JPH0594761A - Field emission type vacuum tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a field emission type vacuum tube and a manufacturing method thereof by which reproducibility or an operational characteristic can be improved and mass productivity can be also improved by simplifying a manufacturing process or by downsizing a device. CONSTITUTION:Plural number of molybdenum conical cold cathodes as an electron emission source are formed on a substrate electrode 10 formed by using a (n) type silicon substrate. An insulating layer 12 of a silicon oxide film is laminated on the substrate electrode 10 around the cold cathodes 11. An anode layer 13 is provided so as to cover these cold cathodes 11 and the insulating layer 12. The anode layer 13 is laminated on the opposite surface to the substrate electrode 10 of the insulating layer 12, and a conical dent 14 is formed in a part opposed to the cold cathodes 11, and this dent 14, that is, a clearance between the anode layer 13 and the cold cathodes 11 is put in a vacuum condition. A material of the cold cathodes 11 is similarly used as a material of the anode layer 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission vacuum tube including an electron emission source that emits electrons according to the principle of field emission, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the field emission type vacuum tube manufacturing technology for emitting electrons in a high electric field has made remarkable progress by the fine processing technology used in the field of integrated circuits or thin films, and in particular, the field emission having an extremely small structure. Molded cold cathodes are 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 type vacuum tube including a large number of electron emission devices has been 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 type vacuum tube are described in Stanford Research Inn. Sea of Stanford Research Institute. A. Journal of Applied Physics by CASpindt et al.
hysics) Vol. 47, No. 12, 5248-5263 (December 1976)
Known from U.S. Pat. No. 3,789,471.

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. However, due to its operating principle, it is necessary to keep them in a vacuum.

FIG. 5 shows the structure of a conventional field emission vacuum tube proposed by Spindt et al., And FIG. 6 shows
The manufacturing method will be described.

As shown in FIG. 5, a conical cold cathode 31 which is an electron emission source is formed on the substrate electrode 30. Although only one cold cathode is shown in this figure, a plurality of cold cathodes 31 are generally formed on the substrate electrode in a linear array or a matrix. A thin-film gate electrode 33 is formed around the cold cathode 31 via an insulating layer 32, and an anode 34 is provided so as to cover the cold cathode 31 and the gate electrode 33. The gap between the anode 34, the cold cathode 31, the gate electrode 33, etc. is in a vacuum state.

Between the cold cathode 31 and the gate electrode 33 and the cold cathode
When a voltage is applied between the anode 31 and the anode 34, a high electric field is generated between them, and electrons are emitted from the cold cathode 31 by the principle of field emission.

Next, the method of manufacturing this field emission vacuum tube will be described with reference to FIG. 6. First, as shown in FIG. 6A, the surface of the substrate of the semiconductor (for example, silicon) which is the substrate electrode 30 is formed. An insulating layer (eg, SiO ₂ ) 32a and a gate electrode layer 33a are sequentially laminated. Next, a resist is applied on the gate electrode layer 33a, a desired pattern is baked on the resist, and development processing is performed to form a resist pattern 35 as shown in FIG. 6B. Expose part of.

The gate electrode layer 33a and the insulating layer 32a exposed from the resist pattern 35 are sequentially removed by etching to form minute holes 36. As shown in FIG. 6C, the hole 36 penetrates the gate electrode layer 33a and the insulating layer 32a and is closed at one end by the surface of the substrate electrode 30. When a metal material forming the electron emitting portion, that is, the cold cathode is vapor-deposited perpendicularly to the opening surface of the hole 36, a conical cold cathode 31 is formed on the substrate electrode 30 in the hole 36 as shown in FIG. Formed in. At this time, the layer 31a of the metal material that constitutes the cold cathode 31 has holes.
While depositing on the gate electrode layer 35 while reducing the opening diameter of 36, if this deposit layer 31a is removed by the lift-off method,
A field emission type vacuum tube as shown in FIG. 6 (E) is constructed.

Further, as shown in FIG. 6 (F), a plurality of cold cathodes 31, gate electrodes 33, etc. are covered with a plate-shaped conductor 34 serving as an anode 34, and the inside thereof is evacuated and sealed, and integrated. The mold vacuum tube is manufactured.

