JPH05250994A - Discharge cathode device and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a discharge cathode device by which a discharge cathode pattern containing an LaB6 layer can be formed easily and the discharge characteristics can be also uniformed. CONSTITUTION:An Al layer 5 is used' as a backing electrode of an LaB6 layer 6, and when a multilayer thin film cathode pattern 12 of Al/LaB6 is formed, the Al layer 5 and the LaB6 layer 6 are etched integrally in a line shape. Though the multilayer thin film cathode pattern 12 can be taken outside electrically through a thin film connecting electrode 13, when the multilayer thin film cathode pattern 12 is formed on a thick film dielectric glass substrate 4, a baking temperature of the connecting electrode 13 is set at a temperature below by more than 50 deg.C from a softening point of the thick film dielectric glass substrate 4. When a cathode side panel substrate 1 where the multilayer thin film cathode pattern 12 and the connecting electrode 13 are formed is sealed on an anode side panel substrate, after they are sealed, a sealing member composed of low melting point glass is formed in such a structure as the multilayer thin film cathode pattern 12 is not passed penetratingly through itself.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge cathode device used for a plasma display panel and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a hexaboride, such as lanthanum hexaboride (LaB ₆ ), which is excellent in electron emission characteristics and resistance to ion bombardment, has been known as a discharge cathode material of this type of discharge cathode device.
For example, in JP-A-55-62647, hexaboride (for example, LaB ₆ ) is used as a cathode of a gas discharge display panel, and a LaB ₆ film is formed on a base electrode such as nickel (Ni),
It is described that driving this significantly reduces the operating voltage. Further, as a conventional method for forming a LaB ₆ film, a thick film printing method and a thin film method are also described in JP-A-55-62647, and JP-A-61-253736 or JP-A-03-
Japanese Patent No. 101033 describes an electron beam impact vapor deposition method or a sputtering method.

[0003]

For example, the cathode of a plasma display panel is required to have a sheet resistance value of 0.1 Ω or less. When the cathode is formed of a LaB ₆ thin film alone, its thickness is several tens of μm. Therefore, it is not practical. Conventionally, a Ni plate has been used as a base electrode of a LaB ₆ film as disclosed in Japanese Patent Laid-Open No. 55-62647. However, in a discharge cathode device such as a plasma display panel, the material of the base electrode of the LaB ₆ film has flexibility, that is, low rigidity, good conductivity, and good adhesion to the LaB ₆ film. It is required to be excellent and to be free from deterioration such as oxidation due to post-treatment in the air (560 ° C to 580 ° C). Conventionally, there are a thick film type and a thin film type in which a Ni material is used as a base electrode. If thin film Ni is to be adopted, it is difficult to say that the Ni material has poor flexibility and conductivity, and also has good thermal oxidation resistance in these respects. Therefore, in order to use the Ni material as the base electrode formed on the substrate, it is necessary to increase the film thickness in order to ensure conductivity. At this time, Ni
The rigidity of the film is increased, and the substrate may be cracked by a heat treatment performed in a later process. Further, the thick film Ni as the base electrode has almost good adhesion with LaB ₆ , but since the surface of the thick film Ni pattern is rough, even if the LaB ₆ film is formed thereon, the desired discharge starting voltage is There is also a problem that it cannot be obtained uniformly for each cell. Further, in the case of using the thin film Ni as the base electrode to form the structure as described in JP-A-55-62647, a thin film Ni pattern as the base electrode,
LaB ₆ film pattern and the need to separately form, it is not easy to align accurately a two layer pattern of the Ni pattern and LaB ₆ film pattern. Therefore, the present invention has been made in order to eliminate such inconvenience, and an object thereof is to provide a novel discharge cathode device in which a discharge cathode is composed of an electrode material excellent in flexibility, conductivity, and thermal oxidation resistance. And
Another object of the present invention is to provide a novel method of manufacturing a discharge cathode device which is made of hexaboride or the like and has a uniform discharge characteristic.

[0004]

