JP3227725B2 - Vacuum electronic device and method of manufacturing the same - Google Patents

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 method of manufacturing the same.

[0002]

2. Description of the Related Art As one of vacuum electronic elements, an element utilizing ballistic conduction in a vacuum space is known. In this element, an emitter and a collector are opposed to each other with a vacuum space interposed therebetween. A base is formed to control the electrons generated. In this micro vacuum transistor device, ballistic electron conduction is performed because a vacuum space that is not scattered by impurities or the like is used, and high-speed switching and the like are also realized.

In this vacuum electronic device, usually, each of an electrode of an emitter, a collector and a base is formed of a metal. The RC constant of a transistor is very small because the base is made of metal, so that an important factor in determining the cutoff frequency of the transistor is the electron transfer time between the emitter and the collector. High-speed operation can be achieved by shortening the electron transfer time as much as possible, but the short electron transfer time can be achieved by shortening the distance between the emitter and the collector.

[0004]

However, when the electrodes of the emitter and the collector are formed by the photolithography technique, the interval between the electrodes is limited to about several thousand mm, and the electrodes with extremely fine intervals are required. It is difficult to form a high-performance transistor by using the current process technology.

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

[0006]

According to a first aspect of the present invention, there is provided a vacuum electronic device comprising: a first electrode having a flat portion; and a second electrode having a substantially acute angle in cross section. And a third electrode whose cross-section has a substantially supplementary angle of the acute angle, and has a structure in which the corner and the plane face each other via a minute vacuum space.

Further, as a method for manufacturing such a vacuum electronic device, the present invention provides a method for manufacturing a vacuum electronic device, comprising: laminating a second electrode layer on a first electrode layer via an insulating film; The layer is divided by forming a groove at an angle inclined obliquely from the surface of the electrode layer, and then the insulating film in the vicinity of the divided part of the second electrode layer is removed.

According to still another method of manufacturing a vacuum electronic device of the present invention, a second electrode layer is laminated on a first electrode layer via an insulating film, and then the first electrode layer, the insulating film and The second electrode layer is cut so as to have a cross section inclined obliquely from the surface of the electrode layer, and a second insulating film is applied to the cross section, and then a third electrode is formed on the second insulating film. A layer is formed, and the first and second insulating films are removed near a connection portion between the insulating films.

[0009]

In the vacuum electronic element of the present invention, the second and third electrodes are opposed to each other at the corners of the cross-section where they are complementary to each other. The electrode layer can be formed to have a structure in which the electrode layer is divided obliquely, or the laminated two electrode layers can be patterned obliquely, which facilitates the production. If the second electrode having a sharp corner is used as the emitter, the third electrode can be used as the base and the first electrode having the flat portion can be used as the collector. The vacuum space can be formed by removing the insulating film formed on the plane portion and separating the groove or the insulating film between the electrodes. In particular, since the distance between the electrodes is determined by the thickness of the insulating film. , Suitable for fine processing.

In one method of manufacturing a vacuum electronic device according to the present invention, since the second electrode layer is divided by forming a groove having an oblique angle, the second electrode layer has an acute corner. The electrode and the corner having the supplementary angle can be simultaneously formed and opposed. Since the second electrode layer is disposed on the first electrode layer with an insulating film interposed therebetween, when the insulating film in the vicinity of the divided portion is removed, the thickness of the insulating film becomes the distance between the electrodes, and the accuracy is reduced. The distance between electrodes can be set well.

Further, in another method of manufacturing a vacuum electronic device according to the present invention, the device is cut obliquely with an insulating film interposed between the first electrode layer and the second electrode layer. By this oblique cutting, the corners of the cross section of the relationship between the acute angle and the supplementary angle are simultaneously formed. Further, a third electrode layer is formed on the cut surface via a second insulating film. At this stage, an insulating film is sandwiched between the electrodes, and a highly accurate distance between the electrodes can be achieved by removing the insulating film.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings.

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

FIG. 1 shows the structure. The collector electrode 1 made of a tungsten film has a substantially flat shape having a plane 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 stacked 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 metal bulk.

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

Similarly, the base electrode 6 is formed on the collector electrode 1 via the insulating film 3 made of a silicon oxide film or the like at the bottom, and the corner 7 of the cross section is formed at the corner 5 of the emitter electrode 4. And a supplementary angle. Base electrode 6
Is supplied with a voltage for controlling the electric field between the emitter and the collector.

