JPH02139841A - Electron emitting element - Google Patents

Abstract

PURPOSE:To eliminate deterioration of film quality and decrease destruction of an electrode by constructing a film electrode part adjoining to the electron emitting part in the form of a pair of mating electrodes. CONSTITUTION:Independent No.1 electrodes 1, 2 are subjected to patterning by photo-litho etching method or liftoff method situated on a base board 6, and at the same time, an interelectrode gap 15 is provided. Then an electrode member is provided over the electrodes 1, 2 by film forming method, and No.2 electrodes 3, 4 are formed by means of photo-litho etching method or liftoff method. This may be embodied in the form of an electron emitting element by arranging an electron emitting substance 5 in the gap 15. As electron emitting part is formed by subjecting the film-formed electrode material to photo-litho etching, etc., the shape and location are controlled precisely, and thereby an element is obtained, in which deterioration of film quality is eliminated and destruction of electrode is hard to be generated, which allows accomplishment of an enlarged amount of electron emission. Also the characteristic variation element by element can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electron-emitting device, and more particularly to a single surface conduction type electron-emitting device.

[Prior Art] Conventionally, as an element that can emit electrons with a simple structure,
For example, M.I.

A cold cathode device announced by John Elinson et al. is known. [Radio Eng, Elec
tron.

Pbys, ) Volume 10, pp. 1290-129B, 1
9E15] This utilizes the phenomenon of electron emission caused by passing a current parallel to the film surface through a small-area thin film formed on a substrate, and is generally called a surface conduction type emitter. ing.

This surface conduction type emission device includes one using the 5nOz (Sb) FM film developed by Ellingson et al., and one using an Au thin film [G.
1nSolid Films”), volume 9, page 317,
(1972) 1. M. Hartwell and C.G. Fonstad゛° by ITOiiM
IEEEE Trans”EEEEEE Conference” (M, Hartwell and C,
G., Fonstad: “IEEE Trans.
D Conf,” ) p. 511, (1975)]
, by carbon thin film [Hisashi Araki et al.: “Vacuum”, No. 2
Volume B, No. 1, p. 22, (1983)] have been reported.

Typical device configurations of these surface conduction type emitters are shown in the sixth section.
As shown in the figure. In the figure, 31 and 32 are electrodes for obtaining electrical connection, 33 is a thin film formed of an electron-emitting material, 34 is a substrate, and 35 is an electron-emitting portion.

Conventionally, in these surface conduction type emitting devices, an electron emitting portion is formed in advance by an electrical heating process called forming before electron emission. That is, by applying a voltage between the electrodes 31 and 32, the thin film 3
3 is energized, and the Joule heat generated thereby causes the thin film 33 to
The electron emitting function is obtained by locally destroying, deforming, or altering the structure to form an electron emitting part 35 that is in an electrically high resistance state.

That is, a portion of the thin film 33 is formed by forming.

The electron emitting portion 35 is formed as an electrically high resistance film.

A high electric field is applied from the thin film portion that did not become the electron emitting portion during the forming into the electron emitting portion, that is, the thin film electrode portion, and electron emission is performed.

However, in the above conventional example, the thin film electrode near the electron emitting part is exposed to the high heat generated during electron emission, ion bombardment and sputtering due to electron emission, and the high electric field of the applied voltage, and is often destroyed, making it difficult to use as an electron emitting device. This caused a loss of ability. The degree of destruction depends on the voltage Vr applied between the electrodes 31 and 32, and when Vf is small, there is little destruction, but there is a drawback that the amount of electron emission is extremely small.

These thin film electrode portions near the electron emitting portions have undergone a heating process by forming, and are usually deteriorated films with non-uniform film quality. Further, the thin film to be formed is generally a high resistance film in order to reduce the power consumption of the current heating treatment, and is usually a thin film of 500 to 100 OA. These thin film electrode portions, which are thin, non-uniform and defective films, are easily destroyed by exposure to a high electric field state during electron emission.

