JPH07220619A - Cold cathode electrode structure and its manufacture - Google Patents

Abstract

PURPOSE:To provide a fine and high-density cold cathode without using fine processing technics. CONSTITUTION:A silicon oxide film 4 and a layer of molybdenum 5 are formed on an aluminum substrate 1, and a plurality of openings 9 are opened. Next, an anode oxide film is formed in the opening 9. Next, a barrier layer 23 is removed, and nickel 24 is buried in the small hole 22 formed in the anode oxide film. Next, a photoresist 2 is removed, and the buried nickel 24 is made a cold cathode, and the molybdenum 5 is made a gate electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention mainly relates to a cold cathode electrode structure in vacuum microelectronics and a manufacturing method thereof.

[0002]

2. Description of the Related Art Cold cathodes used in vacuum microelectronics having a structure as shown in FIG. In FIG. 4 d, reference numeral 1 denotes a silicon (Si) substrate, for example, which has a cold cathode 3 which is a protruding portion on the silicon substrate 1. Further, in the example of this drawing, the periphery of the cold cathode 3 is surrounded by an insulating film, for example, a silicon oxide film (SiO ₂ ) 4, and a metal electrode, for example, molybdenum (Mo) 5 is formed thereon. ,
Between the molybdenum 5 and the silicon substrate 1, for example, several 100V
The voltage is applied to cause electrons to be emitted from the cold cathode 3 by field emission. In order to facilitate field emission, it is necessary that the shape of the cold cathode 3 is steep, and in this example, both the height and the base are 1.5 μm.

Therefore, in order to obtain such a structure, a fine processing technique is required, and an example is shown in FIGS. 4a to 4d. In FIG. 4a, the surface to be the cold cathode on the silicon substrate 1 is covered with a photoresist 2 by photolithography. In this case, the processing accuracy of the photoresist is 1.5μ
The case of m is shown. Then, using this photoresist as an etching mask, the silicon substrate 1 is removed by etching to obtain the structure of FIG. 4b.

Then, as shown in FIG. 4c, silicon oxide films (SiO ₂ ) 4 and 4a are successively deposited, and molybdenum (Mo) 5 and 5a to be gate electrodes are deposited. Next, when the photoresist 2 is removed, the silicon oxide film 4a and the molybdenum 5a on the photoresist are also removed at the same time, so that the structure of FIG. 4d is finally obtained. If a control electrode is to be provided on the gate electrode, a step of depositing a silicon oxide film and then molybdenum may be added to the step of FIG. 4c.

[0005]

One of the problems in the conventional method is that the projections of the cold cathode are formed by the microfabrication method, which guarantees a processing accuracy of 1 μm level. Expensive photomechanical equipment is required.
Further, when a set of cold cathodes and gate electrodes are arranged and used in an array, a variation in the characteristics of the cold cathode electrodes may occur due to process variations in the projection shape. For this reason, a plurality of protruding electrodes are collectively used as blocks 31, 31a, 31b ... As shown in FIG. In this example, a frame of 100 μm × 100 μm is set to 1
A large number of cold cathodes 3 described in FIG. 4 are formed in each block as one block so that even if the characteristics of each cold cathode vary, the characteristics do not vary on average. However, even in this case, the bottom length of the cold cathode is 1.5 as in the example of FIG. 4a.
The number of cold cathodes in one block is at most 1,000 (100 / (1.5 + 1.
5) = 33, 33 × 33 = 1089).

A technique similar to this case is disclosed in Japanese Unexamined Patent Publication No. 5-144.
It is described in Japanese Unexamined Patent Publication No. 370, and it is divided into nine blocks, each block having a size of 100 μm × 100 μm, and cold cathodes having a size of several μm are arranged in an array.

An object of the present invention is to form a cold cathode structure without using a microfabrication technique, and when the cold cathode is used as a block, to increase the area density of the cold cathode contained in the block. Thus, it is intended to obtain a structure of a cold cathode electrode with little variation in characteristics as a block.

Other prior arts include the following. Japanese Unexamined Patent Publication No. 4-36922 discloses an electron emitting portion (cold cathode) for each of the holes generated when an anodized film of aluminum is formed.
And a gate electrode are provided to manufacture the electron-emitting portion with high density and high yield. Note that the invention of this application does not have an electron emitting portion (cold cathode) and a gate electrode for each hole as in this publication. In addition, the manufacturing method of this publication, after removing the lower aluminum,
The cone-shaped cold cathode is formed by irradiating the ion beam from above while tilting and rotating the substrate, and the gate electrode is formed by depositing gold while tilting and rotating the substrate, so the manufacturing method is complicated. Is.

