JP2000188057A - Electron source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce degradation with an elapsed time influenced by Joule heat generated inside an electron emitter. SOLUTION: An electron source comprises: an electron emitter 2 made of porous polysilicon formed at either surface of an n-type silicon substrate 1; a gold surface electrode 3 having a thickness of 10 nm provided in such a manner as to cover a part of the electron emitter 2; an aluminum back face electrode 5 having a thickness of 0.5 μm, formed at the reverse of the silicon substrate 1; and a wiring electrode 6 connecting the surface electrode 3 and a terminal electrode 4. The wiring electrode 6 and the terminal electrode 4 are made of aluminum having a thickness of 1.5 μm. Most of the wiring electrode 6 is sandwiched between insulating layers 7, each of which is made of silicon oxide having a thickness of 0.5 μm, formed on the smooth silicon substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron source.

[0002]

2. Description of the Related Art As a thin film type electron source, FIGS.
As shown in (c), for example, an electron-emitting portion 2 is formed on a silicon substrate 1 and a surface electrode 3 is formed on the surface of the electron-emitting portion 2.
And a terminal electrode 4 provided at one end of the surface electrode 3 has been conventionally provided.

The surface electrode 3 needs to be tunneled into a vacuum provided with an electron source without causing hot electrons emitted from the electron emission portion 2 below the surface electrode 3 to be scattered in the surface electrode 3. Its thickness is as thin as about 10 nm. Reference numeral 5 denotes a back electrode made of aluminum or the like.

[0004]

As described above, when the thickness of the surface electrode 3 is extremely small, the electric resistance of the surface electrode 3 becomes very large due to the effect of the surface of the thin film.

Further, if the electron emitting portion 2 below the surface electrode 3 has an uneven surface such as porous silicon, the electric resistance is further increased. For example, line width 0.0
For a gold surface electrode with a thickness of 7 mm and a thickness of 10 nm,
The resistance was 60 KΩ.

With such a high resistance, heat is generated by the current flowing through the surface electrode 3. Therefore, the heat is wasted and the electron emission efficiency is reduced. In other words, the voltage drop due to the current flowing through the front surface electrode 3 cannot be ignored, and the required operating voltage increases as the voltage actually applied to the electron source becomes lower than the voltage applied from the outside. .

The magnitude of the voltage drop differs depending on the location of the surface electrode 3, but it cannot be ignored, and the voltage applied to the electron source varies depending on the location. There was a problem that it could cause a variation within.

Furthermore, a high electric resistance results in a large electric time constant, so that the operation speed is reduced.
On the other hand, in the case of such a very thin surface electrode 3, there is a problem that disconnections due to steps or irregularities on the surface of the electron-emitting portion 2 are likely to occur, and malfunctions are likely to occur.

Further, from the lower part of the surface electrode 3 having a thickness of about 10 nm, the hot electrons accelerated inside the electron emitting portion 2 are emitted. At this time, since the electron-emitting portion 2 generates heat by Joule heat, there is a problem that the characteristics of the electron source deteriorate with time due to the heat.

This is because the surface electrode 3 is very thin and has poor heat conduction efficiency. When a substrate such as glass having a lower heat conduction efficiency than a silicon substrate is used, heat dissipation becomes an even more important issue.

The present invention has been made in view of the above points, and an object of the present invention is to provide an electron source capable of reducing deterioration over time due to the influence of Joule heat generated in an electron emission portion. It is in.

In addition, it is possible to improve electron emission efficiency or operation voltage, reduce heat generation, improve operation speed, reduce in-plane variation in electron emission efficiency and emission current density, and reduce operation failures due to disconnection of surface electrodes. An object of the present invention is to provide an electron source capable of improving the performance, quality, and manufacturing yield when the device is used.

[0013]

In order to achieve the above-mentioned object, a first aspect of the present invention is to electrically and thermally couple to a surface electrode formed on the surface side of an electron emitting portion and to form a surface electrode. Since it has a wiring electrode provided separately from it.

