JP2632359B2 - Electron emitting device and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cold cathode type 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)], 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 5 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 energization process called forming. That is, the electrode 1
By applying a voltage between the electrode and the electrode 2, the thin film 3 is energized, and the generated Joule heat causes the thin film 3 to be locally destroyed, deformed or deteriorated, thereby emitting electrons in an electrically high resistance state. The electron emission function is obtained by forming the portion 5.

[Problem to be Solved by the Invention] However, in the conventional surface conduction electron-emitting device, as shown in FIG. 4, the electron-emitting portion 5 is formed in the neck-shaped thin film 3, and the electron-emitting portion 5 The actual size of the electron-emitting portion is 0.5 to 4 μm.
It is said to be about m width, which is an extremely fine range, and the position of the formed electron-emitting portion 5 with respect to the energizing direction varies from element to element due to thin-film forming conditions and delicate forming conditions. It was difficult to control.

Such a variation in the position of the electron-emitting portion, when applied as an electron-emitting device, causes an excessive load on an electron control system, and is a factor hindering its application.

On the other hand, the size of the neck-shaped thin film of the conventional surface conduction electron-emitting device is about 0.1 to 0.5 mm in both width and length, and the positional accuracy of the electron-emitting portion is determined by the size of the thin film. That is, it is possible to reduce variations in the position of the electron-emitting portion by reducing the size of the neck-shaped thin film in the direction of current flow. However, on the other hand, a decrease in the distance between the electrodes causes a significant increase in defects such as short circuits, and also causes various problems such as an increase in power consumption during forming.
At present, the production of a device having a thinned thin film has not been performed.

SUMMARY OF THE INVENTION An object of the present invention is to solve such conventional drawbacks and to enable an electron emission portion to be formed at a desired position on a thin film (for example, a neck shape) with high accuracy, thereby increasing the degree of freedom in device design and manufacturing process. An object of the present invention is to provide an electron-emitting device that can further increase the energy required for forming.

[Means for Solving the Problems] A first aspect of the present invention is that a thin film including an electron emitting portion is disposed between electrodes on a flat substrate, and the substrate side surface in contact with the thin film between the electrodes is an insulating surface. Electron-emitting device,
A step portion due to a height difference is formed on the substrate side surface in contact with the thin film between the electrodes, the thin film is disposed so as to straddle the step portion, and the electron emission portion of the thin film is formed at the position of the step portion An electron-emitting device characterized in that:

The first feature of the present invention is further characterized in that the electron-emitting portion is a locally deformed portion of the thin film.

A second aspect of the present invention is a method for manufacturing an electron-emitting device in which a thin film including an electron-emitting portion is disposed between electrodes on a flat substrate, and the substrate-side surface in contact with the thin film between the electrodes has an insulating surface. Forming a step portion due to a height difference on the substrate side surface in contact with the thin film between the electrodes, arranging the thin film so as to straddle the step portion, and energizing the thin film to emit electrons at the position of the step portion. Forming a portion.

The second feature of the present invention is further characterized in that the step of energizing includes a step of forming a locally deformed portion in the thin film.

As used herein, the term “substrate having a step portion” refers to a case where the step portion is formed by providing a step forming material on a flat substrate, A part may be formed.

 Hereinafter, the present invention will be described in detail with reference to the drawings.

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 showing an example of an electron-emitting device of the present invention.

In order to manufacture an electron-emitting device, first, a step forming material 7 is formed by patterning an insulating film on a substrate 4 (see FIG. 1A).

Next, a thin film 3 made of an electron emitting material is deposited and formed so as to straddle the step of the step forming material 7 (see FIG. 1B).

At this time, the film thickness of the thin film 3 at the step portion is generally smaller than that of the flat portion by a film forming method using a vacuum deposition method or a liquid coating method. Therefore, the thin film 3 of the step portion 6 has a film quality that is more easily changed and is a portion that is more easily formed than the other thin film portions during the energization process.

Next, electrodes 1 and 2 are formed by depositing and forming a conductive metal on both ends of the thin film 3 (see FIG. 1 (c)). However, the electrodes 1 and 2 are for improving the electrical connection of a voltage applied from outside for electron emission,
It does not significantly affect the next forming step.
As described later, according to the present invention, the amount of power required for forming can be reduced according to the present invention, and the generation position of Joule heat, heat conduction, thermal expansion, and the like of the material during forming due to the electrode shape are taken into consideration as in the related art. This is because a good forming process can be performed without the need.

