, and display is performed.

A conventional example of such a gas discharge type display device is described in, for example, “PDP Challenges Wall-Mounted Television” (3rd Nikkei Microdevice PDP Seminar 1996.
1: Also described in "Latest trends in process technology realizing 40 types or more and expectations for equipment and members" P1 to P7).

Here, the structure of the bus electrode 4 formed on the front plate 21 will be described in more detail. FIG. 3 shows an example of a bus electrode 4 having a thin film structure according to the prior art.

As the configuration of the electrode, a material having a low resistance is applied to reduce the wiring resistance from the original purpose, and silver (A) is formed by screen printing in the thick film method.
g) is common, but in a thin film system such as sputtering film formation, a structure employing copper (Cu) or aluminum (Al) is generally used.

For a thick film method by screen printing,
A thin film method capable of forming a fine pattern by a photolithography process is advantageous for achieving high definition, and as an electrode structure, for example, for the purpose of suppressing an increase in wiring resistance due to a high-temperature heat treatment in a later process, Cr / Cu / Cr and Cr / Al
Various laminated structures of three layers sandwiching Cu and Al as main conductors, such as / Cr, have been studied. As a conductor material, Cr / Al using Al which causes a problem in selective etching with an ITO film is used. Cr / Cu /
In many cases, a three-layer structure of Cr is employed.

In the structure shown in FIG. 3, a transparent conductive film ITO constituting the display electrode 3 is formed on the glass substrate 2 of the front plate 21.
Then, a three-layer structure of Cr (41) / Cu (42) / Cr (43) constituting the bus electrode 4 is formed by sputtering, and a desired electrode resist pattern is formed by a photolithography process. After that, it is processed by wet etching. At this time, it is possible to etch three consecutive layers with one resist pattern, or to process each layer in a plurality of photolithography steps. Further,
Similarly, after a resist pattern of the display electrode 3 is formed by a photolithography process, it is processed by wet etching. In this formation process, after a transparent conductive film ITO forming the display electrode 3 is formed by sputtering, the pattern of the display electrode 3 is subjected to photolithography / etching processing first, and then Cr (41) / Cu (42) / Cr (4
The pattern formation may be performed by sputtering the three-layer structure of 3).

The prior art related to the present invention is disclosed in JP-A-7-73809 and JP-A-9-199.
No. 038 and the like.

[0012]

In the case of the electrodes formed on the front panel 21 of the display panel device having the above-described structure, a thick dielectric layer made of a low melting glass formed thereon in a later step. In the firing process in an oxidizing atmosphere a plurality of times, such as 5, the connection failure due to an increase in the contact resistance due to the oxidation of the surface of the electrode layer in a region provided on the external terminal, and further, the dielectric and copper (Cu) There has been such a problem that the wiring resistance may increase due to the reaction, or a fatal defect such as a disconnection failure of the wiring due to the progress of the reaction may be caused in a long term.

[0013] The present invention has been made in view of the above problems, and an object of the present invention is to provide a stable electrode that does not impair the reliability of the electrode wiring during the manufacturing process. To provide a gas discharge type display device having the same.

[0014]

In order to achieve the above object, a gas discharge type display device according to the present invention has an entire electrode pattern (at least at least as a bus electrode) formed on a glass surface on a discharge space side of a front substrate. A transparent conductive film made of an oxide constituting the display electrode is formed so as to cover the entire bus electrode pattern as a display element). Furthermore, the bus electrode formed on the discharge space side of the front substrate,
It has a three-layer laminated structure of a first layer of Cr, a second layer of Cu, and a third layer of Cr, which are sequentially laminated from the glass surface, and further has a transparent conductive layer covering the entire electrode pattern of the three-layer laminated structure. The film is formed of an ITO film. Further, a bus electrode formed on the discharge space side of the front substrate is provided with a first Cr layer, a second Cr layer,
It has a three-layer laminated structure of a Cu layer as a layer and a Cr layer as a third layer, and the pattern shape of the first Cr layer has a shape wider than the pattern shape of the second and third layers. The transparent conductive film that covers the entire electrode pattern of the three-layer structure is formed of an ITO film patterned into a desired shape.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a detailed structure of a display electrode 3 and a bus electrode 4 formed on a front plate 21 in a gas discharge display device (plasma display panel) according to one embodiment of the present invention. Also,
FIG. 2 is a process flow chart showing a manufacturing process of the display electrode 3 and the bus electrode 4 formed on the front plate 21 in the gas discharge display device according to one embodiment of the present invention.

Hereinafter, a procedure for manufacturing an electrode formed on the front plate 21 will be described. First, Cr (41) / Cu for forming the bus electrode 4 is formed on the glass substrate 2 as a base material of the front plate 21 by sputtering or vapor deposition.
A laminated film of (42) / Cr (43) (three-layer laminated film) is formed. At this time, each film thickness is the lower Cr film of the first layer (4
1) is formed at 1500 °, the Cu film (42) constituting the second main conductor layer is formed at 2.0 μm, and the upper Cr film (43) of the third layer is formed at 300 ° (process step: (a)).