Furthermore, the electron-emitting part is manufactured using a heating process called forming, which generates a lot of Joule heat and alters the quality of the thin film part where it has accumulated. For this reason, it also has the disadvantage that the shape and position of the electron-emitting portion cannot be precisely controlled.

Due to the above-mentioned problems, surface conduction electron-emitting devices have not been actively applied industrially, despite having the advantage that the terminal structure is in a cylinder.

[Problems to be Solved by the Invention] The present invention has been made in order to eliminate the drawbacks of the conventional examples as described above, and it is possible to obtain the benefits obtained by forming processing without performing the conventional processing called forming as described above. It has a quality equal to or higher than that of the electron-emitting device, has a new structure with less variation in characteristics, and is less likely to cause electrode breakdown even if the voltage Vf applied to the electron-emitting part is increased, reducing the amount of electron emission. The object of the present invention is to provide an electron-emitting device that can increase the size of the electron-emitting device.

[Means and effects for solving the problem] The present invention has an electron emitter in a gap between a pair of electrodes that face each other with a gap, and the distance between the electrode end and the vicinity of the electrode side of the electrode gap is high. A surface conduction electron-emitting device comprising a first electrode made of a melting point material, and at least a second electrode located further away from the electrode spacing than near the upper electrode spacing.

That is, according to the present invention, first, the thin film electrode portion adjacent to the electron emitting portion consisting of the high resistance portion that has been conventionally altered by forming is controlled and formed as a pair of electrodes facing each other with a gap between them. .

This eliminates the deterioration in film quality that occurs when conventional thin film electrode parts are exposed to high heat during forming. Furthermore, it is possible to select the thickness and material of the thin film, thereby reducing electrode breakdown during electron emission.

Furthermore, we use a material that is resistant to electrode breakage as the electrode material at the end of the electrode gap of the thin film electrode and in the vicinity of the gap, and we also use a separately suitable material for the wiring electrode material for voltage application for electron emission, which causes electrode breakage due to electron emission. By using the electron-emitting device in a place where it is difficult for the electrodes to break down, it is possible to provide an electron-emitting device with less electrode breakdown without compromising device drive characteristics.

The present invention will be explained in detail below.

FIG. 1 is a schematic diagram showing one embodiment of the electron-emitting device of the present invention. In the figure, l and 2 are first electrodes that form an electrode gap related to electron emission, 3 and 4 are second electrodes that are electrical wiring, and 5 is a first electrode.
An electron emitter 6 is a substrate arranged in an electrode gap 15 formed by the electrodes 1.2. When this device is placed in a vacuum and a voltage is applied between the second electrodes 3 and 4, electrons are emitted from the vicinity of the electron emitter 5.

Next, the operation of the device according to the present invention will be explained.

In FIG. 1, the electrode spacing portion 15 has a size of several tens of amps to several tens of μl, for example, 50 amps to 20 μl, and the electron emitter 5 is made of a metal material such as Au, Ag, Cu, Pt, or Pd, or an alloy thereof. Or 5na2. I
In the case of an oxide such as n2O3*PbO or a mixture of the metal materials, alloys, oxides, etc., when a voltage of several volts to several too many volts is applied between the second electrode 3.4, the first electrode 1 A high electric field is generated in the electrode gap 15 between the two electrodes, and electrons are emitted from the vicinity of the electron emitter 5.

There is a threshold value for the applied voltage at which electrons are emitted, and this threshold value is determined by the distance between the electrodes 15, the electron emitter 5, and the first electrode 1.
It depends on the material etc. of 2.

Next, the outline of the manufacturing method of the electron-emitting device of this embodiment will be explained in the first part.
This will be explained based on the diagram.