Japanese Unexamined Patent Publication (Kokai) No. 4-264337 aims at uniforming the brightness of the entire flat CRT, improving the yield, and reducing the cost by averaging the emission currents of the electron-emitting devices in each pixel. The density is integrated and the electron emission rate is improved. The manufacturing method is similar to the above-mentioned Japanese Patent Laid-Open No. 4-36922.

[0010]

The cold cathode electrode structure according to claim 1 of the present invention is a substrate of aluminum or aluminum alloy, a first insulating film formed on the main surface of the substrate, and a first insulating film formed on the main surface of the substrate. A first conductive film formed on the insulating film of
A plurality of openings formed in the first conductive film and the first insulating film, an anodized film obtained by anodizing the substrate exposed in the openings, and holes present in the anodized film. And a buried second conductor.

The cold cathode electrode structure according to claim 2 of the present invention is
The cold cathode electrode structure according to claim 1, wherein the size of the opening of the first insulating film is made larger than the size of the opening of the first conductive film to form an eaves part in the first conductive film. The anodic oxide film and the second conductor are formed below the eaves.

The cold cathode electrode structure according to claim 3 of the present invention is
The cold cathode electrode structure according to claim 1 or 2, wherein
The third conductive film is provided on the conductive film of 2 above through the second insulating film.

According to a fourth aspect of the present invention, in the method of manufacturing a cold cathode electrode structure, a first insulating film is formed on a main surface of a substrate of aluminum or aluminum alloy, and then a gate electrode is formed on the first insulating film. A first step of forming a first conductive film, a second step of forming a plurality of openings in the first conductive film and the first insulating film, and anodizing the substrate exposed in the openings. Third step of forming an anodic oxide film, second as a cold cathode by filling voids existing in the anodic oxide film with a conductor
This includes the fourth step of forming the electric conductor.

A method for manufacturing a cold cathode electrode structure according to a fifth aspect of the present invention is the method for manufacturing a cold cathode electrode structure according to the fourth aspect, wherein the barrier layer formed at the bottom of the holes when the anodic oxide film is formed is formed. It includes a step of removing.

[0015]

The cold cathode electrode structure according to claim 1 of the present invention has a structure in which the first surface is formed on the main surface of the substrate of aluminum or aluminum alloy.
An insulating film is formed, a first conductive film is formed on the first insulating film, a plurality of openings are provided in the first conductive film and the first insulating film, and the substrate exposed in the openings An anodic oxide film is formed on the anodic oxide film by filling the holes existing in the anodic oxide film with a second conductor, and the second conductor is used as a cold cathode, and electrons are extracted from the first conductive film. Use as a gate electrode.

The cold cathode electrode structure according to claim 2 of the present invention is
The size of the opening of the first insulating film is made larger than the size of the opening of the first conductive film to form an eaves part in the first conductive film, and the anodic oxide film and the anodic oxide film are formed below the eaves part. A second conductor is formed.

The cold cathode electrode structure according to claim 3 of the present invention is
A third conductive film is provided over the first conductive film with a second insulating film interposed therebetween, and this third conductive film is used as a control electrode for emitted electrons.

In the method for manufacturing a cold cathode electrode structure according to claim 4 of the present invention, in the first step, a first insulating film is formed on the main surface of a substrate of aluminum or aluminum alloy, and then the first insulating film is formed. A first conductive film as a gate electrode is formed on the film, a plurality of openings are provided in the first conductive film and the first insulating film in the second step, and exposed in this opening in the third step. An anodized film is formed by anodizing the formed substrate, and in a fourth step, the holes existing in the anodized film are filled with a conductor to form a second conductor as a cold cathode.

In the method for manufacturing the cold cathode electrode structure according to the fifth aspect of the present invention, the step of removing the barrier layer generated at the bottom of the holes when the anodic oxide film is formed is performed after the third step.

[0020]

【Example】

Example 1. In the present invention, the micropores formed in the anodic oxide film of aluminum (Al) are positively utilized,
It is intended to use the embedded metal as a cold cathode by growing the metal in the micropores by electro-deposition or vapor deposition, chemical vapor deposition, or the like and embedding the metal. That is, as shown in FIG.
The anodic oxide film 21 formed by anodic oxidation in 10% sulfuric acid at 10 ° C. has a hole 2 with a diameter of 120 A (angstrom).
2 are formed at intervals of 360 A (angstrom) ("Aluminum Handbook", Light Metal Association, Asakura Shoten, June 42). Also, an oxide film called a barrier layer 23 of 14 A (angstrom) remains between the hole 22 and aluminum, but after removing this by changing the conditions of etching or anodic oxidation as described later, It is intended to embed a metal therein to act as a cold cathode.

