JPH0574327A - Electron emitter - Google Patents

Abstract

PURPOSE:To provide an electron emitting element which can be manufactured easily and can improve the yield rate and the reliability and can get a high electron beam by suppressing the spread of the electron beam. CONSTITUTION:A base electrode 12 is made on an insulating substrate 11. A plurality of cathode 13 are made radially in the specified sections of base electrode 12. Each cathode 12 is made to have edges 14, and have a wedge part whose width changes gradually, and especially so that the wedge-shaped top 15 may turn in the center direction. An insulating layer 16 and a control electrode 17 are made in order leaving a specified interval with the cathode 13. Electric rays are concentrated to the cathode 13, especially, to the wedge- shaped top 15 by applying voltage between the cathode 13 and the control electrode 17, whereby an electron beam is emitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron-emitting device which can be used as a source of various electron beam devices such as an electron microscope, an electron beam exposure device and a CRT.

[0002]

2. Description of the Related Art In recent years, with the progress of fine processing technology, electron-emitting devices that do not require heating, so-called cold cathodes, especially,
Research and development on micro cold cathodes have become active,
Field emission type electron-emitting devices have been well studied among several types. The field emission type electron-emitting device is needle-shaped so that the tip of the cathode has a curvature of several hundreds nm or less in order to emit electrons, and the cathode tip has a voltage of 10 ⁷ V / c.
Electrons are emitted by concentrating a strong electric field of about m. This field emission type electron-emitting device has features such as (1) high current density, and (2) very low power consumption because it is not necessary to heat the cathode.

Examples of the field emission type electron-emitting device include, for example, Journal of applied Physics, Vol39, No7, P350.
4, 1968 (Journal of Applied Physics, 39, No. 7, p. 3504, 1968) is known. FIG. 10A is a sectional view showing a state in which the conventional electron-emitting device is being manufactured, and FIG. 10B is a sectional view showing a completed state of the conventional electron-emitting device.

As shown in FIG. 10A, first, a conductive film 102, an insulating layer 103 and a conductive film 104 are sequentially deposited on an electrically insulating substrate 101 using a suitable mask to form a plurality of arrays. An array of cavities 105 is created. Next, the opening of the cavity 105 is gradually closed by rotary oblique vapor deposition of a suitable substance 106, and the cathode material 107 is vapor-deposited directly above the opening to form the cavity 105.
Inside, a cathode emitter protrusion 108 whose tip side is gradually thin is formed on the conductive film 102. Finally, substance 10
By removing 6, the electron-emitting device can be manufactured as shown in FIG.

The operation of the above arrangement will be described below. The power supply 109 is connected so that the conductive film 104 is positive and the conductive film 102 is negative, and the cathode emitter projection 1
By applying a voltage equal to or higher than a predetermined voltage determined by the cathode material 107 of No. 08, electrons can be emitted from the cathode emitter protrusion 108 where the electric field is concentrated.

There is also a trial in which the electron-emitting devices are arranged in an array and applied to a flat display (Japan Display '86, P512).

As another example of the conventional electron-emitting device, the structure described in Japanese Patent Application No. 2-133397 is known. 11 (a) to 11 (c) show the conventional electron-emitting device, FIG. 11 (a) is a plan view, and FIGS. 11 (b) and 11 (c) are lines D-D and FIG. 11 (a), respectively. E-
11 is a cross-sectional view taken along line E (in the plan view of FIG. 11A, a part corresponding to FIGS. 11B and 11C is hatched in the same direction for easy understanding). .).

As shown in FIGS. 11A to 11C, a base electrode 112 made of a conductive material is formed on an insulating substrate 111 made of glass or the like, and the base electrode 112 is formed on the base electrode 112. A cathode material layer 113 to which an electric current is supplied is formed. As the cathode material layer 113, a material having a low work function and a high melting point, for example, Si
C, ZrC, TiC, Mo, W, etc. are used. The cathode material layer 113 has a cross shape extending in all directions from the center and is formed in a rectangular shape or a trapezoidal shape in cross section so as to have an edge portion 113a. The shape is set to gradually change linearly up to the size. Base electrode 11
2 and the lower outer edge of the cathode material layer 113 and the cathode material layer 11
An insulating layer 114 is formed on the portion where 3 is not formed. An insulating layer 115 and a control electrode 116 are sequentially formed on the insulating layer 114 around the cathode material layer 113 at predetermined intervals with respect to the cathode material layer 113.
The insulating layer 115 is made of Al ₂ O ₃ , SiO ₂ or the like and is formed to a thickness equal to or larger than the thickness of the cathode material layer 113, and the control electrode 116 is for extracting electrons from the cathode material layer 113. Etc.