The space between the base electrode 6 and the emitter electrode 4 is divided by a groove 8 of a very small size, and the distance L ₁ between the grooves 8 is the distance between the base electrode 6 and the emitter electrode 4. The groove 8 is formed to have substantially parallel side walls over the thickness of the base electrode 6 and the emitter electrode 4, and is inclined with respect to the normal direction of the plane 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 curve that bends itself. The distance L ₂ between the collector electrode 1, the base electrode 6 and the emitter electrode 4 is the same size as the thickness of the insulating film 3. As an example, the interval L ₁ is 5
Is about 00Å, interval L ₂ is about 200Å.

The ballistic transistor in a vacuum of this embodiment having the above-described structure can operate normally normally off by the electric field shown in FIGS.

FIG. 2 shows an electric field distribution when the base voltage is low. A maximum potential difference is applied to the collector electrode 1 and the emitter electrode 4 so that electrons are not emitted from the emitter toward the collector, and an intermediate potential which does not significantly damage the electric field distribution is set as a 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.

In order to turn on the ballistic transistor in a vacuum in this embodiment, the base potential may be slightly increased from the above-described base potential. By increasing the base potential, the electric field intensity near the sharp corner 5 of the emitter electrode 4 increases. As a result, electrons are emitted from the corners 5 of the emitter electrode 4, and the emitted electrons travel ballistically in the vacuum space to reach the collector electrode 1. At this time, the conduction of the vacuum space, can speed because scattering is no such impurities, in order to distance L ₂ of the emitter electrode 4 and the collector electrode 1 is also assumed approximate about 200Å very short, high-speed operation of the element Is possible. As an example of the voltage applied to each electrode so as to turn on the transistor, the emitter voltage is −10 V, the collector voltage is +10 V, and the base voltage is +6 V.

In this embodiment, the interval (width) L of the groove 8 is L.
_{Since 1} is larger than the interval L ₂ , the device operates normally off. 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 device in which an emitter electrode and a base electrode are separated by oblique etching having a small 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 the tungsten film 22 is used as a collector electrode, the tungsten film 22 is formed with a sufficient thickness for the collector electrode.

After the formation of 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 thickness of the insulating film 23 is the distance between the electrodes between the emitter and the collector, the thinner the thickness of the insulating film 23 is, the better for high-speed operation.
As an example, the thickness of the insulating film 23 is about 100 °, and since the distance between the electrodes is determined by the thickness, the reproducibility in manufacturing is excellent.

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

Next, the tungsten film 24 as the second electrode layer is divided by oblique etching using a step. First, as shown in FIG. 5, a resist layer 25 is formed in a pattern that covers one half of the tungsten film 24. This 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.
The surface of the tungsten film 24 in a region not covered with the resist layer 25 is shaved by this anisotropic etching,
A step 26 having a height d ₁ is formed in the tungsten film 24.

After the step 26 is formed, as shown in FIG. 6, an aluminum film 27 having a thickness d ₂ is formed by a vapor deposition method or the like. The aluminum film 27 has a thickness d ₂ is thinner than the height d ₁ of the step 26, step 26
A portion of the tungsten film 24 is exposed at a width of the dimension d ₁ -d ₂ at a portion of the step 26. Here, since the width of the dimension d ₁ -d ₂ is a difference in film thickness, it can be made sufficiently thin.

After the formation of the aluminum film 27, anisotropic etching in an oblique direction is performed to form an oblique groove 28 as shown in FIG. The groove 28 extends obliquely with respect to the main surface of the substrate from the tungsten film 24 exposed at the step 26 at a width of the dimension d ₁ -d ₂ , and divides the tungsten film 24. It has a depth reaching the lower insulating film 23. Due to the formation of the groove 28 by such oblique etching, one of the divided tungsten films 24 becomes an electrode having a sharp corner 29e, and the other becomes an electrode having a corner 29b which is complementary to 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 part of the insulating film 23, the corner 29
A gap 30 is formed near e and 29b. Less than,
By providing the space 30 as a vacuum space and supplying a required voltage to each electrode, ballistic electron conduction is achieved.

Third Embodiment This embodiment is a method of forming a resist layer having a small line width by drawing an electron beam, and separating the electrodes by using the resist layer. Hereinafter, this embodiment will be described with reference to FIGS.

First, a tungsten film 32 as a first electrode layer is formed on an insulating substrate 31 as in the second embodiment. 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 stacked thereon. The tungsten film 34 functions as an emitter electrode and a collector electrode, and the thickness of the insulating film 33 determines the distance between the emitter and the collector.

