JP2646236B2 - Electron emitting device and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electron-emitting device and a method for manufacturing the same, and more particularly to a surface conduction electron-emitting device.

[Prior art] Conventionally, as an element which can obtain electron emission with a simple structure, for example, MIElinson
And the like are known. [Radio Eng. Electron. Phys. Vol. 10, 1290-1296,
1965] This utilizes the phenomenon that electron emission occurs when a current flows through a thin film with a small area formed on a substrate in parallel with the thin surface, and is generally called a surface conduction electron-emitting device. I have.

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)], ITO thin film [M Hartwell and CJ Fontstad “I
M. Hartwell and CGFonstad: “IEEE Trans.ED Con
f. ") p. 519, (1975)], using a carbon thin film [Hisashi Araki et al .:" Vacuum ", Vol. 26, No. 1, p. 22, (1983)
Year)].

FIG. 6 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 11 denotes an electron emitting portion.

Conventionally, in these surface conduction electron-emitting devices, before emitting electrons, an electron-emitting portion is formed by an energizing 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 the Joule heat generated by the application of the voltage, and has a high electrical resistance. An electron emitting function is obtained by forming the electron emitting portion 11 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 between the substrate and the thin film. 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. 7, l = 0.5 mm, w = 0.3 mm, and a 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 intervals, wherein the conductive film is disposed on a member including fine particles, and
The element? The method of manufacturing an electron-emitting device according to any one of claims 1 to 3, further comprising the step of forming minute gaps in the conductive film disposed on the member containing the fine particles.

That is, the present invention separates the fine particles involved in electron emission from the minute gaps of the conductive film that applies a high electric field thereto by the manufacturing method and the material, and can select and manufacture the material suitable for each. An element and a method for manufacturing the same.

 Hereinafter, the present invention will be described in detail.

1 (a) to 1 (d) are process diagrams showing an example of a method for manufacturing an electron-emitting device of the present invention, and FIG. 2 is a plan view of the electron-emitting device of the present invention.

In order to obtain an electron-emitting device, first, fine particles 7 made of a metal or a semiconductor are dispersed in an insulating liquid coating agent, and this is applied on the substrate 4 and fired to form a support 6 containing the fine particles 7 ( FIG. 1 (a)). After that, the surface of the support 6 may be slightly etched to make the fine particles 7 protrude more toward the surface of the support 6.

Next, a thin film 3 made of a metal or a semiconductor having the shape shown in FIG. 2 is formed on the support 6 (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 energized, a crack is generated in the central portion of the thin film 3 to form a minute gap 5 between the thin films. The minute gap is a portion where the thin film 3 is locally broken and deformed by Joule heat generated by energization. With respect to the minute gaps caused by the current application of the thin film, generally, the thin film 3 locally becomes a discontinuous film, and if the thin film 3 is made of a material used as a surface conduction electron-emitting device, the discontinuous portion includes the thin film 3
It is considered that the particles have a shape in which fine particles made of the above materials are arranged, and thus, electron emission can be obtained.

However, if the thin film 3 is made of a conductive material that is not used as a surface conduction electron-emitting device, and only the energization treatment of the thin film on a member having no electron-emitting body, the electron emission is not obtained. I can't.

By the above manufacturing steps, an electron-emitting device having a structure in which the support 6 is provided under the thin film 3 and the fine particles 7 are partially disposed in the discontinuous thin film portion of the minute interval portion 5 is obtained (first example). FIG. (D)).

The element thus formed is placed in a vacuum vessel with electrodes 1,
When a voltage is applied between the two 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 portions 5 of the thin film 3 containing the fine particles 7.

On the other hand, a step can be formed by the shape end of the support on the substrate, and this step can be used as an electron-emitting portion. Third
(A) to (d) show a manufacturing process of the electron-emitting device according to the embodiment.

First, a support containing the fine particles 7 is deposited in the same manner as in the above-described example. Thereafter, half of the support is removed from the substantially central portion of the substrate 4 by photolithography or the like to form a support 8 having a step (see FIG. 3A).