[0011]

However, as described above, in the conventional field emission type vacuum tube, the device manufacturing process and the vacuum sealing process are performed separately, and before the process is transferred to the device vacuum sealing process. Since a process such as lift-off is performed, the element comes into contact with the atmosphere, and the gas contained in the atmosphere is adsorbed on the surface of the electron emission source (cold cathode) 31 to deteriorate the operating characteristics and reproducibility of the element. .. Further, the process is complicated, which hinders mass productivity. Further, it is possible to perform vacuum sealing in the same vacuum chamber after forming the element, but there arises a problem that the structure of the manufacturing apparatus becomes complicated and increases in size.

Therefore, according to the present invention, it is possible to improve the reproducibility and operating characteristics of the field emission type vacuum tube, and to simplify the manufacturing process and the manufacturing apparatus and downsize them to improve the mass productivity. A discharge type vacuum tube and a method for manufacturing the same are provided.

[0013]

According to the present invention, a substrate electrode, a plurality of electron emission sources electrically connected to the substrate electrode and formed on the substrate electrode, and these electron emission sources are provided. A field emission vacuum tube provided with an anode layer facing the surface of the substrate electrode provided with the source and sealing the electron emission source in a vacuum, and the material of the anode layer is the same as the material of the electron emission source. Will be provided.

Further, according to the present invention, a plurality of electron emission sources and an anode layer covering the upper portions of the electron emission sources are formed on the surface of the substrate electrode made of a semiconductor or a metal by a vacuum vapor deposition method using the same vapor deposition source. Provided is a method of manufacturing a field emission vacuum tube for vacuum-sealing an electron emission source.

[0015]

Since the cold cathode, which is the electron emission source, and the anode layer are made of the same material, they can be formed in the same step.
Specifically, a cold cathode and an anode layer, which are electron emission sources, are simultaneously vapor-deposited by the same vapor deposition source using a vacuum vapor deposition method.
Further, when forming the cold cathode and the anode layer, the periphery of the cold cathode is vacuum-sealed by the anode layer. Therefore, it is possible to prevent the gas around the cold cathode of the field emission vacuum tube from coming into contact with the atmosphere and adsorbing the gas contained in the atmosphere onto the surface of the cold cathode.

[0016]

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

FIG. 1 is a side sectional view of the essential part showing the structure of an embodiment of a field emission vacuum tube according to the present invention, and FIG. 2 is a sectional side view of the essential part showing the manufacturing method thereof.

As shown in FIG. 1, a conical cold cathode 11 made of molybdenum metal, which is an electron emission source, is formed on a substrate electrode 10 using an n-type silicon substrate. Although only one cold cathode is shown in the drawing, a plurality of cold cathodes 11 are formed on the substrate electrode 10 in a linear array or a matrix. The material of the cold cathode 11 is excellent in thermal and mechanical properties,
In addition, molybdenum is not particularly limited as long as it has a low work function.

An insulating layer 12 of a silicon oxide film (SiO ₂ ) is laminated on the substrate electrode 10 around the cold cathode 11. An anode layer 13 is provided so as to cover the cold cathode 11 and the insulating layer 12. The anode layer 13 is laminated on the surface of the insulating layer 12 opposite to the substrate electrode 10, and a conical recess 14 is formed in a portion facing the cold cathode 11, and the recess 14 or the anode layer 13 and the cold cathode 11 are formed. The gap between and is in a vacuum state. The material of the anode layer 13 is the same as that of the cold cathode 11.

The field emission type vacuum tube of this embodiment is composed of a bipolar tube. In such a configuration, when a negative voltage and a positive voltage are applied between the cold cathode 11 and the anode layer 13, respectively, a high electric field is generated between them, and electrons are emitted from the cold cathode 11 by the principle of field emission. Therefore, it is possible to form a minute dipole tube.

Next, an embodiment of a method for manufacturing a field emission vacuum tube will be described with reference to FIG. 2 (A)-
The sectional view of (E) shows each stage of the manufacturing process.

First, as shown in FIG. 2A, the specific resistance ρ =
On the surface of the n-type silicon substrate 10 having a thickness of 0.01 to 0.02 Ω · cm, a silicon dioxide layer 12a serving as an insulating layer 12 having a thickness of
It is formed by thermal oxidation so as to have a thickness of μm. A resist is applied to the surface of the silicon dioxide layer 12a by using a spinner, a desired pattern is baked on the resist, and development processing is performed to form a resist pattern as shown in FIG.
15 is formed to expose a part of the silicon dioxide layer 12a.