That is, in FIG. 1, an electrode material that will become a first electrode is first formed on a substrate 6, and independent first electrodes 1 and 2 are patterned by photolithography or a lift-off method, and at the same time the electrode spacing 15 is The electrode material that will become the second electrode is formed on the top of the first electrode 1.2 so as to be connected to the first electrode, and each independent second electrode is formed by photolithography or lift-off method. Electrodes 3, 4
form. If it is desired to form the electrode spacing 15 narrowly, the first electrode can be patterned by direct etching using a focused ion beam instead of the lift-off method. Thereafter, an electron emitter 5 can be arranged between the electrodes 15 to form an electron emitting device. A method for forming and arranging the electron emitter 5 will be described later in Examples. As described above, the electron emitting portion is formed by photolithography or the like on the electrode material formed into a film. Therefore, the shape and position of the electron emitting section can be precisely controlled.

FIG. 2 is a schematic diagram showing another embodiment of the electron-emitting device of the present invention. In the figure, 8 and 9 are first electrodes,
3 and 4 are second electrodes, 6 is a substrate, 7 is formed on the substrate 6, supports the first electrode 9 and the second electrode 4, and has a space between it and the first electrode 8. The step forming member 10 made of an insulating material having a step is an electron emitter located at the step portion of the step forming member and disposed between the first electrodes 8.9, that is, at the electrode interval 16.

In this device as well, the electrode spacing portion 16 is similar to the embodiment described above.
If the size of the second electrode 3, 4 is several 10 A to several 1 mm and the electron emitter is similar to the above-mentioned material, the second electrode 3, 4
By applying a voltage to the electron emitter 10, electrons are emitted from the vicinity of the electron emitter 10.

Next, the outline of the method for manufacturing the electron-emitting device of this embodiment will be explained in the second section.
This will be explained based on the diagram.

That is, in FIG. 2, an insulating material that will become the step forming material 7 is first deposited on the substrate 6, and is partially removed by photolithography or the like to form the step portion.
A film of electrode material that will become the electrode is formed, and independent second electrodes 3 and 4 are formed on the step forming material 7 and the substrate 6 by photolithography or the like. Subsequently, the first electrodes 8, 9
An electrode material is formed into a film, and an electrode spacing 1B is formed by controlling the step so that the electrode material does not cover the step at the stepped portion.

Thereafter, an electron emitter 10 can be arranged in the electrode interval 1B to form an electron emitting device.

The method for forming and arranging the electron emitting body 10 will be described in one or more embodiments below, and the electron emitting portion is formed by a stepped portion of the deposited step forming material. Therefore, the shape and position of the electron emitting section can be precisely controlled.

As shown in the above embodiments, in the present invention, the second electrode is configured to be set back from the first electrode with respect to the distance between the electrodes forming the electron emitting portion.

This is because when electrons are emitted, the electrodes near the electrode spacing are the electron emitters 5. This is because it is exposed to ion bombardment and sputtering generated by heat generation and electron emission from the vicinity of 1O, and a high electric field due to applied voltage.

For example, according to an experiment on a forming-type surface conduction electron-emitting device, a device formed with Au having a thickness of 5 HA and an R film @ 3 ooμm was found to be 1 (in a vacuum on the order of 16 Torr, the voltage applied between the electrodes was about 18 V or more). Significant destruction of the thin film electrode occurred.

In the present invention, as the material of the first electrode, a high melting point electrode material is used as a material that is not susceptible to electrode breakage. for example,
Metals such as Mo, Ta, W, alloys thereof, and T
Carbides such as iC and TaC, carbon, etc. can be used. These materials are less susceptible to deterioration due to heat generation. In addition, the sputtering rate is low and the ion impact resistance is high.

Although the film thickness of the first electrode is not particularly limited, it is usually about several 1 OA to filOpm.

When these materials are used as wiring electrode materials, the wiring resistance becomes higher than that of ordinary materials. Therefore, when using these materials as the first electrode material of a surface conduction electron-emitting device, it is important to minimize the area used and reduce the power consumption of the device without unnecessarily increasing the device resistance. It is effective. For this purpose, as much as possible, the second electrode made of a right-handed low-resistance material is used as the electrode wiring for the electron-emitting part,
That is, it is necessary to form it close to the electrode spacing.

