JPH0594762A - Field emission type electron source and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a field emission type electron source for which a manufacturing process can be simplified and in which a distance between a cold cathode and a gate electrode can be shortened. CONSTITUTION:Thermal oxidation is carried out on the surface of a (n) type silicon substrate 11, and a silicon dioxide layer 14 having thickness of 0.2-0.3mum is formed. Next, for example, a circular pattern is formed on the surface of the silicon dioxide layer 14 by using a resist, and a circular silicon dioxide mask 14a is formed by etching the silicon dioxide layer 14. By etching isotropically the surface of the silicon substrate 11 by a dry etching method, a conical projection part 11a projecting from the substrate being the basis of a cold cathode 10 is formed on the surface of the silicon substrate 11. Thermal oxidation is carried out further on the surface of the silicon substrate 11 on which the projection part 11a is formed, and a silicon dioxide layer 12a having depth of about 0.3-0.5mum is grown up, so that a layer being the basis of an insulating layer 12 can be formed. In this case, thermal oxidation is carried out simultaneously on the surface of the projection part 11a of the silicon substrate 11, so that the conical cold cathode 10 can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission electron source and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, due to the fine processing technology used in the field of integrated circuits or thin films, the field emission type electron source manufacturing technology for emitting electrons in a high electric field has made remarkable progress, and in particular, an electric field having an extremely small structure Emissive cold cathodes are being manufactured. This type of field emission cold cathode is the most basic electron emission device among the main components constituting a triode type micro electron tube or a micro electron gun.

A field emission electron source including a large number of electron emission devices was devised as a constituent element of, for example, a micro triode or a thin display element. The operation and manufacturing method of the field emission electron source is Stanford. Research Institute (Stanford Research Institute) C. A. Journal of Applied Physics by CASpindt et al.
hysics) Vol. 47, No. 12, 5248-5263 (December 1976)
It is known from the research report published in. A.
U.S. Pat. No. 3,789,471 and H. Spint et al.
F. US Pat. No. 4,307, by HF Gray, et al.
No. 507 and No. 4,513,308.

This device is provided with a cold cathode that emits electrons according to the principle of field emission, and a gate electrode that is a field application electrode that applies a positive voltage to apply an electric field to the cold cathode to emit electrons. There is.

As one means for reducing the operating voltage (voltage applied to the electric field applying electrode) of the electron emission type cold cathode, it is possible to mention that the distance between the cathode and the gate electrode is shortened. Emissive electron sources are disclosed in the above-referenced US patents. However, since it is not easy to shorten the distance between the cold cathode and the gate electrode in the conventional structure, an electron emission type cathode having a new structure has been proposed by Sokolich and others (International Electron Device). Meeting: IEDM
1990).

FIG. 3 shows a method of manufacturing an electron emission type cold cathode by Sokolich or the like. First, a mask of silicon nitride (Si ₃ N ₄ ) having a square surface shape is formed on a surface of a silicon substrate having a Miller index of <100>, and an alkaline etchant made of potassium hydroxide or the like is used to form a crystal. Using the difference in etching rate between the surfaces, a square pyramidal recess is formed in the exposed portion other than the mask, and the silicon mold 20 is manufactured. Next, in the post process mold
The surface of the mold 20 is heated in order to peel off 20 to form a thermal oxide layer (silicon dioxide) 21, and polycrystalline silicon 22 is grown on the thermal oxide layer 21 to a thickness of several hundred μm. (A)
To form the structure shown in. Then, the mold 20 is removed, and the polycrystalline silicon 22 having the quadrangular pyramid-shaped or pyramid-shaped protrusions 22a is obtained. The polycrystalline silicon 22 is the substrate electrode of the field emission type electron source, and the protrusion 22a corresponds to the field emission type cold cathode.

Pyramid-shaped protrusions 22 of polycrystalline silicon 22
A silicon dioxide layer 23 to be an insulating layer 23 is formed on the surface having a.
a and a molybdenum layer 24a to be the gate electrode layer 24 are successively deposited to obtain a protrusion structure having a laminated structure shown in FIG. By applying a photoresist 25 on this and etching by oxygen gas plasma, as shown in FIG.
As shown in (C), the tips of the protrusions of the molybdenum layer 24a are exposed. Next, molybdenum layer 24a and silicon dioxide
23a As a result of sequential etching, the projections 22 of the polycrystalline silicon 22
The cold cathode structure shown in FIG. 3D is obtained in which a is exposed and the insulating layer 23 and the gate electrode layer 24 are laminated on the polycrystalline silicon 22 around the protrusion 22a.