According to a first aspect of the present invention, there is provided a discharge cathode device having a discharge cathode made of at least aluminum and hexaboride on a substrate. According to a second aspect of the present invention, there is provided a method of manufacturing a discharge cathode device, wherein an aluminum film is formed on a substrate, a lanthanum hexaboride film is formed adjacent to the aluminum film, and the aluminum film is formed by a predetermined etching solution. The film and the lanthanum hexaboride film are collectively etched to form a desired discharge cathode pattern. According to a third aspect of the present invention, there is provided a method of manufacturing a discharge cathode device, wherein a multi-layer cathode pattern made of at least aluminum and lanthanum hexaboride is formed on a dielectric glass, and an attachment electrode connected to the multi-layer cathode pattern is formed as described above. It is provided on a dielectric glass plate, and the attachment electrode is fired at a temperature lower than the softening point of the dielectric glass. According to a fourth aspect of the present invention, there is provided a discharge cathode device having a discharge cathode made of at least chromium, aluminum and hexaboride on a substrate. According to a fifth aspect of the present invention, there is provided a discharge cathode device manufacturing method, wherein a chromium film, an aluminum film and a lanthanum hexaboride film are provided on a substrate to form a multilayer thin film cathode pattern, and then the multilayer cathode pattern is fired. It is a thing. According to a sixth aspect of the invention, there is provided a discharge cathode device in which the pattern cross section of the discharge cathode according to the fifth aspect is formed in a trapezoid. According to a seventh aspect of the present invention, there is provided a discharge cathode device manufacturing method, wherein a chromium film is formed on a substrate, and an aluminum film is formed adjacent to the chromium film.
Thereafter, a lanthanum hexaboride film was formed adjacent to the aluminum film. In the discharge cathode device according to the invention of claim 8, an insulating thin film is provided on a substrate, and a multilayer cathode pattern made of at least aluminum and hexaboride is provided on the insulating thin film. According to a ninth aspect of the present invention, there is provided a discharge cathode device in which a multilayer cathode pattern made of at least aluminum and hexaboride is provided on a substrate.
Insulators are arranged between adjacent multilayer cathodes in this multilayer cathode pattern. The discharge cathode device according to the invention of claim 10, a multilayer cathode pattern comprising at least aluminum and lanthanum hexaboride is provided on the cathode side panel substrate, and the mounting electrode is connected to the end of the multilayer cathode pattern, A cathode terminal electrode connected to the mounting electrode is provided on the cathode side panel substrate, and an anode side panel substrate on which an anode pattern is formed is arranged to face the cathode side panel substrate, and the mounting electrode or the cathode terminal electrode is provided. In contact with the cathode side panel substrate and the anode side panel substrate by a sealing layer.

[0005]

The aluminum according to the first aspect of the present invention has a strong adhesion to hexaboride, and also has good flexibility, conductivity, and thermal oxidation resistance. Since the predetermined etching solution according to the second aspect of the present invention collectively etches the lanthanum hexaboride film and the aluminum film, it is necessary to separately etch the lanthanum hexaboride film and the aluminum film with separate etching solutions. Disappears. According to the third aspect of the present invention, a mounting electrode connected to a multilayer cathode pattern composed of at least an aluminum film and a lanthanum hexaboride film is provided on the dielectric glass, and the mounting electrode is located above the softening point of the dielectric glass. Since firing is performed at a low temperature, it is difficult for the surface portion of the dielectric glass plate and the multilayer cathode pattern to be uneven. The chromium according to the invention of claim 4 extends the discharge life by transforming aluminum in a bulk manner and exhibiting spatter resistance. According to the invention of claim 5, after forming a multi-layer cathode pattern comprising at least a chromium film, an aluminum film and a lanthanum hexaboride film, by baking this, chromium is diffused into the aluminum film and the resistance of the aluminum film is improved. Sputterability can be secured. Since the discharge cathode according to the sixth aspect of the present invention has a trapezoidal cross section, concentrated discharge is unlikely to occur during discharge light emission, and the light emitting cell shape can be made uniform. In the method for manufacturing a discharge cathode device according to the seventh aspect of the invention, since the aluminum film is formed adjacent to the chromium film, the cross section of the discharge cathode pattern can be finished into a trapezoidal shape through the pattern forming process. The insulating thin film according to the invention of claim 8 protects the dielectric glass substrate from corrosion by the chromium etching solution. The insulator according to the invention of claim 9 can effectively prevent a short circuit that may occur between the multilayer cathodes adjacent to each other. Since the sealing member according to the invention of claim 10 seals the cathode side panel substrate and the anode side panel substrate by connecting to the mounting electrode or the cathode terminal electrode, the airtightness inside both panel substrates is not impaired. Also, abnormal distortion of the multi-layer cathode pattern does not occur.

[0006]