The second electrode material may be any commonly used electrode material, such as Ag, Cu, Au, Aj', old, etc., which has lower resistance than the first electrode, or has good substrate adhesion and surface oxidation resistance. The film thickness is not particularly limited as long as it can be easily handled as an electrode material, but it is usually about several 10 OA to several 100 ILi.

However, if the second electrode is extremely close to the electron emitting section, the electrode is likely to be destroyed due to damage during electron emission. Therefore, by forming the second electrode further back than the first electrode with respect to the electrode interval, that is, with respect to the electron emitting portion, it is possible to protect the second electrode from destruction during electron emission.

As explained above, the operation of the electron-emitting device of the present invention is such that when a voltage is applied between the second electrodes 3.4, the electrode interval 15 formed by the first electrodes 1.2 or 8.9 Alternatively, a high electric field of 1G is generated, and electrons are emitted from the vicinity of the electron emitter 5 or 10. Due to the high electric field, ion bombardment, sputtering, and heat generated between the electrodes due to voltage application at that time, the first electrode is made of a high melting point material or carbon, so electrode breakdown does not occur and electrons are emitted. .

Based on the present invention, the first electrode is made of Ta having a thickness of 100 OA.
In a surface conduction electron-emitting device in which the second electrode is made of Ni, the first electrode width is 3001 mm, and Pd fine particles are arranged as an electron emitter in the electrode gap, a voltage of 30 V is applied to the second electrode. Even when electrons were emitted, there was very little damage to the first electrode.

Furthermore, when a voltage of 14 V is applied, the amount of electron emission is as follows compared to the above-mentioned Au forming type surface conduction type electron-emitting device.
It was about the same level or higher. Furthermore, when a voltage of 20V was applied to this device, the amount of electron emission was approximately twice as much as when a voltage of 14V was applied.

Furthermore, in the present invention, the electron-emitting portion is formed using a microfabrication method such as photolithography or a stepped portion at the edge of the deposited thin film, so the shape of the electron-emitting portion is smaller than that of a method in which the electron-emitting portion is formed by an energization process called forming. As mentioned above, the position can be precisely controlled. Furthermore,
Since there is no need to make the film thickness of the electrode high-resistance, that is, thin film, since no current treatment is performed, the film thickness of the first electrode can be selected from a wide range, and the film thickness that causes less damage to the electrode during electron emission can be selected. You can choose.

[Example] Example 1 FIGS. 3(a) to 3(f) are sectional views showing the device manufacturing process of a first example of the electron-emitting device of the present invention. Figure 3(a)
In ~(f), 3 and 4 are second electrodes, 1.2 is a first electrode, 5 is an electron emitter, 6 is a substrate, 11.12 is a resist for patterning the electrodes, and 14 is an external power source. This electrode is used to improve electrical connection when applying voltage.

First, a photoresist 11 having a width of 11 pm was formed on a quartz substrate 6 having a thickness of l+sm [FIG. 3(a)'].

Next, Aj > thickness 400 with Cr thickness 50A as the underlay
0A was vacuum-deposited using a mask to form an external pattern on the substrate 6 and regimen 11 [Figure 3(b)]
.

Subsequently, by a lift-off process in which the photoresist 11 is peeled off, the deposited Or and AR are partially removed and patterned to form a second electrode 3.4. At this time, the electrode spacing of the second electrode 3.4 is the width of the photoresist) 11, 1
1 Bm [Figure 3 (C)].

Next, a width 1 is placed at the center of the pattern interval part of the second electrode 3.4.
P and m photoresists 12 were formed. Furthermore, Ta was deposited to a thickness of 200 OA using a mask to form an external pattern [FIG. 3(d)].