Thereafter, when an energization process is performed between the electrodes 1 and 2, the electron emitting portion 5 in which the thin film 3 in the step portion 6 is formed is formed, and an electron emitting element can be obtained (FIG. 1 (d)).
reference).

In the present invention, in order to form a stepped portion, in addition to using an insulating film layer as shown in FIG. 1, the surface itself of the substrate 8 is processed by a photolithographic etching method as shown in FIG. It is also possible to obtain a step portion, on which the electron-emitting portion 5 can be formed by the method shown in FIGS. 1 (b) to 1 (d).

The step portion may be provided in advance at a desired position in the thin film where the electron emission portion is to be formed. Further, since the shape of the step portion in the direction of the substrate surface is based on a photolithographic etching method or the like, a fine and free shape step portion can be formed. Therefore, a plurality of electron-emitting portions can be formed finely and freely in the direction of the substrate surface.

In addition, since the electron-emitting portion has a structure obtained by forming the thin film on the side surface of the step portion, the area of the thin film portion on the side surface of the step portion can be made very narrow by adjusting the height and the thickness of the thin film. For example, when a step forming material and a thin film are formed by a vacuum deposition method, it is easy to control the film thickness in units of several + Å.
It can also be made as small as 100 mm. Therefore, the area of the electron emitting portion obtained by forming the thin film portion on the side surface of the step portion can be reduced to about several hundreds of degrees, and can be controlled with high accuracy.

In addition, by limiting and miniaturizing the area where the forming process is actually performed, the energy required for forming can be reduced as compared with the related art. Therefore, the thin film to be formed can be formed easily even with a material having a relatively high melting point or a material having a low resistance, without worrying about cracking of the substrate or peeling of the thin film due to heat generation as compared with the conventional example.

In the present invention, as the material of the thin film forming the electron-emitting portion, a wide range of materials commonly used can be used without any particular limitation, for example, SnO ₂ , In ₂ O ₃ , PbO
And the like, metals such as Au and Ag, carbon, and various other semiconductors can be used.

The thickness of the thin film may be any thickness 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 0.01 to 5 μm, preferably 0.01 to 5 μm. ２2 μm.

Further, as the electrode member, a wide range of commonly used electrode members can be used without any particular limitation.For example, a normal metal such as Ni, Pt, Al, Cu, Au or other conductive member is used. can do.

Further, the step forming material is not particularly limited as long as it is a commonly used high-resistance insulating material, for example, glass, SiO ₂ , Si ₃ N ₄ , MgO, TiO ₂ , Al ₂ O _{3 and the} like. Can be used.

It is necessary to adjust the film thickness of the step forming material by the film thickness of the thin film deposited on the step and the film forming method. Usually, the thin film on the step portion is not electrically disconnected, and It is necessary that the thickness of the thin film is smaller than that of the other portions or the quality of the film is 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.

Example Example 1 The electron-emitting device of the present invention shown in FIG. 2 was manufactured by the manufacturing steps shown in the process diagrams of FIGS. 1 (a) to 1 (d).

First, a thin film of Si ₃ N ₄ (silicon nitride) is deposited on a clean quartz glass substrate having a thickness of about 1 mm by a plasma CVD method to a thickness of 1000 mm, and is patterned by a photolithographic etching method. 2 and the step forming member 7 was provided.

Next, on the substrate, a thin film of Au was formed in a shape shown in FIG. At this time, the shape of the thin film was l = 2 mm and w = 0.3 mm shown in FIG. 2 (see FIG. 1B). In FIG. 1 (b) and FIG. 2, the intersection of the constricted neck portion of the thin film 3 and the pattern end of the step forming material 7 becomes the step portion 6 of the thin film 3. Further, the thin film 3 is deposited so as to straddle the stepped portion 6, and electrical conduction at the stepped portion is maintained.

Next, electrodes 1 and 2 were formed by laminating 1000 mm thick Ni (nickel) on a 50 mm thick underlying layer of Cr (chromium) by a mask EB vapor deposition method so as not to overlap the neck-shaped thin film 3 (first example). FIG. (C)).

The element thus formed is placed in a vacuum vessel with electrodes 1,
A voltage of about 2 V was applied to 2 to conduct and heat, and a forming process was performed. The power consumption required for the forming process is 0.
It was about 2W. When observed with an electron microscope after the forming process, local deformation that was recognized as an electron-emitting portion was observed at the stepped portion 6.