【Example】

Example 1. An embodiment of the present invention will be described in detail below with reference to the drawings. 1-a, b, and c are a plan view and a cross-sectional view of the plasma display panel, and FIG.
It is an enlarged view of the A portion of FIG. In FIGS. 1-a, b, and c, 1 is a cathode-side panel substrate using soda glass as a base material, and 2 is a cathode-side panel substrate 1 as shown in FIG. 1-b.
Using the conductive paste such as Ag as the raw material, the thick film method is used.
3 and 4 is a trigger electrode, 3 is a terminal electrode formed of a conductive paste such as Ag by a thick film method similarly to the trigger electrode 2, and 4 is a thick film made of a dielectric glass paste as a raw material on the trigger electrode 2. It is a dielectric glass substrate with a film thickness of about 40 μm. If the average surface roughness of the dielectric glass substrate 4 is suppressed to a level of 1 to 2 μm or less, it is possible to reduce the discharge variation (shape, discharge starting voltage, etc.) of each light emitting cell that follows. Reference numeral 5 is a thin aluminum layer formed on the dielectric glass substrate 4 at a substrate temperature of 200 ° C. by a sputtering method, a vacuum deposition method or an ion plating method so as to have a thickness of about 2 μm. The aluminum layer 5 is preferably 0.5 μmt or more from the viewpoint of ensuring conductivity. Reference numeral _{6 is} a thin LaB ₆ layer formed on the aluminum layer 5 by a sputtering method or the like to a thickness of about 0.2 μm. This LaB ₆ layer 6 has a film thickness of 0.1 to cover the underlying aluminum layer 5.
μm or more is desirable. In this way, the multilayer thin film cathode pattern 12 is formed by the aluminum layer 5 and the LaB ₆ layer 6. The multi-layer thin film cathode pattern 12 constitutes a discharge cathode. However, generally in the case of forming by the thin film method a film of LaB ₆ layer 6 by sputtering or the like, LaB ₆
Since the layer 6 has a large internal stress, it is difficult to maintain the form of a thin film and easily scatters into powder. However, since the aluminum layer 5 is provided as the underlayer in the above-mentioned embodiment, the flexibility of aluminum causes the aluminum layer 5 to absorb a considerable amount of the above-mentioned internal stress, so that the film thickness of the LaB ₆ layer 6 becomes a sub-μm level. Can be formed. Further, 8 is an anode side panel substrate using soda glass as a base material, 9 is an anode pattern formed on the anode side panel substrate 8 in a plurality of lines, and 10 is shown in FIG.
As shown in -b, barrier ribs provided between the anode lines of the anode pattern 9 and 11 are sealing members made of low melting point glass for bonding the cathode side panel substrate 1 and the anode side panel substrate 8 at the outer peripheral portion. is there. Ne inside the sealing member 11
-A discharge gas such as Ar is hermetically sealed to form a plasma display. Here, in the above-mentioned embodiment, the aluminum layer 5 was used as the base of the LaB ₆ layer 6, but in place of this aluminum layer 5, in addition to conventional Ni, Ag and Au materials are conceivable. Appropriate comparison of the conventional Ni, Al and Ag, Au materials of the above-mentioned examples as the base electrode of LaB ₆ layer 6 is shown in Table 1.
Shown in.

[0007]

[Table 1]

From Table 1, Al has good flexibility, conductivity, LaB ₆ adhesion and thermal oxidation resistance, and LaB ₆ adhesion is particularly best. Even if the aluminum film 5 in the above embodiment is formed by a thin film method such as sputtering, LaB ₆
The adhesion was excellent. In contrast, Ni is the LaB ₆ adhesion
It is similar to Al, but not so good in terms of flexibility and conductivity. Must be thick film. However, the thick film cannot utilize the discharge characteristics of LaB ₆ . Also, although the conductivity is the best for Ag, the adhesion of LaB ₆ is not so good in the thin film Ag, and the flexibility and the conductivity of Au, which cannot be maintained as the film and are separated in powder form, are It has good LaB ₆ adhesion, which is not so high as that of Al, but has a certain degree of goodness and good thermal oxidation resistance, and thus can be used as a base electrode for the LaB ₆ layer 6. However, it is more problematic than Al in terms of Kotos. In the above embodiments than this, Al is considered to be optimal as a base electrode of the LaB ₆ layer 6 from the viewpoint of bulk patterning of the cost and LaB ₆ layer 6. Further, in the above embodiment, the case where the LaB ₆ layer 6 is provided on the Al layer 5 has been described. However, other hexaborides other than the LaB ₆ layer 6 on the Al layer 5, such as CeB ₆ and PrB _{6 are used.} ，
Hexaborides of the same lanthanoid element as YB ₆ such as NdB ₆ , SmB ₆ , EuB _{6 and} LaB ₆ may be formed.

Example 2. Next, FIGS. 3-a, b, c, and d are process drawings showing the manufacturing process of the plasma display panel. In FIG. 3A, the trigger electrode 2 and the terminal electrode 3 are formed on the cathode side panel substrate 1 using a conductive paste such as Ag as a raw material by a thick film method, and then the dielectric glass substrate 4 is thickened on the trigger electrode 2. The film is formed to have a film thickness of about 40 μm. In FIG. 3B, the Al layer 5 and the LaB ₆ layer 6 are formed on the dielectric glass substrate 4.
To form a multi-layered thin film layer 7. In the above film formation, if a mask is applied so that the exposed portion of the trigger electrode 2 and the region of the terminal electrode 3 are not covered, the entire portions of the trigger electrode 2 and the terminal electrode 3 are protected by a resist in a later patterning process. By doing so, it is possible to protect from erosion by an etching solution or the like. In FIG. 3C, a photoresist film is applied on the entire surface of the multilayer thin film layer 7, the photoresist film is exposed through a predetermined mask pattern, and then a predetermined photoresist pattern is formed by a developing process. After that, the LaB ₆ layer 6 and the Al layer 5 are collectively etched with an etching solution composed of a mixed solution of phosphoric acid, acetic acid and nitric acid. That is, first, the LaB ₆ layer 6 is etched to expose the surface of the Al layer 5, and then the etching of the Al layer 5 is started. Finally, the multilayer thin film cathode pattern 12 of the multilayer thin film layer 7 corresponding to the resist pattern is formed. Then, the resist pattern is peeled off to obtain the state of FIG.
In FIG. 3D, in order to connect the multilayer thin film cathode pattern 12 to the terminal electrode 3, the connection electrode 13 is formed by a thick film method using a conductive paste of Ag as a raw material. The cathode-side panel substrate is completed through the above steps.