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

After forming a thin linear resist layer 35 by the EBIR method, a mask material layer 36 of an aluminum layer or the like is formed on the entire surface including the resist layer 35 as shown in FIG. 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, 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, an 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 oblique to the main surface of the substrate. The trench 38 divides the tungsten film 34 and has a depth reaching the insulating film 33 below the tungsten film 34. Groove 3 by such oblique etching
Due to the formation of 8, one of the tungsten films 34 to be divided becomes an electrode having a sharp corner 39e, and the other becomes an electrode having a corner 39b which is complementary to the acute angle.

Subsequently, as shown in FIG. 14, the mask material layer 36 is removed, and the corners 39e and 39b are formed by hydrofluoric acid treatment or the like.
Is removed in the vicinity of. Due to the partial removal of the insulating film 33, the gap 40 is formed near the corners 39e and 39b.
Is formed. Hereinafter, the space 40 is defined as a vacuum space,
By applying wiring to each electrode and supplying a required voltage from the wiring, ballistic conduction of electrons is achieved.

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

First, the structure is shown in FIG. The substrate is a silicon nitride substrate 41 having selectivity for etching with a silicon oxide film. On this silicon nitride substrate 41, a base electrode 42, an emitter electrode 43, and a collector electrode 44 form third, second, and first electrodes, respectively. It is formed so as to form.

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 inclined with respect to the main surface of the substrate is formed at the tip of the protruding portion, and the angle between the cross section 48 and the corner 47 of the electrode surface is obtuse. The fact that a part of the silicon nitride substrate 41 is raised below the other part under the base electrode 42 is due to over-etching when the cross section 48 is formed.

The emitter electrode 43 is also formed of a patterned tungsten film, and although not shown, a silicon oxide film, which is an insulating film below the emitter electrode 43, is formed on the base electrode 42 near the center of the pattern. Exists.
Since the emitter electrode 43 is initially formed of a tungsten film laminated on the base electrode 42 via a silicon oxide film,
The emitter electrode 43 and the base electrode 42 have a parallel lamination relationship. The emitter electrode 43 has a pattern substantially overlapping the base electrode 42, and has a shape protruding in the in-plane direction of the substrate main surface, 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. 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 fixed interval.
The portion continuous to zero 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 interval therebetween is particularly the distance between the emitter and the collector. Silicon nitride substrate 41 of collector electrode 44
And a wiring is applied to the portion, and a collector voltage is supplied from the wiring.

The base electrode 42 and the emitter electrode 4
3. The gap 45 sandwiched between the collector electrodes 44 is a vacuum space. After the electrodes having the respective structures are formed, the whole is covered with a silicon oxide film, so that vacuum sealing is possible.

In this embodiment, the electrode material is a tungsten film. However, any other metal material may be used as long as it has good fine processing characteristics and electric characteristics and a small work function. good.

Fifth Embodiment This embodiment is an example of a method of manufacturing a ballistic transistor in a vacuum according to the fourth embodiment. In particular, a manufacturing method of forming minutely spaced vacuum spaces by using wet etching. It is. Hereinafter, this embodiment will be described with reference to FIG.
This will be described with reference to 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.
The thickness of this silicon oxide film 53 is set to about 100 ° or less in order to determine the distance between the emitter and the base. The silicon oxide film 53 has selectivity for etching with respect to the silicon nitride substrate 51. Then, as shown in FIG. 16, on the silicon oxide film 53, a tungsten film 54 as a second electrode layer is formed.

After the formation of the tungsten film 54, FIG.
As shown in FIG. 7, a resist layer 55 is selectively formed. The resist layer 55 covers an area where a pattern as an emitter electrode or a base electrode is left. Resist layer 55
Is formed, for example, by applying a resist material, selectively exposing, and developing.

Next, as shown in FIG. 18, using the selectively formed resist layer 55 as a mask, oblique anisotropic etching is performed on the main surface of the substrate. As a result of this etching, the tungsten films 52 and 54 become oblique cross sections 52a and 5a.
4a, and the silicon oxide film 53
The silicon nitride substrate 41 is cut so as 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 also determines the angle of the corner of the base electrode.

Next, as shown in FIG.
A silicon oxide film 5 is formed on the entire surface including the slopes
6 is formed. Since the thickness of the silicon oxide film 56 is the distance between the emitter and the collector, the silicon oxide film 56 has a thickness of about 100 ° or less.

