JPH02126532A - Electron emission element - Google Patents

Abstract

PURPOSE:To obtain a good electron emission element having no ununiformity in characteristics of each of the element by making the surface of a thin first insulator layer and a second insulator layer into a same plane without a difference in level and a metal layer formed thereon into a film without recessed and projecting parts. CONSTITUTION:An electron emission element is constituted such that a part of a conductive layer 11 is convexly formed, and a thin insulating layer 12 is formed on the convex part of the conductive layer 11, and an insulator layer 13 with such a thickness that can make the same plane with the surface of the thin insulator layer 12 is formed on the conductive layer 11 excluding the convex part. Moreover, a thin metal layer 14 is formed on the insulators 12 and 13 of the above 2 parts. It is possible, therefore, to form the thin insulator layer 12 and the thin metal layer 14 from which an electron is emitted as an uniform film without recessed and projecting parts. Thereby, it is possible to form a good electron emission element free from a crack, unstability and deterioration in the characteristics of the element at a part without a difference in level.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electron-emitting device that can be used as an electron source for various electron beam application devices such as electron microscopes, electron beam exposure devices, and CRTs.

BACKGROUND OF THE INVENTION Conventionally, thermionic emission from a hot cathode has been used as an electron source in electron beam devices such as electron microscopes and CRTs. However, electron emission using such a hot cathode has problems such as the need for heating means and energy loss due to heating. Therefore, research has been conducted on electron-emitting devices that do not rely on heating, that is, so-called cold cathodes, and several types of electron-emitting devices have been proposed.

For example, apply a reverse bias voltage to the PN junction.

A voltage is applied to a metal that causes an avalanche breakdown phenomenon to emit electrons out of the device, or a metal with a shape that tends to cause electric field concentration to generate a locally high-density electric field, and electrons are emitted from the metal to the outside of the device. Field-effect type devices that emit
MIM type, etc., which have an insulator layer-metal layer structure, and by applying a voltage between these two metals, electrons that have passed through the insulator layer are emitted from the metal layer to the outside of the element due to a tunnel effect. Electron-emitting devices have been proposed.

Among the cold cathodes, the MIM type electron-emitting device will be described in detail with reference to FIG.

The MIM type electron-emitting device has a structure in which a thin metal layer 43 is laminated on a metal layer 41 with a thin insulating layer 42 interposed therebetween, as shown in FIG.

By applying a voltage higher than the work function of the metal layer 43 to the metal layer 41 and the metal layer 43 by the power source 44, electrons having energy higher than the vacuum level among the electrons tunneled through the insulator layer 42 are transferred to the metal layer 43. layer 43
They are emitted from the surface as emitted electrons 45. In addition, in order to obtain a high release effect.

It is desirable to form the insulator layer 42 as thin as possible within a range that does not cause dielectric breakdown, and the metal layer 43 as thin as possible within a range that allows sufficient current to flow.

Conventionally, this MIM type electron-emitting device has a configuration as shown in Fig. 5 presented in "Cathode Ray Tube Using Tunnel Cathode J (April 30, 1968)" of the Materials of the Electronic Equipment Research Committee of the Television Society. Monoya, Japanese Patent Publication No. 63-67
There is a structure as shown in FIG. 6, which is described in Japanese Patent No. 17. That is, in the case of FIG.
The structure is such that a metal layer 52 of l is formed, Al2O3 is formed as an insulator layer 53 on it, SiO is formed as an insulator layer 54, and a metal layer 55 of Au is formed thereon. By applying a voltage between the metal layer 550,
This is to cause electrons to be emitted from the electron emission region 56 of the metal layer 55. In the case shown in FIG. 6, a metal layer 62 is formed on a substrate 61, and an insulator layer 63 is further formed on the metal layer 62. Then, a metal layer 64 is formed in a direction perpendicular to the direction of the metal layer 62.
By applying a voltage between the metal layer 62 and the metal layer 64, electrons are emitted from the region where the metal layer 62 and the metal layer 64 intersect.

Problems to be Solved by the Invention However, due to the structure of the previously proposed MIM type electron-emitting device, the thin insulating layer through which electrons pass through tunnels and the thin metal layer through which electrons are emitted are uneven. Since the insulator layer and the metal layer are formed on a solid base, the formed insulator layer and metal layer also tend to have unevenness, the film thickness becomes non-uniform, and the characteristics thereof tend to become unstable. In particular, when a thin metal layer has irregularities, it is easy to cause poor conduction due to cracks at the stepped portions, and deterioration of characteristics due to uneven film thickness.Furthermore, if multiple layers of these are formed in an array, the characteristics of each element will be affected. There was a problem that the non-uniformity became significant. The present invention aims to solve the problems of the prior art.

Means for Solving the Problems The first invention provides a conductive layer formed in a partially convex shape, a thin first insulating layer formed on the conductive layer formed in a convex shape, a second insulator layer formed on the conductive layer so as to be flush with the surface of the thin first insulator layer; and a metal formed on the two portions of the insulator layer. It has a layer.

Further, a second aspect of the present invention provides a substrate, a conductive layer formed on a predetermined portion thereof, a thin first insulator layer formed on the conductive layer, and a thin first insulator layer formed on the conductive layer. The second insulator layer is formed on a predetermined portion of the substrate so as to be flush with the layer surface, and the metal layer is formed on the insulator layer in the two portions.

According to the above structure, the present invention can form a thin insulator layer and a thin metal layer from which electrons are emitted as a uniform film with no unevenness, so cracks at step portions and device characteristics can be avoided. It is possible to provide a good electron-emitting device without instability or deterioration, and even if a plurality of devices are formed in an array, a good electron-emitting device without non-uniformity in the characteristics of each device can be provided. It is something that can be provided.