The operation of the above arrangement will be described below. Cathode material layer 113 is negative, control electrode 116
When a voltage is applied between the two so that the value becomes positive, the lines of electric force are concentrated on the edge portion 113a of the cathode material layer 113, resulting in a strong electric field. At this time, since the widths of the cathode material layer 113 and the control electrode 116 gradually change depending on places,
The electric field strength will also change. Therefore, even if the pattern accuracy of the cathode material layer 113 and the control electrode 116 varies during fabrication, the edge portion of the cathode material layer 113 that provides the electric field strength necessary for electron emission always exists, and therefore stable electron emission is achieved. Emission characteristics can be obtained.

[0010]

However, of the above-mentioned conventional examples, the former configuration has a plurality of array-shaped cavities 1.
When forming the cathode emitter projection 108 in the substrate 05, it is necessary to simultaneously perform the rotary oblique vapor deposition and the direct vapor deposition from directly above, and it is very difficult to accurately control this simultaneous vapor deposition. there were.

On the other hand, in the latter configuration, the cathode material layer 113
There is a problem that the electron beam emitted from the electron beam spreads outward and the quality of the electron beam is deteriorated.

The present invention solves the above-mentioned problems of the prior art and can be easily manufactured.
An electron-emitting device capable of improving yield and reliability and suppressing a spread of an electron beam emitted from a cathode portion to obtain a high-quality electron beam. It is intended to be provided.

[0013]

The technical means of the present invention for achieving the above object is to provide an insulating substrate, a base electrode formed on the insulating substrate, and a radial pattern at a predetermined portion on the base electrode. A plurality of cathode portions each having an edge portion and having a wedge-shaped portion whose width gradually changes, and an insulating layer formed at a predetermined interval from at least the wedge-shaped portion of the cathode portion. , And a control electrode for extracting electrons from the cathode portion, which is formed on the insulating layer.

Another technical means of the present invention for attaining the above object is to form an insulating substrate, a base electrode formed on the insulating substrate, and a predetermined portion on the base electrode sequentially in a radial pattern. A plurality of cathode portions each having a wedge-shaped portion having a gradually changing width and a cathode connection portion and an edge portion on the cathode connection portion; and at least a predetermined interval with the wedge-shaped portion of the cathode portion. And an insulating layer, and a control electrode formed on the insulating layer for extracting electrons from the cathode portion.

Still another technical means of the present invention for achieving the above object is, in each of the above technical means, an insulating layer formed on a control electrode for extracting electrons from a cathode portion, and the insulating layer. And a control electrode for squeezing the extracted electrons formed thereon.

Further, in any of the above technical means, the cathode side is formed in a reverse mesa shape in which the front surface side is wider than the back surface side, and the front surface side edge is an edge portion with an acute cross section, and the cathode connecting portion. In the case of using, the back surface side of the cathode portion is wider than the front surface side, and the back surface side edge is preferably formed in a mesa shape having an edge portion with an acute cross section.

In any of the above technical means, it is preferable to direct the wedge-shaped tips of the plurality of cathode portions toward a certain center, and to insulate the base electrode surface between the insulating layer and at least the periphery of the cathode portions. It is preferably coated with layers.

[0018]

Therefore, according to the present invention, when a voltage is applied between the cathode portion and the control electrode, the lines of electric force are concentrated in the wedge-shaped portion of the cathode portion and a strong electric field is generated, so that electrons are emitted. At this time, since the plurality of cathode portions are radially arranged and the control electrode is arranged at a predetermined distance from at least the wedge-shaped portions of these cathode portions, the spread of the electron beam can be suppressed. Further, it can be easily manufactured by a thin film manufacturing technique.

[0019]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 (a) is a plan view of an electron-emitting device according to the first embodiment of the present invention, and FIG. 1 (b) is A in FIG. 1 (a).
1 is a cross-sectional view taken along line A (note that in the plan view of FIG. 1A, a part corresponding to FIG. 1B is hatched in the same direction for easy understanding). ..

