JPH09270229A - Field emission electron source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a field emission electron source which can provide high electric current density. SOLUTION: An intense electric field is converged into tip end parts 3 and electrons are emitted out of the cathode tip end parts 3 due to the field effect by applying positive voltage to a second electrode layer 6 relative to a first electrode layer 2. The electron emitted out of the cathode tip end parts 3 are accelerated and come into collision against a mesh electrode 7 by applying higher voltage to the mesh electrode 7 than that applied to a gate electrode 6. At that time, secondary electrons in the number more than that of primary electrons are emitted out of the mesh electrode 7 made of a metal and the secondary electrons amplified and emitted by the mesh electrode 7 arrive at an anode 8 to which further higher voltage is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold electron source which is expected to be applied to a flat type solid state display device or an ultra high speed micro vacuum device. In particular, the present invention relates to a field emission electron source capable of realizing a large current operation.

[0002]

2. Description of the Related Art Advances in fine processing technology for semiconductors have made it possible to form minute field emission cathodes. Spindt et al. Proposed a cone-type field emission cathode, and attention has been paid to a small field emission electron source (Reference 1: CASpindt,
J. Appl. Phys. Vol.39, p.3504 (1986)).

The structure and manufacturing method of the field emission cathode proposed by Spindt are shown in FIG. 4 as a first conventional example. (A) An insulating layer 102 and a metal film 103 to be a gate are formed on the surface of the conductive substrate 101. Small holes 104 are formed in the metal film 103 and the insulating layer 102 by a normal photolithography process.
(B) Next, a sacrificial layer 105 of an alumina layer is deposited on the substrate 101 at a shallow angle. By this step, the gate diameter is reduced and the gate electrode film is covered with the sacrificial layer 105. (C) Metal 1 that will later become the emitter such as molybdenum
06 is deposited perpendicular to the substrate. Since the gate diameter becomes smaller with vapor deposition, a conical emitter (cathode) 107 can be formed inside the small hole. (D) Then, unnecessary metal is removed by a lift-off method by etching the sacrificial layer. This element operates by drawing electrons into a vacuum from the tip of the emitter 107 by the gate electrode 103 and receiving the electrons by an anode electrode (anode) separately provided opposite to the emitter.

[0004]

Since the electron source shown in the above embodiment has a steep cathode tip portion and a minute gate aperture, it is possible to generate an electric field by applying a relatively low voltage to the gate electrode. It is possible to obtain the emission current. However, since the area of the electron emitting portion at the tip of the cathode is extremely small, the current that can be emitted from one element of the electron source is limited to several μA to several tens of μA.

In order to increase the current density, a method of arranging and using an electron source in a high density has been proposed, but since the electron source is manufactured by the photolithography technique, the integration density is limited. . Further, even if integrated at a high density, only the electron source that easily emits a specific current operates due to the variation in the photolithography technique, and eventually it is difficult to obtain a sufficiently large current density. .
Therefore, the range of application is limited, and there is a problem in reliability during high current operation.

The present invention overcomes such problems and provides a highly reliable field emission electron source with a large current density.

[0007]

The present invention is based on the fact that the emission current from the cold cathode is increased by using the electron amplification function of secondary electrons. Specifically, the means for solving the problems according to the invention of claim 1 emits secondary electrons by receiving a primary electron source made of a cold cathode which emits electrons from a solid surface by a field effect and a primary electron emitted from the cold cathode. A field emission type electron source having a secondary electron source.

The invention of claim 2 is the field emission type electron source according to claim 1, wherein the number of the secondary electrons is larger than the number of the primary electrons.

According to a third aspect of the present invention, the primary electron sources are arranged in an array on the substrate, and the secondary electron sources are arranged so as to face the primary electron source at a constant distance. The field emission type electron source according to claim 1.

The invention of claim 4 is the field emission type electron source according to claim 1, wherein the primary electron source and the secondary electron source are formed on the same substrate.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) The structure of a field emission electron source according to the first embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 is a glass substrate on which a first electrode layer 2 is formed. And
On the surface of the electrode layer 2, a cone-shaped microstructure 4 having a sharp tip 3 is formed. An insulating layer 5 and a second electrode layer 6 (gate electrode) are formed on the peripheral surface of the substrate. Further, a metal mesh electrode 7 serving as a secondary electron source is installed at a fixed distance from the tip portion 3. By applying a positive voltage (V1) to the second electrode layer 6 with respect to the first electrode layer 2, a high electric field is concentrated on the tip 3 and electrons are emitted from the cathode tip 3 due to the field effect. . A voltage (V2) higher than the voltage applied to the gate electrode 6 is applied to the mesh electrode 7, and the primary electrons 9 emitted from the cathode tip 3 are accelerated and collide with the mesh electrode 7. At this time, the number of secondary electrons 10 that are equal to or larger than the number of primary electrons is emitted from the mesh electrode 7 made of metal, and the secondary electrons amplified and emitted from the mesh electrode 7 are applied to the anode 8 to which a higher voltage (V3) is applied. To reach.

In this embodiment, a glass substrate is used for the structure of the primary electron source and a substrate having an electrode layer formed on the surface thereof is used. However, a conductive substrate such as a semiconductor substrate made of silicon or a metal substrate is used. Is also possible. Further, although a metal material is used for the secondary electron source, it is not particularly limited as long as it is a conductive material that emits secondary electrons. It is also possible to coat the surface of a conductive material with a material such as an oxide that easily emits secondary electrons. In addition, in the present embodiment, one hole of the mesh of the secondary electron source is installed corresponding to one element of the primary electron source, but the secondary electron is provided for a plurality of primary electron sources. It is also possible to install one hole of the source mesh correspondingly.

