JP2630984B2 - Method for manufacturing electron-emitting device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an electron-emitting device, and more particularly to a method for manufacturing 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 Engineering Electron Phys. Vol. 10, 1290-1296, 19
65 years] This utilizes the phenomenon that electron emission occurs when a current flows through a small-area thin film formed on a substrate in parallel with the film surface, 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)], by ITO thin film [M Hartwell and CJ Vonstad “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. 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 8 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 the Joule heat generated by the application of the voltage, and has a high electrical resistance. The electron emission function is obtained by forming the electron emission portion 8 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.

At the time of electric 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. 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 about 1.
It was about 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 a method for manufacturing an electron-emitting device having a conductive film including minute spaces, wherein the method includes a step of disposing fine particles at least in the minute spaces of the conductive film in which minute spaces are formed. This is a method for manufacturing an electron emitting device.

That is, the present invention separates the fine particles involved in the electron emission and the minute gaps of the conductive film that gives a high electric field thereto by the manufacturing method and the material, and selects an appropriate material, and can design the manufacturing of the electron emitting element. It is a manufacturing method.

 Hereinafter, the present invention will be described in detail.

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

In the manufacturing method 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, 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 (b)).

Further, when the electrodes 1 and 2 are energized, a crack is generated at the center of the thin film 3, and a minute interval 5 of the thin film is formed. The minute interval is a portion where the thin film 3 is locally discontinuous (see FIG. 1 (c)). Depending on the material of the thin film, the thin film may be electrically disconnected by the energization treatment. However, in the present invention, by performing the following steps, the disconnected portion finally becomes an electrically high resistance, and the electron emission An element can be manufactured.

Thereafter, fine particles are dispersed and applied onto the element. As a coating method, there is a method of spin-coating or dip-coating an organic solvent containing fine particles or an organic solvent containing an organic metal or the like, followed by drying. By this step, a structure is obtained in which the fine particles 6 are arranged in the minute interval portions 5 of the thin film 3, that is, in the discontinuous film portion, 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 portions 5 of the thin film 3 containing the fine particles 6.

On the other hand, in the structure of an example of the electron-emitting device manufactured according to the present invention and the manufacturing method thereof, a step forming material is provided,
A substrate having a step portion may be used, and the step portion which is the shape end of the step forming material may be an electron emitting portion. 3 (a) to 3 (d) show the structure and the manufacturing method. In the figure, a step forming material 7 made of an insulating material is deposited and formed on a substrate 4 (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 step forming material 7 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 (see FIG. 3 (c)). Here, the electrodes 1 and 2 are for improving the electrical connection of the voltage applied from the outside for emitting electrons, and do not largely influence the next energization process. As described later, according to this example, the amount of power required for the energization process can be reduced, and the generation position of the Joule heat, the heat conduction and the thermal expansion of the material during the energization process by the electrode shape can be reduced as described later. This is because good energization processing is performed without much consideration.

After that, when the electrodes 1 and 2 are subjected to an energizing process, the step portion of the thin film 3 is energized and a minute interval portion 5 of the thin film is formed. The minute interval portion is a portion where the thin film 3 is locally discontinuous as described above (see FIG. 3D).

Also in this example, the thin film may be electrically disconnected by the energization process. However, as described above, the disconnected portion eventually becomes an electrically high resistance, and can be used as an electron-emitting device.

Thereafter, fine particles are dispersed in the same manner as in the above-described example, and the thin film 3 is dispersed.
In this case, the fine particles 6 are arranged in the minute gap portions 5, that is, in the discontinuous film portion located on the side wall of the step portion of the step forming material 7, and an electron-emitting device is obtained (see FIG. 3E).

The element formed in this manner can obtain electron emission in the same manner as in the above-described example. Note that, in this example, apart from the above-described example, 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 electron-emitting device according to the present invention shown in the above example, the material of the thin film forming the minute gaps related to the electron emission, that is, the discontinuous thin film portion, is a wide range of materials commonly used as surface conduction electron-emitting devices. , For example Sn
Materials suitable as the electron-emitting material, such as metal oxides such as O ₂ , In ₂ O ₃ and PbO, metals such as Au and Ag, carbon, and various other semiconductors, can be used. However, in the present invention, since fine particles relating to electron emission can be separately arranged, 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 interval by an energization process. Can be used. 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 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,
Examples include, but are not limited to, Cu, Al, Ni, Pd, Pt, W, Ta, Mo, Cr, Ti.

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
Metal, oxides such as SnO ₂ , In ₂ O ₃ , BaO, MgO, etc., or carbon or a mixture thereof, but is not limited thereto. In addition, in the present invention, the size of the fine particles is usually preferably several tens to several thousand of 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 , and Al ₂ O ₃ , the surface of the substrate itself can be processed and the substrate material itself can be used as a step forming material.

