JPH0537043A - Vacuum electronic device and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To manufacturing a device comprising three electrodes opposing to each other through a minute vacuum space with high precision and good reproducibility. CONSTITUTION:A collector electrode 1 is in the form of a flat board and an emitter electrode 4 opposing to the collector electrode 1 is so constituted as to have an angle part 5 of acute-angle, and also a base electrode 6 is so constituted as to have an angle part 7 of obtuse-angle which is supplementary to the angle part 5. With this structure, the base electrode 6 and the emitter electrode 4 can be formed by dividing into sections with a groove 8 obtained by aslant-etching one of electrode layers, or by using a section obtained by aslant- etching two electrode layers, whereby a vacuum electronic device with high precision can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum electronic device utilizing a ballistic conduction phenomenon of electrons in a vacuum space and a manufacturing method thereof.

[0002]

2. Description of the Related Art An element utilizing ballistic conduction in a vacuum space is known as one of vacuum electronic elements. This element has an emitter and a collector opposed to each other across a vacuum space, and further emits from the emitter. A base is formed to control the emitted electrons. In this fine vacuum transistor element, since a vacuum space that does not receive scattering of impurities and the like is used, ballistic electron conduction is performed, and high-speed switching is also realized.

In this vacuum electronic device, the emitter, collector and base electrodes are usually made of metal. The RC constant of the transistor is very small because the base is made of metal, and as a result, the important factor that determines the cutoff frequency of the transistor is the electron transfer time between the emitter and collector. High speed operation can be achieved by making the electron transfer time as short as possible, but short electron transfer time can be achieved by shortening the distance between the emitter and the collector.

[0004]

However, when each electrode of the emitter and the collector is formed by the photolithography technique, the interval between the electrodes is limited to about several thousand Å. It is difficult to form a high-performance transistor by using the current process technology.

Therefore, the applicant of the present invention has previously proposed, for example, Japanese Patent Application No. 3-115 as a method for obtaining a fine electrode interval.
It proposes a technique for forming an X-shaped groove by oblique etching from two directions intersecting in a substrate as described in the specification and drawings of No. 432. It is an object of the present invention to provide a vacuum electronic device and a method for manufacturing the same that further improve the technique for obtaining the fine electrode spacing, have excellent reproducibility of the manufacturing process, and reduce the number of etchings.

[0006]

A vacuum electronic device of the present invention for achieving the above object comprises a first electrode having a flat surface portion and a second electrode having a cross-section whose corners are substantially acute. The third electrode whose corners of the cross section are substantially complementary to the acute angle face each other through a minute vacuum space between the corners and the flat surface.

Further, as a method for manufacturing such a vacuum electronic device, the present invention is one in which a second electrode layer is laminated on a first electrode layer via an insulating film, and then the second electrode layer is laminated. The layer is divided by forming a groove having an angle oblique to the surface of the electrode layer, and then the insulating film in the vicinity of the divided portion of the divided second electrode layer is removed.

Further, according to another method of manufacturing a vacuum electronic device of the present invention, a second electrode layer is laminated on the first electrode layer with an insulating film interposed, and then the first electrode layer, the insulating film and The second electrode layer is cut so as to have a cross section obliquely inclined from the surface of the electrode layer, a second insulating film is deposited on the cross section, and then a third electrode is formed on the second insulating film. It is characterized in that a layer is formed and the first and second insulating films are removed in the vicinity of a connecting portion between the insulating films.

[0009]

In the vacuum electronic device of the present invention, since the corner portions of the cross section where the second and third electrodes are complementary to each other are opposed to each other, the second and third electrodes are formed of, for example, one flat plate. The electrode layers can be divided obliquely, or the two laminated electrode layers can be patterned obliquely, which facilitates the production. If the second electrode having a sharp corner is used as an emitter, the third electrode can be used as a base and the first electrode having a flat surface can be used as a collector. The vacuum space can be formed by removing a groove for separating the insulating film formed on the flat surface or by removing the insulating film between the electrodes, and in particular, the distance between the electrodes is determined by the thickness of the insulating film. , Will be suitable for fine processing.