However, if the connecting electrode 13 is fired at a temperature near the softening point of the dielectric glass substrate 4, the surface of the fired multi-layered thin film pattern 12 and the connecting electrode 13 is raised to a level difference of 20 μm. Discharge variations in each cell may occur significantly. FIG. 4-a is a cross-sectional view of the multilayer thin film cathode pattern 12 etc. before firing of the connecting electrode 13, FIG.
FIG. 4 is a cross-sectional view of the multilayer thin film cathode pattern 12 and the like showing an undulated state after the firing. The mechanism of undulation as shown in FIG. 4-b will be described below. During the temperature rising process of firing the connection electrode 13, the softening point of the thick film dielectric glass substrate 4 (for example, 58
In the temperature range lower than 50 ° C by more than 5 ° C, the state of Fig. 4-a is maintained. This is because Al in the Al layer 5 generally has a larger coefficient of thermal expansion than the thick-film dielectric glass substrate 4, so that the substrate surface is distorted during the temperature rising process. However, the Al layer 5 having flexibility adheres to the thick-film dielectric glass substrate 4 and accumulates compressive stress inside. Next, when the temperature reaches or exceeds the softening point of the thick film dielectric glass substrate 4, the thick film dielectric glass substrate 4
Is lost, and the Al layer 5 tries to increase its surface area to release the compressive stress accumulated therein. As a result, the thick film dielectric glass substrate 4 having lost its rigidity becomes the Al layer 5
The surface is raised as shown in FIG. In this state, the strain on the substrate surface is relieved significantly. Lastly, the strain on the substrate surface remains relaxed until the temperature reaches the softening point of the thick film dielectric glass 4 in the temperature decreasing process. However, even if the softening point is exceeded and the temperature is greatly reduced, the thick film dielectric glass substrate 4 is hardened while maintaining the undulated state as shown in FIG. In the subsequent temperature lowering process, the Al layer 5
Although there is no force for deforming the thick-film dielectric glass substrate 4 even if it shrinks, the aluminum layer 5 is eventually burned while the tensile stress is accumulated in the Al layer 5 while leaving the undulations on the substrate surface.

However, the firing temperature of various thick film patterns of a plasma display panel is generally in the range of 560 ° C to 600 ° C. This is determined by the mechanical strength of the various thick film patterns after firing. Therefore, in the process of FIG.
Baking in the temperature range of 560 ℃ ~ 600 ℃. However, this temperature range is the softening point (50
Since it corresponds to a temperature in the vicinity of 0 to 600 ° C. or higher, if the connecting electrode 13 in the process of FIG. 3D is fired in that temperature range, the above-mentioned undulation on the substrate surface will occur. For example, thick film dielectric glass substrate 4 with a softening point of 585 ° C
In the case of using, when the firing temperature of the connecting electrode 13 is about 540 ° C., the result shows that the undulation of the substrate surface begins to appear remarkably. Therefore, if the baking temperature of the connecting electrode 13 is set to a temperature lower than the softening point of the thick film dielectric glass substrate 4 by about 50 ° C. or more, undulation is unlikely to occur, and therefore the baking temperature of the connecting electrode 13 is a low temperature close to 540 ° C. It was burnt. However, since the connecting electrode 13 is for the purpose of electrically connecting the multilayer thin film cathode pattern 12 to the outside, the path can be relatively short. Therefore, since the electrical conductivity of the connecting electrode 13 itself is relatively lenient, it suffices to pay attention only to its mechanical strength in low temperature firing near 540 ° C. This mechanical strength is determined by selecting a paste such as Ag which is a raw material of the connecting electrode 13 and containing a relatively large amount of a low melting point glass component in the paste, so that the connecting electrode can be formed even at low temperature firing. A mechanical strength of 13 can be guaranteed. In addition, at the stage of low-temperature firing of the thick film connection electrode 13, the multilayer thin film cathode pattern
An extremely thin insulating layer may appear at the bonding interface between the connection electrode 12 and the connection electrode 13, and the multilayer thin film cathode pattern may not be electrically connected to the outside as it is. However, after assembling the plasma display panel as shown in FIG. 1-a using this cathode side panel substrate, if a voltage (100 V to 200 V) is applied to the plasma display panel to generate discharge light emission, the insulating layer is immediately released. Since it is destroyed, there is no problem in actual use.