In this state, first, a resist pattern 12 having a desired shape corresponding to the shape of the upper layer of the bus electrode 4 is formed. At this time, examples of the type of the resist include a liquid type resist used in a general substrate process and a dry film resist which is said to be superior in handling a large-area substrate, but are resistant to various etching solutions used in a later process. If stable processing is possible,
Any resist may be used. In the case of the present embodiment, a dry film resist which is capable of forming a uniform film over a large area and which is considered to be advantageous for cost reduction is applied. The working procedure is such that a target film resist is uniformly applied to a substrate preheated to 60 to 80 ° C. by lamination, and the resist 12 is patterned through exposure and development steps (process step: (b)).

Subsequently, the upper Cr film (43) was coated with aluminum chloride [AlCl ₃ .6H ₂ O] (250 g / l): phosphoric acid [H ₃ PO ₄ ] (200 ml / l) (liquid temperature = 40 ° C.). And the Cu film (42) of the conductor layer
The sample was subjected to etching treatment using a ferrite sulfate-based (liquid temperature = 40 ° C.) etchant and a shower oscillating method, using a “C1505 solution manufactured by Asahi Denka Co., Ltd.” main component. At this time, Cu
At the end of the etching of the film (42), overhang of the upper Cr film (43) occurs due to side etching. This phenomenon is caused by the resist or ITO
In order to deteriorate the coverage (coverability) of the transparent conductive film or the like, after the Cu etching, the Cr film (43) forming an overhang of the upper layer was additionally etched using the etchant. In this state, the lower Cr film (4
Since 1) is also eroded at the same time, a short-time treatment is desirable. In this embodiment, the lower Cr film (4
In 1), the initial film thickness was reduced by about 500 ° from 1500 ° and formed to about 1000 °. Then, the resist pattern 12 is peeled off, and the upper Cr film (43) and the conductor layer C are removed.
The patterning of the u film (42) is completed (process step: (c)).

Subsequently, a resist 13 having a desired shape for patterning the lower Cr film (41) is formed in a similar procedure. The pattern dimension at this time is formed to be a pattern wider than the dimensions of the upper Cr film (43) and the Cu film (42) of the conductor layer. The purpose of this is to improve the coverage of the ITO transparent conductive film formed as the display electrode 3 on the bus electrode 4 in a later step.
This is because, when the film (41) is also continuously etched in the same manner as in the prior art, the side-etching of the Cr film (41) underlying the film deteriorates the coverage of the ITO transparent conductive film. Further, it is for ensuring a sufficient contact area between the ITO film and the Cr film (lower layer) and stabilizing the characteristics as a display electrode. This dimension may be about 10 to 15 μm wider than the pattern of the upper Cr film (43) and the conductor layer Cu film (42). Then, using the same etchant, the lower Cr film (41) is etched, and then the resist pattern 13 is peeled off.
The bus electrode 4 is completed (process steps: (d) and (e)).

Subsequently, a transparent conductive film constituting the display electrode 3, that is, an ITO (Indium Tin Oxide) film is formed by sputtering to a thickness of about 1500 to 2000 ° (process step: (f)). Then, after a desired resist pattern 14 is formed by the same photolithography process, a shower oscillating operation is similarly performed using a ferric chloride + hydrochloric acid system (liquid temperature = 35 ° C.) as an etchant “LCD Beak” manufactured by Asahi Denka Co. And etching was performed. afterwards,
The resist pattern 14 was peeled off to form the display electrode 3 (process steps: (g) and (h)).

By the above procedure, the bus electrodes 4 and the display electrodes 3 are formed on the front plate 21. Subsequently, although not shown, the dielectric layer 5 made of low-melting glass is formed by thick-film screen printing. A protective layer 6 of magnesium oxide (MgO) is formed thereon under electron beam evaporation under desired conditions to complete a front panel (front panel 21) (the dielectric layer 5 and the protective layer 6 are shown in FIG. 4 is the same as the conventional configuration shown in FIG. 4). Then, it is combined with the back plate 22 having the same configuration as that shown in FIG. 4 to produce a plasma display panel.

According to the bus electrode 4 and the display electrode 3 having the above-described structures, in the bus electrode 4 having the three-layer structure, the pattern width of the lower Cr film (41) is set to the main conductor pattern (the upper Cr film (43)). ) And a Cu film (4
By making the pattern width wider than 2)), the coverage of the ITO film (display electrode 3) and the contact state in external connection are remarkably improved, and the dielectric film formed in an oxidizing atmosphere at about 600 ° C. During the firing process of the body layer and the high-temperature firing process similarly performed in the process of assembling and sealing with the back plate 22, the connection with the connection member due to the oxidation of the conductor layer of the external lead-out terminal area (not shown) which has occurred conventionally. Failure, and increase in wiring resistance due to the reaction between the thick dielectric glass and the main conductor layer Cu film.
Fatal defects are significantly reduced, and a highly reliable plasma display panel (gas discharge display device) can be manufactured.

