JP2001312960A - Electron emitting element, electron source, image forming apparatus, and electron emitting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron emission element, an electron source, an image- forming device and electron emission device, capable of simultaneously realizing both improvement in the electron emission efficiency and the control of the electron orbit. SOLUTION: An insulating layer 3 is piled on the element electrode 2 which is to become a low potential electrode and an element electrode 4 which is to become a high potential electrode is piled in continuing to the insulating layer 3. The element electrode 4 similarly to the element electrode 2 is selected from a conductive material of which the electron affinity is negative.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electron-emitting device that emits electrons, an electron source having the electron-emitting device, an image forming apparatus having the electron source, and an electron-emitting device.

[0002]

2. Description of the Related Art Conventionally, two types of electron-emitting devices, a thermionic electron-emitting device and a cold cathode electron-emitting device, are known. The cold cathode electron emitting device includes a field emission type (hereinafter, referred to as “FE type”), a metal / insulating layer / metal type (hereinafter, referred to as “MIM type”), a surface conduction type electron emitting device, and the like.

As an example of the FE type, W. P. Dyke &
W. W. Dolan, 'Field Emissio
n ', Advance in Electron Ph
ysics, 8, 89 (1956) or C.I. A. S
pindt, 'PHYSICAL Property
s of thin-film field emis
sion cathodes with mollybd
eneium cones', J. et al. Appl. Phys
s. , 47, 5248 (1976).

As an example of the MIM type, C.I. A. Mea
d, 'Operation of Tunnel-Em
issue Devices', J.M. Apply. P
hys. , 32, 646 (1961).

In a recent example, Toshiaki.
Kusunoki, 'Fractation-fre
e electron emission from
non-formed metal-insulato
r-metal (MIM) cathodes Fabr
icated by low current Ano
dic oxidation ', Jpn. J. App
l. Phys. vol. 32 (1993) pp. L16
95, Mutsumi suzuki et al'An
MIM-Cathode Array for Ca
side luminescent display
s', IDW'96, (1996) pp. 529 etc. have been studied.

[0006] As an example of the surface conduction type, a report by Elinson (MI Elinson Radio Eng. E) is available.
electron Phys. , 10 (1965)), and the surface conduction type electron-emitting device emits electrons when a current flows through a small-area thin film formed on a substrate in parallel with the film surface. It utilizes the phenomenon.

Among the surface conduction type devices, those using the SnO ₂ thin film and those using the Au thin film described in the above-mentioned report of Ellison (G. Dittmer. Thin Solid)
Films, 9, 317, (1972)), In ₂ O ₃ /
According to SnO ₂ thin film (M. Hartwell an)
d C.I. G. FIG. Fonstad, IEEE Trans.
ED Conf. , 519 (1983)).

[0008] Among these surface conduction types, flat and vertical electron-emitting devices as shown in FIGS. 16 and 17 have been proposed by the present applicants. Further, as an example of arranging a large number of these electron-emitting devices, see, for example,
It is disclosed in JP-A-4-31332, JP-A-1-283737, JP-A-1-257552 and the like.

[0009]

However, in the case of the above-described prior art, the following problems have occurred.

In order to realize an image forming apparatus using the above-described electron-emitting device, electrons emitted from the electron-emitting device collide with a phosphor disposed opposite to the electron-emitting device.
Although light is emitted, in a high-definition image forming apparatus, control of electron trajectory, electron emission efficiency (the efficiency described here is
Indicates the amount of the current flowing between the electron-emitting devices that reaches the anode or the phosphor above the device. ), Reduction in element size, etc. are required.

In particular, the control of the electron orbit and the improvement of the electron emission efficiency generally have a trade-off relationship, and it has been difficult to realize these relationships simultaneously.

For example, in the case of the FE type electron-emitting device,
Japanese Patent No. 6714 discloses a method of arranging an electrode for converging electrons in addition to an electron emission electrode and an electron extraction electrode and converging an electron orbit, and the like. Problems, such as an increase in electron emission efficiency and a decrease in electron emission efficiency.

Further, in the surface conduction type electron-emitting device, Japanese Patent Application Laid-Open Nos. Hei 3-20941 and Hei 7-2352
No. 56, etc., regarding the miniaturization of the element size,
JP-A-9-82214, JP-A-9-265894
Japanese Patent Application Laid-Open Publication No. H11-133969 discloses techniques for improving efficiency, but none of these techniques is sufficient to realize a high-definition image forming apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to provide an electron emitting device and an electron source capable of simultaneously improving electron emission efficiency and controlling electron trajectories. And an image forming apparatus and an electron emission device.

[0015]

In order to achieve the above object, according to the present invention, a high-potential electrode and a low-potential electrode are positioned so as to overlap with each other in the electron emission direction, and Is provided on the electron emission direction side than the low potential electrode, and an electron emission element that emits electrons by applying a voltage between the high potential electrode and the low potential electrode,
At least a part of the high-potential electrode is made of a negative electron affinity material, and has an exposed portion near the electron emission portion where the negative electron affinity material portion is exposed.

Therefore, since the negative electron affinity material portion has an exposed portion in the region including the electron emitting portion, the electron emitting efficiency is improved, and the high potential electrode is located closer to the electron emitting direction. Is provided, the scattering of electrons can be suppressed.

