JP2646235B2 - Electron emitting device and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron-emitting device and a method of manufacturing the same, and more particularly, to a surface conduction electron-emitting device.

[Prior art] Conventionally, as an element which can obtain electron emission by a simple manufacturing, for example, MIElinson
And the like are known. [Radio Engineering Electron Phys. Vol. 10, 1290-1296, 19
65 years] This uses development in which electron emission is caused by flowing a pre-current parallel to the thin surface on a small-area thin film formed on a substrate, and is generally called a surface conduction electron-emitting device. ing.

Examples of the surface conduction electron-emitting device include a device using a SnO ₂ (Sb) thin film developed by Elinson et al. And a device using an Au thin film [G. Dittmer: “Thin Solid Films”. "), Volume 9, 317
Page, (1972)], using ITO thin film [M. Hartwell and C.G.Fonstad “IIE Transformer”
Hartwell and CGFonstad: “IEEE Trans.ED Conf.”) 5
19, (1975)], and those using a carbon thin film [Hisashi Araki et al .: "Vacuum", Vol. 26, No. 1, p. 22, (1983)].

FIG. 4 shows a typical device configuration of these surface conduction electron-emitting devices. In the figure, 1 and 2 are electrodes for obtaining electrical connection, 3 is a thin film formed of an electron-emitting material,
Denotes a substrate, and 10 denotes an electron emitting portion.

Conventionally, in these surface conduction electron-emitting devices, before emitting electrons, an electron-emitting portion is formed in advance by an electric heating process called forming. That is, by applying a voltage between the electrode 1 and the electrode 2, the thin film 3 is energized, and the thin film 3 is locally broken, deformed or deteriorated by Joule heat generated by the application of the voltage. An electron emitting function is obtained by forming the electron emitting portion 10 in the state.

[Problems to be Solved by the Invention] However, the following problems have been encountered in the electron-emitting devices formed by the above-described energization heat treatment.

During energization heating, the thin film peels off due to the difference in thermal expansion coefficient of the thin film on the substrate. In addition, since the substrate is locally heated, fatal cracking may occur. For this reason, there are restrictions on the upper limit of the heating temperature and the combination of the selection of the substrate material and the thin film material. In particular, when the thin film is made of a high melting point material or a high resistance thin film, it is difficult to form the film by conducting heat treatment, and it is very difficult to use these materials as an electron emitting material.

Until the forming is completed, relatively high power is required, but particularly high power is required when the thin film material is a high melting point material. For example, in FIG. 4, l = 0.5 mm, w = 0.3 mm, thickness of about 5
The amount of power required for forming a 00Å SnO ₂ (Pb) film is approximately
It was about 1.5W. Therefore, depending on the thin film material, a large-capacity power source was required for forming a large number of elements.

Due to the above-mentioned problems, the surface conduction electron-emitting device has not been actively applied in industry, despite the advantage that the device structure is simple.

[Means for Solving the Problems] The present invention has been made to solve the above-described drawbacks of the conventional example. Conventionally, in a high-resistance portion of a thin film formed by electric heating, a crack is generated in the thin film and the thickness is 1 μm.
m or less, and has an island-like structure composed of fine particles in the minute space. The minute gaps and the island-like structure are made of the material used for the thin film.

The present invention provides an electron-emitting device having a conductive film including minute spaces, wherein the minute spaces and the surface of the conductive film are
An electron-emitting device having fine particles, and
An object of the present invention is to provide a method for manufacturing an electron-emitting device, comprising a step of forming minute intervals in a conductive film having fine particles disposed on its surface.

That is, according to the present invention, the fine particles involved in electron emission and the minutely spaced portions of the conductive film for applying a high electric field thereto are separated from each other, and appropriate materials can be selected and manufactured.

 Hereinafter, the present invention will be described in detail.

1 (a) to 1 (d) are explanatory views showing the steps of manufacturing the electron-emitting device of the present invention, and FIG. 2 is a plan view showing an example of the electron-emitting device of the present invention.

In order to manufacture the electron-emitting device of the present invention, first, a thin film 3 made of a metal or a semiconductor having a shape shown in FIG. 2 is formed on a substrate 4 (see FIG. 1A).

