JP3232195B2 - Electron-emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron-emitting device used as an electron source in a flat panel display or the like.

[0002]

2. Description of the Related Art Recently, a field emission type electron-emitting device has been employed as an electron source of a flat panel display device or the like. In a flat panel display device, it is required to uniformly irradiate an electron beam to a light emitting surface having a relatively large area. Therefore, in an electron-emitting device used in this kind of application, a large number of field emission cathodes are arranged in an array. It is considered that they can be formed as a cold cathode array by arranging them in a matrix (Technical Digest of IVMC
91, Nagahama 1991, p.50, Japan Electronic Industry Development Association, Vacuum Microelectronics Research Report I, 1992
March, p.37).

That is, as shown in FIG. 7B, a base layer 2 having a base electrode 1 and a gate electrode 3 are laminated with an insulating layer 5 interposed therebetween, and a gate layer comprising the gate electrode 3 and the insulating layer 5 is formed. 4 has a structure in which an emitter 7 is formed in a recess 6 formed to reach the base layer 2. Emitter 7
7A are distributed over the entire surface of the gate layer 4 as shown in FIG. Further, the emitter 7 is located within the recess 6 in the base layer 2.
Of the emitter 7 has a radius of curvature of 10 μm or less, and faces the gate electrode 3 via a small gap (1 μm or less). Here, the base electrode 1 and the gate electrode 3 are formed of chromium, the tip of the emitter 7 is formed of a high melting point material such as tungsten or molybdenum, and the base of the emitter 7 on the base layer 2 side is formed of silicon. I have. As is clear from the above description, all the emitters 7 forming the cold cathode array are connected in parallel using the base electrode 1 and the gate electrode 3 in common.

In the electron-emitting device having such a configuration, a voltage of 50 to 200 V is applied between the base electrode 1 and the gate electrode 3 (the gate electrode 3 is made a positive electrode), so that the gate electrode 3 and the emitter 7 are turned on. A strong electric field of about 100 MV / m is formed between the two, and electrons are emitted from the surface of the emitter 7 by field emission. The electron flow emitted from one emitter 7 is about 10 to 100 nA, but by forming an array with an appropriate distribution density, an electron flow of about ^{20 to} 100 μA per 1 mm ² can be obtained. .

[0005]

In the electron-emitting device having the above structure, if an overcurrent flows between the gate electrode 3 and the emitter 7 for some reason, the tip of the emitter 7 evaporates and the insulating layer 5 May adhere to In the base layer 2 and the gate layer 4 having the above-described configurations, the base electrode 1 and the gate electrode 3 are exposed.
When the emitter 7 evaporates and adheres to the insulating layer 5, a short circuit occurs between the base electrode 1 and the gate electrode 3 via the adhered metal film, and a problem arises in that electrons are not emitted from the emitter 7. In addition, in the above configuration, the base electrode 1 and the gate electrode 3 are commonly used for each of the emitters 7. Therefore, when the base electrode 1 and the gate electrode 3 are short-circuited by the evaporation of one emitter 7, the gates of all the emitters 7 are removed. An electric field cannot be formed between the electrodes 3 and
There is a problem that electrons cannot be emitted from the emitter 7 that has not evaporated. In other words, generally, if an array is formed, even if an abnormality occurs in one location, the function of another location can be maintained, but in the above configuration, if an abnormality occurs in one location, the other location is normal. A problem arises in that the device cannot be used.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron-emitting device which can maintain the function of emitting electrons from another emitter even if one of the emitters evaporates. It is something to offer.

[0007]

According to a first aspect of the present invention, there is provided a semiconductor device comprising: a plurality of recesses formed by laminating a gate electrode on a base layer having a base electrode via an insulating layer, and forming a large number of gate layers formed of the gate electrode and the insulating layer; An emitter whose front end faces the gate electrode through a small gap protrudes from one surface of the base layer on the gate layer side of the base layer, and a voltage is applied between the base electrode and the gate electrode. An electron-emitting device in which electrons are field-emitted from an emitter by a strong electric field formed between the emitter and the gate layer.
Is not good in at least the part of the gate electrode facing the emitter
Covered with conductor coating, poor conductors form gate electrode
It is a metal oxide .

[0008]

[0009]

[0010]

[0011]

[0012]

According to the structure of the first aspect of the present invention , the gate layer has a gate layer.
At least a part of the electrode is covered with a coating of a poor conductor.
Therefore, the emitter evaporates and the base layer and gate layer
Even if evaporating substances adhere between them, the base electrode and gate electrode
The presence of a poor conductor between the base electrode
Potential difference between the gate electrode and the
An unsuccessful normal emitter can continue to emit electrons .