The high-potential electrode preferably has a coating made of a negative electron affinity material on its surface.

The high-potential electrode preferably has a layer structure, and has an exposed portion of a negative electron affinity material on a side wall thereof.

It is preferable that only the side wall has an exposed portion of a negative electron affinity material.

The high-potential electrode may be provided on the surface of the low-potential electrode so as to be stacked in a region narrower than the surface region, and the surface of the low-potential electrode may be exposed at both ends of the high-potential electrode. .

The high-potential electrode may locally include a non-conductive portion near the electron-emitting portion.

Preferably, the non-conductive portion is an opening formed in a high potential electrode having a layer structure.

A surface conduction electron-emitting device is preferred.

Further, the electron source of the present invention is characterized in that a plurality of the above-mentioned electron-emitting devices are arranged.

It is preferable that the electron-emitting devices are arranged in a matrix.

In the image forming apparatus of the present invention,
It is characterized by including the above-mentioned electron source, and an image forming member for forming an image by the electrons emitted from the electron source.

Preferably, the image forming member is a phosphor which emits light by collision of electrons.

A first electrode disposed on the substrate;
An electron-emitting device having a second electrode disposed on the first electrode via an insulating layer; and a third electrode spaced from the substrate so as to face the electron-emitting device. An electrode, and voltage applying means for applying a potential higher than the first electrode to the second electrode and applying a potential higher than the potential applied to the second electrode to the third electrode. An electron-emitting device, wherein the second electrode has a negative electron affinity material.

Preferably, the negative electron affinity material is present on a surface of the second electrode.

The second electrode preferably has a coating made of a negative electron affinity material on its surface.

The electron-emitting device is characterized in that a plurality of the above-mentioned electron-emitting devices are arranged.

Preferably, the electron-emitting devices are arranged in a matrix.

Preferably, the electron emission device has an image forming member, and the third electrode is arranged between the image forming member and the electron emission element.

The image forming member is preferably a phosphor that emits light by collision of electrons.

[0035]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

An electron-emitting device and an electron-emitting device according to an embodiment of the present invention will be described with reference to FIGS. For the sake of simplicity, the same components as those in the drawings cited in the above description of the related art will be described with the same reference numerals.

First, the overall structure of the electron-emitting device and the electron-emitting device according to the embodiment of the present invention will be described in detail with reference to FIGS. 1A and 1B are schematic views of an electron-emitting device according to an embodiment of the present invention. FIG. 1A is a schematic cross-sectional view, FIG. 1B is a schematic plan view, and FIG. FIG. 2 is a schematic diagram showing a driving state of an electron-emitting device according to an embodiment and an electron-emitting device of the present invention. Also,
FIG. 3 is a schematic process diagram showing a method for manufacturing an electron-emitting device according to an embodiment of the present invention.

An example of a method for manufacturing an electron-emitting device according to an embodiment of the present invention will be described. Quartz glass whose surface is cleaned, glass in which impurities such as Na are reduced, blue plate glass,
And a device in which an element electrode (first layer) is formed on a laminated body obtained by laminating an insulating material on a silicon substrate or the like;
Are laminated.

The element electrode 2 generally has conductivity, and is formed by a general vacuum film forming technique such as a vapor deposition method or a sputtering method, or a photolithography technique. The thickness of the device electrode 2 is set in a range of several tens nm to several mm,
Preferably, it is selected in the range of several hundred nm to several μm.

Next, an insulating layer 3 is deposited following the device electrode 2. The insulating layer 3 is formed by a general vacuum film forming method such as a sputtering method, a thermal oxidation method, an anodic oxidation method, or the like, and its thickness is set in a range of 3 nm to 1 μm, preferably several tens nm to several μm. It is selected from the range of 100 nm.

Further, following the insulating layer 3, the device electrode (the second
Is deposited (a state shown in FIG. 3A). The device electrode 4 has the same conductivity as the device electrode 2 and is selected from a material having a negative electron affinity.
Materials having a negative electron affinity include diamond-terminated carbon whose surface is terminated by hydrogen, diamond-like carbon, and gallium arsenide whose surface is coated with cesium-oxygen.

Next, by photolithography technology,
A part of the insulating layer 3 and the device electrode 4 is removed from the substrate 1, and a step structure is formed on the device electrode 2 between the insulating layer 3 and the device electrode 4 (the state shown in FIG. 3B). However, this etching step may be stopped on the device electrode 2 (see FIG. 1).
(State shown in FIG. 15A), and a part of the device electrode 2 may be etched and stopped (state shown in FIG. 15A).

In the case of the device electrode structure formed as described above, the device electrode (first electrode) 2 is a low potential electrode, the device electrode (second electrode) 4 is a high potential electrode, and the device electrode is a low potential electrode. A voltage is applied between the electrode 2 and the device electrode 4 serving as a high-potential electrode, and electrons are emitted from the gap 5.

In the electron-emitting device according to the embodiment of the present invention, electrons may be emitted by controlling the distance between the high potential electrode and the low potential electrode, or a structure in which the electric field is concentrated on the low potential electrode may be formed. To make it easier to emit electrons.