Next, as shown in FIG. 20, a tungsten film 57 is laminated on the silicon oxide film 56. The tungsten film 57 is a third electrode layer for forming a collector electrode, and in particular, the silicon oxide film 5 covering the slope.
6 is coated on the silicon oxide film 56.

After the formation of the tungsten film 57, FIG.
As shown in FIG. 7, the whole is cut by an ion milling method or the like to expose a portion 56a of the silicon oxide film 56 formed below the tungsten film 57. After the portion 56a of the silicon oxide film 56 is exposed, patterning is performed to obtain planar patterns of an emitter electrode, a base electrode, and a collector electrode as in the structure of the fourth embodiment. The base end of each of the emitter electrode, the base electrode and the collector electrode has a pattern having a large area such that the entire lower or upper oxide film is not removed even by the next wet etching of hydrofluoric acid. The size is set according to the collector current of the transistor.

Next, as shown in FIG. 22, the silicon oxide film 56 and the silicon oxide film 53 between the respective electrodes are removed by hydrofluoric acid treatment as wet etching. Part 5 of the silicon oxide film 56 exposed by the wet etching
It proceeds from 6a and stops 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 facing each other in the vicinity of the slope, and the respective electrodes are arranged with a small electrode distance. The silicon oxide film 5
The etching for removing 6, 53 is wet etching. Therefore, fine processing can be performed without being affected by the limit of RIE. At the time of this wet etching, the silicon nitride substrate 51 as a substrate does not need to be cut.

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

[0054]

The vacuum electronic device of the present invention has the second electrode having an acute corner and the third electrode having a corner forming a supplementary angle of the acute angle. The electrode can be formed by dividing one electrode layer, or two electrode layers can be formed by the same oblique etching, and has advantages such as the number of times of oblique etching can be reduced in manufacturing as compared with the related art. Since the second and third electrodes face the first electrode having a flat portion via a minute vacuum space, an insulating film or the like is disposed on the flat portion of the first electrode in advance. Finally, the insulating film can be removed, and the distance between the first electrode and the other electrode can be set with high accuracy.

In one method of manufacturing a vacuum electronic device according to the present invention, when manufacturing the vacuum electronic device, the second electrode layer is divided by forming a groove by oblique etching to form an emitter, Each electrode such as a base is formed, and then an 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, in manufacturing the vacuum electronic layer, the first and second electrode layers are obliquely etched to form an inclined cross section. To form an emitter electrode and a base electrode, and further form a third electrode layer on the cross section via an insulating film,
The vacuum film is formed by removing the insulating film and the insulating film between the first and second electrodes. Therefore, the distance between the electrodes is set by each insulating film, and the element can be manufactured with high reproducibility.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram showing a potential distribution in an off state of the first embodiment together with a cross-sectional structure of an element.

FIG. 3 is a schematic diagram showing a potential distribution in an ON state of the first embodiment together with a sectional structure of an element.

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

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

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

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

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

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

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

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

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

FIG. 13 is a process cross-sectional view after an oblique etching process for separating electrodes in the method for manufacturing a vacuum electronic device of the third embodiment.

FIG. 14 is a process cross-sectional view after a process of partially removing an insulating film and the like in the method for manufacturing a vacuum element of the third embodiment.

FIG. 15 is a perspective sectional view showing a main part of a structure of a ballistic transistor in a 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 a method of manufacturing a vacuum electronic device according to a fifth embodiment of the present invention.

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

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

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

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

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

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

[Explanation of symbols]

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

Claims (3)

(57) [Claims] A first electrode having a plane portion, a second electrode having a cross-section at a substantially acute angle, and a third electrode having a cross-section at a substantially complementary angle to the acute angle. The vacuum electronic device has a structure in which each of the corners and the flat portion faces each other via a minute vacuum space. 2. A method according to claim 1, wherein a second electrode layer is laminated on the first electrode layer via an insulating film, and then the second electrode layer is formed with a groove inclined at an angle oblique to the surface of the electrode layer. Divide by
And removing the insulating film in the vicinity of the divided portion of the divided second electrode layer. 3. A second electrode layer is stacked on the first electrode layer via an insulating film, and then the first electrode layer, the insulating film, and the second electrode layer are separated from the surface of the electrode layer. After cutting so as to have a cross section inclined obliquely and applying a second insulating film to the cross section, a third electrode layer is formed on the second insulating film, and the first and second electrodes are formed. Removing the insulating film in the vicinity of the connection between the insulating films.