Next, fine particles are dispersed and applied onto the thin film 3. In the dispersion coating, spin coating of an organic solvent in which fine particles are dispersed or an organic solvent containing an organic metal or the like is performed by dipping. Thereafter, baking is performed to dispose the fine particles 5 on the thin film 3 (see FIG. 1B).

Further, electrodes 1 and 2 are formed by depositing and forming a conductive metal having the shape shown in FIG. 2 on both ends of the thin film 3 (see FIG. 1 (c)).

Thereafter, when the electrodes 1 and 2 are subjected to an energizing treatment, a crack is generated in the center of the thin film 3 to form a minute gap 6 between the thin films. The minute gap 6 has a structure in which the fine particles 5 are arranged, and an electron-emitting device is obtained (see FIG. 1 (d)).

The element thus formed is placed in a vacuum vessel with electrodes 1, 2
When a voltage is applied between the electrodes and a high voltage is applied to the upper part of the element by an extraction electrode (not shown), electrons are emitted from the minute interval including the fine particles 5.

In the above-described structure of the electron-emitting device and the method of manufacturing the same according to the present invention, the step-forming material 7 may be formed, and the step portion serving as the shape end of the step-forming material may be used as the electron-emitting portion. (A) to (d) show the structure and the manufacturing method thereof. 3, a step forming material 7 made of an insulating material is formed on the substrate 4 by volume (see FIG. 3 (a)).

Next, the thin film 3, the fine particles 5, and the electrodes 1 and 2 are formed on the step forming material 7 and the substrate 4 as described above. At this time, the thin film 3 is deposited so as not to be broken at the step (FIG. 3B,
(C)). However, the electrodes 1 and 2 are provided for improving the electrical connection of a voltage applied from the outside for emitting electrons, and do not significantly influence the next energization process / process. This is because, as will be described later, according to the present embodiment, the amount of power required for the energization process can be reduced. This is because good energization processing can be performed without much consideration of thermal expansion and the like.

Further, when the electrodes 1 and 2 are energized, the steps of the thin film 3 are energized to form minute gaps 6 between the thin films. By this step, the structure in which the fine particles 5 are arranged in the minute interval portions 6 of the thin film is obtained, and the electron-emitting device is obtained (see FIG. 3D).

The device formed in this manner can obtain electron emission in the same manner as in the above-described example. This embodiment has the following features in addition to the above-described embodiment. That is, it is possible to specify the generation position of the minute interval, reduce the amount of power to be processed, and control the minute interval region.

In the present invention shown in the above examples, as the material of the thin film forming the minute gaps related to the electron emission, that is, the discontinuous thin film portion, a wide range of materials usually used as surface conduction electron-emitting devices, for example, SnO ₂ , an in ₂ O _3, metal oxides, such as PbO, Au, metal such as Ag, carbon and other various semiconductors, is itself suitable as an electron emitting material can be used. However, in the present invention, since it is possible to separately arrange fine particles involved in electron emission, any material can be used as long as it has the function of a thin-film electrode as a thin-film material and can form a minute gap by energization treatment. Available for use. In general, a high melting point material requires a large amount of electric power and Joule heat during energization processing. However, as in the example shown in FIG. 3, in the method of energizing the thin film at the step portion,
Since the amount of power for energization processing can be reduced, energization processing can be performed relatively easily even with a high melting point material. Therefore, as a material of the thin film, a general electrode material, a conductive high melting point metal, or the like can be used in addition to the above examples. For example, Cu, Al, Ni, Pd, Pt, W, Ta, M
o, Cr, Ti, etc., but not limited thereto.

The thickness of the thin film may be any thickness as long as it is used for an ordinary surface conduction electron-emitting device. Specific examples thereof vary depending on the type of material used, but are usually 0.01 to 5 μm, preferably 0.01 to 2 μm. It is about.