Further, according to one of the methods for manufacturing a vacuum electronic device of the present invention, the second electrode layer is divided by forming a groove having an obliquely inclined angle, so that the second electrode layer has an acute corner portion. The electrode and the corner portion having the complementary angle can be formed at the same time to face each other. Since the second electrode layer is arranged on the first electrode layer via the insulating film, when the insulating film in the vicinity of the divided portion is removed, the film thickness of the insulating film becomes the inter-electrode distance, and the accuracy is improved. The distance between electrodes can be set well.

Further, in another method of manufacturing a vacuum electronic device according to the present invention, an insulating film is interposed between the first electrode layer and the second electrode layer to cut obliquely. By this oblique cutting, the corner portion of the cross section having the relation of the acute angle and its complementary angle is simultaneously formed. Further, a third electrode layer is formed on the cut surface through the second insulating film. At this stage, insulating films are sandwiched between the electrodes, and by removing the insulating films, a highly accurate inter-electrode distance can be achieved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the drawings.

First Embodiment In this embodiment, an emitter having an acute-angled section corner and a base having an obtuse-angled section corner complementary to the emitter are formed on a collector having a flat section. It is an example of a ballistic transistor in a vacuum.

The structure is shown in FIG. The collector electrode 1 made of a tungsten film has a substantially flat plate shape having a flat surface portion 2. A collector voltage is supplied to the collector electrode 1 at a portion not shown. An emitter electrode 4 and a base electrode 6 are formed so as to be laminated on the collector electrode 1, and the emitter electrode 4 and the base electrode 6 are also made of a tungsten film. The collector electrode 1 may be a bulk of metal.

The emitter electrode 4 is formed on the collector electrode 1 with an insulating film 3 made of a silicon oxide film or the like at the bottom thereof, and a corner 5 of its cross section has an acute angle. Therefore, the electric field at the acute angle portion is concentrated, and electrons can be emitted into the vacuum space. An emitter voltage is supplied to the emitter electrode 4.

Similarly, the base electrode 6 is also formed on the collector electrode 1 at the bottom through the insulating film 3 made of a silicon oxide film or the like, and the corner 7 of the cross section is the corner 5 of the emitter electrode 4. It is considered to be an angle that makes a complementary angle with. Base electrode 6
Is supplied with a voltage for controlling the electric field between the emitter and the collector.

The base electrode 6 and the emitter electrode 4 are separated from each other by a groove 8 having a minute size, and the distance L ₁ between the grooves 8 is the distance between the base electrode 6 and the emitter electrode 4 as it is. The groove 8 is formed to have sidewalls that are substantially parallel to each other across the thicknesses of the base electrode 6 and the emitter electrode 4, and is inclined with respect to the normal line direction of the flat surface portion 2 of the collector electrode 1. The groove 8 may be a straight line in any direction as the in-plane direction of the plane portion 2, but may be a line or a curved line that bends itself. The distance L ₂ between the collector electrode 1, the base electrode 6, and the emitter electrode 4 is the same as the thickness of the insulating film 3. As an example, the interval L ₁ is 5
The distance L ₂ is about 200Å.

The ballistic transistor in vacuum of this embodiment having a structure as described above is capable of normally-off transistor operation by an electric field as shown in FIGS.

FIG. 2 is a diagram showing the electric field distribution when the base voltage is low. A maximum potential difference is given to the collector electrode 1 and the emitter electrode 4 to the extent that electrons are not emitted from the emitter to the collector, and a potential of about an intermediate potential that does not largely destroy the electric field distribution is set as the base potential. In this state, no electrons are emitted from the emitter electrode 4 toward the collector electrode 1, and the transistor is off. As an example of the voltage applied to each electrode so as to turn off the transistor, the emitter voltage is −10 V,
The collector voltage is + 10V and the base voltage is + 2V.