FIG. 1-a shows a DC discharge type plasma display panel in which the cathode side panel substrate thus completed is face-to-face sealed with the anode side panel substrate. By applying a voltage between the anode and the cathode of such a plasma display panel, discharge light emission can be performed. In the experiment, the cell pitch is 0.35 mm, the width of the multilayer thin film cathode pattern 12 is 0.18 mm, and the width / height of the barrier rib 10 is 0.15 mm.
/0.15mm, the discharge gas to be filled is Ne-350 Torr
A sample was prepared as Al (0.5 Vol%). When no voltage was applied to the trigger electrode, the initial discharge start voltage was about 180 V in each cell. After that, when the above voltage application is continued, the aging effect appears for a while and the emission brightness increases, and the discharge start voltage is 110 to 120 V and the discharge sustain voltage is 95 to
It became 100 V, and the characteristics as a LaB ₆ cathode were obtained.

Embodiment 3. However, as this aging progressed, the shape of the light emitting cell collapsed as shown in FIG. 5, and there was a case where only a part of the cell emitted light or the alignment was disturbed a lot. However, even under such a condition, if aging is continued at 150 V, the disorder of the shape of the light emitting cell is gradually improved, but it does not return to the original alignment state as shown in FIG. In some cases, it could collapse and become stable. Moreover, like this
When aging was continued at 150 V for a long time, a short circuit occurred between the adjacent multilayer thin film cathode patterns 12, which also occurred. Then, looking at the multilayer thin film cathode pattern 12, as shown in FIG. 6, the conductive film 14 has grown from the flank of the multilayer thin film cathode pattern 12 in the gap portion of the adjacent multilayer thin film cathode patterns 12, It was found that the multilayer thin film layers 7 adjacent to each other through the coating 14 were short-circuited. Further, it was found that the main component of the coating film 14 was Al, and it is expected that the coating film 14 was formed because the flank of the Al layer 5 which was originally exposed was sputtered through aging. One of the causes is that localized sputter damage is amplified because the pattern edge is prominent and concentrated discharge is likely to occur. From the above, a multilayer thin film cathode pattern composed of the Al layer 5 and the LaB ₆ layer 6 as shown in FIG.
In practical application of 12, The discharge emission shape is left unordered. 2. The applied voltage is set to a level of 120 V or less and the discharge current is also suppressed as much as possible to reduce the flank of the Al layer 5 from being sputtered. There must be a constraint. However, this restriction is a major obstacle in terms of display quality and brightness. Therefore,
It is necessary to adjust the cell shape of discharge light emission after aging and to suppress the occurrence of short circuit between the multilayer thin film cathode patterns without the restrictions 1 and 2 being imposed.
Next, one embodiment made from such a need will be described.

FIG. 7 is a cross-sectional view of the multilayer thin film cathode pattern according to the present invention cut vertically to the multilayer thin film cathode pattern 12. In the figure, 15 is a Cr thin film layer, 16 is a Cr thin film layer 15, Al
It is a multilayer thin film cathode pattern consisting of layer 5 and LaB ₆ layer 6. Using this multilayer thin film cathode pattern 16 with an applied voltage of about 150 V, the multilayer thin film cathode pattern 16
It was confirmed that they would not be short-circuited next to each other.
As a result, by providing the Cr thin film layer 15 under the Al layer 5, the shape of the light emitting cell and the short circuit between the cathodes can be greatly improved. In general, the purpose of providing the Cr thin film layer 15 on the base of the Al layer 5 is often to enhance the adhesion of the Al layer 5 to the base. However, it cannot be considered that the adhesive force is directly connected to the significant improvement of the discharge characteristics. Because, the Al / LaB ₆ multilayer thin film cathode pattern in the above-mentioned embodiment
This is because 16 does not seem to have peeled off when aging is completed. Therefore, as a result of the verification, it was confirmed that Cr was diffused into the interior of Al and the Al layer 5 was bulk-altered by the heat treatment in the subsequent step. As a result, it is presumed that the pattern edge of the Al-Cr alloy exhibits sputter resistance during discharge light emission, and the discharge life is extended.