As shown in FIGS. 1A and 1B, Al is formed on an insulating substrate 11 made of glass, ceramics or the like.
A base electrode 12 made of Au, Mo, Cr, Ta or the like is formed, and a plurality of cathode parts 13 (six in the illustrated example) are formed in a radial arrangement on a predetermined portion of the base electrode 12. The material of the cathode portion 13 is Mo, W, Z.
rC, LaB _6, etc. are used, each of which has an edge portion 14, and is formed to have a so-called wedge-shaped portion in which at least a part of the width thereof gradually changes. It is formed so as to face a certain point. The insulating substrate 11 and the base electrode 12 are covered with Si on the periphery of the cathode portion 13 at a predetermined distance from the cathode portion 13.
An insulating layer 16 made of O ₂ , Al ₂ O ₃ , Si ₃ N ₄ or the like is formed, and a control electrode 17 made of Cr, Mo, W or the like for extracting electrons from the cathode portion 13 is formed on the insulating layer 16. ing.

The operation of the above configuration will be described below. Base electrode 12, that is, cathode portion 13
When a voltage is applied between the negative electrode and the control electrode 17 so that the voltage is negative and the control electrode 17 is positive, the lines of electric force are concentrated on the edge portion 14 of the cathode portion 13, particularly on the wedge-shaped tip portion 15, and a strong electric field is formed. And
When the electric field exceeds a predetermined electric field, the electrons are mainly transmitted through the wedge-shaped tip 15 into the vacuum due to the tunnel phenomenon, and the electrons are emitted. Further, as a result of the simulation, it has been found that the direction of the lines of electric force has a component in the direction of the wedge-shaped tip portion 15 of each cathode portion 13, and further, the wedge-shaped tip portion 15 of each cathode portion 13 as described above. The electrons are emitted from each wedge-shaped tip portion 15 because they are formed so as to face a certain central direction. Therefore,
The electron beam emitted from the electron-emitting device in the present embodiment is a centripetal and high-quality electron beam that does not spread to the outside.

Next, a method of manufacturing the electron-emitting device of the first embodiment shown in FIGS. 1A and 1B will be described with reference to FIG.
This will be described with reference to the cross-sectional views for explaining the manufacturing process shown in (a) to (e).

First, as shown in FIG. 2A, a base electrode 12 made of a conductive material such as Al, Ta, and Cr is vacuum-deposited or sputtered on an insulating substrate 11 made of glass or the like. The cathode material layer 18 made of Mo, W, ZrC, TiC or the like is similarly formed to have a predetermined film thickness on the base electrode 12. Further, Al, Sn, Ti, SiO ₂ is formed on the cathode material layer 18.
Similarly, the lift-off material 19 made of, for example, is formed thicker than the film thickness of the insulating layer 16 described later and is covered. The lift-off material 19 may be a metal or an insulator, and may be a material that withstands during the etching process of the cathode material layer 18 in the process described later and does not corrode other materials when removing it. Good.

Next, as shown in FIG. 2B, a photoresist 20 having a somewhat large similar shape with the pattern of the cathode portion 13 is formed on the lift-off material 19. At this time, the wedge-shaped tip portions 15 of the plurality of cathode portions 13 to be formed are formed in a pattern so as to face a certain central direction. Then, using the photoresist 20 as a protective film, the lift-off material 19 and the cathode material layer 18 are etched into the same pattern as the photoresist 20. Next, as shown in FIG. 2C, only the cathode material layer 18 is etched and processed into a pattern smaller than the lift-off material 19 by a predetermined amount to form the cathode portion 1.
3 is formed.

Next, as shown in FIG.
Stroke 20 is removed, SiO₂, Al ₂O₃And the like
Edge layer 16 and a control electrode made of a metal such as Cr, Mo, W
The poles 17 are sequentially formed on the entire surface from above by a sputtering method.
It The base electrode 12 and the insulating layer 16 and the insulating layer 16 and the control
To improve the adhesion with the control electrode 17, heat the whole
If this is the case, please refer to the above
By removing the strike 20, it will be disassembled and tested.
You can keep the charges clean.