When the gap 5 serving as an electron emitting portion is formed, the conductive thin film (coating) 7 is arranged only in a desired region, so that the high potential electrode and the low potential electrode are concentrated due to the concentration of electric field or the heat generation effect. In some cases, the gap 5 may be selectively formed in a region sandwiched between them.

The formation of the gap 5 using the conductive thin film 7 is a step called energization forming.
After forming the conductive thin film 7 as shown in (c), a current is applied to the conductive thin film 7 to locally break, alter, or deform, thereby forming a gap.

The conductive thin film 7 is formed by a vacuum evaporation method, a sputtering method, or the like. In the embodiment of the present invention, the conductive thin film 7 is selected from negative electron affinity materials and has a surface terminated with hydrogen, diamond-like carbon, cesium. Gallium arsenide having a surface coated with oxygen; In addition, the conductive thin film 7 may cover a general metal thin film or semiconductor thin film with the above-described negative electron affinity material.

Further, in the electron-emitting device according to the embodiment of the present invention, in order to facilitate electron emission, a voltage is applied to the device electrode 2 and the device electrode 4 in the presence of an organic material, so that the electron is emitted. In some cases, a step called activation for generating carbon in the emission region and forming an electron emission point is performed.

The vacuum processing apparatus used in the activation step will be described with reference to FIG. FIG. 4 is a schematic configuration diagram illustrating the activation step.

In FIG. 4, reference numeral 45 denotes a vacuum vessel;
Reference numeral 6 denotes an exhaust pump, and reference numeral 47 denotes an organic gas supply source used when generating carbon on the side wall of the insulating layer between the high potential electrode and the low potential electrode of the electron-emitting device according to the embodiment of the present invention.

An element according to the embodiment of the present invention is arranged in the vacuum container 45. That is, 1 is a substrate, 2 is a device electrode (first electrode) which becomes a low potential electrode, 3 is an insulating layer,
Is a device electrode (second electrode) to be a high potential electrode, 5 is a gap, 7 is a conductive thin film, and 41 is a device voltage V applied to the electron-emitting device.
f, a power supply 40 for applying an electric current f, an ammeter 40 for measuring an element current If flowing between the element electrode 2 and the element electrode 4, and an anode electrode 6 for supplementing a current emitted from the element. 3 electrode).

Reference numeral 43 denotes an anode electrode (third electrode)
A high voltage source for applying a voltage to 6 and an ammeter 42 for measuring an emission current emitted from the electron-emitting device.

As an example, when the voltage of the anode electrode 6 is 0 to
The measurement can be performed with the range of 10 kV and the distance H between the anode electrode 6 and the electron-emitting device in the range of 100 μm to 8 mm. The vacuum vessel 45 is provided with equipment required for measurement in a vacuum atmosphere, such as a vacuum gauge (not shown), so that measurement and evaluation can be performed in a desired vacuum atmosphere.

The exhaust pump 46 is composed of a normal high vacuum system including a turbo pump and a rotary pump, and an ultra high vacuum system including an ion pump.

With the above structure, first, the substrate 1 is placed in the vacuum container 45, and the substrate 1 is evacuated to a vacuum atmosphere. Then, the organic gas is introduced into the vacuum container 45 from the organic gas supply source 47, and the organic material is removed. In an atmosphere containing gas, the device electrode 4
And a voltage is applied between the device electrodes 2.

The voltage waveform is repeatedly applied as a pulse waveform. This includes a method of continuously applying a pulse having a pulse peak value of a constant voltage, and a method of applying a voltage pulse while increasing the pulse peak value. Further, the step of producing the present carbon may be performed by mixing several kinds of gases as necessary.

By the above-described carbon generation process, carbon is deposited from the organic material present in the atmosphere between the element electrode 2 and the element decoration 4 or in the gap formed by energization, and electron emission occurs at a low voltage. Possible shapes may be formed.

Next, the electron emission characteristics of the electron-emitting device according to the embodiment of the present invention will be described in detail with reference to the prior art.

First, a conventional surface conduction electron-emitting device will be described for comparison. FIG. 16 shows a conventional flat type,
FIG. 17 shows a conventional vertical element structure. For the sake of simplicity, the same components as those described in the present embodiment are denoted by the same reference numerals. In FIG. 17, reference numeral 33 denotes a deposit deposited with an insulating material to provide a step.

SID '98 Digest, Okud
According to a and et al, in this type of surface conduction electron-emitting device, there is a gap in the electron-emitting portion, and when a driving voltage Vf is applied to this gap, electrons are emitted from the tip of the low potential electrode by a tunnel phenomenon. It is described that the electrons are isotropically scattered at the tip of the high potential electrode.

More precisely, it is described that when electrons are isotropically scattered at the tip of the high potential electrode, the experiment and the numerical calculation prediction are consistent with each other.

In this case, the majority of electrons emitted from the low potential electrode are elastically scattered (multiple scattering) several times on the high potential electrode.
It is described that electrons exceeding the characteristic distance Xs bound by the electric field formed by the low potential electrode and the high potential electrode reach the anode electrode (phosphor).

The characteristic distance Xs is expressed as follows: Xs = D / 2√ [1+ (2H × Vf / (π × Va ×
D)) × 2] ≒ (H × Vf) / (π × Va). Here, H is the distance between the electron-emitting device and the anode electrode, π is the pi, D is the gap width formed in the electron-emitting portion, Vf is the drive voltage, and Va is the voltage of the anode electrode.