Next, a thin film 3 made of a metal, a semiconductor, or the like having the shape shown in FIG. 2 is deposited and formed on the support 8 and the substrate 4 so as not to be electrically disconnected at the steps (see FIG. 3B).

Further, electrodes 1 and 2 are deposited and formed in the same manner as in the above example.
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. This is because, according to the present embodiment, as described below, the amount of power required for the energization process can be reduced, and as in the conventional case, the position where Joule heat is generated at the time of forming by the electrode shape, the heat conduction and thermal expansion of the material, etc. This is because good energization processing can be performed without taking into account (see FIG. 3 (c)).

Thereafter, when the electrodes 1 and 2 are energized, cracks are formed in the steps of the thin film 3 and minute gaps between the thin films are formed. The minute gap is a portion where the thin film 3 is locally broken and deformed by Joule heat generated by energization. In particular, the thin film 3 on the side wall of the step portion is different from the thin film in other portions in thickness and film quality. In the portion, the thin film 3 is liable to crack.

That is, in this example, the position of the thin film where a crack occurs can be specified by the step position of the support 8 and the shape of the thin film 3. Further, the thin film 3 on the side wall of the step portion is thinner than the thin film of the other portion, and it is easy to make the film strength weak, and it can be said that the thin film 3 is liable to be cracked by Joule heat due to the energization treatment. Therefore, the amount of power required for the energization process is smaller than that in the above-described example. Further, the height region of the thin film 3 on the side wall of the step portion of the support can be controlled by the layer thickness of the support 8 and the deposition thickness of the thin film 3. Therefore, it is possible to control the region of the thin film 3 where cracks are likely to occur, and it is also possible to control the region of the discontinuous thin film in the minute interval portion 5 that becomes the electron emitting portion.

By the manufacturing steps up to this point, a structure is obtained in which the projecting fine particles 7 are arranged on the side wall of the stepped portion of the support 8 on the discontinuous thin film portion of the minute interval portion 5, and the electron-emitting device is obtained (FIG. d)).

In the above-described example, the support 8 is etched until the surface of the base substrate 4 is completely exposed. However, the step is formed only on the step surface of the support 8 without etching the surface of the base substrate 4. Is also good.

1 to 3 show examples of the electron-emitting device in which the fine particles are dispersedly contained in the support. However, as will be described in another embodiment, the fine particles are dispersed on the surface of the member or the surface of the step forming portion on the member. A similar electron-emitting device can be obtained also when it is arranged above.

In the present invention shown in the above examples, as the material of the thin film forming the minute space involved in electron emission, a wide range of materials that are usually used as surface conduction electron-emitting devices,
For example, metal oxides such as SnO ₂ , In ₂ O ₃ , and PbO, metals such as Au and Ag, carbon, and various other semiconductors can be used as appropriate as the electron emitting material. However, in the present invention, fine particles involved in electron emission can be separately arranged, so that 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. It is possible. Generally, a high melting point material requires a large amount of electric power and Joule heat at the time of energization processing. However, in the method of energizing the thin film at the step portion as in the example shown in FIG. 3, the energizing power can be reduced, so that the energizing process 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, Mo, Cr, Ti, etc., but are not limited thereto.

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

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 preferably preferably about 10 to several thousand mm in diameter. When the electron emitter is formed as a thin film, the thickness thereof is also preferably about several tens to several thousands of mm.

Further, 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 support including the step forming material and the fine particles. For example, SiO ₂ , Si ₃ N ₄ , TiO ₂ ,
Ta ₂ O ₅ , Al ₂ O _{3 and the} like, and a laminate thereof or a mixture thereof may be used. Further, in the step forming material, the surface of the substrate itself can be processed, and the substrate material itself can be used as the step forming material.

The thickness of the support including the step forming material and the fine particles must be adjusted by the 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 It is necessary that the thickness of the upper thin film is smaller than the thin film thickness of the other portion or that the film quality is changed. Typically,
The thickness of the step forming material or the support, that is, the height of the step portion is preferably about 1/3 to 3 times the thin film to be deposited.