Next, the exposed region of the silicon dioxide layer 12a is etched by reactive ion etching to form a hole 16 penetrating the silicon dioxide layer 12a to expose the surface of the silicon substrate 10 which is the substrate electrode. The structure shown in FIG. 2C is obtained.

After removing the resist pattern 15 on the insulating layer 12 by ashing with oxygen gas, the whole structure is placed in a vacuum vapor deposition apparatus and molybdenum, which is a material of the cold cathode 11 and the anode layer 13, is used as a vapor deposition source. When molybdenum is vapor-deposited on the opening of the hole 16 from the direction indicated by the arrow A shown in 2 (D), a conical cold cathode 11 is formed on the substrate electrode 10 in the hole 16 as shown in FIG. 2 (E). As it is formed, at the same time,
Molybdenum is deposited on the silicon dioxide layer 12 while reducing the opening diameter of the hole 16, and the anode layer 13 is formed so as to vacuum-seal the cold cathode 11. At this time, since molybdenum is laminated on the silicon dioxide layer 12 while reducing the opening diameter of the hole 16, the cold cathode 11 is formed in a conical shape. In this case, the cold cathode
After 11 is formed on the substrate electrode 10 and the opening of the hole 16 is closed, molybdenum is further deposited by about 0.5 μm for vacuum sealing.

Therefore, according to the above-described embodiment, since the cold cathode 11 and the anode layer 13 are formed of the same material in the same manufacturing process, the entire element comes into contact with the atmosphere and the gas in the atmosphere is the electron emission source. It is possible to prevent adsorption to the surface of the cold cathode 11 to improve the reproducibility and operating characteristics of the element, and also to simplify the manufacturing process and manufacturing apparatus and downsize them to improve mass productivity. ..

Next, another embodiment of the present invention will be described with reference to FIGS.

FIG. 3 is a side sectional view of a main part showing the structure of another embodiment of the field emission vacuum tube, and FIG. 4 is a side sectional view of the main part showing a manufacturing method thereof.

As shown in FIG. 3, a conical cold cathode 21 made of molybdenum metal which is an electron emission source is formed on a substrate electrode 20 using an n-type silicon substrate. Although only one cold cathode is shown in the drawing, a plurality of cold cathodes 21 are formed on the substrate electrode 20 in a linear array or a matrix. The material of the cold cathode 11 is excellent in thermal and mechanical properties,
In addition, molybdenum is not particularly limited as long as it has a low work function.

An insulating layer 22 of a silicon oxide film (SiO ₂ ) is laminated on the substrate electrode 20 around the cold cathode 21. A gate electrode layer is formed on the surface of the insulating layer 22 opposite to the substrate electrode 20.
23 and the insulating layer 24 are laminated in this order. And
An anode layer 25 is provided so as to cover the cold cathode 21, the insulating layer 24 and the like. The anode layer 25 is laminated on the surface of the insulating layer 24 opposite to the substrate electrode 20, and a conical recess 26 is formed in a portion of the anode layer 25 facing the cold cathode 21, and the recess 26, that is, the anode layer 25. The gap between the cold cathode 21 and the cold cathode 21 is in a vacuum state. The material of the anode layer 25 is the same as that of the cold cathode 21.

The vacuum tube of this embodiment is composed of a triode. When a negative voltage is applied to the cold cathode 21 and a positive voltage is applied to both the gate electrode layer 23 and the anode layer 25,
Electrons are emitted from the cold cathode 21 by the principle of field emission, so that a minute triode can be constructed.

Next, an embodiment of a method for manufacturing a field emission vacuum tube will be described with reference to FIG. FIG. 4 (A)-
The sectional view of (E) shows each stage of the manufacturing process.

First, as shown in FIG. 4A, the specific resistance ρ
= 0.01 to 0.02 Ω · cm, a silicon dioxide layer 22a serving as an insulating layer is formed on the surface of the substrate electrode 20 using an n-type silicon substrate by thermal oxidation so as to have a thickness of 1 μm. Silicon dioxide layer 22 using vacuum deposition equipment
A molybdenum film 23a to be a gate electrode layer is formed to a thickness of about 0.3 μm on a, and then a silicon dioxide film 24a to be an insulating layer is formed to a thickness of 0. Deposition is about 5 μm.