The second approximate expression of this expression is Vf / D≫V
This is satisfied in the case of a / H, but is sufficiently satisfied in the case of a normal surface conduction electron-emitting device.

The electron emission efficiency is governed by the decrease in the number of electrons due to the fact that the electrons emitted from the gap are partially absorbed by the high potential electrode by multiple scattering until the electrons exceed the above-mentioned characteristic distance Xs. I have.

The ratio (scattering coefficient) β scattered by the collision of electrons of about several tens eV is not clear, but is estimated to be about 0.1 to 0.5 per one scattering.
Since β is 1 or less in such a scattering mechanism, it can be seen that the amount of electrons extracted in vacuum (existence probability) decreases with a power as the number of times of scattering increases.

Therefore, in the surface conduction electron-emitting device according to the prior art as shown in FIGS. 18 and 19, at least one electron emitted from the gap 5 is located on the high potential electrode facing the emission portion within the characteristic distance Xs. Each time, many electrons are scattered a plurality of times, so that the number of electrons that are taken into the high potential electrode and disappear is increased, and the electron emission efficiency is reduced.

As a method of solving the above problem, as shown in FIG. 20, the present applicants have studied a region where electrons are repeatedly scattered, in this case, a device electrode 4 which becomes a high potential electrode, or a high potential electrode. (Japanese Patent Application Laid-Open No. 9-26589).
No. 4). According to this method, electrons captured in the element electrode 4 serving as the high-potential electrode in the process of scattering electrons excite the electrons of the Fermi level of the element electrode 4 serving as the high-potential electrode into the conduction band, and the electrons are returned to the conduction band. It could be released into a vacuum, improving efficiency.

On the other hand, regarding the beam diameter, in the conventional device shown in FIG. 16, SID'98 Digest, Ok
Uda, et al describe that Lh 記述 2Kh × H√ (Vf / Va) Lw ≒ 2Kw × H√ (Vf / Va).

Here, Lh indicates the size of the beam in the vertical direction, and Lw indicates the size of the beam in the horizontal direction. Also, Kh, Kw
It is described that may be slightly different depending on the element structure, but can be approximated by about 1.

In the structure of FIG. 16 described above, when viewed from the anode disposed above the element, as shown in FIG. 21, the scattering region of electrons is wide due to the structure of the element. As a result, it is difficult to control the electron orbit. This is disadvantageous for reducing the beam diameter.

Accordingly, in the device structure disclosed in Japanese Patent Application Laid-Open No. 9-265894, electrons scatter over a wide area of a high potential electrode formed of a material having a negative electron affinity, and apparently electrons are scattered from the wide scattering area. Is observed, which is disadvantageous for controlling the electron trajectory and reducing the beam diameter, and it has been difficult to use the device in a high-definition image forming apparatus.

The electron-emitting device according to the present invention considers the above-mentioned problems, and simultaneously improves the electron-emitting efficiency and reduces the beam diameter. Hereinafter, features of the electron-emitting device according to the embodiment of the present invention will be described in detail.

One example of the electron-emitting device according to the embodiment of the present invention is shown in FIG. 1 as described above, and FIG. 5 shows an electron trajectory when the electron-emitting device shown in FIG. 1 is actually driven. Show.

Also in the electron-emitting device according to the embodiment of the present invention, the above-mentioned SID '98 Digest, Oku
Assuming that electrons are emitted by the same mechanism as the surface conduction electron-emitting device reported by Da, et al, the electrons emitted from the low potential electrode are scattered isotropically at the high potential electrode tip. Then, after scattering several times on the high potential electrode, the light reaches the anode above the element.

In the scattering process, since the element electrode 4 serving as the high-potential electrode is formed of the negative electron affinity material, the negative electron affinity material is exposed on the surface thereof (exposed portion). As shown, even in the case of electrons once taken into the high-potential electrode, the injection of the electrons excites electrons in the valence band of the element electrode 4 serving as the high-potential electrode into the conduction band and re-emitted into vacuum.

Further, in the electron-emitting device according to the embodiment of the present invention, a device electrode (first electrode) 2 serving as a low-potential electrode is disposed on a substrate 1 with an insulating layer 3 interposed therebetween, as shown in FIG. (A high potential electrode and a low potential electrode are arranged in the electron emission direction, that is, the direction of the anode electrode (third electrode) 6). And the high-potential electrode is closer to the anode electrode 6), so that the electron scattering region can be concentrated on the side wall of the device electrode 4. As a result,
When observing the electron emission part from the anode arranged above the element,
As shown in FIG. 7, the electron scattering region can be limited to the boundary between the element electrode 2 and the element electrode 4, an electron beam with a uniform orbit can be obtained, and the beam diameter can be reduced (the electron scattering region 10). ).

Further, it is not necessary that all of the high-potential electrodes are made of a negative electron affinity material, and a part thereof is made of this material, especially if the negative electron affinity material is exposed near the electron emitting portion. Needless to say, the predetermined purpose can be achieved. Further, a structure in which the negative electron affinity material is exposed only on the side wall of the high potential electrode, that is, for example, as shown in FIG.
By arranging the material 48 having a non-negative electron affinity on the device electrode 4 serving as a high-potential electrode, the negative electron-affinity material is exposed only on the side wall side. At the top of the high-potential electrode, re-emission of electrons can be suppressed. Orbit control becomes easier.