According to a second aspect of the present invention, in the first aspect of the present invention, the wiring electrode is made thicker than the surface electrode.

A third aspect of the present invention is characterized in that, in the first or second aspect of the invention, the material of the surface electrode and the material of the wiring electrode are made different.

According to a fourth aspect of the present invention, in the third aspect of the invention, the surface electrode is formed using a material having at least one of a low work function and high oxidation resistance, and the wiring electrode has a low resistivity. It is characterized by being formed using a material.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, an insulating layer is formed below the wiring electrode.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, at least a part of a surface in contact with the back surface of the wiring electrode is formed as a smooth surface.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the electron emission portion is formed of a polycrystalline material, and at least a part of a portion of the polycrystalline material located below the inner wiring electrode is removed. It is characterized by comprising.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the wiring electrode is made of the same material and the same thickness as the electrodes other than the surface electrode.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

(Embodiment 1) The electron source of this embodiment is shown in FIG.
(A) to (c), an electron-emitting portion 2 made of porous polysilicon formed on one surface of an n-type silicon substrate 1, and a low work function provided to cover a part of the electron-emitting portion 2. Thus, a gold surface electrode 3 having a thickness of 10 nm, which is excellent in high oxidation resistance, and a thickness of 0,0 nm formed on the back surface of the silicon substrate 1.
A back electrode 5 of 5 μm aluminum and a wiring electrode 6 connecting the front electrode 3 and the terminal electrode 4 are formed. The wiring electrode 6 and the terminal electrode 4 are both formed of aluminum having a thickness of 1.5 μm, and the wiring electrode 6 is installed so as to be electrically connected to the surface electrode 3. Between them, an insulating layer 7 made of silicon oxide having a thickness of 0.5 μm is formed.

In this embodiment, since the wiring electrode 6 having a large thickness and a low resistance is separately provided separately from the surface electrode 3, the electron emission efficiency is improved, the operating voltage is reduced, the heat generation is reduced, and the operation is reduced. It is possible to improve the speed, reduce the in-plane variation of the electron emission efficiency and emission current density, further reduce the operation failure due to the disconnection of the surface electrode 3, and further improve the performance, quality and manufacturing yield when used for a display or the like.

Further, since the insulating layer 7 made of silicon oxide having a thickness of 0.5 μm is formed between the wiring electrode 6 and the electron emitting portion 2, electrons can jump from the electron emitting portion 2 directly into the wiring layer. Can eliminate the reactive current, and the provision of the wiring electrode 6 can further improve the electron emission efficiency.

Furthermore, since both the wiring electrode 6 and the terminal electrode 4 are made of the same thickness and the same material, the wiring electrode 6 can be formed simultaneously with the formation of the terminal electrode 4. Therefore, the wiring electrode 6 is separately provided. Also, the number of manufacturing steps does not increase.

By providing a thick wiring electrode 6 separately from the surface electrode 3 having a thickness of about 10 nm, Joule heat generated in the electron emitting portion 2 can be effectively released by the wiring electrode 6. This makes it possible to improve the stability over time of the electron source.

The structure in which the periphery of the surface electrode 3 is surrounded by the thick wiring electrode 6 enhances heat radiation and further improves the stability over time of the electron source.

(Embodiment 2) The electron source of this embodiment is shown in FIG.
(A) to (c), an electron-emitting portion 2 made of porous polysilicon formed on one surface of an n-type silicon substrate 1, and a low work function provided to cover a part of the electron-emitting portion 2. Thus, a gold surface electrode 3 having a thickness of 10 nm, which is excellent in high oxidation resistance, and a thickness of 0,0 nm formed on the back surface of the silicon substrate 1.
A back electrode 5 of 5 μm aluminum and a wiring electrode 6 connecting the front electrode 3 and the terminal electrode 4 are formed. The wiring electrode 6 and the terminal electrode 4 are both formed of aluminum having a thickness of 1.5 μm, and the wiring electrode 6 is installed so as to be electrically connected to the surface electrode 3. Porous polysilicon, which is the material of the electron-emitting portion 2, is removed except for a part of the lower portion of the wiring electrode 6, and most of the wiring electrode 6 is formed on a smooth silicon substrate 1 with a thickness of 0.1 mm. It is sandwiched between insulating layers 7 of 5 μm silicon oxide.