Examples of the fine particle material related to electron emission include a substance that easily emits electrons in a field, a substance that easily emits secondary electrons,
Alternatively, any substance that easily emits electrons by the impact of electrons and has high heat resistance and corrosion resistance may be used. For example, W, Ti, Au, Ag, Cu, Cr, Al having a low work function and high heat resistance may be used. , Pt, Pd
Or oxides such as SnO ₂ , In ₂ O ₃ , BaO, MgO, etc., or carbon or a mixture thereof, but is not limited thereto. In the present invention, the size of the fine particles is usually preferably about several tens to several thousand millimeters in diameter.

As the electrode member, a wide range of commonly used electrode materials can be used without any particular limitation.

An insulating material is used as a material of the step forming material. For example, in addition to SiO ₂ , Si ₃ N ₄ , TiO ₂ , Ta ₂ O ₅ , Al ₂ O _3, etc., the surface of the substrate itself can be processed and the substrate material itself can be used as a step forming material.

The thickness of the step forming material needs to be adjusted by the film thickness of the thin film deposited on the step and the film forming method. Usually, the thin film on the step is not electrically disconnected, and the film thickness on the step is usually small. It is necessary that the thickness of the thin film be smaller than that of the other portions or that the film quality be changed. Generally, the thickness of the step forming material, that is, the height of the step portion is preferably about 1/3 to 3 times the volume of the thin film.

Regarding the substrate material, in addition to the materials conventionally used for surface conduction electron-emitting devices, such as quartz glass,
By selecting a material for the thin film, the amount of heat generated in the energization treatment can be reduced, so that even a blue plate made of a material, such as glass, which generates a large amount of stress due to local heating can be used without causing a substrate crack or the like.

As described above, in the present invention, particularly, the selection material of the thin film having the fine particles involved in the electron emission and the minute gap for applying a high electric field thereto has been remarkably increased as compared with the conventional example.

Therefore, the thin film material to be subjected to the energization process has the following characteristics: the amount of electric power during the energization process, the amount of locally generated heat, the coefficient of thermal expansion with respect to the substrate material, and the withstand voltage, heat resistance, and life of the electrode during electron emission. A number of materials can be selected for consideration.

Also, for the fine particles, a material that easily emits electrons, such as heat resistance, corrosion resistance, and a low work function material, can be selected from many materials.

[Example] Example 1 An electron-emitting device having an embodiment shown in Fig. 2 was manufactured based on the manufacturing process shown in Fig. 1 described above.

First, as a manufacturing method, a thin film 3 was formed on a clean quartz glass substrate having a thickness of about 1 mm by mask EB vapor deposition with a thickness of 1000 mm in the form shown in FIG. At this time, 1 = 0.5 mm and w = 0.3 mm among the shapes shown in FIG. 2 (see FIG. 1A).

Next, an organic solvent containing an organic palladium compound (Catapaste CCP manufactured by Okuno Pharmaceutical Co., Ltd.) is spin-coated on the thin film 3 by a spinner, baked at about 250 ° C. for 10 minutes, and the dispersed and coated Pd fine particles 5 are arranged (No. (See FIG. 1 (b)). In addition, 500 mm thick Cr is used as an underlayer on both ends of the thin film 3.
Thick Au electrodes 1 and 2 were formed by a mask evaporation method (first
FIG. (C)).

Thereafter, the electrodes 1 and 2 were energized to form a minute gap 6 in the center of the thin film 3. The power consumption of the energization process is about 0.
It was about 8 W (see FIG. 1 (d)).

As a result of measuring the electron emission characteristics of the electron-emitting device manufactured by the above steps, the emission current _Ie = 0.8 μA and the emission efficiency α
(Ratio of emission current to in-film current) = 0.8 × 19 ^-4 degree electron emission was obtained.

Example 2 An electron-emitting device having a step portion obtained by the process shown in FIG. 3 was manufactured.

As a manufacturing method, first, a SiO ₂ liquid coating agent (OCD manufactured by Tokyo Ohka Kogyo Co., Ltd.) is spin-coated on a clean quartz glass substrate having a thickness of about 1 mm with a spinner.
After baking for a time, an SiO ₂ film having a thickness of about 2000 ° was obtained, and a step forming material 7 having a step was formed by a photolithographic etching method (see FIG. 3A).

Further, the thickness of the step forming material 7 is set to 1000 so as to cover the step.
Ni Ni thin film 3 is formed in volume, and then in the same manner as in Example 1.
Pd fine particles 5 were arranged (see FIG. 3B).