It is necessary to adjust the thickness of the step forming material 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 the film thickness on the step is 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. In general, the thickness of the step forming material, that is, the height of the step portion is preferably about 1/3 to 3 times the thickness of the deposited 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 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, according to the present invention, particularly, the selection materials of the thin film having the fine particles related to the electron emission and the minute gap for applying a high electric field thereto are 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 having an embodiment shown in Fig. 2 was manufactured based on the manufacturing process shown in Fig. 1 described above.

First, a thin film 3 was formed on a clean quartz glass substrate having a thickness of about 1 mm by depositing Ni in 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, 50 mm thick Cr is used as an underlayer on both ends of the thin film 3.
Au electrodes 1 and 2 having a thickness of 0 ° were formed by a mask vapor deposition method (see FIG. 1B).

Further, the electrodes 1 and 2 were subjected to an energization treatment, and a minute interval 5 was formed in the center of the thin film 3. The power consumption of the energization process is
It was about 0.8W. (See FIG. 1 (c)).

Then, an organic solvent containing an organic palladium compound (Catapaste CCP manufactured by Okuno Pharmaceutical Co., Ltd.) is spin-coated on the device by a spinner, baked at about 250 ° C. for 10 minutes, and dispersed and coated Pd fine particles are arranged. 6 (first
FIG. (D)).

As a result of measuring the electron emission characteristics of the electron-emitting device manufactured in the above steps, the electron emission having an emission current _Ie = 1 μA and an emission efficiency α (ratio of the emission current to the in-film current) = 1 × 10 ⁻⁴ was found. Obtained.

Example 2 As shown in FIG. 3, a step portion was formed on a substrate 4 using a step forming material 7, and an electron-emitting device was manufactured by the same steps as in Example 1 below.

As a manufacturing method, first, an SiO ₂ liquid coating agent (OCD manufactured by Tokyo Ohka Kogyo Co., Ltd.) is spin-coated on a clean quartz glass substrate with a thickness of about 1 mm by a spinner, and then about 400 ° C.
For 1 hour to obtain a SiO ₂ film having a thickness of about 2000 °, and a step forming material 7 having a step portion was formed by a photolithographic etching method (see FIG. 3A).

Next, a thickness of 1000 mm is applied so as to cover the step portion of the step forming material 7.
(See FIG. 3 (b)).

Thereafter, the electrodes 1 and 2 were formed in the same manner as in Example 1, and an energization process was performed to form the minute interval portions 5. The power consumption of the energization process was about 0.2 W. Further, Pd fine particles were arranged at minute intervals by applying and baking an organic solvent containing an organic palladium compound, and this was used as fine particles 6 (FIGS. 3 (c) and (d)).
(E)).

As a result of measuring the electron emission characteristics of the electron-emitting device manufactured by the above process, the emission current _Ie = 2 μA and the emission efficiency α = 5 ×
About 10 ^-4 electron emission was obtained.

In Examples 1 and 2, the Pd material was used as the fine particles. However, even when the SnO ₂ fine particles having a primary particle size of about 100Å are dispersed and dissolved in an organic solvent together with an organic binder, the SnO ₂ fine particles are applied to the device and fired to arrange the SnO ₂ fine particles. An emission device was obtained.

[Effects of the Invention] As described above, in the present invention, by arranging the fine particles in the minute gaps of the thin film generated by the energization process, the fine grains involved in electron emission and the minute gaps of the thin film for applying an electric field thereto are formed. It is possible to select, manufacture, and design a suitable material for each material, separated by manufacturing method and material.

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 an explanatory view showing a method for manufacturing an electron-emitting device according to the present invention, FIG. 2 is a plan view showing an electron-emitting device manufactured according to the present invention, and FIG. FIG. 4 is an explanatory view showing a method, and FIG. 4 is an explanatory view showing a conventional electron-emitting device.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Takeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-1-279540 (JP, A) JP-A-2 -192638 (JP, A)

Claims (8)

(57) [Claims] 1. A method for manufacturing an electron-emitting device having a conductive film including minute spaces, comprising a step of disposing fine particles at least in the minute spaces of the conductive film having minute spaces. Of manufacturing an electron-emitting device. 2. The electron-emitting device according to claim 1, wherein the conductive film is provided so as to straddle a step on the substrate, and the minute interval is provided at the step. Production method. 3. The method for manufacturing an 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 method for manufacturing an electron-emitting device according to claim 1, wherein said minute interval is 1 μm or less. 5. The method for manufacturing an electron-emitting device according to claim 1, wherein the minute interval is a crack formed in a part of the conductive film. 6. The method of manufacturing an electron-emitting device according to claim 1, wherein the step of forming the minute interval includes a step of applying a voltage to the conductive film. 7. The method for manufacturing an electron-emitting device according to claim 1, wherein said conductive film is disposed between a pair of electrodes. 8. The method according to claim 1, wherein said electron-emitting device is a surface conduction electron-emitting device.