JPH06251694A - Manufacture of electron gun - Google Patents

Abstract

PURPOSE:To form an emitting part and a gate electrode in very good reproducibility and uniformly by independently forming wedge-shaped each one surface of an electron emitting part, in forming the electron emitting part. CONSTITUTION:A metal film 7 serving as a gate electrode is molded on the first/second insulating films 4, 6. Next on the first/second insulating films 4, 6, a metal, wire 7 serving as a gate electrode is filmed. In molding this metal film 7, for instance, Al, gold, tungsten, molybdenum, etc., are filmed by a vacuum evaporation method. Here is formed a dogleg-shaped upper part of the first insulating film into a mask, to self align the metal film divided into a protruding part and the other part in the point end of an electron gun electron emitting part formed of the first and second faces (111), and an oxidized film of the electron gun electron emitting part is placed in an exposed condition to mold a film. Next by removing SiO3 which is an insulating film in the point end of the electron gun emitting part 10, the emitting part point end is exposed to form the gate electrode 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electron gun, and more particularly to a method for manufacturing a silicon electron gun used as an electron emission source for vacuum microdevices, cathode ray tubes, electron microscopes and the like.

[0002]

2. Description of the Related Art One of electron guns using silicon has an electron emitting portion having a wedge shape. As a conventional method of manufacturing a wedge-type electron gun, for example, H. H.
G. The method disclosed by Gray et al. (Technical Direst of I
VMC91, Nagahama 1991, pp. 34-35).

In this manufacturing method, first, as shown in FIG. 3, a SiO ₂ film is formed on a silicon substrate 101, and as shown in the drawing, a mask 102 is formed by leaving the SiO ₂ film in a rectangular shape. Etching with an etching solution. At this time, since the underside of the mask 102 is under-etched, as shown in FIG. 4a, the portion of the silicon substrate 101 in contact with the mask 102 is the upper side of the trapezoid and is controlled to be substantially linear. Etching is performed.

Next, the silicon substrate 101 is thermally oxidized to form a SiO ₂ film 103, and as shown in FIG. 4B, the apex of the cross section becomes a sharp triangle due to the crevice of silicon due to the oxidation. Thus, the wedge type electron gun electron emission portion is formed.

Next, as shown in FIG. 4C, a metal film to be the gate insulating film 104 and the gate electrode 105 is formed. Then, by removing the mask 102 SiO ₂ formed by (SiO ₂₎ and thermal oxidation, as shown in FIG. 4d, is formed a gate electrode 105 formed on a self-aligned by the mask 102, an electron gun Manufactured.

In this conventional manufacturing method, it is necessary to finish the etching when the contact with the mask 102 becomes a thin line as much as possible when under-etching the bottom of the mask 102. It is very difficult to identify the point accurately, and specifically, it is done by adjusting the etching time (the time of immersion in the etching solution), but the etching rate differs due to a slight change in the solution temperature. The tip of silicon may be over-etched and the mask 102 may be peeled off due to an error in the time taken out from the etching solution, or conversely, the tip may be sharp because the etching is insufficient and the tip remains wide. The reproducibility of the thermal oxidation process is extremely long, and the electron gun with a uniform shape cannot always be obtained. There is a problem that.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing an electron gun capable of manufacturing an electron gun having a uniform shape with good reproducibility.

[0008]

Means for Solving the Problems The above objects are to provide a step of forming a mask material on the surface of a single crystal silicon substrate having a plane orientation (100) and a step of etching an opening of the mask material formed on the silicon substrate. Then, the silicon surface exposed by the etching is anisotropically etched to obtain the first (11
1) a step of exposing the surface, a step of forming a first insulating film on the exposed silicon surface including the first (111) surface, a step of removing the mask material, and a step of removing the mask material. A step of etching the silicon surface exposed by removing, and a second step of anisotropically etching the silicon substrate.
Exposing the (111) plane of the second (111)
A second insulating film on the exposed silicon surface including the surface, a step of forming a metal film on the first insulating film and the second insulating film, and the first (111) Surface and the second insulating film covering the apex of the corner formed by the second (111) surface, and the step of removing the second insulating film. Achieved by