Finally, as shown in FIG. 2 (e), by removing the lift-off material 19, the insulating layer 16 and the control electrode 17 on the lift-off material 19 are also removed at the same time,
The cathode part 13 is exposed to expose the edge part 14 and the wedge-shaped tip part 15.
The insulating layer 16 and the control electrode 17 can be formed so as to surround the cathode portion 13 with a predetermined interval.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 3A is a plan view of the electron-emitting device according to the second embodiment of the present invention, and FIG. 3B is a sectional view taken along the line BB in FIG. 3A. In the plan view of FIG. 3A, a part corresponding to FIG. 3B is shaded in the same direction for easy understanding.

In the present embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.
The different configuration will be described. The feature of this embodiment is that, as shown in FIGS. 3A and 3B, the insulating layer 21 is formed on the control electrode 17 on the outer periphery surrounding the plurality of cathode portions 13, and the insulating layer 21 is further formed. The point is that the control electrode 22 for narrowing down the extracted electrons is formed.

According to the present embodiment, by applying a voltage to the control electrode 22 and further squeezing the electrons emitted from the cathode portion 13, a very high quality electron beam can be obtained.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows an electron-emitting device according to the third embodiment of the present invention and is a sectional view similar to FIG. 1 (b).

In this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.
The different configuration will be described. As shown in FIG. 4, the feature of the present embodiment is that the front surface 23 side of the cathode portion 13 is wider than the back surface 24 side, and the edge on the front surface 23 side is the edge portion 14 having an acute cross section, that is, the so-called reverse. It is a point formed in a mesa shape.

According to the present embodiment, since the edge portion 14 and the cathode tip portion 15 of the cathode portion 13 are formed in the inverted mesa shape having an acute angle in section, the electric field at the edge portion 14, particularly the wedge-shaped tip portion 15, is generated. The degree of concentration can be increased.
Therefore, it is possible to operate at a low voltage and improve the electron emission characteristics.

Next, a method of manufacturing the electron-emitting device according to the third embodiment shown in FIG. 4 will be described with reference to the sectional views for explaining the manufacturing process shown in FIGS. ..

First, as shown in FIG. 5A, a base electrode 12 made of a conductive material such as Cr, Ta, In ₂ O ₃ is vacuum-deposited or sputtered on an insulating substrate 11 made of glass or the like. Of the cathode material layer 1 made of Mo, W or the like on the base electrode 12 by the method
8 is similarly formed to have a predetermined film thickness. Further, a lift-off material 19 made of Al, Sn, Ti, SiO ₂ or the like is formed on the cathode material layer 18 in the same manner as the lift-off material 19 so as to have a thickness larger than that of an insulating layer 16 which will be described later and is coated. The lift-off material 19 may be a metal or an insulator, and may be a material that withstands during the etching process of the cathode material layer 18 in the process described later and does not corrode other materials when removing it. Good.

Next, as shown in FIG. 5B, a photoresist 20 having a similar pattern with a predetermined pattern of the cathode portion 13 is formed on the lift-off material 19. At this time, the wedge-shaped tip portions 15 of the plurality of cathode portions 13 formed are
The pattern should be oriented toward a certain center. Then, using the photoresist 20 as a protective film, the lift-off material 19 is etched into the same pattern as the photoresist 20, and then the cathode material layer 18 is etched using the etched lift-off material 19 as a mask. In the processing of the cathode material layer 18, for example, first, by reactive ion etching (RIE), the ionized radical molecules are obliquely inclined to the surface of the cathode material layer 18 under anisotropic etching conditions. The arrangement is such that it is incident, and etching is performed while rotating the substrate 11 and the like. As a result, the cathode material layer 18 can be formed in an inverted mesa shape in which the back side is narrowed. Then R
By changing the IE etching condition to an isotropic etching condition and performing the etching, the cathode material layer 18 is processed into a pattern smaller than the lift-off material 19 by a predetermined amount as shown in FIG. 13 can be formed.

Next, as shown in FIG.
Stroke 20 is removed, SiO₂, Al ₂O₃And the like
Control of edge layer 16 and metal such as Cr, Nb, Mo
The electrode 17 is sequentially moved upward by a vacuum deposition method, a sputtering method, or the like.
From the entire surface.