FIG. 8 shows the sheet resistance of the multilayer thin film cathode pattern 16 before and after heat treatment of the multilayer thin film cathode pattern 16 after forming the multilayer thin film cathode pattern 16 of Cr / Al / LaB _6. It is a characteristic diagram showing how it changes according to. In FIG. 8, the horizontal axis represents the heat treatment temperature (° C.), and the vertical axis represents the sheet resistance value (mΩ) of the multilayer thin film cathode pattern 16 after the heat treatment. The heat treatment time is 15 minutes. Multi-layer thin film cathode pattern of Cr / Al / LaB ₆ before heat treatment 16
Had a sheet resistance value of 15 mΩ. This has a thickness of 2 μm
The sheet resistance value (14 mΩ) of the defect-free Al layer 5 is substantially the same as the sheet resistance value (14 mΩ). However, as shown in FIG. 8, when heat treatment is performed, the sheet resistance value rises according to the heat treatment temperature. For example, the firing temperature of the connection electrode 13 (approximately
At temperatures corresponding to 500 ℃), the temperature has tripled. Such a change can only be explained by the fact that the Al thin film 5 is bulk-altered by the heat treatment.
Note that this change in sheet resistance value is due to Al not including the Cr thin film 15.
This is a phenomenon that is not seen at all in the multilayer thin-film cathode pattern 12 of / LaB ₆ .

Further, FIG. 9 shows the sheet resistance of the multilayer thin film cathode pattern 16 of Cr / Al / LaB ₆ when the heat treatment temperature is fixed at 580 ° C. on the horizontal axis and the film thickness of the Al layer 5 on the horizontal axis. FIG. 6 is a characteristic diagram showing how the sheet resistance value changes. From FIG. 9, it was confirmed that the thinner the Al layer 5, the larger the rate of change of the sheet resistance value. From the above experimental data, it is considered certain that some diffusion occurs at the interface between the Cr thin film layer 15 and the Al layer 5 during the heat treatment. The diffusion depth reaches the level of 2 μm. Therefore, the flank of the Al layer 5 causes a composition change through the firing of the connecting electrode 13,
It has resistance to being sputtered in a discharge atmosphere and can have a long life.

Next, a method of forming the multilayer thin film cathode pattern 16 will be described. A cathode side panel substrate 1 on which a trigger electrode 2, a terminal electrode 3 and a thick film dielectric glass substrate 4 are formed.
A multilayer thin film is formed on the top in the order of Cr / Al / LaB ₆ by using a sputtering method or the like. At this time, the thickness of each thin film layer was 0.15 μm / 2 μm / 0.2 μm. The thickness of the Cr thin film layer is about 0.05 to 0.3 μmt. Next, Cr / Al / LaB ₆
A photoresist is applied to the entire surface of the cathode side panel substrate on which the thin film layer is placed, the photoresist is exposed through a prescribed mask pattern, and then a prescribed resist pattern is formed by development processing. Then, the LaB ₆ layer 6 is first etched by immersing the substrate in a mixed solution of phosphoric acid, acetic acid and nitric acid, and the surface of the underlying Al layer 5 appears. Then, the etching of the Al thin film with the mixed solution starts, and the underlying Cr thin film layer 15
Is exposed. Finally, when the substrate is dipped in a warm aqueous solution of thiourea / sulfuric acid, the Cr thin film layer is etched, so that a Cr / Al / LaB ₆ multilayer thin film cathode pattern 16 corresponding to the resist pattern is formed. Then, the resist pattern is peeled off to obtain the state shown in FIG. As shown in FIG. 7, the above-mentioned Cr
In the etching process of the thin film layer 15, the edge of the Al layer 5 is tapered, that is, trapezoidal. Therefore, the rate of concentrated discharge occurring during discharge light emission is reduced, and the light emitting cell shape can be made uniform.

Next, after the state shown in FIG. 7 is obtained, the manufacturing process of the cathode side panel substrate is completed by forming the thick film connecting electrode 13 at a firing temperature of about 500.degree. And Figure 1
A DC discharge plasma display panel is manufactured using the cathode side panel in the same manner as in. Here, similarly to the above, the cell pitch is 0.35 mm, the width of the multilayer thin film cathode pattern 16 is 0.18 mm.
mm, width / height of barrier rib 12 is 0.15mm / 0.15mm respectively
Create as.

Then, the same voltage application test as described above was conducted. When no voltage is applied to the trigger electrode, the initial discharge start voltage is about 180 V for each cell, and the shape of the light emitting cell at this time shows uniform surface emission as shown in FIG. 2, and each light emitting cell is in a grid pattern. They are arranged in an eye shape. However, when the aging effect started to appear after the above voltage application was continued for a while, the emission brightness was increased without breaking the regular emission shape shown in FIG. Thus, at the end, the discharge start voltage of each cell was 110 to 120 V and the discharge sustaining voltage was 95 to 100 V while maintaining the regular emission shape of FIG. 2, and the characteristics as the LaB ₆ cathode were obtained.

Example 4. By the way, in the above example, Cr
The thin film layer 15 is directly mounted on the thick film dielectric glass substrate 4. In this structure, the thick film dielectric glass substrate 4 is exposed to the etching solution when the Cr thin film layer 15 is etched. It will be. However, since the thick film dielectric glass substrate 4 that is generally used in the plasma display panel contains a component that dissolves in the Cr etching liquid (a mixed liquid of thiourea and sulfuric acid), after the Cr thin film layer 15 is etched, The exposed surface of the thick film dielectric glass substrate 4 becomes rough as shown in FIG. Therefore, the surface is whitish in appearance, and the surface roughness has uneven strength. When a plasma display panel is assembled by using such a cathode side panel substrate 1, the contrast is deteriorated as a whole even when visually recognized and it becomes unsightly because of unevenness. In addition, when the surface roughness is severe, even if the Cr thin film layer 15 is provided, the experimental result that the discharge light emission shape may be collapsed by aging as shown in FIG. 5 was obtained.