Thereafter, the electrodes 1 and 2 were formed in the same manner as in Example 1, and the energization process was performed to form the minute interval portions 6. The power consumption of the energization process was about 0.2 W (see FIG. 3 (c)).

As a result of measuring the electron emission characteristics of the electron-emitting device manufactured by the above process, the emission current _Ie = 1.6 μA and the emission efficiency α = 1
Electron emission of about × 10 ^-4 was obtained.

In the above examples, a Pd material was used as the fine particles. However, when the SnO ₂ fine particles having a primary particle diameter of about 100 mm are dispersed and dissolved in an organic solvent together with an organic binder, the SnO ₂ fine particles dispersion liquid is applied to the element and baked to arrange the SnO ₂ fine particles. An emission device was obtained.

[Effects of the Invention] As described above, according to the present invention, by applying a current to a thin film having fine particles and arranging the fine particles at minute intervals of the thin film, the fine particles involved in electron emission and the thin film that gives an electric field thereto The minute intervals can be separated by a material, and a suitable material can be selected and designed.

Therefore, by using a high melting point material, etc., which was considered difficult in the conventional method, as the power emitting material, and by using a thin film material with low power consumption in the energizing process, the energizing process can be performed without requiring large power. have.

[Brief description of the drawings]

FIG. 1 is a process diagram showing an example of the manufacturing method of the present invention, FIG. 2 is a plan view showing an example of the electron-emitting device of the present invention, and FIG. 3 is a process diagram showing another example of the manufacturing method of the present invention. FIG. 4 is an explanatory view showing a conventional electron-emitting device.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Nomura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-1-186740 (JP, A) JP-A-1 -200532 (JP, A) JP-A-1-279540 (JP, A) JP-A-1-279541 (JP, A) JP-A-7-122323 (JP, B2) JP-A-7-97473 (JP, B2) ) Tokiko Hei 6-87391 (JP, B2)

Claims (16)

(57) [Claims] 1. An electron-emitting device having a conductive film including a minute gap, wherein the fine-grain portion and the surface of the conductive film have fine particles. 2. The electronic device according to claim 1, wherein the conductive film is disposed so as to straddle a step formed on the substrate, and the minute interval is formed in the step. Emission element. 3. The electron-emitting device according to claim 1, wherein the diameter of the fine particles is in the range of several tens to several thousand degrees. 4. The electron-emitting device according to claim 1, wherein said minute interval is 1 μm or less. 5. The electron-emitting device according to claim 1, wherein the minute interval is a crack formed in a part of the conductive film. 6. The electron-emitting device according to claim 1, wherein said conductive film is disposed between a pair of electrodes. 7. The electron-emitting device according to claim 1, wherein said electron-emitting device is a surface conduction electron-emitting device. 8. A method for manufacturing an electron-emitting device having a conductive film including an electron-emitting portion, comprising the step of forming minute intervals in a conductive film having fine particles disposed on its surface. A method for manufacturing an emission element. 9. The method for manufacturing an electron-emitting device according to claim 8, wherein the conductive film on which the fine particles are arranged is arranged so as to straddle a step formed on the substrate. 10. The electron-emitting device according to claim 8, wherein the conductive film on which the fine particles are arranged is formed by dispersing fine particles on the surface of the conductive film after forming the conductive film. Manufacturing method. 11. The method for manufacturing an electron-emitting device according to claim 8, wherein the diameter of the fine particles is in the range of several tens to several thousand degrees. 12. The method according to claim 1, wherein the minute interval is 1 μm or less. 13. The method for manufacturing an electron-emitting device according to claim 8, wherein the minute interval is a crack formed in a part of the conductive film. 14. The electron-emitting device according to claim 8, wherein the step of forming minute intervals in the conductive film on which the fine particles are arranged includes a step of applying a voltage to the conductive film. Production method. 15. The method according to claim 8, wherein the conductive film on which the fine particles are arranged is arranged between a pair of electrodes. 16. The method according to claim 8, wherein said electron-emitting device is a surface conduction electron-emitting device.