Finally, as shown in FIG. 5E, the lift-off material 19 is removed to simultaneously remove the insulating layer 16 and the control electrode 17 on the lift-off material 19 to expose the cathode portion 13. The insulating layer 16 and the control electrode 17 can be formed so as to surround the cathode portion 13 at a predetermined interval.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 6A is a plan view of an electron-emitting device according to the fourth embodiment of the present invention, and FIG. 6B is a sectional view taken along the line CC of FIG. 6A.

In this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.
The different configuration will be described.

The feature of this embodiment is that FIG.
As shown in (a) and (b), at a predetermined portion on the base electrode 12, a cathode connecting portion 25 made of Au, Cr, C, Si, Ge or the like and M on the cathode connecting portion 25.
A plurality of cathode parts 26 (six in the illustrated example) are sequentially formed in a radial pattern from o, W, ZrC, LaB _6, etc., and the back surface 30 side of each cathode part 26 is wider than the front surface 29 side, and the back surface 30 side The edge portion 2 is formed in a so-called mesa shape whose edge is an edge portion 27 having an acute angle in section and includes a wedge-shaped tip portion 28.
7 is formed so as to project to the side of the cathode connecting portion 25 and float in the air.

According to this embodiment, the edge portion 27 and the cathode tip portion 28 of the cathode portion 26 are formed in a mesa shape having an acute cross section, so that the edge portion 27, in particular, the wedge-shaped tip portion 2 is formed.
The degree of concentration of the electric field at 8 can be increased. Therefore, it can be operated at a low voltage and the electron emission characteristics can be improved. In addition, the edge portion (including the wedge-shaped tip portion 28) 2 where the electric field is concentrated in the cathode portion 26
Since 7 is formed so as to project to the side of the cathode connecting portion 25 and float in the air, it is possible to reduce the electric field concentration on an unnecessary portion and stabilize the electron emission. Further, by using a semiconductor material for the cathode connecting portion 25, when the electron emission current increases, the cathode connecting portion 2
5, a voltage drop can be caused, and damage to the cathode portion due to excessive current emission can be prevented.

Next, a method of manufacturing the electron-emitting device in the fourth embodiment shown in FIGS. 6A and 6B will be described with reference to FIGS. 7A to 7E. A description will be given with reference to cross-sectional views (note that each figure is C in FIG. 6A).
It is a sectional view corresponding to the -C line. ).

First, as shown in FIG. 7A, glass,
On the substrate 11 made of Al ₂ O ₃ or ceramics,
Base electrode 1 made of Cr, Pt, In ₂ O ₃ , Ta, etc.
2, a cathode connection material layer 31 made of Au, C, Cr, Si, Ge, etc., a cathode material layer 32 made of Mo, W, etc., and a lift-off material 19 made of Al, SiO _2, etc.
The layers are sequentially formed by a method such as vacuum deposition or sputtering.

Next, as shown in FIG. 7B, a photoresist 20 is formed on the lift-off material 19 by using an ordinary lithography technique so as to have a somewhat large similar shape with the pattern of the cathode portion 26, and this resist is formed. The lift-off material 19 is etched using 20 as a mask, and then the lift-off material 19 thus etched is used as a mask, and the cathode material layer 32 is removed from the lift-off material 19 by reactive ion etching with CF ₄ gas, for example. The cathode portion 26 is formed by processing so as to be slightly smaller than the pattern. When the cathode portion 26 is processed under the condition of isotropic etching, a hem is widened, that is, a mesa shape in which the back surface 30 is wider than the front surface 29 is formed.
An edge portion 27 having an acute cross-section is provided on the back surface side edge, and a sharp wedge-shaped tip portion 28 is provided on the tip back surface side (see FIGS. 6A and 6B).
Can be processed to have. Therefore, it is necessary to use, as the material layer 31 for the cathode connection portion, a material that is not etched by the CF ₄ -based gas.

Next, as shown in FIG. 7C, the lift-off material 19 and the cathode portion 26 are used as a mask and, for example, Cl is used.
_The cathode connecting portion 25 is formed by etching the cathode connecting portion material layer 31 using a ₂ system gas so as to be slightly smaller than the pattern of the cathode portion 26, and the edge portion including the wedge-shaped tip portion 28 of the cathode portion 26 is formed. 27 is projected to the side of the cathode connecting portion 25 and floated in the air. Therefore, it is necessary to use, as the cathode material layer 32, a material that is not etched by the Cl ₂ -based gas.