A similar idea has already been described in JP-A-2-270247. However, in the method described therein, all the metal embedded in the holes of the anodic oxide film is used as a cold cathode. There is a drawback that the gate electrode cannot be integrally formed on the cold cathode. In the present invention, it is not possible to utilize all the metals embedded in the holes,
The gate electrode is provided with an opening, and only the metal embedded close to the opening is used as a cold cathode to realize integration of the gate electrode and the cold cathode.

An embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram corresponding to FIG. 5 of a conventional example,
The size of the electrode block 31 is the same for both 100 μm ×
It is 100 μm. In the case of FIG. 1, 20 μm × 20 μm openings are provided in the electrode block 31, and nine anodic oxide films 21 are arranged at equal intervals of 20 μm in the openings. Therefore, the number of holes existing along the periphery of this anodic oxide film (four sides of 20 μm square), that is, the number of electrodes when a metal is embedded in each hole is one block,
In the case of the example of the hole pitch 360A (angstrom) of FIG. 6, 20 μm × 4 sides × 9 holes / 360A (angstrom)
= 20,000, and the number of electrodes per block is 20 times that in the case of FIG.

Next, a manufacturing method for obtaining such a structure will be described with reference to FIG.
The portion of the electrode block 31 will be described with reference to FIG. FIG. 2a shows a state in which a silicon oxide film (SiO ₂ ) 4 is formed on aluminum (Al) 11, molybdenum (Mo) 5 is further formed thereon, and then a pattern of photoresist 2 is formed by photolithography. Is. In this case, the width and interval of the photoresist 2 do not need to be fine, and in this example, it is set to 20 μm (10 μm may be used). Therefore, expensive transfer equipment such as a stepper is unnecessary.

Then, using the photoresist 2 as an etching mask, the molybdenum 5 and then the silicon oxide film 4 are removed by etching to form an opening 9 as shown in FIG. 2b. The exposed aluminum 11 portion of the opening 9 is anodized to form an anodized film 21 as shown in FIG. 2c. The method of this anodic oxidation is described in detail in the above-mentioned "Aluminum Handbook", but the properties of the anodic oxide film formed by the chemicals of the bath solution, temperature, applied voltage, etc.
It is known that the sizes and intervals of the two are different.

In this example, a 15% sulfuric acid solution was used and
When applying 5 V, it is known that the pore diameter is 120 A (angstrom) and the space is 360 A (angstrom). Next, the barrier layer 23 is removed and the hole 22 is filled with metal. This is the embedding method,
A method of embedding Ni by electrolytic deposition for the purpose of improving the hardness of the anodic oxide film is known (“Metal / inorganic material / polymer material No. 4”, Science and Technology Agency, Institute of Industrial Technology, Metal Material Research Institute, Institute for Inorganic Materials, Laboratory for Fiber and Polymer Materials, Research and Development Materials, Science and Technology Bulletin Foundation, March 1, 1984).

According to this method, the barrier layer can be removed by lowering the voltage at the end of anodic oxidation to cut off the electrolysis current, and then connecting the aluminum substrate and the counter electrode with an external lead wire and leaving them in the bath. (Fig. 2d). Then, electrolytic deposition of Ni is _{NiSO 4 · 7H 2 O, NiCl} 2 · 6H 2 O, H
It has also been described in the above-mentioned document that a mixed solution of ₃ BO ₃ may be used, and the hole is filled with nickel (Ni) 24 as shown in FIG. The photoresist 2 is then removed, resulting in the structure of Figure 2f. In this figure, molybdenum 5 acts as a gate electrode, and nickel 24 in the vicinity thereof acts as a cold cathode.

Example 2. As another embodiment of the present invention, FIG. 3 shows the structure of FIG.
In this example, a second molybdenum (Mo) 7 is further provided on the gate electrode (molybdenum 5) of FIG. 2f via a silicon oxide film 6 to serve as a control electrode. In order to obtain this structure, a silicon oxide film and molybdenum are further laminated before the step of FIG. 2a, and the subsequent steps are the same as those described in FIG.

Example 3. As another embodiment of the present invention, in order to more accurately finish the relationship between the gate electrode and the nickel cold cathode, the silicon oxide film 4 is slightly over-etched after the step of FIG. 2b. Then, as shown in Figure 3,
The eaves portion 8 of molybdenum 5 is formed, the anodic oxide film 21 is located below the eaves portion 8, and the nickel 24 is also located below the eaves portion 8. By doing so, field emission can be efficiently performed.