In this embodiment, in addition to the advantages of the first embodiment, the porous polysilicon, which is the material of the electron-emitting portion 2, is partially removed from the lower portion of the wiring electrode 6. The wiring electrode 6 can be formed on the smooth silicon substrate 1 surface, not on the large polysilicon, so that disconnection and increase in resistance can be prevented, and the electron emission efficiency is further improved or the operating voltage is reduced as compared with the first embodiment. And heat generation, operation speed improvement, reduction of in-plane variation of electron emission efficiency and emission current density, and further reduction of operation failure due to disconnection of the surface electrode 3, and furthermore, performance when used for a display, etc.
Quality and manufacturing yield can be improved.

(Embodiment 3) This embodiment is shown in FIG.
As shown in (b), an electron emitting portion 2 made of porous polysilicon is formed in a matrix on a substrate, for example, a silicon substrate 1, and the surface of each electron emitting portion 2 has the same thickness as in the first and second embodiments. The surface electrodes 3 made of gold are formed, and the wiring electrodes 6 are formed so as to be parallel to the respective rows, corresponding to the respective surface electrodes 3 in the same row. The wiring electrode 6 is made of aluminum having the same thickness as that of the first and second embodiments, and the corresponding surface electrode 3 is shown in FIGS.
As shown in (1), while being electrically connected via the coupling electrode 8 having substantially the same thickness as the surface electrode 3, heat generated in each electron-emitting portion 2 is transmitted and radiated through the coupling electrode 8 and the silicon substrate 1. Is available. An insulating layer 7 is formed below the wiring electrode 6.

In the above case, the surface electrode 3 is coupled to the wiring electrode 6 by the coupling electrode 8, but as shown in FIGS. May be formed to electrically connect the surface electrode 3 and the wiring electrode 6. In this case, the heat radiation effect of the wiring electrode 6 can be further expected.

[0032]

According to the first aspect of the present invention, a surface electrode formed on the surface side of the electron emission portion is electrically and thermally coupled to a surface electrode, and has a wiring electrode provided separately from the surface electrode. Therefore, Joule heat generated in the electron-emitting portion can be effectively released by the wiring electrode, and there is an effect that the temporal stability of the electron source can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the wiring electrode is thicker than the surface electrode, so that the wiring electrode having a low resistance improves the electron emission efficiency or reduces the operating voltage and the heat generation. , Operation speed improvement, electron emission efficiency
This has the effect of reducing the in-plane variation of the emission current density, reducing the operation failure due to the disconnection of the surface electrode, and improving the performance, quality and manufacturing yield when used for a display or the like.

According to the third aspect of the present invention, since the material of the surface electrode and the material of the wiring electrode are different from each other in the first or second aspect of the invention, an appropriate material can be selected for each electrode.

According to a fourth aspect of the present invention, in the third aspect, the surface electrode is formed using a material having at least one of a low work function and a high oxidation resistance, and the wiring electrode has a low resistivity. Since it is formed using a material, there is an effect that the performance can be further improved.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, since an insulating layer is formed below the wiring electrode, electrons jump directly from the electron-emitting portion 2 into the wiring layer. As a result, the reactive current can be eliminated, and as a result, there is an effect that the electron emission efficiency can be further improved by providing the wiring electrode.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, at least a part of the surface in contact with the back surface of the wiring electrode is a smooth surface. It is possible to prevent an increase in the electron emission efficiency or to reduce the operating voltage and the heat generation, improve the operation speed, and reduce the in-plane variation of the electron emission efficiency and emission current density.