When the ballistic transistor in vacuum according to the present embodiment is turned on, the base potential may be raised slightly from the above-mentioned base potential. By increasing the base potential, the electric field strength increases in the vicinity of the acute corner portion 5 of the emitter electrode 4. As a result, electrons are emitted from the corners 5 of the emitter electrode 4, and the emitted electrons conduct ballistically in the vacuum space and reach the collector electrode 1. At this time, the conduction in the vacuum space can be accelerated because there is no scattering of impurities and the like, and the distance L ₂ between the emitter electrode 4 and the collector electrode 1 is also extremely short, about 200 Å. Is possible. As an example of the voltage applied to each electrode so as to turn on the transistor, the emitter voltage is -10V, the collector voltage is + 10V, and the base voltage is + 6V.

In this embodiment, the space (width) L between the grooves 8 is L.
_{Since 1} is larger than the interval L ₂ , it operates normally. However, when L ₁ <L ₂ , it is used for both normally-on and normally-off, like other ballistic transistors in vacuum. Is possible.

Second Embodiment This embodiment is a method of manufacturing a vacuum electronic element in which an emitter electrode and a base electrode are separated by oblique etching with a fine width using a step. Hereinafter, this embodiment will be described with reference to FIGS.

First, a tungsten film 2 is formed as a first electrode layer on a substrate 21 in which an insulating film such as an oxide film or a nitride film is formed on a glass substrate or a semiconductor substrate which is an insulating substrate.
Form 2. Since this tungsten film 22 is used as a collector electrode, the tungsten film 22 is formed with a sufficient film thickness on the collector electrode.

After forming the tungsten film 22, an insulating film 23 such as a silicon oxide film or a silicon nitride film is formed on the entire surface of the tungsten film 22. Since the film thickness of the insulating film 23 becomes the distance between the electrodes between the emitter and the collector, it is preferable that the film thickness of the insulating film 23 is thin for high speed operation.
As an example, the film thickness of the insulating film 23 is about 100 Å, and since the distance between the electrodes is determined by this film thickness, the reproducibility in manufacturing is also excellent.

After forming the insulating film 23, as shown in FIG.
The tungsten film 24 serving as the second electrode layer is replaced with the insulating film 23.
Form on the entire upper surface. This second electrode layer is divided as described below and used for both the emitter electrode and the base electrode.

Next, the tungsten film 24, which is the second electrode layer, is divided by oblique etching using the steps. First, as shown in FIG. 5, a resist layer 25 is formed in a pattern covering half to one side of the tungsten film 24. The resist layer 25 is formed by applying a resist layer,
It can be formed by selective exposure and development. Next, anisotropic etching is performed using the resist layer 25 as a mask.
By this anisotropic etching, the surface of the tungsten film 24 in the region not covered with the resist layer 25 is shaved,
A step 26 having a height d ₁ is formed on the tungsten film 24.

After forming such a step 26, as shown in FIG. 6, an aluminum film 27 having a film thickness d ₂ is formed by a vapor deposition method or the like. The thickness d _{2 of the} aluminum film 27 is made smaller than the height d _{1 of} the step 26, so that the step 26
A step break is caused at the portion, and the tungsten film 24 is partially exposed at the step 26 with a width of dimension d ₁ -d ₂ . Here, since the width of the dimension d ₁ -d ₂ is the film thickness difference, it can be made sufficiently thin.

After forming the aluminum film 27, diagonal anisotropic etching is performed to form diagonal grooves 28 as shown in FIG. The groove 28 extends obliquely with respect to the main surface of the substrate from the exposed tungsten film 24 having a width of the dimension d ₁ -d ₂ at the step 26, divides the tungsten film 24, and cuts the tungsten film 24. It has a depth reaching the lower insulating film 23. By forming the groove 28 by such oblique etching, one of the tungsten films 24 to be divided becomes an electrode having an acute corner portion 29e, and the other becomes an electrode having a corner portion 29b forming a complementary angle with the acute angle.

Subsequently, as shown in FIG. 8, the aluminum film 27 and the resist layer 25 used as the mask are removed.

After removing the aluminum film 27 and the like, the insulating film 23 near the corners 29e and 29b is removed by hydrofluoric acid treatment or the like. By removing a part of the insulating film 23, the corner portion 29
A void portion 30 is formed near e and 29b. Less than,
By making this void 30 a vacuum space and supplying a required voltage to each electrode, ballistic conduction of electrons is achieved.