Further, a structure in which a non-conductive portion is locally provided in the vicinity of the electron-emitting portion, that is, as shown in FIG. 9, for example, an opening region where no high-potential electrode is present is arranged in a part of the high-potential electrode. As a result, an electric field due to the relationship with the low-potential electrode disposed below the high-potential electrode is formed above the high-potential electrode, and scattering of electrons at the top of the high-potential electrode can be suppressed. Can do it.

The effect described above can be achieved by arranging the low potential electrode below the high potential electrode so that the electron scattering region can be controlled to a narrow region. As a result, the re-emission phenomenon of electrons by forming the scattering region with negative electron affinity and the convergence effect of the electron orbit can be realized at the same time.
It is possible to realize a high-definition electron-emitting device.

Next, preferable driving conditions of the electron-emitting device according to the embodiment of the present invention will be described. The electron trajectory shown in FIG. 5 is such that Vf = 15 V at the electron detector, Va = 1 at a distance H = 2 mm from the anode (anode electrode 6) above the element.
0 kV was applied. In the device according to the embodiment of the present invention, Vf is not particularly limited, but Va is selected from a region capable of holding a vacuum withstand voltage, and its range is selected from several hundred V to several tens kV.

Next, other structural examples of the electron-emitting device according to the embodiment of the present invention will be described.

In the electron-emitting device according to the embodiment of the present invention, the low-potential electrode is disposed substantially below the high-potential electrode formed of a material having a negative electron affinity via the insulating layer. As another configuration example, there is an element structure as shown in FIG.

In the structure shown in FIG. 10A, the high potential electrode is provided on the surface of the low potential electrode so as to be stacked in a region narrower than the surface region, that is, on both sides of the high potential electrode. The high potential electrode is stacked in a region where the low potential electrode exists below the high potential electrode so that the low potential electrode exists (is exposed).

With this configuration, electrons emitted in a vacuum can direct their electron trajectories by an electric field formed above the low-potential electrode in a region where no electron-emitting portion exists.

As in the element structure shown in FIG. 10B, in addition to the structure shown in FIG. 10A, an opening region in which no high-potential electrode is present is disposed in a part of the high-potential electrode. Thus, as described above, scattering at the top of the high-potential electrode can be suppressed, and a high-definition electron-emitting device can be realized.

The shape of the above-mentioned opening region where the high potential electrode does not exist has a structure in which a plurality of pores are present as shown in a schematic view of FIG. 11 (FIGS. 11B and 11C are plan views thereof). (FIG. 11B) or a structure in which a plurality of slits are arranged (FIG. 11C). In addition, FIG.
FIG. 12 is a schematic sectional view of the structure shown in FIGS. 11 (b) and 11 (c).

Further, in order to easily extract electrons into a vacuum, the tip of the electron emission portion of the low potential electrode may be sharpened (processed portion 25) as shown in FIG. The material forming the electron emitting portion in this case is
It may be selected from conductive metals and semiconductors, and may be formed of a negative electron affinity material.

Next, FIG. 12 shows a diagram comparing the beam shapes of the electron-emitting device according to the embodiment of the present invention shown in FIG. 5 and the electron-emitting device according to the prior art shown in FIG.

In the conventional planar type, the majority of electrons emitted from the device electrode 2 serving as a low-potential electrode are scattered a plurality of times on the device electrode 4 serving as a high-potential electrode. ). In this case, it is known that the electrons are isotropically scattered. For this reason, the traveling direction of the electrons is random, and the uniformity of the electron trajectory is lost as the number of scattering increases.

Also in the electron-emitting device in which the high-potential electrode shown in FIG. 20 is formed with a negative electron affinity, electrons that have been repeatedly scattered a plurality of times reach the anode above the device.
This was disadvantageous for the convergence of the electron beam.

On the other hand, since the electron-emitting device according to the embodiment of the present invention has a structure capable of suppressing the number of times of scattering, the non-uniformity of the electron orbit due to isotropic scattering can be suppressed as much as possible.
Since the scattering region is formed with a negative electron affinity, the electron beam can be converged and the electron emission efficiency can be increased at the same time.

Next, an electron source using the electron-emitting device according to the embodiment of the present invention will be described with reference to FIG. FIG. 13 is a schematic diagram of the electron source according to the embodiment of the present invention.

In FIG. 13, reference numeral 1011 denotes an electron source base, 1
Reference numeral 012 denotes an X-direction wiring, and reference numeral 1013 denotes a Y-direction wiring. Reference numeral 1014 denotes an electron-emitting device according to the embodiment of the present invention, and 1015 denotes a connection.

A scanning signal applying means (not shown) for applying a scanning signal for selecting a row of the electron-emitting devices 1014 according to the embodiment of the present invention arranged in the X direction is connected to the X-direction wiring 1012. You.

On the other hand, the Y-direction wiring 1013 has the electron-emitting devices 101 according to the embodiment of the present invention arranged in the Y-direction.
A modulation signal generating means (not shown) for modulating each of the columns 4 according to the input signal is connected.