Therefore, in order to solve the above problem, Cr
Before forming the thin film layer 15, the entire surface of the dielectric glass substrate 4 may be covered with a thin film of an insulator having chemical resistance to a Cr etching solution such as SiO ₂ . FIG. 10 is a cross-sectional view perpendicular to the multilayer thin film cathode pattern 16 showing one embodiment thereof. 17 in the figure is a thickness of 0.3 formed by the sputtering method.
It is a μm SiO ₂ thin film. This SiO ₂ thin film 17 protects the underlying thick-film dielectric glass substrate 4 from being attacked by the Cr etching solution, and as a result, good visibility as a plasma display panel can be maintained. The insulating thin film may be a glassy coating film obtained by thermally decomposing alkoxide glass or the like.

Embodiment 5. Further, in the above-mentioned embodiment, the occurrence of short circuit between the multi-layer thin film cathode patterns 12 is suppressed by changing the composition of the Al layer 5. However, as shown in FIG. A method of geometrically suppressing a short circuit by forming the quality bank 18 using a material such as thick film glass is also effective.

Example 6. Figure 12 shows a multilayer thin film cathode pattern 12
FIG. 1B is a cross-sectional view of the portion of FIG. In the figure, 8 is an anode side panel substrate using soda glass as a base material, 9 is an anode pattern formed on the anode side panel substrate, 10 is a barrier rib separating individual anode lines, and 11 is a cathode side panel substrate 1 and an anode. It is a sealing layer made of low melting point glass, which is bonded to the side panel substrate 8 at the outer peripheral portion. A discharge gas such as Ne-Ar is hermetically sealed inside the plasma display panel. By the way, at the time of this sealing, the multilayer thin film cathode pattern 12 is prevented from penetrating the sealing layer 11 and extending to the outside of the panel. This is because if the multilayer thin film cathode pattern 12 penetrates the sealing member 11, the airtightness inside the panel will be impaired. The mechanism will be described. In the sealing process, generally, the low-melting glass is heated to about 430 ° C. to be in a molten state so that the glass is adapted to the cathode side panel substrate 1 and the anode side panel substrate 8 and is cured through the subsequent cooling process to seal the sealing member 11. To form.
At this time, when the multi-layer thin film cathode pattern 12 is in contact with the sealing member 11, the multi-layer thin film cathode pattern 12 is pulled by the base substrate from the bottom and the cured sealing layer from the top in the cooling process.
It will be pulled to 11. Then, even if the difference in the coefficient of thermal expansion between the base substrate and the sealing layer is small, the multilayer thin film cathode pattern
Abnormal distortion occurs in 12 and it is in a state where there is no choice but to peel off either the top or bottom. The mechanism is that airtightness is impaired through this peeled portion. Therefore, it is necessary to have a structure in which the sealing member 11 is in contact with the interface of the connecting electrode 13 or the terminal electrode 3 which is not in contact with the multilayer thin film cathode pattern 12.

[0024]

According to the first aspect of the present invention, aluminum is suitable as a base electrode of hexaboride because it has a strong adhesion to hexaboride and has good flexibility, conductivity, and thermal oxidation resistance.
According to the second aspect of the present invention, the predetermined etching solution simultaneously etches the lanthanum hexaboride film and the aluminum film, so that the discharge cathode pattern can be easily formed. According to the invention of claim 3, since the connecting electrode for connecting to the multilayer cathode pattern is provided on the dielectric glass substrate and the connecting electrode is fired at a temperature lower than the softening point of the dielectric glass, Undulation is unlikely to occur on the surface portion of the dielectric glass substrate. According to the invention of claim 4, chromium changes the quality of aluminum and exhibits spatter resistance, so that the discharge life is extended. According to the invention of claim 5,
Since a multilayer cathode pattern including a chromium film, an aluminum film and a lanthanum hexaboride film is formed and then baked, chromium can be diffused into the aluminum film and the spatter resistance of the aluminum film can be secured. According to the sixth aspect of the invention, since the discharge cathode has a trapezoidal shape, concentrated discharge is unlikely to occur during discharge light emission, the shape of the light emitting cell can be made uniform, and the sputter damage of the discharge cathode can be mitigated. According to the invention of claim 7, since the aluminum film is formed adjacent to the chromium film, the pattern cross section of the aluminum film can be trapezoidal when the chromium film is etched into a predetermined pattern. Concentrated discharge is less likely to occur during discharge light emission, the shape of the light emitting cell can be made uniform, and damage to the sputtering of the discharge cathode can be mitigated. Claim 8
According to the present invention, the insulating thin film protects the dielectric glass substrate from being attacked by the chromium etching solution. According to the invention of claim 9, an insulator can be provided between adjacent discharge cathodes in the multilayer cathode pattern to effectively prevent a short circuit. According to the invention of claim 10, since the sealing member seals the cathode side panel substrate and the anode side panel substrate by contacting the connecting electrode or the cathode terminal electrode, the abnormal distortion of the multilayer cathode pattern is prevented. It can be prevented.