Third Embodiment This embodiment is a method of forming a resist layer having a narrow line width by drawing with an electron beam and separating the electrodes by utilizing the resist layer. The present embodiment will be described below with reference to FIGS.

First, similarly to the second embodiment, the tungsten film 32 as the first electrode layer is formed on the insulating substrate 31. This tungsten film 32 is used as a collector electrode. Next, an insulating film 33 such as a silicon oxide film or a silicon nitride film is formed on the entire surface of the tungsten film 32,
A tungsten film 34 as a second electrode layer is laminated on top of this. The tungsten film 34 functions as an emitter electrode and a collector electrode, and the film thickness of the insulating film 33 determines the distance between the emitter and the collector.

When the tungsten film 34 which is the second electrode layer is formed, a thin linear resist layer 35 is formed by the EBIR technique as shown in FIG. This E
The BIR technique is a technique in which an electron beam is drawn in the atmosphere of the constituent material of the resist layer, and the constituent material of the resist layer is selectively formed only in the drawn portion. Therefore, by scanning the electron gun in a thin linear shape, the thin linear resist layer 3
5 is formed corresponding to the position where the tungsten film 34 is to be divided.

After forming the thin linear resist layer 35 by the EBIR method, as shown in FIG. 11, a mask material layer 36 made of an aluminum layer or the like is formed on the entire surface including the resist layer 35. The mask material layer 36 deposited on the resist layer 35 is cut at a step from the mask material layer 36 deposited on the tungsten film 34.

After forming the mask material layer 36 on the entire surface, as shown in FIG.
As shown in FIG. 2, the thin linear resist layer 35 formed by using the EBIR technique is removed together with the mask material layer 36 laminated on the resist layer 35. By removing the resist layer 35, the opening 37 having a fine line width is formed in the mask material layer 36.

Next, as shown in FIG. 13, a groove 38 is formed inside the opening 37 of the mask material layer 36 by anisotropic etching from a direction obliquely inclined with respect to the main surface of the substrate. The groove 38 divides the tungsten film 34 and has a depth reaching the insulating film 33 below the tungsten film 34. Groove 3 formed by such oblique etching
Due to the formation of No. 8, one of the tungsten films 34 to be divided becomes an electrode having an acute angle portion 39e, and the other becomes an electrode having an angle portion 39b forming a supplementary angle with the acute angle.

Then, as shown in FIG. 14, the mask material layer 36 is removed, and the corner portions 39e and 39b are subjected to hydrofluoric acid treatment or the like.
The insulating film 33 in the vicinity of is removed. By removing a part of the insulating film 33, a space 40 is formed near the corners 39e and 39b.
Is formed. Hereinafter, this void portion 40 will be referred to as a vacuum space,
By providing wiring to each electrode and supplying a required voltage from the wiring, ballistic electron conduction is achieved.

Fourth Embodiment This embodiment is an example of a transistor having a structure in which two electrode layers are formed with an inclined cross section and another electrode layer is formed on the cross section with an insulating film interposed therebetween.

First, the structure is shown in FIG. The substrate is a silicon nitride substrate 41 having a silicon oxide film and etching selectivity, and a base electrode 42, an emitter electrode 43, and a collector electrode 44 are provided on the silicon nitride substrate 41 with the third, second, and first electrodes, respectively. It is shaped like an eggplant.

First, the base electrode 42 is made of a patterned tungsten film, and a part of the pattern has a shape protruding in the in-plane direction of the main surface of the substrate. A cross section 48 that is inclined with respect to the main surface of the substrate is formed at the tip of this protruding portion, and the angle formed between this cross section 48 and the corner 47 of the electrode surface is an obtuse angle. The part of the silicon nitride substrate 41 that is raised above the other part under the base electrode 42 is due to overetching when the cross section 48 is formed.