[0013]

[0014]

[0015]

Moreover, since the non-conforming conductor formed on the gate layer is an oxide of a metal forming the gate electrode, the non-conforming conductor can be formed on the surface of the gate layer by forming the gate electrode and oxidizing the surface. This makes it possible to simplify the manufacturing process and to form a uniform coating as compared with the case where a layer of a poor conductor is separately formed.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, reference examples 1 to 5 will be described, and then the embodiment will be described.
I will tell. Reference Example 1 In this reference example , as shown in FIG. 1, a base layer 2 is a laminate of a base electrode 1 made of chromium and a non-conforming conductor layer 8 of alumina (Al ₂ O ₃ ) as a non-conforming conductor. Except for this point, the configuration is the same as the conventional configuration shown in FIG. That is, an insulating layer 5 made of silicon oxide is stacked on the base electrode 1 via the poor conductor layer 8, and a gate electrode 3 made of chromium is stacked on the surface of the insulating layer 5. Here, the gate layer 4 is formed by the gate electrode 3 and the insulating layer 5.
A recess 6 whose bottom reaches the base layer 2 is formed in the gate layer 4, and an emitter 7 projects from the bottom of the recess 6. The tip of the emitter 7 is formed of tungsten or molybdenum, and the base 7a on the base layer 2 side is formed of silicon. That is, in order to form an electron-emitting device having such a structure, an alumina film and silicon oxide are sequentially stacked on the base electrode 1 and then the silicon oxide is etched to form the base 7a of the emitter 7 and the recess 6. Is formed, and the tips of the gate electrode 3 and the emitter 7 may be further deposited. Here, the base 7a of the emitter 7a becomes silicon by the reduction process. The dimensional relationship is the same as that described in the conventional example.

The poor conductor layer 8 is formed by using a technique such as high-frequency sputtering so as to have a thickness of about 10 nm.
Even if the evaporating substance adheres to the gate electrode 4 with a thickness of about 10 nm, the cross-sectional area where the current flows in the non-conducting layer 8 between the base electrode 1 and the gate electrode 3 is very small. Resistance between the gate electrode 3 and the gate electrode 3 is 100 MΩ
That is all. That is, the base electrode 1 and the gate electrode 3 are substantially insulated by the poor conductor layer 8. On the other hand, the resistance between the base electrode 1 and the emitter 7 is 10 to 100 MΩ, which is sufficiently smaller than the resistance of the discharge path in vacuum, so that there is no problem in energizing the base electrode 1 to the emitter 7. In this configuration, the normal current flowing from the base electrode 1 to the emitter 7 is about 10 nA at the maximum, so that the voltage drop in the non-conducting conductor layer 8 becomes almost negligible (about 1 V at the maximum).

When an overcurrent flows from the base electrode 1 to the emitter 7, a large voltage drop occurs in the poor conductor layer 8, so that a discharge is not generated between the gate electrode 3 and the emitter 7. An increase in the potential difference between the electrode 3 and the emitter 7 can be suppressed, and as a result, an overcurrent can be prevented from flowing. As described above, even if the emitter 7 evaporates due to the presence of the poor conductor layer 8, it is possible to prevent a short circuit between the base electrode 1 and the gate electrode 3 due to the evaporating substance, thereby keeping the potential difference. Thus, an overcurrent which causes evaporation of the emitter 7 can be prevented.

In this embodiment , the poor conductor layer 8 is made of alumina, but the same effect can be obtained by using silicon oxide or the like. (Reference Example 2) In Reference Example 1, the non-conforming conductor layer 8 was formed by applying a material different from that of the base electrode 1, but in this reference example ,
The poor conductor layer 8 is formed by oxidizing the surface of the base electrode 1. That is, as shown in FIG. 2, the surface of the base electrode 1 made of chromium is oxidized to form the poor conductor layer 8 made of a chromium oxide layer, and then the insulating layer 5 and the emitter 7 are formed. The nonconductive layer 8 can be formed by a simple process of oxidizing the surface of the base electrode 1. Such step is so that the oxidation process in comparison with the conventional process is increased, Reference Example 1
As compared with the case of forming a film of another material as described above, the time required for the process is shorter and the non-conductive layer 8 can be formed uniformly. Other configurations and operations are for reference
Same as Example 1.

(Embodiment 3) In this embodiment , as shown in FIG. 3, the non-conducting layer 8 formed on the base layer 2 and the silicon portion excluding the metal portion of the emitter 7 are continuously and integrally formed. In addition, the poor conductor layer 8 is formed continuously and integrally with the insulating layer 5. That is, the silicon non-conducting layer 8 (insulating layer 5) having a relatively large thickness is laminated on the base electrode 1 so that the base electrode 1 does not reach the base electrode 1 in the etching process when the emitter 7 and the recess 6 are formed. The recess 6 is formed in the non-conforming conductor layer 8. By such an operation, the surface portion of the base layer 2, the insulating layer 5, and a part of the emitter 7 can be continuously and integrally formed. In addition, in such an operation process, the thickness of the silicon to be laminated for forming the insulating layer 5 is increased as compared with the conventional process, and the etching depth of the silicon only needs to be adjusted. Because it does not increase, manufacturing becomes easier.

In the above configuration, if the thickness of the silicon forming the poor conductor layer 8 of the base layer 2 and the thickness of the silicon forming the emitter 7 are each set to about 1 μm ,
It can be operated with the same specifications as in Reference Example 1. Also in the present embodiment , even when the metal portion of the emitter 7 evaporates, the base electrode 1 and the gate electrode 3 are not short-circuited, and the effect of suppressing the overcurrent to the emitter 7 by the poor conductor layer 8 is also obtained. To play. Other configurations and operations are
The same as in the first embodiment .