Next, as shown in FIG.
Stroke 20 is removed, SiO₂, Al ₂O₃, Si₃N_Four
Insulating layer 16 composed of etc. and Mo, W, Cr, Nb, etc.
The control electrode 17 consisting of
Form on the entire surface.

Finally, as shown in FIG. 7E, the lift-off material 19 is removed by lift-off together with the insulating layer 16 and the control electrode 17 on the lift-off material 19, so that the cathode portion 26 is removed.
It is possible to manufacture the electron-emitting device of the present embodiment in which the insulating layer 16 and the control electrode 17 are formed with the cathode layer 26 exposed at a predetermined distance.

By forming the cathode portion 26 with the cathode connecting portion 25 interposed in this way, different materials can be used for both, and therefore the cathode portion 26 can be formed into a desired shape by the above manufacturing method. Can be easily processed.

The front surface 29 side of the cathode portion 26 is the back surface 30.
The edge portion 27 (particularly, the wedge-shaped tip portion 2) is formed by forming the inverted-mesa shape that is wider than the side and sharpening the edge portion (including the wedge-shaped tip portion 28) 27 of the edge on the surface side of the cathode portion 26.
8 can increase the degree of electric field concentration, operate at a low voltage, and improve the electron emission characteristic. Further, the edge portion 27 including the wedge-shaped tip portion 28 is projected to the side of the cathode connecting portion 25 to be in the air. By forming it so as to float, electric field concentration does not occur in an unnecessary portion, and the operation of the electron-emitting device can be stabilized.

(Embodiment 5) Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings.

FIG. 8 shows an electron-emitting device according to the fifth embodiment of the present invention and is a sectional view similar to FIG. 1 (b).

In the present embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.
The different configuration will be described. A feature of this embodiment is that the surface of the base electrode 12 between the insulating layer 16 and at least the periphery of the cathode portion 13 is covered with the insulating layer 33, as shown in FIG.

According to this embodiment, the insulating layer 33 can reduce the leak current on the surface of the base electrode 12 and improve the withstand voltage between the base electrode 12 and the control electrode 17.

(Embodiment 6) A sixth embodiment of the present invention will be described below with reference to the drawings.

FIG. 9 shows an electron-emitting device according to the sixth embodiment of the present invention and is a sectional view similar to FIG. 3 (b).

In this embodiment, the same parts as those in the second embodiment are designated by the same reference numerals and the description thereof will be omitted.
The different configuration will be described. A feature of this embodiment is that, as shown in FIG. 9, the surface of the base electrode 12 between the insulating layer 16 and at least the periphery of the cathode portion 13 is covered with the insulating layer 33.

According to the present embodiment, similarly to the fifth embodiment, the insulating layer 33 reduces the leak current on the surface of the base electrode 12 and increases the withstand voltage between the base electrode 12 and the control electrode 17. Can be improved.

[0062]

As described above, according to the present invention, by applying a voltage between the cathode portion and the control electrode, the lines of electric force are concentrated in the wedge-shaped portion of the cathode portion and a strong electric field is obtained.
Electrons can be emitted. At this time, a plurality of cathode portions are radially arranged, and at least a wedge-shaped portion of these cathode portions is provided with a control electrode at a predetermined interval, so that the spread of the electron beam can be increased. Can be suppressed. Therefore,
A high-quality electron beam can be obtained. Further, since it can be easily manufactured by the thin film manufacturing technique, the yield can be improved and the reliability can be improved.

By forming the cathode portion with the cathode connecting portion interposed therebetween, different materials can be used, and therefore, the cathode portion can be easily processed into a desired shape. In particular, the cathode connecting portion can be formed. By using a semiconductor material for the portion, when the electron emission current is increased, a voltage drop is caused at this cathode connection portion, and damage to the cathode portion due to excessive current emission can be prevented.

Further, by further controlling the emitted electron beam with the second control electrode, the spread of the electron beam can be suppressed more effectively, and a higher quality electron beam can be obtained.

Further, by forming the edge of the cathode portion into an inverted mesa shape in which the edge portion has an acute-angled edge portion or a mesa shape and sharpening it, the electric field concentration can be increased and the device can be operated at a low voltage. The electron emission characteristics can be improved. Further, the edge portion where the electric field is concentrated in the cathode portion is configured to be projected laterally and floated in the air, so that the electric field is not concentrated on an unnecessary portion and the operation can be stabilized.