Although not shown in the figure, the emitter electrode 43 is also made of a patterned tungsten film, and a silicon oxide film which is an insulating film below the emitter electrode 43 is formed on the base electrode 42 in the vicinity of the approximate center of the pattern. Exists.
Since the emitter electrode 43 is initially made of a tungsten film laminated on the base electrode 42 with a silicon oxide film interposed therebetween,
The emitter electrode 43 and the base electrode 42 have a parallel laminated relationship. The emitter electrode 43 has a pattern that substantially overlaps the base electrode 42, and has a shape protruding in the in-plane direction of the main surface of the substrate similarly to the base electrode 42. A cross section 49 inclined with respect to the main surface of the substrate is formed at the tip portion thereof. The cross section 49 exists in the same plane as the cross section 48 of the base electrode 42. The angle formed by the cross section 49 and the corner 46 of the electrode surface is an acute angle, and in particular, the corner 47 and the corner 46 are complementary to each other.

The collector electrode 44 has a cross-section facing portion 50 which faces the cross-section 48 of the base electrode 42 and the cross-section 49 of the emitter electrode 43 at a constant interval.
A portion continuous with 0 extends on the silicon nitride substrate 41. The back surface of the cross-section facing portion 50 is used as a flat portion of the collector electrode and has a structure facing the cross-sections 48 and 49 in parallel, and the distance between them is particularly the emitter-collector distance. Silicon nitride substrate 41 of collector electrode 44
And a wiring is applied to the portion, and the collector voltage is supplied from the wiring.

The base electrode 42 and the emitter electrode 4
3. The void 45 sandwiched between the collector electrodes 44 is a vacuum space, and after the electrodes of each structure are produced, the entire space is covered with a silicon oxide film to enable vacuum sealing.

In this embodiment, the tungsten film is used as the electrode material, but other metal materials may be used as long as they have good fine processing characteristics and electric characteristics, and have a small work function. good.

Fifth Embodiment This embodiment is an example of a method of manufacturing a ballistic transistor in vacuum according to the fourth embodiment, and particularly a manufacturing method of forming vacuum spaces with fine intervals by using wet etching. Is. Hereinafter, this embodiment will be described with reference to FIG.
~ It demonstrates, referring FIG.

First, a tungsten film 52 as a first electrode layer is formed on a silicon nitride substrate 51, and a thin silicon oxide film 53 is formed on the tungsten film 52.
Since the silicon oxide film 53 determines the distance between the emitter and the base, its thickness is set to about 100 Å or less. In addition, the silicon oxide film 53 has etching selectivity with respect to the silicon nitride substrate 51. Then, as shown in FIG. 16, a tungsten film 54 as a second electrode layer is formed on the silicon oxide film 53.

After forming the tungsten film 54, as shown in FIG.
As shown in, the resist layer 55 is selectively formed. The resist layer 55 covers the region where the patterns as the emitter electrode and the base electrode are left. Resist layer 55
Is formed, for example, by applying a resist material, selectively exposing it, and developing it.

Next, using the resist layer 55 selectively formed as a mask, anisotropic etching is performed obliquely with respect to the principal surface of the substrate, as shown in FIG. As a result of this etching, the tungsten films 52 and 54 have diagonal cross sections 52a and 5a.
4a and is cut, and the silicon oxide film 53 also has a cross section 5
It is cut to have the same cross section as 2a and 54a, and a part of the surface of the silicon nitride substrate 41 is also etched. At this time, the angle of the oblique anisotropic etching becomes the angle of the acute corner of the emitter, and at the same time determines the angle of the corner of the base electrode.

Next, as shown in FIG. 19, an oblique cross section 5
Silicon oxide film 5 on the entire surface including slopes such as 2a and 54a
6 is formed. The thickness of the silicon oxide film 56 is the distance between the emitter and the collector, so that the silicon oxide film 56 is a thin film of about 100 Å or less.

Next, as shown in FIG. 20, a tungsten film 57 is laminated on the silicon oxide film 56. This tungsten film 57 is a third electrode layer for forming a collector electrode, and in particular, the silicon oxide film 5 covering the slopes.
6 is covered from above the silicon oxide film 56.