(Second Embodiment) In the above-described embodiment, an example is shown in which the secondary electron source is separately installed facing the primary electron source with a certain distance therebetween. The secondary electron source and the secondary electron source can be formed on the same substrate.
The structure of the field emission electron source thus formed on the same substrate will be described as a second embodiment.

The structure of the field emission electron source according to the second embodiment of the present invention will be described below with reference to FIG.

In FIG. 2, reference numeral 21 is a glass substrate, on the surface of which a first electrode layer 22 is formed. A cone-shaped microstructure 24 having a steep tip portion 23 is formed on the surface of the electrode layer 22. An insulating layer 25 and a second electrode layer 26 (gate electrode) are formed on the peripheral surface of the substrate. Furthermore, the insulating layer 2 is formed on the surface of the insulating layer 2.
A third electrode (secondary electron electrode) 27 is installed via 5 '. By applying a positive voltage (V1) to the gate electrode 26 with respect to the first electrode layer 22, a high electric field is concentrated on the tip portion 23, and primary electrons 29 are emitted from the cathode tip portion 23 due to the electric field effect. Further, the secondary electron electrode 27 has a voltage (V2) higher than the voltage applied to the gate electrode 26.
Is applied, the electrons emitted from the cathode tip portion 23 are accelerated and collide with the third electrode 27 (secondary electron electrode). At this time, secondary electrons 30 more than the number of primary electrons are emitted from the third electrode 27 made of metal, and the secondary electrons amplified and emitted from the third electrode are applied to the anode 28 to which a higher voltage (V3) is applied. To reach.

Also in this embodiment, a glass substrate is used for the structure of the primary electron source and a substrate having an electrode layer formed on the surface thereof is used. However, a conductive substrate such as a semiconductor substrate made of silicon or a metal substrate is used. Is also possible. Similarly, although a metal material is used for the secondary electron source, it is not particularly limited as long as it is a conductive material that emits secondary electrons. It is also possible to coat the surface of a conductive material with a material such as an oxide that easily emits secondary electrons.

(Third Embodiment) In the above-mentioned embodiment, an example in which the secondary electron source is installed facing the primary electron source with a certain distance is shown. It is also possible that the secondary electron source is formed on the same surface of the substrate. The structure of the field emission electron source thus formed on the same surface will be described as a third embodiment.

The structure of the field emission electron source according to the third embodiment of the present invention will be described below with reference to FIG.

In FIG. 3, reference numeral 31 is a conductive silicon substrate, on the back surface of which a first electrode layer 32 is formed. Then, a sharp tip 33 is formed on the surface of the silicon substrate.
Forming a cocktail glass-shaped microstructure 34. An insulating layer 35 and a second electrode layer 36 (gate electrode) are formed on the peripheral surface of the substrate. Also, a third electrode (secondary electron electrode) made of metal on the surface of the insulating film
37 is installed. Further, an anode electrode 38 is provided on the surface of the insulating film 35.

A gate electrode 36 is formed on the first electrode layer 32.
When a positive voltage is applied to the cathode 33, a high electric field is concentrated on the tip 33 and electrons are emitted from the cathode tip 33 due to the field effect. Further, a voltage higher than the voltage applied to the gate electrode 36 is applied to the metal electrode 37, and the cathode tip 33
The primary 39 electrons emitted from the electrons are accelerated and collide with the third electrode 37. At this time, secondary electrons 40 more than the number of primary electrons are emitted from the metal third electrode 37, and the secondary electrons amplified and emitted from the third electrode reach the anode 38 to which a higher voltage is applied.

In this embodiment, a cocktail glass type electron source formed on a silicon substrate was used, but a cone type cathode structure may be used. Further, in this embodiment, the anode is also formed on the same substrate, but it is also possible to arrange the anode outside as in the second embodiment. Further, in the above-mentioned present invention, the electrode for emitting the secondary electron is provided in one stage, but the electrode for emitting the secondary electron can be provided in multiple stages.

[0023]

As described above, the present invention overcomes the limitation of the current density of the conventional field emission electron source and provides an electron source of large current density. Due to the increase in the large current density, the application range of the electron source can be expanded and high reliability can be realized, and an extremely great effect in industry can be expected.

[Brief description of drawings]

FIG. 1 is a sectional view of a field emission electron source according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a field emission electron source according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a field emission type electron source according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a conventional field emission electron source and a method for manufacturing the same.

[Explanation of symbols]

 1 Glass Substrate 2 First Electrode Layer 3 Cathode Tip 4 Cone-shaped Microstructure 5 Insulating Layer 6 Gate Electrode 7 Mesh-like Electrode 8 Anode

Claims (4)

[Claims] 1. A primary electron source composed of a cold cathode that emits electrons from a solid surface by a field effect, and a secondary electron source that receives primary electrons emitted from the cold cathode and emits secondary electrons. Field emission electron source. 2. The field emission electron source according to claim 1, wherein the number of secondary electrons is larger than the number of primary electrons. 3. The primary electron sources are arranged in an array on a substrate, and the secondary electron sources are arranged to face the primary electron source with a certain distance therebetween. Item 1. A field emission electron source according to Item 1. 4. The field emission electron source according to claim 1, wherein the primary electron source and the secondary electron source are formed on the same substrate.