Further, in particular, by directing the wedge-shaped tip of each cathode part toward a certain central direction, an electron beam with high centripetality can be emitted, and the spread of the electron beam can be suppressed even more effectively. Therefore, a higher quality electron beam can be obtained.

By covering the surface of the base electrode with the insulating layer at least around the cathode portion with the insulating layer, the surface leak current can be reduced. Therefore, the withstand voltage between the base electrode and the control electrode can be improved.

[Brief description of drawings]

1A is a plan view showing an electron-emitting device according to a first embodiment of the present invention, FIG. 1B is a sectional view taken along the line AA of FIG.

2A to 2E are cross-sectional views for explaining a manufacturing process of the electron-emitting device according to the first embodiment of the present invention.

3A is a plan view showing an electron-emitting device according to a second embodiment of the present invention, FIG. 3B is a sectional view taken along the line BB of FIG. 3A, showing the same electron-emitting device.

FIG. 4 is a sectional view showing an electron-emitting device according to a third embodiment of the present invention, similar to FIG. 1 (b).

5A to 5E are sectional views for explaining a manufacturing process of an electron-emitting device according to a third embodiment of the present invention.

FIG. 6A is a plan view showing an electron-emitting device according to a fourth embodiment of the present invention. FIG. 6B is a sectional view taken along line CC of FIG. 6A showing the same electron-emitting device.

7A to 7E are cross-sectional views for explaining a manufacturing process of an electron-emitting device according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing an electron-emitting device according to a fifth embodiment of the present invention, similar to FIG. 1 (b).

FIG. 9 is a sectional view showing an electron-emitting device according to a sixth embodiment of the present invention, similar to FIG.

FIG. 10A is a cross-sectional view showing a state of the conventional electron-emitting device during manufacturing, and FIG. 10B is a cross-sectional view showing a completed state of the same electron-emitting device.

11A is a plan view showing another conventional electron-emitting device, FIG. 11B is the same electron-emitting device, and FIG. 11A is a sectional view taken along the line D-D of FIG. Sectional drawing which shows an emission element and which follows the EE line of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Insulating substrate 12 Base electrode 13 Cathode part 14 Edge part 15 Wedge-like tip part 16 Insulating layer 17 Control electrode 21 Insulating layer 22 Control electrode 25 Cathode connecting part 26 Cathode part 27 Edge part 28 Wedge-like tip part 33 Insulating layer

Claims (7)

[Claims] 1. An insulating substrate, a base electrode formed on the insulating substrate, a radial portion formed on a predetermined portion of the base electrode, having an edge portion, and at least a portion of the width gradually changing. A plurality of cathode portions having wedge-shaped portions, an insulating layer formed at a predetermined distance from at least the wedge-shaped portions of the cathode portion, and a control for extracting electrons from the cathode portions, which is formed on the insulating layer. An electron-emitting device having an electrode. 2. An insulating substrate, a base electrode formed on the insulating substrate, a cathode connection portion radially formed in a predetermined portion on the base electrode, and an edge portion on the cathode connection portion. A plurality of cathode portions having a wedge-shaped portion of which the width gradually changes, and an insulating layer formed at least with a wedge-shaped portion of the cathode portion at a predetermined interval;
An electron-emitting device having a control electrode formed on the insulating layer for extracting electrons from the cathode portion. 3. An insulating layer formed on a control electrode for extracting electrons from the cathode part, and an insulating layer formed on the insulating layer,
The electron-emitting device according to claim 1, further comprising a control electrode for narrowing down the extracted electrons. 4. The front side of the cathode portion is wider than the back side,
4. The electron-emitting device according to claim 1, wherein the edge on the front surface side is formed in an inverted mesa shape having an edge portion with an acute angle in section. 5. The back side of the cathode portion is wider than the front side,
The electron-emitting device according to claim 2 or 3, wherein the back-side edge is formed in a mesa shape with an edge portion having an acute cross section. 6. The electron-emitting device according to claim 1, wherein the wedge-shaped tip portions of the plurality of cathode portions are oriented toward the center. 7. The electron-emitting device according to claim 1, wherein the base electrode surface between the insulating layer and at least the periphery of the cathode portion is covered with the insulating layer.