According to a seventh aspect of the present invention, in the sixth aspect of the invention, the electron emission portion is formed of a polycrystalline material, and at least a part of a portion of the polycrystalline material located below the inner wiring electrode is removed. Since the wiring electrodes can be formed on a smooth substrate surface rather than on a polycrystalline material having large surface irregularities, disconnection and increase in resistance can be further prevented, electron emission efficiency can be improved, operating voltage can be reduced, heat generation can be reduced, and operation can be performed. It is possible to improve speed, reduce in-plane variation of electron emission efficiency and emission current density, and further reduce operation failure due to disconnection of a surface electrode, and further improve performance, quality, and manufacturing yield when used for a display or the like.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects of the present invention, the wiring electrodes are formed of the same thickness and the same material as the electrodes other than the surface electrodes. The wiring electrode can be formed at the same time as the formation, and therefore, there is an effect that the number of manufacturing steps does not increase even if the wiring electrode is separately provided.

[Brief description of the drawings]

FIG. 1A is a top view of a first embodiment of the present invention.
(B) is a side sectional view of the same. (C) is XX sectional drawing of (a) same as the above.

FIG. 2A is a top view of a second embodiment of the present invention.
(B) is a side sectional view of the same. (C) is a YY sectional view of (a) of the above.

FIG. 3A is a top view of a third embodiment of the present invention.
(B) is sectional drawing of AA of the same as the above (a).

FIG. 4A is an enlarged plan view of a main part of the above.
(B) is BB sectional drawing of (a) same as the above.

FIG. 5A is an enlarged plan view of a main part of another example of the embodiment. (B) is CC sectional drawing of (a) same as the above.

FIG. 6A is a top view of a conventional example. (B) is a side sectional view of the same. (C) is a ZZ sectional view of (a) of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Electron emission part 3 Front surface electrode 4 Terminal electrode 5 Back surface electrode 6 Wiring electrode 7 Insulating layer

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[Procedure amendment]

[Submission date] September 13, 1999 (1999.9.1)
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

Further, if the electron emitting portion 2 below the surface electrode 3 has an uneven surface such as porous silicon, the electric resistance is further increased. For example, line width 0.0
For a 7 mm, 10 nm thick gold surface electrode, about 3
The resistance was 60 KΩ.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Koichi Aizawa 1048 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Works, Ltd. (72) Inventor Yoshiaki Honda 1048 Kadoma Kadoma, Osaka Pref.Matsushita Electric Works Co., Ltd. (72) Inventor Yoshifumi Watanabe 1048 Odaka Kazuma Kadoma, Osaka Pref. Takashi Ino 1048 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Works, Ltd.

Claims (8)

[Claims] An electron source electrically and thermally coupled to a surface electrode formed on the surface side of an electron emission portion, and having a wiring electrode provided separately from the surface electrode. . 2. The electron source according to claim 1, wherein the wiring electrode is made thicker than the surface electrode. 3. The electron source according to claim 1, wherein the material of the surface electrode and the material of the wiring electrode are different from each other. 4. The method according to claim 1, wherein the surface electrode is formed using a material having at least one of low work function and high oxidation resistance characteristics, and the wiring electrode is formed using a low resistivity material. The electron source according to claim 3, wherein 5. The electron source according to claim 1, wherein an insulating layer is formed below the wiring electrode. 6. The electron source according to claim 1, wherein at least a part of a surface in contact with the back surface of the wiring electrode is a smooth surface. 7. The electron source according to claim 6, wherein the electron emission portion is formed of a polycrystalline material, and at least a part of a portion of the polycrystalline material located below the inner wiring electrode is removed. . 8. The electron source according to claim 1, wherein the wiring electrode has the same material and the same thickness as the electrodes other than the surface electrode.