[0008]

However, the manufacturing method using Sokolich or the like is as follows.
A silicon mold 20 is manufactured, and the surface of the mold 20 is heated to form a thermal oxide layer 21, and polycrystalline silicon 22 is grown on the thermal oxide layer 21 to a thickness of several hundreds of μm to form a substrate electrode. There is a problem that the manufacturing process is complicated as compared with the conventional manufacturing method such as manufacturing. Further, according to this manufacturing method, the distance between the cold cathode (protrusion 22a) and the gate electrode layer 24 can be shortened, but this distance is an electrical property of the insulating layer deposited on the cold cathode 22a after manufacturing. There is a problem in that the distance between the cold cathode (protrusion 22a) and the gate electrode layer 24 cannot be sufficiently shortened due to a large restriction due to the insulating property.

Therefore, the present invention provides a method for manufacturing a field emission electron source in which the manufacturing process is simplified and the distance between the cold cathode and the gate electrode is shortened.

[0010]

According to the present invention, a convex portion which is a base of a cold cathode which emits electrons based on the principle of field emission formed on the surface of a substrate made of a semiconductor or a metal, and this convex portion are included. A field emission electron source including an electrically insulating insulating layer formed by oxidizing the surface of the substrate and a field applying electrode formed on the insulating layer, and a method for manufacturing the same. ..

[0011]

According to the present invention, with the above structure, a convex portion which is a base of a cold cathode is formed on a substrate made of a semiconductor or a metal, and an insulating layer is formed by oxidizing the surface of the substrate including the convex portion. The manufacturing process can be simplified as compared with the case where the insulating layer is formed on the polycrystalline silicon by vapor deposition or the like as in the conventional example. Further, specifically, the distance between the cold cathode and the gate electrode which is the electric field applying electrode can be shortened.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view of an essential part showing an embodiment of a method of manufacturing a field emission electron source according to the present invention, and FIG. 2 is an electric field manufactured by the method of manufacturing a field emission electron source shown in FIG. It is a principal part side sectional view of an emission type electron source.

In FIG. 2, the portion of the cold cathode 10 is formed so as to project in a conical shape on the silicon substrate 11 which serves as a substrate electrode. Although only one cold cathode is shown in the drawing, a plurality of cold cathodes are usually formed on the silicon substrate 11. An insulating layer 12 is formed around the cold cathode 10 on the silicon substrate 11.
Is formed by oxidizing the surface of the silicon substrate 11, and a gate electrode layer 13 which is an electric field application electrode to which a positive voltage is applied to further emit electrons from the cold cathode 10 is laminated on the insulating layer 12. Has been done. In this case, the insulating layer 12 and the gate electrode layer 13 are formed so as to surround the periphery of the cold cathode 10 and expose the tip portion of the cold cathode 10 as shown in FIG. The upper surface of the gate electrode layer 13 in the vicinity of the cold cathode 10 is formed so as to have the same height as the height of the tip portion of the cold cathode 10.

Next, an embodiment of a method for manufacturing a field emission type electron source will be described with reference to FIG.

First, as shown in FIG. 1A, the specific resistance ρ
= 0.01 to 0.02 Ω · cm, the surface of the n-type silicon substrate 11 is thermally oxidized to form a silicon dioxide layer 14 having a thickness of 0.2 to 0.3 μm. Next, a circular (or square) pattern is formed on the surface of the silicon dioxide layer 14 using a resist, and the silicon dioxide layer 14 is etched to form a circular silicon dioxide mask as shown in FIG. 1 (B). Forming 14a.

Using this silicon dioxide mask 14a, the surface of the silicon substrate 11 is isotropically etched by the dry etching method, and as shown in FIG. 1C, a conical shape protruding from the base substrate of the cold cathode 10 is formed. The convex portion 11a having the is formed on the surface of the silicon substrate 11. In this embodiment, the convex portion 11
Although a has a conical shape, the shape of the cold cathode is not limited to this.