Subsequently, the deposited Ta was partially removed by a lift-off process in which the photoresist 12 was peeled off, and patterned to form the first electrode 1.2. At this time, the electrode interval 15 of the first electrode 3.4 was 1 μm width of the resist 12 [3rd
Figure (e)].

Thereafter, the electrode 14 was formed using Au with a thickness of 100 OA to improve the electrical connection from an external power source by mask vapor deposition at the end of the second electrode, and finally, an organometallic Pd solution (Okuno Pharmaceutical Co., Ltd. CCP4230) manufactured by CCP4230) was coated using a spinner and baked at 250°C for 10 minutes to provide an electron emitting body 5 to form the electron emitting device of this example.
Figure (f) ].

The device obtained by the above manufacturing method was prepared by applying a voltage Vf of 14 V between the first electrodes 3 and 4 in a vacuum chamber of 1 (16 Torr level), and applying a flat plate parallel to the device surface in a space perpendicular to the top surface of the device. When a voltage va of IKV was applied, electrons were emitted from the vicinity of the electron emitter 5.

The amount of electron emission 1e at that time was about 0.5 pA.

When Vr is further increased to 20V, Ie becomes 2. It rose to the level of OA. After this, when the first electrode on the side of the electron-emitting device was observed, almost no electrode breakdown had occurred. Furthermore, even when Vf was increased to 30V, the occurrence of electrode breakdown was small.

Embodiment 2 FIGS. 4(a) to 4(e) are sectional views showing the device manufacturing process of a second embodiment of the electron-emitting device of the present invention. Figure 4(a)
In ~(e), 3 and 4 are the second electrodes, and 8.9 is the first electrode.
, 14 is an electrode, 6 is a substrate, 13 is a resist, 7 is a step forming material for forming the electrode interval of the electron emitting section, and 10 is an electron emitter dispersed in the step forming material.

First, on a quartz substrate 6 with a thickness of lam, an organic metal P was coated on a Si02 liquid coating material (Tokyo Ohka Kogyo type OCD).
A mixture of d solution (CC94230 manufactured by Okuno Pharmaceutical Co., Ltd.) was applied using a spinner, and then baked at 400°C for 30 minutes.
A Si02 film containing Pd fine particles was formed. This was partially removed by photolithography to form a step-forming material 7 having a step portion and having an electron emitter IO disposed on the surface of the step portion [FIG. 4(a)].

Next, a photoresist 13 was formed with a thickness of 4 μm to cover the top and bottom of the stepped portion [FIG. 4(b)].

In addition, Ni thickness is 400 mm with Cr thickness of 50 mm as an underlay layer.
0A was deposited using a mask [FIG. 4(C)].

By a lift-off process for peeling off the resist 13, the deposited Or and old materials were partially removed and patterned to form second electrodes 3 and 4 [FIG. 4(d)].

Thereafter, the electrode 14 is formed of Au with a thickness of 100 OA, and finally carbon with a thickness of 100 OA is deposited around the stepped portion using a mask. At this time, by making the substrate surface of the substrate 6 oblique with respect to the carbon evaporation source, the vapor deposition step coverage at the stepped portion is deteriorated, and the first electrode 8°9 having a carbon electrode spacing is formed at the stepped portion. The electron-emitting device of this example was prepared [FIG. 4(e)].

When the device obtained by the above manufacturing method was subjected to electron emission in the same manner as in Example 1, almost the same level of electron emission was obtained, and the first electrode was hardly destroyed after electron emission. It had not occurred.

Embodiment 3 FIGS. 5(a) to 5(e) are sectional views showing the device manufacturing process of an embodiment of the electron-emitting device of the present invention. Figures 5(a) to (e)
), 19.20 is the second electrode, 17° 18 is the first electrode, 1O is the electron emitter, 7 is the step forming material, and 21 is the resist for patterning the electrode and the step forming material. This embodiment is structurally very similar to the first embodiment, but is based on a manufacturing method that allows the second electrode to be located very close to the edge of the electrode spacing.