Regarding the substrate material, in addition to the materials conventionally used for surface conduction electron-emitting devices, such as quartz glass,
By selecting the material of the thin film, the amount of heat generated during the energization process can be reduced, so that even a material such as a soda lime 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 related to the electron emission and the minute gap for applying the 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. As for the fine particles, a material which 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 according to the present invention was manufactured in the manner shown in FIGS. 1 and 2 described above.

As a manufacturing method, first, SiO ₂ liquid coating an organic solvent containing a (manufactured by Tokyo Ohka Kogyo OCD) in an organic palladium compound (Okuno Chemical Industries Ltd. Kyatabesuto CCP) were mixed, SiO _2: the molar ratio of Pd of about 10 1: Make a prepared solution,
It was spin-coated by a spinner on a clean quartz glass substrate having a thickness of about 1 mm. Thereafter, it was baked at about 400 ° C. for 1 hour to obtain a SiO ₂ support 6 containing Pd fine particles 7 having a thickness of about 1500 °.
Thereafter, the surface of the support layer was etched with a hydrofluoric acid aqueous solution for 1 second (see FIG. 1 (a)).

Next, 500 nm of Ni is coated on the support 6 by a mask EB evaporation method.
A thin film 3 was deposited and formed in the form shown in FIG. At this time, l = 0.5 mm and w = 0.3 mm among the shapes in FIG.
Fig. (B).

Further, on both ends of the thin film 3, Au electrodes 1 and 2 having a thickness of 500 mm were formed by a mask evaporation method using a 50 mm-thick Cr underlayer (see FIG. 1 (c)).

Thereafter, the electrodes 1 and 2 were subjected to an energization treatment to form a minute interval 5 in the center of the thin film 3. The power consumption of the energization process is approximately
It was about 0.8W.

As a result of measuring the electron emission characteristics of this device, the emission current I _e
= 1 μA and emission efficiency α (ratio of emission current to in-film current) = 1 × 10 × ⁻⁴ were obtained.

Example 2 As shown in FIG. 3, the support 6 containing the fine particles 7 used in Example 1 was removed to the center of the substrate to form a support 8 having a step, and an electron-emitting device was manufactured in the same manner as in Example 1 below. did.

The support 8 was etched with a hydrofluoric acid aqueous solution by a photolithographic etching method to form a step (FIG. 3A).
reference).

Next, a Ni thin film 3 having a thickness of 500 mm was deposited and formed so as to cover a stepped portion of the support 8 having a thickness of 1500 mm (see FIG. 3B).

Thereafter, electrodes 1 and 2 were formed in the same manner as in Example 1, and a current-passing process was performed to form minute gaps 5 to obtain an electron-emitting device. The power consumption of the energization process was about 0.2 W. As a result of measuring the electron emission characteristics of this device, electron emission having an emission current _{Ie of} 2 μA and an emission efficiency α of about 5 × 10 ⁻⁴ was obtained.

As described above, in Examples 1 and 2, the organic solvent of the organometallic compound was used as the material of the fine particles 7, but the SnO having a primary particle size of about 100 ° was used.
_A similar electron-emitting device could be obtained with the SiO ₂ liquid coating agent in which _two fine particles were dispersed.

Example 3 As shown in FIG. 4, the substrate 4 on which the fine particles 9 were dispersed and coated was used without using the support 6 containing the fine particles 7 used in Example 1.
An electron-emitting device can be obtained by providing the thin film 3 and the electrodes 1 and 2 thereon and conducting an electric current.

First, an organic solvent containing an organic palladium compound (Catapaste CCP manufactured by Okuno Pharmaceutical Co., Ltd.) was spin-coated on a substrate 4 by a spinner and baked at 250 ° C. for 10 minutes. This gives P
d Particles 9 were formed on the substrate 4 (see FIG. 4A).