The driving voltage applied to each electron-emitting device is
It is supplied as a difference voltage between the scanning signal and the modulation signal applied to the element. The Y-direction wiring is connected to a high potential and the X-direction wiring is connected to a low potential.

Next, an image forming apparatus constructed using such an electron source having a simple matrix arrangement will be described with reference to FIG. FIG. 14 is a schematic perspective view of the image forming apparatus according to the present embodiment, showing a display panel of the image forming apparatus using soda lime glass as a glass material.

In FIG. 14, reference numeral 1111 denotes an electron source substrate on which a plurality of electron-emitting devices are arranged, and 1211 denotes an electron source substrate 111.
1126 is a glass plate 11
Fluorescent film (phosphor) 1 as image forming member on inner surface of 23
This is a face plate on which a metal back 124 and a metal back 1125 are formed.

Reference numeral 1122 denotes a support frame, and a rear plate 1121 and a face plate 1126 are connected to the support frame 1122 using frit glass or the like.

Reference numeral 1127 denotes an envelope, which is 45
Baking is performed for 10 minutes in a temperature range of 0 degrees to form a seal.

Reference numeral 1114 corresponds to the electron-emitting portion in FIG. Reference numerals 1112 and 1113 denote an X-direction wiring and a Y-direction wiring connected to a pair of device electrodes of the electron-emitting device according to the embodiment of the present invention.

The envelope 1127 includes the face plate 1126, the support frame 1122, and the rear plate 11 as described above.
21. Meanwhile, a face plate 1126,
By installing a support (not shown) called a spacer between the rear plates 1121, an envelope 1127 having sufficient strength against atmospheric pressure can be formed.

In the image forming apparatus using the electron-emitting device according to the embodiment of the present invention, the phosphor is arranged above the device in alignment in consideration of the emitted electron trajectory.

[0105]

The following is a more specific example based on the above embodiment.

(Example 1) First, the manufacturing process of this example will be described.

(Step 1) A 200-nm-thick T-substrate as a device electrode 2 serving as a low-potential electrode was placed on a sufficiently cleaned quartz substrate 1.
a, SiO ₂ having a thickness of 50 nm was deposited as an insulating layer 3 by a sputtering method.

Next, diamond having a thickness of 50 nm was formed as a device electrode 4 serving as a high potential electrode by a CVD method.

Next, a mask pattern was transferred in a photolithography step. Thereafter, using the patterned resist as a mask, the element electrode 4 and the insulating layer 3 were dry-etched to form steps (the structure shown in FIG. 1).

(Step 2) Next, the device electrode 4 was subjected to a hydrogen plasma treatment to make the electron affinity negative.

The device manufactured as described above was placed in a vacuum vessel as shown in FIG. 4 and driven. The driving voltage is V
f = 30 V, Va = 10 kV, and the distance H between the electron-emitting device and the anode electrode was H = 2 mm. Here, the size of the electron beam was observed using an electrode coated with a phosphor as an anode electrode. The electron beam size mentioned here is
The size was set up to a region of 10% of the peak luminance of the emitted phosphor.

As a result, a converged electron beam having a beam diameter of 100 μm was obtained, and the ratio of the current If flowing between the high-potential electrode and the low-potential electrode of the electron-emitting device to the current Ie due to the electrons reaching the anode electrode on the upper part of the device. The electron emission efficiency Ie / If represented by is 3.7%. Further, a beam diameter of 100 μm was obtained. In the case of the conventional flat type, the beam diameter was about 200 μm and the efficiency was about 1%.

Example 2 A structure similar to that of Example 1 was manufactured. Here, a protruding structure is formed on the low potential electrode,
A structure capable of emitting electrons at a low voltage was formed. The formation method is
20 nm of Mo was deposited on the step region between the high-potential electrode and the low-potential electrode, and formed by an Ar ion milling process from the oblique direction (the structure shown in FIG. 15B).

As a result, driving was possible at Vf = 15 V, and an electron emission efficiency of 3.7% was obtained as in Example 1. Further, a beam diameter of 100 μm was obtained.

(Example 3) In the same manner as in Example 1, Ta was formed as the device electrode 2 serving as the low potential electrode, SiO ₂ was formed as the insulating layer 3, and diamond was formed as the device electrode 4 serving as the high potential electrode. In the lithography step, the high potential electrode and part of the insulating layer 3 were removed. Further, in a photolithography step, a part of the high potential electrode was removed to form a region where no high potential electrode was present (the structure shown in FIG. 9).

As a result, when a voltage of Vf = 30 V was applied between the high-potential electrode and the low-potential electrode, and the electron emission properties were evaluated, scattering of electrons at the top of the high-potential electrode could be suppressed.
An electron emission efficiency of 3.7% and a beam diameter of 90 μm were obtained.

(Example 4) On a quartz substrate, Ta was used as the device electrode 2 serving as a low-potential electrode, SiO ₂ was used as the insulating layer 3, and
Diamond as an element electrode 4 serving as a high-potential electrode was laminated, and a high-potential electrode and part of the insulating layer were removed by a photolithography process. Next, a diamond-like carbon thin film was deposited on the side wall of the step formed by the high potential electrode and the insulating layer.