In this manufacturing method, after patterning both the step forming material 7 containing the electron emitter 1O and the material of the second electrode 19, that is, the original thickness of 3000 A with an underlying layer of 50 A, using a photolithographic etching method, Again, the second
The electrode 19 was side-etched by wet etching, and was moved back about 2500 A from the edge of the step portion of the step forming material 7 [FIG. 5(a)].

(b) ].

After that, the old/Cr thickness 30 of the second electrode 20 on the substrate 6 is
QOA/50A was formed by mask evaporation and lift-off method [FIGS. 5(C) and 5(d)].

Finally, after forming an electrode 14 made of Au by mask evaporation, carbon is deposited to a thickness of 250 mm around the stepped portion of the step forming material 7.
The first electrodes 17 and 18 were formed by diagonal evaporation of A, and at the same time, the electrode spacing part that would become the electron emitting part was also formed [Figure 5 (
e) ].

The device obtained by the above manufacturing method has a structure in which the second electrode 19.20 is substantially set back by about 2500 A from the end of the first electrode 17.18 in the electrode gap. That is, at the upper end of the step forming material 7, the second electrode 19 is set back by 250 OA by side etching, and at the lower end of the step, the second electrode 20 is set back by 250 OA than the first electrode 18.
Because it is laminated with OA, it is actually 250 OA in the thickness direction.
The second electrode is set back from the first electrode.

If such a method is used, it becomes possible to control the amount of retraction of the second electrode to be extremely small.

In this device as well, it was possible to obtain electron emission characteristics equivalent to those in Examples 1 and 2.

Furthermore, in this embodiment, if the amount of retraction of the second electrode with respect to the first electrode is set to 2000A or less, compared to the above embodiment,
The applied breakdown voltage of the second electrode became low, making it impossible to obtain a large amount of electron emission.

[Effects of the Invention] As explained above, in the present invention, a high melting point material or carbon is used as the material of the electrode near the electrode gap involved in electron emission, that is, the first electrode, and a voltage is applied for electron emission. For the wiring electrode, that is, the second electrode, by using a separately suitable material in a place where electrode breakdown due to electron emission is unlikely to occur, the device drive characteristics can be maintained, and even if the device drive voltage is increased, electrode breakdown will not occur. This has the effect that it is possible to obtain an element that is less likely to generate electrons, and that it is possible to increase the amount of electron emission.

Furthermore, the electron emitting part of the surface conduction type electron emitting device is an electrode spacing part and an electron emitter disposed within the electrode spacing part,
By controlling and forming this constant, it becomes possible to precisely control the shape 1 position of the electron emitting part. Therefore, there is an effect that variations in characteristics from element to element can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an element showing a first embodiment of the present invention, FIG. 2 is a cross-sectional view of an element showing a second embodiment of the present invention, and FIG.
Figures (a) to (D) are cross-sectional views of an element showing a first embodiment of the present invention, Figures 4 (a) to (e) are cross-sectional views of an element showing a second embodiment of the present invention, and Figure 5. (a) to (e) are device cross-sectional views showing a third embodiment of the present invention, and FIG. 6 is a schematic diagram showing a conventional surface conduction type electron-emitting device. 1.2, 8, 9.17 .18...first electrode 3.4,
19.20... Second electrode 5.10... Electron emitter 7... Step forming material 15.16... Electrode spacing

Claims (2)

[Claims] (1) A pair of electrodes that face each other with a space therebetween, each having an electron emitting body within the space between the electrodes, and the space from the electrode end to the vicinity of the electrode side of the electrode space consists of a first electrode made of a high melting point material; A surface conduction electron-emitting device characterized in that at least a second electrode is located further away from the electrode spacing than near the electrode spacing. (2) The electron-emitting device according to claim (1), wherein the first electrode is made of a carbon material.