[0009]

In the method of manufacturing the electron gun of the present invention, the plane orientation (10
The mask material is formed on the single crystal silicon substrate of 0), the opening is formed in the mask material, the substrate surface is dug down, and the silicon surface exposed by the etching is anisotropically etched to form the mask material. The first (111) plane having a V-shaped cross section is exposed on the vertical wall surface. The portion below the first (111) surface of the V-shape serves as one surface of the electron emitting portion of the wedge type electron gun.

Then, a first insulating film is formed on the first (111) surface to protect the first (111), the mask material is removed, and the silicon surface of the portion where the mask material is removed is removed. To dig down by etching. At this time, the first
The (111) plane of is protected by the first insulating film serving as a mask. Further anisotropic etching is performed to obtain the second (111)
Expose the surface. As a result, the electron gun electron emission portion is formed by the first (111) surface and the second (111) surface,
Then, the first insulating film remains in a V shape, and the upper portion of the V shape projects above the electron emission portion.

Then, a second insulating film is formed on the second (111) plane, and a metal film to be a gate electrode is formed on the first insulating film and the second insulating film. At this time, the upper portion of the V-shape of the first insulating film serves as a mask, and the metal film is self-aligned to form the first (111) plane and the second (11) plane.
1) The film is divided into a portion protruding from the tip of the electron gun electron emission portion formed by the surface and the other portion, and the oxide film on the electron gun electron emission portion is exposed to form a film.

Finally, the insulating film at the tip of the electron gun electron emission portion exposed from the metal film portion is removed to expose the electron emission portion.

As described above, in the method of manufacturing the electron gun of the present invention, the electron emission portion is formed independently on each of the wedge-shaped surfaces of the electron emission portion, so that a uniform shape is always obtained. An electron gun can be manufactured with good reproducibility.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. 1 and 2 show a method of manufacturing an electron gun according to the present invention in the order of steps.

The method of manufacturing the electron gun of the present invention will be described with reference to FIG.
As shown in a, a silicon nitride film (SiN) is formed on the surface of the single crystal silicon substrate 1 having a plane orientation (100), and this is applied with resist, photolithography and RIE.
At the same time as forming the mask material 2 by patterning with, the RIE is further continued and the silicon substrate 1 is dug down.

Next, as shown in FIG. 1b, the silicon substrate 1 on which the mask material 2 is formed is not etched only in the anisotropic etching solution such as KOH aqueous solution, hydrazine aqueous solution and ethylenediaminepyrocatechol solution. Etching is performed using an anisotropic etching solution, and the first (11
1) The surface 3 is exposed. At this time, in the etching of silicon by anisotropic etching, the (111) plane is gradually exposed from the end portion of the mask material 2 to the vertical wall portion of the silicon substrate 1 by digging down the silicon substrate 1. While progressing, the first (11
1) Surface 3 is exposed. The (111) plane does not proceed in the (111) plane direction because the silicon substrate surface is covered with the mask material 2 and is stopped by the end portion of the mask material 2 due to the anisotropy of etching.

Next, as shown in FIG. 1c, the exposed silicon surface including the first (111) surface 3 is thermally oxidized to S.
An iO ₂ film is formed to form a first insulating film 4.

Next, as shown in FIG. 1d, the mask material 2 is removed.

Next, as shown in FIG. 1e, the silicon surface exposed by removing the mask material 2 is selectively etched by, for example, CDE to dig down the silicon. At this time, the SiO ₂ film formed on the first (111) plane 3 as a first insulating film serves as a mask to protect the first (111) plane 3. The depth to be dug will determine the size of the electron emitting portion when the electron emitting portion of the electron gun is completed, so it is preferably about 0.1 to 2 μm. By the step of digging the silicon surface, the metal film formed immediately above the tip of the electron emitting portion in the subsequent steps is projected. Here, in order to dig down the silicon surface, C
The reason for using DE is that the etching selection ratio of SiO ₂ and silicon that protects the first (111) plane 3 is good, and S
It is preferable because only silicon can be etched without etching iO ₂ , and the silicon surface can be self-aligned with the SiO ₂ portion as a mask. In addition to CDE, RIE having selectivity may be used.