Example Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic cross-sectional view of an electron-emitting device according to a first embodiment of the present invention.

In the same figure, 11 is a conductive layer, 12 is a thin insulating layer,
13 is an insulator layer, 14 is a metal layer, and 15 is an electron emission region. In the electron-emitting device of the present invention, a part of the conductive layer 11 is formed in a convex shape, a thin insulating layer 12 is formed on the convex part of the conductive layer 11, and a thin insulating layer 12 is formed on the conductive layer 11 other than the convex part. An insulator layer 13 is formed to a thickness such that it is flush with the surface of a thin insulator layer 120 . Furthermore, a thin metal layer 14 is formed on the insulator layers 12 and 13 of these two parts. Then, the metal layer 14 is set to “+”,
By applying a negative voltage to the conductive layer 11, a strong electric field is formed in the thin insulator layer 12 below the electron emission region 15, electrons are extracted from the conductive layer 11, and the thin insulator layer 12
Electrons are transmitted through the metal layer 14 by a tunneling phenomenon, and electrons having an energy higher than the work function of the metal layer 15 are emitted from the electron emission region 15.

According to the structure of the present invention, since there is no step part, the thin insulating layer 12 and the metal layer 14 can be formed in a planar shape, and the film thickness can be easily made uniform, thereby stabilizing the device characteristics. was completed.

Next, FIG. 2 (al~+g+) shows the manufacturing process of the electron-emitting device of the present invention. First, a metal made of, for example, At, Ta, etc. is placed on a glass substrate 21 as a conductive layer 22.
For example, a film having a thickness of about 0.1 to 1 μm was formed by a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputter vapor deposition method, etc. (FIG. 2(a)). Next, a resist layer 23 is formed on the conductive layer 22 by a conventional photolithography technique (FIG. 2(b)), and then, for example, by an ion milling method.
The conductive layer 22 is etched to a thickness d, for example, about 0.05 to 0.5 μm, using a wet etching method or the like as shown in FIG. 2(C).
), and further thereon, for example, 5iOz, Al 203. T
After forming an insulator such as azOs to a thickness of d using, for example, electron beam evaporation or sputter evaporation (Fig. 2(d))
, the resist layer 23 was lifted off and removed (Fig. 2 (
e)). Next, a thin insulator layer 25, such as Alz03 or T, is formed by thermal oxidation in an oxygen atmosphere or anodic oxidation.
A 205 was formed to have a thickness t, for example, about 50 to 200 mm (FIG. 2(f)). Then, a metal layer 26, for example Aμ, is formed on the insulator layers 24 and 25 of the two parts.

AI, Mo, W, etc. were formed to a thickness of about 50 to 200 mm by resistance heating evaporation, electron beam evaporation, sputter evaporation, etc., to form an electron-emitting device of the present invention (FIG. 2(g)). . As a result, an electron-emitting device with uniform electron-emitting characteristics and good stability was obtained.

Note that although the above-mentioned practical example shows an example in which a substrate is provided under the conductive layer, the effects of the present invention are not lost even if the substrate is not provided.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a schematic cross-sectional view of an electron-emitting device according to a second embodiment of the present invention, in which 31 is a substrate, 32 is a conductive layer, 33 is an insulator layer, 34 is a thin insulator layer, and 35 is a metal layer. show.

The structure of the electron-emitting device of this example is that a conductive layer 32 is formed at a predetermined portion on a substrate 31, a thin insulating layer 34 is formed on this conductive layer 32, and a conductive layer 34 is further formed on the substrate 31. An insulator layer 33 is formed in a predetermined part other than the part where the layer 32 is formed so as to be flush with the surface of the thin insulator layer 340.0 and 1, the insulator layer 33 in these two parts A thin metal layer 35 is formed on and 34. The electron-emitting device of the present invention has a first
It can be created in exactly the same way as the process after etching the conductive layer into a convex shape in the manufacturing process in the example of
As a result, the characteristics of the electron-emitting device were uniform, completely stable, and good.

Note that, although an embodiment relating to a single electron-emitting device has been described here, the effects of the present invention are also exhibited in an array formed by forming a plurality of electron-emitting devices.

Effects of the Invention As described above, the present invention makes the surfaces of the thin first insulating layer and the second insulating layer the same plane with no steps, and the metal layer formed thereon is a film with no unevenness. By doing so,
A uniform film with no cracks at the step portions was obtained, and an electron-emitting device with stable and uniform characteristics could be obtained. Alternatively, a plurality of electron-emitting devices may be formed in an array.

It is possible to provide a good electron-emitting device with no non-uniformity in the characteristics of each device.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an electron-emitting device according to the first embodiment of the present invention, FIG. The figure is a schematic cross-sectional view of an electron-emitting device according to a second embodiment of the present invention, and FIGS. 4, 5, and 6 are schematic cross-sectional views of conventional electron-emitting devices. 11, 22, 32, etc. - Conductive layer, 12.13.24.
25.33°34...Insulator layer, 14.26.35.
...metal layer, 21.31...substrate. Name of agent: Patent attorney Shigetaka Awano and one other famous confectionery diagram (0'1 Figure 55)

Claims (2)

[Claims] (1) a partially convex conductive layer; a thin first insulator layer formed on the convex conductive layer;
a second insulator layer formed on the conductive layer so as to be flush with the surface of the thin first insulator layer; and a metal formed on the two portions of the insulator layer. An electron-emitting device characterized by having a layer. (2) a substrate, a conductive layer formed on a predetermined portion of the substrate, a thin first insulator layer formed on the conductive layer, and a surface flush with the surface of the thin first insulator layer; An electron-emitting device comprising: a second insulator layer formed on a predetermined portion of the substrate; and a metal layer formed on the insulator layer of the two portions. .