As a result of measuring the electron emission characteristics of these devices, electron emission having an emission current Ie = 0.5 μA and an emission efficiency α (ratio of emission current to in-film current) = 1 × 10 ⁻⁴ was obtained.

The element manufactured in the above-described steps can be selectively etched at the time of photolithographic etching of the step forming material 7 and the substrate 4, and the factor that determines the height of the step is not the control of the etching depth but the control of the step. It is determined by controlling the deposition thickness of the forming material 7. In this embodiment, as described above, the deposited film thickness by the vacuum deposition method can be controlled with high accuracy of several tens of units. Therefore, since the deposition control accuracy of the electrodes 1 and 2 may be high, it has a feature of a manufacturing method capable of controlling even if the region of the electron emitting portion is extremely narrow.

In the present embodiment, a Si ₃ N ₄ film formed by plasma CVD was used as the step forming material. Alternatively, a liquid coating material of SiO ₂ (for example, OCD manufactured by Tokyo Ohka Kogyo Co., Ltd.) was coated on the substrate 4 by a spinner. Then, by sintering at a temperature of 400 ° C. or more for about 1 hour, the SiO 2 having a controlled film thickness is obtained.
_Two films can be obtained. An electron-emitting device using the same as the step forming material 7 was able to obtain an electron-emitting device similar to that described above.

Example 2 An electron-emitting device was manufactured by processing the substrate surface of the substrate 8 itself to form a step as shown in FIG. 3 without using the step forming material as in Example 1.

That is, first, a photoresist was patterned on a clean quartz glass substrate having a thickness of about 1 mm. This quartz substrate was etched with a hydrofluoric acid aqueous solution. Etching depth is almost 10
00 °. Thereafter, the photoresist was peeled off, and the remaining etching portion was used as a step portion. And Example 1
An electron-emitting device was manufactured in the same manner as in Example 1 and the electron-emitting characteristics were measured. As a result, the same characteristics were exhibited.

This manufacturing method has a feature that the manufacturing process can be simplified because there is no step of forming the step forming material.

[Effects of the Invention] As described above, the electron-emitting device of the present invention specifies the forming position based on the step shape and the step height on the substrate and the shape and thickness of the thin film deposited thereon, and determines the position of the electron-emitting portion. By controlling the position and the area, the position and the area of the electron emitting portion with respect to the direction of current, which have been difficult to control conventionally, can be controlled and formed with extremely high precision and high reproducibility. Also, unlike the conventional method in which the neck portion of the thin film itself is miniaturized to control the position and area of the electron-emitting portion, there is no instability in manufacturing the device. Therefore element design,
The range of options for manufacturing process design can be greatly expanded.

Furthermore, if the region of the electron-emitting portion is controlled by a vacuum deposition method capable of controlling the film thickness with high accuracy, the portion serving as the emission region can be limited to a very small value. Therefore, since the energy required for forming can be reduced, the range of choice of the thin film material can be expanded as compared with the conventional method.

[Brief description of the drawings]

1 (a) to 1 (d) are process diagrams for manufacturing the electron-emitting device of the present invention, FIG. 2 is a plan view showing an example of the electron-emitting device of the present invention, and FIG. FIG. 4 is a plan view of a conventional electron-emitting device.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshihiko Takeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP44-27852 (JP, B1) JINKO Sho44 −24419 (JP, Y1)

Claims (4)

(57) [Claims] 1. An electron-emitting device in which a thin film including an electron-emitting portion is disposed between electrodes on a flat substrate, and the substrate-side surface in contact with the thin film between the electrodes has an insulating surface. A step portion due to a height difference is formed on the substrate side surface in contact with the substrate, the thin film is disposed so as to straddle the step portion, and the electron emission portion of the thin film is formed at the position of the step portion. Characteristic electron-emitting device. 2. The electron-emitting device according to claim 1, wherein the electron-emitting portion is a locally deformed portion of the thin film. 3. A method for manufacturing an electron-emitting device in which a thin film including an electron-emitting portion is disposed between electrodes on a flat substrate and a substrate-side surface in contact with the thin film between the electrodes has an insulating surface. A step portion due to a height difference is formed on the substrate side surface in contact with the thin film between them, and the thin film is arranged so as to straddle the step portion and the thin film is energized to form an electron emission portion at the position of the step portion. A method for manufacturing an electron-emitting device, comprising: 4. The method according to claim 3, wherein the step of energizing includes a step of forming a locally deformed portion in the thin film.