Next, in the same manner as in Example 1, a Ni
A thin film 3 and Au electrodes 1 and 2 were formed (FIG. 4 (b),
(C)). Thereafter, the thin film 3 was energized to form minute gaps 5 to produce an electron-emitting device (see FIG. 4D).

When the electron emission characteristics of this device were measured, the same results as in Example 1 were obtained.

Embodiment 4 As shown in FIG. 5, a step portion is formed in the center of a substrate 4 by a step forming material 10, fine particles are dispersed and applied, a thin film is provided on the step, and a current is applied to obtain an electron-emitting device. Can be.

First, a SiO ₂ liquid coating agent (OC manufactured by Tokyo Ohka Kogyo Co., Ltd.
D) was spin-coated on the substrate 4 by a spinner. Thereafter, it was baked at about 400 ° C. for 1 hour to produce a step forming material made of SiO ₂ having a thickness of about 1500 ° and formed by a photolithographic etching method. Further, Pd fine particles 9 were formed on the steps 4 on the substrate 4 in the same manner as in Example 3 (see FIG. 5A).

Next, a thin film 3 and electrodes 1 and 2 were formed in the same manner as in Example 2 (see FIGS. 5B and 5C). Thereafter, the thin film 3 was energized, and the minute gaps 5 were formed to produce an electron-emitting device (see FIG. 5D).

When the electron emission characteristics of this device were measured, the same results as in Example 2 were obtained.

As described above, in Examples 3 and 4, the organic solvent of the organometallic compound was used as the material of the fine particles 9, but the primary particle diameter of SnO was about 100 °.
_A similar electron-emitting device could be obtained by using a dispersion of SnO ₂ in which _two fine particles were dispersed and dissolved in an organic solvent together with an organic binder.

[Effects of the Invention] As described above, in the present invention, a thin film on a member having fine particles is subjected to an electric current treatment to form minute gaps in the thin film, and the electron emission in the production in which the fine particles are located in the minute gaps By forming the element, fine particles involved in electron emission and minute gaps of a thin film for applying an electric field thereto can be separated by a manufacturing method and a material, and an appropriate material can be selected, manufactured, and designed.

Therefore, by using a high melting point material, etc., which was considered difficult in the conventional method, as an electron 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 view showing a manufacturing process of the electron-emitting device of the present invention, FIG. 2 is a plan view of the electron-emitting device of the present invention, and FIGS. 3 to 5 are electron-emitting devices of another embodiment according to the present invention. Manufacturing process diagram,
FIG. 6 is a plan view showing a conventional electron-emitting device.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Takeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-1-200532 (JP, A) JP-A-2 JP-A-192638 (JP, A) JP-A-1-279541 (JP, A) JP-B-6-101297 (JP, B2) JP-B-7-114106 (JP, B2)

Claims (15)

(57) [Claims] 1. An electron-emitting device having a conductive film including a minute gap, wherein the conductive film is disposed on a member containing fine particles. 2. The conductive film is disposed so as to straddle a step formed on a substrate by a member containing the fine particles, and the minute interval is disposed in the step. The electron-emitting device according to claim 1. 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 method 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 a step of forming minute intervals in a conductive film disposed on a member including fine particles. A method for manufacturing an electron-emitting device. 9. The electron-emitting device according to claim 8, wherein the conductive film is disposed so as to straddle a step formed on the substrate by the member containing the fine particles. 10. 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. 11. The method for manufacturing an electron-emitting device according to claim 8, wherein said minute interval is 1 μm or less. 12. The method according to claim 8, wherein the minute gap is a crack formed in a part of the conductive thin film. 13. The electron-emitting device according to claim 8, wherein the step of forming a minute interval in the conductive thin film on which the fine particles are arranged includes a step of applying a voltage to the conductive film. Production method. 14. The method according to claim 8, wherein the conductive film on which the fine particles are arranged is arranged between a pair of electrodes. 15. The method of manufacturing an electron-emitting device according to claim 8, wherein said electron-emitting device is a surface conduction electron-emitting device.