Thereafter, a minute gap was formed in the diamond-like carbon thin film by a forming step of applying a pulse voltage between the high potential electrode and the low potential electrode. The element thus manufactured is placed in a vacuum chamber,
Acetone gas was introduced at 7 × 10 ⁻⁴ Pa, a pulse voltage was applied between the high-potential electrode and the low-potential electrode, and carbon was generated between the gaps (structure shown in FIG. 3).

The device manufactured as described above has Vf = 1.
When driven by applying a voltage of 5 V, the electron emission efficiency is 3.7.
% And a beam diameter of 100 μm were obtained.

(Example 5) On a quartz substrate, Ta was used as an element electrode 2 serving as a low-potential electrode, SiO ₂ was used as an insulating layer 3,
Diamond was deposited to 300 nm, 50 nm, and 200 nm as the device electrode 4 serving as a high potential electrode. Next, the high potential electrode and part of the insulating layer 3 were removed from the substrate by a photolithography process. Here, the high-potential electrode is arranged in the region where the low-potential electrode exists (the structure shown in FIG. 10A).

Next, a diamond-like carbon thin film was deposited on the side wall of the step formed by the high potential electrode and the insulating layer 3. Thereafter, a minute gap was formed in the diamond-like carbon thin film by a forming step of applying a pulse voltage between the high potential electrode and the low potential electrode.

The device thus manufactured was placed in a vacuum chamber, acetone gas was introduced at 7 × 10 ⁻⁴ Pa, and a pulse voltage was applied between the high-potential electrode and the low-potential electrode.
Carbon was produced between the gaps.

The device fabricated as described above has Vf = 1
When driven by applying a voltage of 5 V, the electron emission efficiency is 3.6
% And a beam diameter of 100 μm were obtained.

(Embodiment 6) In the same manner as in Embodiment 5,
The high-potential electrode and the insulating layer were removed, and a region where the high-potential electrode did not exist was formed in part of the high-potential electrode (FIG. 10).
(Structure shown in (b)). Further, in the same manner as in Example 5, the forming step and the activation step were performed to manufacture an element.
As a result, good electron emission characteristics were obtained.

(Example 7) As in Example 1, Ta was used as the device electrode 2 serving as a low potential electrode, and SiO 2 was used as the insulating layer 3.
_{2. A} diamond film was formed as the device electrode 4 serving as a high potential electrode, and the high potential electrode and a part of the insulating layer 3 were removed from the substrate. Next, an opening region where no high-potential electrode exists was formed in part of the high-potential electrode by photolithography (the structure shown in FIG. 9). As a result, good electron emission characteristics were obtained at Vf = 30 V.

(Example 8) On a quartz substrate, Ta was used as the device electrode 2 serving as a low potential electrode, SiO ₂ was used as the insulating layer 3,
Diamond was deposited as a device electrode 4 to be a high potential electrode, and Al was further deposited thereon to 200 nm. Next, the high potential electrode and part of the insulating layer 3 were removed from the substrate by photolithography.

Subsequently, Al was anodically oxidized to form a plurality of pores, and the pores were used as a mask to etch the diamond of the high-potential electrode, thereby transferring the plurality of pores to the high-potential electrode. 11). As a result, when the device was driven, good electron emission characteristics were obtained.

(Embodiment 9) As in Embodiment 1, 300 n of Ta is used as an element electrode 2 serving as a low potential electrode on a quartz substrate.
m, 100 nm of SiO ₂ was deposited as the insulating layer 3 and 100 nm of diamond were deposited as the device electrode 4 to be a high potential electrode. Further, 10 nm of graphite was formed as a material 48 having a non-negative electron affinity on the diamond.

Next, by a photolithography process,
A part of each of the graphite, the high-potential electrode, and the insulating layer was removed from the substrate to produce an element (structure shown in FIG. 8). When Vf = 30 V was applied to the device manufactured in this way and driven, scattering at the top of the high-potential electrode could be suppressed, and a result with high efficiency and a small beam diameter was obtained.

Example 10 An image forming apparatus was manufactured using the electron-emitting devices manufactured in Examples 1 to 9. As an example, a case where the device of the first embodiment is used will be described.

The electron-emitting devices of Example 1 were arranged on a 10 × 10 matrix, and the x-direction wiring was connected to the high potential electrode, and the y-direction wiring was connected to the low potential electrode. 2m above the element
The phosphors were arranged at a distance of m.

The driving conditions were as follows: Va = 10 kV, Vf = 30 V
When set to, high-definition image display was possible.

[0133]

As described above, the electron-emitting device of the present invention has an exposed portion where the negative electron affinity material portion is exposed near the electron-emitting portion, so that the electron-emitting efficiency is improved.
In addition, the high-potential electrode and the low-potential electrode are in a positional relationship overlapping with each other in the electron emission direction, and the high-potential electrode is provided closer to the electron-emitting direction than the low-potential electrode. Since scattering can be suppressed, it is possible to simultaneously improve the electron emission efficiency and control the electron orbit.

By applying the electron-emitting device of the present invention, a high-definition image forming apparatus can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic view of an electron-emitting device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a driving state of the electron-emitting device according to the embodiment of the present invention.

FIG. 3 is a schematic process diagram illustrating a method for manufacturing an electron-emitting device according to an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram illustrating an activation step.

FIG. 5 is a diagram showing an electron trajectory when the electron-emitting device according to the embodiment of the present invention is driven.