[Brief description of drawings]

1A to 1C are a plan view, a sectional view and a partially enlarged view of a plasma display according to the present invention.

FIG. 2 is a state diagram showing a state where light emitting cell shapes according to the present invention are uniformly arranged.

3A to 3D are process drawings showing the manufacturing process of the discharge cathode device according to the present invention.

4A and 4B are cross-sectional views showing a manner of undulation for explaining an embodiment of the present invention.

FIG. 5 is a state diagram showing a state in which a part of the shape of a light emitting cell is broken to explain one embodiment of the present invention.

FIG. 6 is a cross-sectional view showing that a film is formed between the multilayer cathodes according to the present invention.

FIG. 7 is a sectional view showing an embodiment of the present invention.

FIG. 8 is a sheet resistance characteristic diagram of the processing temperature-Cr / Al / LaB ₆ thin film according to the present invention.

FIG. 9: Thickness of Al thin film according to the present invention-Cr / Al / LaB ₆
It is a sheet resistance characteristic diagram of a thin film.

FIG. 10 is a sectional view in which an insulating thin film is provided as an embodiment of the present invention.

FIG. 11 is a cross-sectional view in which an insulating bank is provided as an embodiment of the present invention.

FIG. 12 is a cross-sectional view of the vicinity of a sealing member as an embodiment of the present invention.

[Explanation of symbols]

1 Cathode Side Panel Substrate 2 Trigger Electrode 3 Terminal Electrode 4 Dielectric Glass Substrate 5 Aluminum Layer 6 LaB ₆ Layer 7 Multilayer Thin Film Layer 8 Anode Panel Substrate 9 Anode Pattern 10 Barrier Rib 11 Sealing Member 12 Multilayer Thin Film Cathode Pattern 13 Connection Electrode 14 Coating 15 Cr thin film layer 16 Multi-layer thin film cathode pattern 17 SiO ₂ thin film 18 Insulator bank

Claims (10)

[Claims] 1. A discharge cathode device having a discharge cathode made of at least aluminum and hexaboride on a substrate. 2. A step of forming an aluminum film on a substrate, a step of forming a lanthanum hexaboride film adjacent to the aluminum film, and a step of forming the aluminum film and the lanthanum hexaboride film with a predetermined etching solution. And a step of collectively etching to form a desired discharge cathode pattern. 3. A multilayer cathode pattern comprising at least an aluminum film and a lanthanum hexaboride film is formed on a dielectric glass plate, and a connecting electrode connected to the multilayer cathode pattern is provided on the dielectric glass plate. A method for manufacturing a discharge cathode device, wherein the connecting electrode is fired at a temperature lower than the softening point of the dielectric glass plate. 4. A discharge cathode device having a discharge cathode made of at least chromium, aluminum and hexaboride on a substrate. 5. A chromium film, an aluminum film and a lanthanum hexaboride film are provided on a substrate to form a multilayer cathode pattern,
Then, the above-mentioned multilayer cathode pattern is fired, and a method for manufacturing a discharge cathode device. 6. A discharge cathode device, wherein the pattern cross section of the discharge cathode is formed in a trapezoidal shape. 7. A step of forming a chromium film on a substrate, a step of forming an aluminum film adjacent to the chromium film, and a step of forming a lanthanum hexaboride film adjacent to the aluminum film. A method for manufacturing a discharge cathode device characterized by the above. 8. A discharge cathode device comprising an insulating thin film provided on a dielectric glass and a multilayer cathode pattern made of chromium, aluminum and hexaboride on the insulating thin film. 9. A discharge cathode device characterized in that a multilayer cathode pattern comprising at least aluminum and hexaboride is provided on a substrate, and an insulator is formed between adjacent multilayer cathodes in the multilayer cathode pattern. 10. A multilayer cathode pattern provided on a cathode side panel substrate, comprising at least aluminum and lanthanum hexaboride, and provided on the cathode side panel substrate and connected to an end of the multilayer cathode pattern. Connection electrodes,
A cathode terminal electrode provided on the cathode side panel and connected to the connection electrode, and an anode side panel substrate on which an anode pattern is formed are arranged to face the cathode side panel substrate, and the connection electrode or the cathode A discharge cathode device, comprising: a sealing member which is in contact with a terminal electrode and seals the cathode side panel substrate and the anode panel substrate.