Example 4. In the examples so far,
Although nickel (Ni) by electrolytic deposition has been described as the metal to be embedded in the hole 22 of the anodic oxide film, another metal or alloy such as molybdenum (M
o), tungsten (W), molybdenum silicide (M
oSi ₂ ) or the like may be used. Further, although the example of the silicon oxide film (SiO ₂ ) is described as the insulating film arranged under the gate electrode or the control electrode, other insulating films such as alumina (Al ₂ O ₃ ) and silicon nitride film (Si ₃ N _{4) are used.} ) Or the like may be used.

Example 5. As the substrate, other metal, glass, ceramics, or the like may be used instead of aluminum. In that case, aluminum or an aluminum alloy may be formed on the substrate by a vacuum deposition method, a sputtering method, or the like and used. In the present invention, these are included in an aluminum or aluminum alloy substrate.

[0031]

According to the first aspect of the present invention, a fine structure of the cold cathode electrode can be obtained without using a fine processing technique. Further, it is possible to form high-density electrodes per unit area, and it is possible to obtain uniform cold cathode characteristics that are not affected by variations in individual electrodes.

According to the second aspect of the present invention, since the eave portion is formed on the first conductive film, the field emission can be efficiently performed.

According to the third aspect of the present invention, since the third conductive film is provided, it is possible to control the emitted electrons by using the third conductive film as a control electrode for the emitted electrons.

According to the fourth or fifth aspect of the present invention, it is possible to obtain a method of manufacturing a fine cold cathode electrode structure without using a fine processing technique. Further, it is possible to form a high-density electrode per unit area, and it is possible to obtain a method for manufacturing a cold cathode electrode structure having uniform cold cathode characteristics that is not affected by variations in individual electrodes.

[Brief description of drawings]

FIG. 1 is a plan view of an array of cold cathodes according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the manufacturing process of the cold cathode electrode structure according to the first embodiment of the present invention.

FIG. 3 is a structural cross-sectional view when a control electrode is provided on a cold cathode of Example 2 of the present invention and when an eaves portion is provided on a gate electrode of Example 3;

FIG. 4 is a cross-sectional view showing a manufacturing process of a conventional cold cathode electrode structure.

FIG. 5 is a plan view of a case where a large number of conventional cold cathodes are arranged in an array and used.

FIG. 6 is a cross-sectional view showing the structure of an aluminum anodic oxide film.

[Explanation of symbols]

1 Silicon Substrate (Si) 2 Photoresist 3 Cold Cathode 4, 4a Silicon Oxide Film (SiO ₂ ) 5, 5a Molybdenum (Mo) 6 Silicon Oxide Film (SiO ₂ ) 7 Molybdenum (Mo) 8 Eaves 9 Opening 11 Aluminum (Al) 21 Anodized film 22 Pore 23 Barrier layer 24 Nickel (Ni) 31, 31a, 31b Cold cathode electrode block

Claims (5)

[Claims] 1. An aluminum or aluminum alloy substrate, a first insulating film formed on a main surface of the substrate, and a first conductive film formed on the first insulating film.
A plurality of openings formed in the first conductive film and the first insulating film, an anodized film obtained by anodizing the substrate exposed in the openings, and a space present in the anodized film. A cold cathode electrode structure, comprising: a second conductor filling the hole, wherein the second conductor is a cold cathode, and the first conductive film is a gate electrode for extracting electrons. 2. The cold cathode electrode structure according to claim 1, wherein the size of the opening of the first insulating film is larger than the size of the opening of the first conductive film, and the first conductive film is covered. A cold cathode electrode structure characterized in that a portion is formed, and an anodic oxide film and a second conductor are formed below the eave portion. 3. The cold cathode electrode structure according to claim 1, wherein a third insulating film is formed on the first conductive film via a second insulating film.
2. A cold cathode electrode structure, characterized in that the conductive film is provided, and the third conductive film is used as a control electrode for emitted electrons. 4. A first step of forming a first insulating film on a main surface of an aluminum or aluminum alloy substrate, and then forming a first conductive film as a gate electrode on the first insulating film. A second step of forming a plurality of openings in the first conductive film and the first insulating film, and a third step of forming an anodized film by anodizing the substrate exposed in the openings
A method of manufacturing a cold cathode electrode structure, comprising: a step of filling a hole existing in the anodic oxide film with a conductor to form a second conductor as a cold cathode. 5. The cold cathode electrode structure according to claim 4, including a step of removing a barrier layer generated at the bottom of the holes when the anodic oxide film is formed. Manufacturing method.