Further, a silicon substrate on which the convex portion 11a is formed
The surface of 11 was thermally oxidized and, as shown in FIG.
A silicon dioxide layer 12a having a depth of about 0.5 μm
Grow. At this time, the surface of the convex portion 11a of the silicon substrate 11 is also thermally oxidized at the same time to form the conical cold cathode 10.

A silicon substrate 11 having such a structure is placed in a vacuum vapor deposition apparatus, and a cold cathode is formed as shown in FIG.
While rotating the substrate 11 around the perpendicular 15 of the axis 10, molybdenum metal to be the gate electrode layer 13 is vapor-deposited obliquely from above the silicon substrate 11 as indicated by an arrow A in FIG.
A degree of gate electrode layer 13 is deposited on the silicon dioxide layer 12a.

Finally, the silicon dioxide mask 14a and a part of the silicon dioxide layer 12a, which are unnecessary as an electron emission source, are removed by a mixed aqueous solution of hydrofluoric acid and ammonium fluoride, and silicon is removed as shown in FIG. Cold cathode 10 on substrate 11
The part corresponding to is exposed. As a result, the insulating layer 12
The gate electrode layer 13 and the gate electrode layer 13 are formed so as to surround the periphery of the cold cathode 10 so that the tip portion of the cold cathode 10 is exposed, and the upper surface of the gate electrode layer 13 near the cold cathode 10 has the tip of the cold cathode 10. It is formed to have the same height as the height of the portion.

Therefore, according to the above-mentioned embodiment, the insulating layer is formed by forming the convex portion 11a, which is the basis of the cold cathode 10, on the silicon substrate 11 and then thermally oxidizing the surface of the silicon substrate 11.
Since 12 is formed, the manufacturing process can be simplified as compared with the case where the insulating layer 12 is formed on the polycrystalline silicon 11 by vapor deposition or the like as in the conventional example. In addition, since the silicon dioxide that is the insulating layer 12 is formed by oxidizing single crystal silicon and has excellent insulating properties, the distance between the cold cathode 10 and the gate electrode layer 13 can be further shortened. It becomes possible to improve the electron emission efficiency.

Although the silicon substrate is used as the substrate in this embodiment, the present invention is not limited to this. For example, a conductive thin film via a support may be used. Also,
Although molybdenum metal was used as the gate electrode, it is not limited to this as long as it has equivalent performance.

[0022]

As described above, according to the present invention, the insulating layer is formed by forming a convex portion which is a base of a cold cathode on a substrate made of a semiconductor or a metal and oxidizing the surface of the substrate including the convex portion. Therefore, the manufacturing process can be simplified as compared with the case of forming the insulating layer on the polycrystalline silicon by vapor deposition or the like as in the conventional example. Further, specifically, since the insulating layer formed by oxidizing single crystal silicon has excellent insulating properties, it is possible to shorten the distance between the cold cathode and the gate electrode that is the electric field applying electrode. is there. As a result, the operating voltage of the field emission electron source can be reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part showing an embodiment of a method of manufacturing a field emission electron source according to the present invention.

FIG. 2 is a side sectional view of a main part of a field emission electron source manufactured by the method for manufacturing the field emission electron source shown in FIG.

FIG. 3 is a side sectional view of an essential part showing a method for manufacturing a conventional field emission electron source.

[Explanation of symbols]

 10 Cold cathode 11 Silicon substrate 12 Insulating layer 13 Gate electrode layer

Front page continuation (72) Inventor Yutaka Akagi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation

Claims (1)

[Claims] 1. A convex portion which is a base of a cold cathode that emits electrons based on the principle of field emission formed on the surface of a substrate made of a semiconductor or a metal, and is formed by oxidizing the surface of the substrate including the convex portion. A field-emission electron source, comprising: an electrically insulating insulating layer formed on the insulating layer; and an electric field applying electrode formed on the insulating layer. 1. A surface of a substrate made of a semiconductor or a metal is formed with a convex portion that serves as a basis of a cold cathode that emits electrons on the basis of the principle of field emission, and the surface of the substrate including the convex portion is oxidized to electrically conduct. A method of manufacturing a field emission electron source, comprising: forming an insulating layer that is insulative, and forming an electric field applying electrode on the insulating layer.