FIG. 6 is an explanatory diagram illustrating the principle of electron emission by a negative electron affinity material.

FIG. 7 is an explanatory diagram showing an electron scattering region of the electron-emitting device according to the embodiment of the present invention.

FIG. 8 is a schematic diagram of an electron-emitting device (a configuration in which a negative electron affinity material is exposed only on a side wall) according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of an electron-emitting device (a structure in which a non-conductive portion is locally provided near an electron-emitting portion) according to an embodiment of the present invention.

FIG. 10 is a schematic diagram of an electron-emitting device (a configuration in which a low-potential electrode exists on both sides of a high-potential electrode) according to an embodiment of the present invention.

FIG. 11 is a schematic diagram of an electron-emitting device (a structure in which a non-conductive portion is locally provided near an electron-emitting portion) according to an embodiment of the present invention.

FIG. 12 is a comparison diagram of the spread of an electron beam.

FIG. 13 is a schematic diagram of an electron source according to an embodiment of the present invention.

FIG. 14 is a schematic perspective view of the image forming apparatus according to the present embodiment.

FIG. 15 is a schematic cross-sectional view showing a structural modification of the electron-emitting device according to the embodiment of the present invention.

FIG. 16 is a schematic view of a (planar) electron-emitting device according to the related art.

FIG. 17 is a schematic view of a conventional (vertical / stepped) electron-emitting device.

FIG. 18 is a schematic diagram showing a state of scattering of emitted electrons of an electron-emitting device according to a conventional technique.

FIG. 19 is a schematic view showing a state of scattering of emitted electrons of an electron-emitting device according to a conventional technique.

FIG. 20 is a schematic view of a (planar) electron-emitting device according to the related art.

FIG. 21 is a schematic view showing a state of a beam diameter of a (planar) electron-emitting device according to the related art.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 element electrode (low-potential electrode) 3 insulating layer 4 element electrode (high-potential electrode) 5 gap 6 anode electrode 7 conductive thin film 40 ammeter 41 power supply 42 ammeter 43 high-voltage power supply 45 vacuum vessel 46 exhaust pump 47 organic gas Source 48 Material with non-negative electron affinity 1011 Electron source base 1012 X-direction wiring 1013 Y-direction wiring 1014 Electron-emitting device 1015 Connection

Claims (19)

[Claims] 1. A high-potential electrode and a low-potential electrode are positioned so as to overlap with each other in the electron-emitting direction, and the high-potential electrode is provided closer to the electron-emitting direction than the low-potential electrode. In an electron-emitting device that emits electrons by applying a voltage between an electrode and a low-potential electrode, at least a part of the high-potential electrode is made of a negative electron affinity material, An electron-emitting device having an exposed portion from which a negative electron affinity material portion is exposed. 2. The electron-emitting device according to claim 1, wherein said high-potential electrode has a coating made of a negative electron affinity material on its surface. 3. The electron-emitting device according to claim 1, wherein the high-potential electrode has a layered structure, and has an exposed portion of a negative electron affinity material on a side wall thereof. 4. The electron-emitting device according to claim 3, wherein an exposed portion of a negative electron affinity material is provided only on the side wall. 5. A high potential electrode is provided on a surface of the low potential electrode so as to be laminated in a region narrower than the surface region, and the surface of the low potential electrode is exposed at both ends of the high potential electrode. The electron-emitting device according to claim 1, wherein: 6. The electron-emitting device according to claim 1, wherein the high-potential electrode locally includes a non-conductive portion near the electron-emitting portion. 7. The electron-emitting device according to claim 6, wherein the non-conductive portion is an opening formed in a high potential electrode having a layer structure. 8. The electron-emitting device according to claim 1, wherein the electron-emitting device is a surface conduction electron-emitting device. 9. An electron source comprising a plurality of the electron-emitting devices according to claim 1. 10. The electron source according to claim 9, wherein said electron-emitting devices are arranged in a matrix. 11. An electron source according to claim 9 or 10,
An image forming member that forms an image with electrons emitted from the electron source. 12. An image forming apparatus according to claim 11, wherein said image forming member is a phosphor which emits light by collision of electrons. 13. A first electrode disposed on a substrate;
An electron-emitting device having a second electrode disposed on the electrode with an insulating layer interposed therebetween; and a third electrode disposed at an interval from the substrate so as to face the electron-emitting device; Voltage applying means for applying a higher potential than the first electrode to the second electrode and applying a higher potential to the third electrode than the potential applied to the second electrode. An electron emission device, wherein the second electrode comprises a negative electron affinity material. 14. The electron-emitting device according to claim 13, wherein said negative electron affinity material exists on a surface of said second electrode. 15. The electron-emitting device according to claim 13, wherein the second electrode has a coating made of a negative electron affinity material on a surface thereof. 16. An electron-emitting device comprising a plurality of the electron-emitting devices according to claim 13. 17. The electron-emitting device according to claim 16, wherein said electron-emitting devices are arranged in a matrix. 18. The electron emission device according to claim 16, further comprising an image forming member, wherein the third electrode is arranged between the image forming member and the electron emission element. An electron-emitting device according to claim 1. 19. An electron emission device according to claim 18, wherein said image forming member is a phosphor which emits light by collision of electrons.