Next, as shown in FIG. 1f, the silicon surface after being dug is anisotropically etched to form a second (111).
The surface 5 is exposed. This step is the same as the first (11
1) The same as when the surface 3 is exposed. Etching in the (111) plane direction is stopped by the appearance of the second (111) plane 5 so that the second (111) plane 5 is just in contact with the above-mentioned first (111) plane. A portion where the first (111) surface 3 and the second (111) surface 5 are in contact with each other has a triangular vertex in a cross section as shown in the drawing, and the electron emission portion 10 of the wedge type electron gun is formed. Then, the first insulating film has a structure in which the first insulating film protrudes directly above the electron emitting portion 10 in a V shape.

Next, as shown in FIG. 1g, the second (11
1) A SiO ₂ film is formed on the exposed silicon surface including the surface 5 by thermal oxidation to form a second insulating film 6.

Next, as shown in FIG. 2h, a metal film 7 to be a gate electrode is formed on the first insulating film 4 and the second insulating film 6.
To form a film. The metal film 7 is formed by vacuum evaporation, for example, aluminum, gold, tungsten, molybdenum, or the like. At this time, the upper part of the V-shape of the first insulating film serves as a mask, and the metal film is self-aligned and
The oxide film on the electron-gun electron-emitting portion is exposed by being divided into the portion protruding from the tip of the electron-gun electron-emitting portion formed by the (111) plane and the second (111) plane and the other portion. Then, the film is formed.

Next, as shown in FIG. 2i, the SiO ₂ which is the first and second insulating films 4 and 6 at the tip of the electron gun electron emission portion 10 exposed from the metal film 7 is removed to emit electrons. By exposing the tip of the portion 10, the electron emission portion 1
An electron gun having gate electrodes 11 formed on both sides of 0 is completed.

[0024]

As described above, according to the method of manufacturing an electron gun of the present invention, the electron gun electron emission portion is not formed by under-etching while performing strict control under the mask by the conventional method. Since the electron emitting portion and the gate electrode of the electron gun can be formed extremely reproducibly and uniformly, mass production becomes possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining the method of manufacturing an electron gun of the present invention in the order of steps.

FIG. 2 is a cross-sectional view for explaining the method of manufacturing the electron gun of the present invention in order of steps subsequent to FIG.

FIG. 3 is a perspective view for explaining a conventional method for manufacturing an electron gun.

FIG. 4 is a cross-sectional view for explaining a conventional method for manufacturing an electron gun.

[Explanation of symbols]

1 ... Silicon substrate, 2 ... Mask, 3 ... First (111) plane, 4 ...
First insulating film, 5 ... second (111) plane,
6 ... second insulating film, 7 ... metal film,
10 ... Electron emission part, 11 ... Gate electrode.

Claims (1)

[Claims] 1. A step of forming a mask material on a surface of a single crystal silicon substrate having a plane orientation (100), a step of etching an opening of the mask material formed on the silicon substrate, and a silicon surface exposed by the etching. Anisotropic etching to expose the first (111) plane, forming a first insulating film on the exposed silicon surface including the first (111) plane, and the mask A step of removing a material, a step of etching the silicon surface exposed by removing the mask material, and an anisotropic etching of the silicon substrate to perform a second (11)
1) exposing a surface, a step of forming a second insulating film on the exposed silicon surface including the second (111) surface, and the first insulating film and the second insulating film. Forming a metal film on the first insulating film and the second insulating film covering the apex portion of the corner formed by the first (111) surface and the second (111) surface. And a step of removing the electron gun.