( Embodiment 4) As shown in FIG. 4, this embodiment has the same structure as the conventional structure shown in FIG.
Is formed of chromium, whereas the present embodiment is different in that it is formed of silicon. That is,
The gate electrode 3 is formed of a high resistance material.

If such a configuration is adopted, the emitter 7
If the metallic material is evaporated base electrode 1 and the gate electrode 3 is covered with the evaporation material, becomes no potential difference between the base electrode 1 and the gate electrode 3 in the recess 6 corresponding to an emitter 7 evaporated Although the emission of electrons from the emitter 7 is stopped, the potential difference between the base electrode 1 and the gate electrode 3 can be maintained in the other recess 6 because the gate electrode 3 has a high resistance, and The release can be continued. Other configurations and operations are the same as in the first embodiment .

Reference Example 5 In this reference example , as shown in FIG. 5, a portion extending from the surface portion of the gate electrode 3 to the insulating layer 5 in the conventional electron-emitting device shown in FIG. This is covered with a coating 9 of a poor conductor made of (SiO ₂ ). Participation in this configuration
As in the case of the first embodiment, even if the evaporating substance adheres between the base layer 2 and the gate layer 4 when the emitter 7 evaporates,
Non-conductive coating 9 between base electrode 1 and gate electrode 3
, The insulation is maintained, and as a result, the other emitters 7 can continue to emit electrons.

The voltage applied between the base electrode 1 and the gate electrode 3 is 50 to 200 V as described in the conventional example, and the withstand voltage of silicon oxide is about 1 GV / m. To obtain a coating 9 of 20
What is necessary is just to have a film thickness of 0 μm or more. Other configurations and operations are the same as in the first embodiment . (Embodiment ) In this embodiment, as shown in FIG. 6, the gate electrode 3 was formed of silicon as in Reference Example 4, and the surface of the gate electrode 3 was oxidized to form a coating 9 made of silicon oxide. Things. In other words , the configuration of Reference Example 4 has a configuration in which thermal oxidation is performed so that only the surface of the portion to be the gate electrode 3 is made of silicon oxide. Thus , reference
Even if the gate electrode 3 is formed of silicon as in Example 4, short-circuit between the base electrode 1 and the gate electrode 3 due to evaporation of the emitter 7 does not occur, and furthermore, the gate electrode 3 is formed by thermal oxidation. By having the coating 9 formed, a short circuit can be more reliably prevented. In addition, since the coating 9 is formed by the thermal oxidation treatment , the production becomes easier as compared with the case where another material is applied as in Reference Example 5. Other configurations and operations are the same as in the first embodiment .

[0027]

According to the first aspect of the present invention , the gate layer has a gate electrode.
Are at least some of the poles covered with a poor conductor coating?
When the emitter evaporates, the vapor evaporates between the base layer and the gate layer.
Even if the emitting material adheres, the gap between the base electrode and the gate electrode
The base electrode and the gate
Can maintain the potential difference between the
This has the effect that electrons can be continuously emitted from a normal emitter .

[0028]

[0029]

[0030]

Further , since the non-conforming conductor formed on the gate layer is an oxide of a metal forming the gate electrode, the non-conforming conductor can be formed on the surface of the gate layer by forming the gate electrode and oxidizing the surface. This is advantageous in that the manufacturing process can be simplified as compared with the case where a layer of a poor conductor is separately formed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of Reference Example 1.

FIG. 2 is a sectional view of a main part of Reference Example 2.

FIG. 3 is a cross-sectional view of a main part of Reference Example 3.

FIG. 4 is a sectional view of a main part of Reference Example 4.

FIG. 5 is a sectional view of a main part of Reference Example 5.

Figure 6 is a fragmentary cross-sectional view of an embodiment.

7A and 7B show a conventional example, in which FIG. 7A is a plan view, and FIG. 7B is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base electrode 2 Base layer 3 Gate electrode 4 Gate layer 5 Insulating layer 6 Depression 7 Emitter 8 Non-conductive layer 9 Coating

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yosuke Mizuyama 1048 Odakadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (56) References JP-A-5-94760 (JP, A) JP-A-6-124649 (JP, A) JP-A-4-229922 (JP, A) JP-A-7-240143 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 1/304

Claims (1)

(57) [Claims] A gate electrode is laminated on a base layer having a base electrode with an insulating layer interposed therebetween, and a plurality of recesses formed in the gate layer including the gate electrode and the insulating layer are formed on one surface of the base layer on the gate layer side. By applying a voltage between the base electrode and the gate electrode, a strong electric field is formed between the gate electrode and the emitter. An electron emission device in which electrons are emitted from an emitter in a field emission manner , wherein a gate layer has at least an emitter of a gate electrode.
Is covered with a coating of a poor conductor.
An electron-emitting device comprising an oxide of a metal forming a gate electrode .