JPH06131971A - Manufacture of electron gun - Google Patents

Abstract

PURPOSE:To easily manufacture an electron gun having a sharp tip and a uniform shape without using a special method. CONSTITUTION:Vertical etching is applied to a (111) silicon substrate, then anisotropic etching is applied to the vertically etched face to form a (111) plane, and these actions are repeated. The tip section of an electron gun is formed with the etched face (111) and the (111) plane on the surface of the substrate.

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. In particular, the present invention relates to a method for manufacturing an electron gun that can be used in a micro vacuum tube, various electronic signal processing circuits, electronic signal amplifiers, flat panel displays and the like.

[0002]

2. Description of the Related Art As a conventional method of manufacturing an electron gun, a well-known method is a method of forming a cold cathode emitter (called Spindt method) developed by Spindt (CASpindt). This method begins with, as shown in FIG.
An insulating film 42 such as SiO 2 is formed on a substrate 41, a hole of about 1 μm is formed in a part of the insulating film 42, and the metal 43, 44 is vapor-deposited obliquely on the insulating film to open the insulating film A metal film is bulged from the portion in the shape of an eaves to form a pinhole 45 having a very small radius at the opening. Next, as shown in FIG. 4B, a metal 46 such as Mo that becomes an emitter (electron gun) is vapor-deposited from a direction perpendicular to the substrate 41. At this time, as Mo is vapor-deposited and becomes thicker, the pinhole is closed by the vapor-deposited film, whereby a cone-shaped emitter 47 having a tip diameter of about 500 angstrom is formed in the opening portion in the insulating film. As shown in FIG. 4c, the emitter which is an electron gun is formed by removing the upper portion from the metal film 44.

Another method is the Television Society Journal v.
ol. 45, No. 5, p.612-617 (199
As a method disclosed by Kanamaru et al. In 1), there is an example of manufacturing a lateral type triode element. In this method, first, as shown in FIG. 5a, W52 and Al53 films are laminated and accumulated on a quartz substrate 51, and then the photoresist 54 patterned by photolithography is used as a mask to make it reactive by SF ₆ gas. Ion etching is performed to remove the W film from the emitter 53a, the gate 53b, and the anode 5 as shown in FIG. 5b.
3c Electrode shape. Note that FIG. 5b 'is a view of the emitter 53a as viewed from above. After that, as shown in FIG. 5c, the lower layer Al is etched with a phosphoric acid-based etching solution to form a structure in which the W film protrudes like an eaves.
In this method, an emitter, which serves as an electron gun, a gate, and an anode are simultaneously formed.

In the former Spindt method as described above, a special method such as vapor deposition of a metal film from an oblique direction is required to form a pinhole, and the pinhole itself has an opening diameter. However, it is difficult to form a cone with a sharp tip, and the pinhole is blocked to form a cone-shaped emitter itself. Therefore, it is difficult to form a uniform emitter.

In the latter case of the lateral triode, since the emitter, gate and anode are formed side by side on the same plane on the substrate, more electrons emitted from the emitter flow into the gate than necessary. It is not practical because there are problems such as it getting stuck.

[0006]

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

[0007]

The above objects are achieved by etching a silicon substrate through a first etching window in a first mask material formed on a silicon substrate having a plane orientation (111). A step of forming a vertical etching surface, a step of etching the first vertical etching surface by anisotropic etching to form a (111) surface,
Forming a second mask material on the (111) etched surface, removing a part of the first mask material to form a second etching window, and passing the second etching window through the second etching window. The step of etching the silicon substrate to form a second vertical etching surface, and the step of etching the second vertical etching surface by anisotropic etching (11
1) A method of manufacturing an electron gun, comprising: a step of forming a surface; and a step of removing the first and second mask materials. Achieved by

[0008]

In the method of manufacturing the electron gun of the present invention, as shown in FIG. 2, the vertex of the deformed triangular pyramid composed of three (111) planes. For this reason, the tip portion thereof has a sharpness at the atomic level (several nanometers), electric field concentration is extremely likely to occur, and the structure is suitable for electron emission.

The method of manufacturing an electron gun according to the present invention uses the plane orientation (1
11) First, the silicon substrate 1 is first vertically etched through the first mask material 2 formed on the silicon substrate 1, for example, a first etching window in which a part of the silicon nitride film or the like has been removed. Then, an etching surface other than the (111) surface is formed. Then, the first vertical etching surface is etched with an anisotropic etching solution to expose the (111) etching surface 3. next,
This etching surface 3 is protected by forming a second mask material 4, for example, a silicon oxide film or the like, to protect it.
Is partially removed to open the second etching window. The portion where the first mask material 2 is removed is etched to form an etching surface other than the (111) surface. Then, the first vertical etching surface is etched with an anisotropic etching solution such as a KOH aqueous solution, a hydrazine aqueous solution or an ethylenediaminepyrocatechol solution,
The (111) etched surface 5 is exposed.

As a result, an electron gun whose tip portion is composed of three (111) faces as shown in FIG. 2 is formed.

As described above, according to the manufacturing method of the present invention, since the electron gun having the tip portion of three (111) planes is formed by etching using an anisotropic etching solution, electrons of the same shape are formed. The gun can be easily obtained with good reproducibility, and the tip portion thereof has a sharpness at the atomic level (several nm), electric field concentration is extremely likely to occur, and the structure is suitable for electron emission.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

First, FIGS. 1a and b (FIG. 1a is a plan view,
1b is a cross-sectional view taken along the line AA in FIG. 1a).
On the silicon substrate 1 of 11), a silicon nitride film 2 is formed as a first mask material in a thickness of 0.05 to 0.2 μm, and photolithography and reactive ion etching (RIE) or chemical dry etching (CDE) is performed.
A part of the first etching window 3 is removed by means of, and one side of the opening part 3 has a plane orientation equivalent to the (110) direction.
Open so as to have a.