After forming the tungsten film 57, as shown in FIG.
As shown in FIG. 7, the whole is shaved by an ion milling method or the like to expose a part 56a of the silicon oxide film 56 formed under the tungsten film 57. After the part 56a of the silicon oxide film 56 is exposed, patterning for obtaining respective plane patterns of the emitter electrode, the base electrode, and the collector electrode is performed as in the structure of the fourth embodiment. The base ends of the emitter electrode, the base electrode, and the collector electrode have a pattern with such a large area that the entire oxide film in the lower or upper part is not removed by the next wet etching with hydrofluoric acid. It is sized according to the collector current of the transistor.

Next, hydrofluoric acid treatment, which is wet etching, removes the silicon oxide film 56 and the silicon oxide film 53 between the electrodes, as shown in FIG. Part 5 of the silicon oxide film 56 exposed by this wet etching
It progresses from 6a, and is stopped when the base end of each electrode is etched to some extent. As a result of this etching, the tungsten films 57, 54, and 52 have a structure in which they face each other in the vicinity of the slope, and the electrodes are arranged with a minute electrode distance. Also, this silicon oxide film 5
Etching for removing 6, 53 is wet etching. Therefore, fine processing can be performed without being influenced by the limit of RIE. In this wet etching, the silicon nitride substrate 51, which is the substrate, need not be ground.

In the following, wiring is provided on the base end side of each electrode and a required voltage is supplied to the wiring to function as a vacuum electronic element which performs ballistic conduction. In particular, in the case where the device was manufactured by this example,
Since the distance between the electrodes is set by the silicon oxide films 53 and 56, a reliable distance between the electrodes can be obtained with good reproducibility. Further, since these silicon oxide films 53 and 56 are removed by wet etching, fine processing exceeding the limit of RIE can be realized.

[0054]

Since the vacuum electronic device of the present invention has the second electrode having an acute angle portion and the third electrode having an angle portion forming a supplementary angle to the acute angle, the second and third electrodes are provided. The electrodes can be configured by dividing one electrode layer, or two electrode layers can be formed by the same oblique etching, and there is an advantage in manufacturing that the number of oblique etching can be reduced as compared with the conventional case. Further, since the second and third electrodes face the first electrode having the flat surface portion through the minute vacuum space, an insulating film or the like is previously arranged on the flat surface portion of the first electrode. Finally, the insulating film can be removed, and the distance between the first electrode and the other electrode can be set with high accuracy.

According to one of the methods for manufacturing a vacuum electronic device of the present invention, when the vacuum electronic device is manufactured, the second electrode layer is divided by forming grooves by oblique etching, Each electrode such as a base is formed, and then the insulating film between the electrode layers is removed to form a vacuum space.
Therefore, the distance between the electrodes is set by the insulating film, and the reproducibility in the process is improved.

Further, in another method of manufacturing a vacuum electronic device according to the present invention, when manufacturing the vacuum electronic layer, the first and second electrode layers are obliquely etched to form an inclined cross section. Then, each electrode of the emitter and the base is formed, and further the third electrode layer is formed on the cross section through the insulating film,
The insulating film and the insulating film between the first and second electrodes are removed to form a vacuum space. Therefore, the distance between the electrodes is set by each insulating film, and the element can be manufactured with good reproducibility.

[Brief description of drawings]

FIG. 1 is a perspective sectional view of an essential part showing the structure of a ballistic transistor in vacuum according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing an electric field distribution in an off state of the first embodiment together with a sectional structure of an element.

FIG. 3 is a schematic diagram showing an on-state electric field distribution of the first embodiment together with a cross-sectional structure of an element.

FIG. 4 is a process cross-sectional view after a process of forming a tungsten film in the method of manufacturing a vacuum electronic device according to the second embodiment of the present invention.

FIG. 5 is a process cross-sectional view after an anisotropic etching process using a resist layer as a mask in the method of manufacturing a vacuum electronic device according to the second embodiment.

FIG. 6 is a process sectional view after a process of forming an aluminum film in the method of manufacturing a vacuum electronic device according to the second embodiment.