The display electrode 3 covering the bus electrode 4 may be formed so as to remove the external connection terminal portion of the bus electrode 4. That is, the bus electrode 4 as a display element
The display electrode 3 may be formed so as to cover only the entire electrode pattern.

In the above, the stable structure of the bus electrodes and the display electrodes formed on the front panel of the plasma display panel has been described. However, this configuration has the same effect on the stabilization of the address electrodes provided on the rear panel. Needless to say, it can be applied based on the wiring rules.

[0025]

As described above, according to the present invention, an increase in wiring resistance due to oxidation or reaction, a fatal disconnection failure, and the like are suppressed, and the connection reliability of the terminal portion is significantly improved.
A highly reliable gas discharge display device such as a plasma display panel can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of a bus electrode and a display electrode formed on a front plate in a gas discharge display device according to an embodiment of the present invention.

FIG. 2 is a process flow chart showing a process of manufacturing a bus electrode and a display electrode formed on a front plate in the gas discharge display device according to one embodiment of the present invention.

FIG. 3 shows a conventional gas discharge type display device.
FIG. 3 is a cross-sectional view illustrating a structure of a display electrode and a bus electrode formed on a front plate.

FIG. 4 is a cross-sectional view illustrating a structure of a conventional gas discharge display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Glass substrate 3 Display electrode 4 Bus electrode 5 Dielectric layer 6 Protective layer 7 Address electrode 8 Electrode protective layer 9 Barrier rib (partition) 10 Phosphor layer 11 Discharge space area 12 Resist 13 Resist 14 Resist 21 Front plate (front surface) Substrate) 22 Back plate (Back substrate)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Fukushima 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Hitachi, Ltd. Production Technology Research Laboratory (72) Kazuo Suzuki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd., Production Technology Laboratory (72) Inventor Shigeaki Suzuki 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture, Ltd.Information Media Business Unit, Hitachi, Ltd. (72) Inventor Naoto Yanagihara Yoshida, Totsuka-ku, Yokohama-shi, Kanagawa No. 292, Hitachi, Ltd. Information Media Business Division of Hitachi, Ltd. (72) Inventor Kazuhiro Mochida 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Information Media Business Division of Hitachi, Ltd. 5C040 DD01 DD02

Claims (5)

[Claims] 1. A gas discharge type display in which a plurality of discharge cells are formed as display elements by a front substrate having a plurality of electrodes, a back substrate having a plurality of electrodes, and barrier ribs provided therebetween. In the device, a transparent conductive film made of an oxide constituting a display electrode is formed on a glass surface on a discharge space side of the front substrate, and so as to cover at least an entire electrode pattern constituting the display element. A gas discharge type display device. 2. The first layer of Cr and the second layer of the electrode formed on the discharge space side of the front substrate covered with the transparent conductive film, the first layer being sequentially stacked from a glass surface. A three-layer structure of a Cu layer and a third Cr layer, and the transparent conductive film covering the entire electrode pattern of the three-layer structure is made of an ITO film. apparatus. 3. The electrode according to claim 1, wherein the electrodes formed on the discharge space side of the front substrate covered with the transparent conductive film are a first Cr layer and a second layer sequentially stacked from a glass surface. Has a three-layer laminated structure of a Cu layer and a third Cr layer, and the pattern shape of the first Cr layer has a shape wider than the pattern shape of the second and third layers. The gas discharge type display device, wherein the transparent conductive film covering the entire three-layer laminated electrode pattern is an ITO film patterned into a desired shape. 4. A gas discharge type display in which a plurality of discharge cells as display elements are formed by a front substrate having a plurality of electrodes, a back substrate having a plurality of electrodes, and barrier ribs provided therebetween. A wiring board for the front substrate used in an apparatus, wherein the wiring board is formed on a glass surface on a discharge space side of the wiring board for the front substrate, and covers at least an entire electrode pattern constituting the display element. A transparent conductive film made of an oxide constituting a display electrode. 5. The electrode according to claim 4, wherein the electrodes formed on the discharge space side of the front substrate covered by the transparent conductive film are a first layer of Cr and a second layer sequentially stacked from a glass surface. Has a three-layer laminated structure of a Cu layer and a third Cr layer, and the pattern shape of the first Cr layer has a shape wider than the pattern shape of the second and third layers. The wiring substrate, wherein the transparent conductive film covering the entire three-layer laminated electrode pattern is an ITO film patterned into a desired shape.