[0014]

[Outer 1]

Then, the silicon substrate 1 is vertically etched by RIE or CDE through the first etching window 3 to form first vertical etching surfaces 3b and 3c.
Was formed. At this time, the etching depth is about 0.5 μm
It was about degree. Although the silicon nitride film is used as the first etching mask material in this embodiment, it plays a role as an oxidation resistant film when the silicon oxide film is formed as the second mask material in the following steps. The reason for this is that the resist is not limited to the silicon nitride film, but may be a normal resist or silicon oxide.

Next, as shown in FIG. 1c, the substrate 1 is immersed in an anisotropic etching solution of 60 ° C. and 30% KOH aqueous solution for about 2 minutes to etch the first etching surfaces 3b and 3c. The (111) plane 4 was exposed. This (1
11) As a result of the experiment, as shown in FIG. 1c, the (111) plane 4 is formed on the etching plane in a state where only one of the parallel first vertical etching planes 3b and 3c is overhung. Was done. As the anisotropic etching solution, it is possible to use an aqueous solution of hydrazine or an ethylenediaminepyrocatechol solution in addition to the KOH solution. Especially, when the metal potassium (K) is disliked, these etching solutions are used. Although effective, in this example, the KOH aqueous solution was used because the KOH aqueous solution has excellent anisotropy selectivity of etching only the (111) plane and etching the planes of other orientations.

Next, as shown in FIG. 1d, a silicon oxide film 5 is formed as a second mask material on the (111) plane 4 by, for example, a thermal oxidation method or a CVD method. The thickness of this oxide film is about 0.1 to 0.5 μm. Then, as shown in FIG. 1e, a part of the silicon nitride film 2 which is the first mask material is removed, and the second etching window 6 is opened. One side of the opening of the second etching window 6 is (1
10) The opening is formed so as to have a side 6a that intersects with one side 3a of the etching window 3 formed by the first mask material at an angle of 60 ° in a plane orientation equivalent to the direction 10). In this example, the (101) direction was adopted.

Next, referring to FIG. 1f (FIG. 1f shows a line BB in FIG. 1e).
The silicon substrate 1 is vertically etched by RIE or CDE through the etching window 6 to form second vertical etching surfaces 6b and 6c as shown in FIG. At this time, the etching depth was about 0.5 μm.

Next, as shown in FIG. 1g, the silicon substrate 1
Is etched with a KOH aqueous solution to expose the (111) etched surface 7.

Next, the silicon nitride film 2 which is the first mask material and the silicon oxide film 5 which is the second mask material.
By removing all of them, an electron gun tip portion composed of three (111) planes was formed. 2h shows a plan view of this state, and FIG. 2i shows a cross section taken along line CC of FIG. 2h.
The DD cross section is shown in FIG. 2j.

Next, as shown in FIG. 3, a silicon oxide film 8 is deposited by the CVD method. The film thickness of the silicon oxide film 8 is a gate oxide film that determines the distance between the gate electrode to be formed later and the electron gun tip. In this embodiment, the film thickness is about 0.3 to 0.5 μm. Next, the gate electrode 9 is formed from above the silicon oxide film 8, for example, Mo or A.
A film of u, Ni, Ta or the like is formed to remove a part of the unnecessary gate oxide film. The film formation of the gate electrode 9 is performed by vacuum vapor deposition, so that the position of the gate electrode 9 is determined in the self alignment because the tip of the electron gun acts as a mask.

[0022]

As described above, the electron gun formed by the manufacturing method of the present invention has a triangular pyramid shape composed of three (111) faces, and its tip has a regular tetrahedral structure made of Si. The sharpness is at the apex at the atomic level (several nm), which is one of the vertices, and extremely high electric field concentration easily occurs. Further, since the tip of the electron gun is formed by performing anisotropic etching twice, a silicon electron gun that is sharp at the atomic level can be formed with good reproducibility, regardless of process conditions and fine photolithography.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment according to the present invention.

FIG. 2 is a drawing subsequent to FIG. 1 for explaining an embodiment according to the present invention.

3 is a drawing subsequent to FIG. 2 for explaining an embodiment according to the present invention. FIG.

FIG. 4 is a drawing for explaining a conventional manufacturing method.

FIG. 5 is a drawing for explaining another conventional manufacturing method.

[Explanation of symbols]

1 ... Silicon substrate, 2 ... Silicon nitride film,
3, 6 ... Etching window, 3a, 6a ... (11
Sides equivalent to 0) direction, 3b, 3c ... First vertical etching surface, 4, 7 ... (111) surface, 5 ... Silicon oxide film, 6a, 6b ... Second vertical etching surface, 8 ... Gate Oxide film, 9 ... Gate electrode.

Claims (1)

[Claims] 1. A method of etching a silicon substrate through a first etching window in a first mask material formed on a silicon substrate having a plane orientation (111) to form a first vertical etching surface. Etching the first vertical etching surface by anisotropic etching (111)
A step of forming a surface and a second step on the (111) etched surface.
Forming a mask material, and removing a part of the first mask material to form a second etching window,
Etching the silicon substrate through the second etching window to form a second vertical etching surface;
Etching the second vertical etching surface by anisotropic etching to form a (111) surface;
And a step of removing the second mask material, the method of manufacturing an electron gun.