FIG. 7 is a process cross-sectional view after an oblique etching process for dividing an electrode in the method of manufacturing a vacuum electronic device according to the second embodiment.

FIG. 8 is a process cross-sectional view after a process of removing an aluminum film and the like in the method of manufacturing a vacuum electronic device according to the second embodiment.

FIG. 9 is a process cross-sectional view after a partly removing process of an insulating film and the like in the method of manufacturing a vacuum electronic device according to the second embodiment.

FIG. 10 is a process cross-sectional view after a resist layer forming process by an EBIR method in the method of manufacturing a vacuum electronic device according to the third embodiment of the present invention.

FIG. 11 is a process cross-sectional view after a mask material layer forming process in the method of manufacturing a vacuum electronic device according to the third embodiment.

FIG. 12 is a process cross-sectional view after a resist layer removing process in the method of manufacturing a vacuum electronic device according to the third embodiment.

FIG. 13 is a process cross-sectional view after an oblique etching process for dividing an electrode in the method for manufacturing a vacuum electronic device according to the third embodiment.

FIG. 14 is a process sectional view after a partly removing process of an insulating film and the like in the method of manufacturing a vacuum electronic device according to the third embodiment.

FIG. 15 is a perspective sectional view of an essential part showing the structure of a ballistic transistor in vacuum according to a fourth embodiment of the present invention.

FIG. 16 is a process cross-sectional view after a process of forming a tungsten film in the method of manufacturing a vacuum electronic device according to the fifth embodiment of the present invention.

FIG. 17 is a process cross-sectional view after a resist layer forming process in the method of manufacturing a vacuum electronic device according to the fifth embodiment.

FIG. 18 is a process cross-sectional view after an oblique etching process in the method of manufacturing a vacuum electronic device according to the fifth embodiment.

FIG. 19 is a process cross-sectional view after the process of forming an insulating film on the entire surface including the inclined cross section in the method of manufacturing a vacuum electronic device according to the fifth embodiment.

FIG. 20 is a process cross-sectional view after a process of forming a tungsten film in the method of manufacturing a vacuum electronic device according to the fifth embodiment.

FIG. 21 is a process cross-sectional view after a milling process in the method of manufacturing a vacuum electronic device according to the fifth embodiment.

FIG. 22 is a process sectional view after the step of partially removing the insulating film in the method of manufacturing a vacuum electronic device according to the fifth embodiment.

[Explanation of symbols]

1, 44 ... Collector electrode 2 ... Planar part 3 ... Insulating film 4, 43 ... Emitter electrode 5, 46 ... Corner part (acute angle) 6, 42 ... Base electrode 7, 47 ... Corner part (obtuse angle) 8 ... Grooves 41, 51 ... Silicon nitride substrate 48 ... Cross section 21, 31 ... Substrate 22, 24, 32, 34, 52, 54, 57 ... Tungsten film 23, 33, 53, 56 ... Insulating film 25, 35 ... Resist layer 26 ... Step 27 ... Aluminum Nume film 28, 38 ... Groove 30, 40 ... Void portion

Claims (3)

[Claims] 1. A first electrode having a flat surface portion, a second electrode having a cross-section corner portion having a substantially acute angle, and a third electrode having a cross-section corner portion having a substantially complementary angle to the acute angle. A vacuum electronic device having a structure in which the corners and the flat surface face each other via a minute vacuum space. 2. A second electrode layer is laminated on the first electrode layer via an insulating film, and then a groove is formed in the second electrode layer at an angle inclined from the surface of the electrode layer. Divide by
Next, a method of manufacturing a vacuum electronic element, characterized in that the insulating film in the vicinity of the divided portion of the divided second electrode layer is removed. 3. A second electrode layer is laminated on the first electrode layer via an insulating film, and then the first electrode layer, the insulating film and the second electrode layer are formed from the surface of the electrode layer. After cutting so as to have an obliquely inclined cross section, and applying a second insulating film to the cross section, a third electrode layer is formed on the second insulating film to form the first and second The method for manufacturing a vacuum electronic element, comprising removing the insulating film in the vicinity of a connecting portion between the insulating films.