Next, as in the first embodiment, FIG.
As shown in FIG. 7, a resist is applied to the surface of the silicon dioxide film 24a using a spinner, a desired pattern is baked on the resist, and a developing process is performed to form a resist pattern
Is formed to expose a part of the uppermost silicon dioxide film 24a. Then, the exposed region is etched by reactive ion etching to form a hole 28 as shown in FIG. 4C through the silicon dioxide film 24a, the molybdenum film 23a and the silicon dioxide layer 22a, and the surface of the substrate electrode 20. Expose. That is, the surface of the substrate electrode 20 is closed at one end of the hole 28 and is opened at the other end to the upper part in the figure. Then, the resist pattern 27 on the insulating layer 24 is removed by ashing with oxygen gas.

The structure formed in FIG. 4C is set in a vacuum evaporation system, and molybdenum, which is the material of the cold cathode 21 and the anode layer 25, is used as the evaporation source, as shown by the arrow B in FIG. 4D. When molybdenum is vapor-deposited from the direction toward the opening of the hole 28, a conical cold cathode 21 is formed on the substrate electrode 20 in the hole 28 as shown in FIG. Are deposited on the insulating layer 24 while reducing the opening diameter of the hole 28, and are formed so as to vacuum-seal the cold cathode 21. At this time, molybdenum reduces the opening diameter of the hole 28 while insulating layer 24
Since it is stacked on top, the cold cathode 21 is formed in a conical shape.
In this case, after the cold cathode 21 is formed on the substrate electrode 20 to close the opening of the hole 28, vacuum sealing is performed by depositing molybdenum to about 0.5 μm.

Therefore, also in the above embodiment, since the cold cathode 21 and the anode layer 25 are formed of the same material and in the same manufacturing process, the entire element is exposed to the atmosphere and the gas in the atmosphere emits the electron emission source. That is, it is possible to prevent adsorption to the surface of the cold cathode 21 to improve the reproducibility and operating characteristics of the element, and also to simplify the manufacturing process and manufacturing apparatus and downsize them to improve mass productivity. it can.

Although the n-type silicon substrate is used as the substrate electrode in the above embodiment, the present invention is not limited to this, and a semiconductor thin film such as a p-type silicon substrate or a conductive thin film formed through a support is used. May be. Further, although silicon dioxide is used as the insulating layer, the material is not limited to this as long as the material has equivalent performance.

[0037]

As described above, according to the present invention, the cold cathode, which is an electron emission source, and the anode layer are made of the same material, so that they can be formed in the same process. Specifically, a cold cathode and an anode layer, which are electron emission sources, are simultaneously vapor-deposited by the same vapor deposition source using a vacuum vapor deposition method. Further, when forming the cold cathode and the anode layer, the periphery of the cold cathode is vacuum-sealed by the anode layer. Therefore, it is possible to prevent the gas contained in the atmosphere from being adsorbed on the surface of the cold cathode by contacting the atmosphere around the cold cathode of the field emission vacuum tube. As a result, the reproducibility and operating characteristics of the field emission vacuum tube can be improved, and the manufacturing process and apparatus of the field emission vacuum tube can be simplified and miniaturized to improve mass productivity.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part of an embodiment of a field emission vacuum tube according to the present invention.

FIG. 2 is a side sectional view of an essential part showing a method for manufacturing the field emission vacuum tube shown in FIG.

FIG. 3 is a side sectional view of a main part of another embodiment of the field emission vacuum tube according to the present invention.

FIG. 4 is a side sectional view of an essential part showing the method for manufacturing the field emission vacuum tube shown in FIG.

FIG. 5 is a side sectional view of a main part of an example of a conventional field emission vacuum tube.

FIG. 6 is a side sectional view of an essential part showing the method for manufacturing the field emission vacuum tube of FIG.

[Explanation of symbols]

 11, 21 Cold cathode 12, 22, 24 Insulation layer 23 Gate electrode 13, 25 Anode layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yu Akagi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (2)

[Claims] 1. A substrate electrode, a plurality of electron emission sources electrically connected to the substrate electrode and formed on the substrate electrode, and the substrate electrode on the side where the electron emission source is formed. A field emission type which is provided so as to face the surface of the electron emission source and which seals the electron emission source in vacuum, and the material of the anode layer is the same as the material of the electron emission source. Vacuum tube. 2. A plurality of electron emission sources and an anode layer covering the tops of the electron emission sources are formed on a surface of a substrate electrode made of a semiconductor or a metal by a vacuum vapor deposition method using the same vapor deposition source, and the electron emission sources are formed. A method for manufacturing a field emission vacuum tube, which comprises vacuum-sealing.