JP2001283719A - Electron emission element, electron source and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron emission element capable of simultaneously realizing an improvement of an electron emission efficiency and a convergence of electron orbit and a high definition electron source and an image formation device therewith. SOLUTION: The element is arranged on a substrate and equipped with a high-voltage electrode 2 with a convex portion at a given region, an insulating layer 3 that is arranged on the high-voltage electrode 2 and positioned in the region except an upper region of the convex of the high-voltage electrode 2, and a low-voltage electrode 4 that has a distance 6 between the high-voltage electrode 2 to be positioned in a pair on the insulating layer 3 through the convex portion and is arranged on the insulating layer 3.

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, an electron source having a plurality of the electron-emitting devices, and an image forming apparatus using the electron source.

[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 devices include 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.

[0003] As an example of the FE type, W. P. Dyke &
# 38; W. Dolan, " Field
Emission ", Advance in
Electron Physics, 8, 89 (195)
6) Alternatively, C.I. A. Spindt, " P
HYSICAL Properties of thi
n-film field emission cat
hoses withmolybdenium con
es " Appl, Phys,. 47,52
48 (1976) and the like are known.

Further, as another example of the FE type, there is a so-called edge emitter structure in which electrons are emitted from an edge of a metal or the like.

As an example of the MIM type, C.I. A. Mea
d. " Operationof Tunnel
-Emission Devices "
Apply. Phys. , 32, 646 (1961).

In a recent example, Toshiaki.
Kusunoki, " Fractation
-Free electron emission f
rom non-formed metal-insu
later-metal (MIM) cathodes
Fabricated by low current
Anodic oxidation ", Jp
n. J. Appl. Phys. vol. 32 (199
3) pp. L1695, Mutsumi suzuki
et al " An MIM-Cathode
Array for Cathode lumines
cent Displays ", IDW '9
6, (1996) pp. 529 etc. have been studied.

[0007] As an example of the surface conduction type, there is a report by Elinson (MI Elinson Radio Eng. E).
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.

[0008] As the surface conduction type device, a device using an SnO ₂ thin film, a device using an Au thin film, and a device using an Au thin film described in the above-mentioned report of Elinson (G. Dittmer. Thin Soli) are used.
dFilms. 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)).

Heretofore, in these surface conduction electron-emitting devices, it has been general to form an electron-emitting portion on a conductive thin film in advance by an energization process called energization forming before electron emission.

That is, the energization forming is to apply a DC voltage or a very slowly increasing voltage, for example, about 1 V / min, to both ends of the conductive thin film and to apply an electric current to locally destroy, deform or alter the conductive thin film. The purpose is to form an electron-emitting portion in a high resistance state.

Further, by a process called activation in which an organic gas is introduced in a vacuum and current is applied, an organic material is deposited on the tip of a conductive thin film opposed to the insulating film with an insulating layer interposed therebetween, thereby further improving electron emission characteristics. An electron emission portion is formed.

In the surface conduction type electron-emitting device which has been subjected to the energization forming process and the activation process, a voltage is applied to the conductive thin film and a current is caused to flow through the device so that electrons are emitted from the electron-emitting portion. is there.

Conventionally, in image forming apparatuses such as display apparatuses, in recent years, flat panel display apparatuses using liquid crystal have been widely used instead of CRTs. However, since they are not self-luminous, they must have a backlight. Therefore, a self-luminous display device has been desired.

The self-luminous display device is an image forming device that combines an electron source in which a number of surface conduction electron-emitting devices are arranged and a phosphor that emits visible light by electrons emitted from the electron source. Devices (eg, US Pat. No. 5,066,883).

As an example in which a large number of surface conduction electron-emitting devices are arrayed, surface conduction electron-emitting devices are arranged in parallel, and both ends (both device electrodes) of each surface conduction electron-emitting device are wired (common). An electron source in which a number of rows each connected by a wiring are arranged (ladder-like arrangement) (for example, JP-A-64-31332, JP-A-1-283749, JP-A-1-257552, etc.).

[0016]

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

In a flat panel display device using the above-mentioned surface conduction electron-emitting device, the beam diameter of the electron beam on the anode is substantially determined by the magnitudes of Va and Vf and the distance H between the device and the anode. (SID98
Digest, Okuda, et, al). FIG. 16 shows a conventional electron-emitting device.

In FIG. 16, reference numeral 311 denotes a substrate, 312,
313 is a facing electrode, 314 is a conductive film, 315 is a gap, and 316 is an anode electrode.

The diameter of the electron source given in the conventional example is also about 0.1 mm, and has a sufficient resolution as an image forming apparatus.

However, in recent years, higher resolution has been required for image display devices.

Therefore, the problem to be solved by the present invention is to obtain a higher-definition beam by controlling the electron trajectory, while improving the efficiency in order to prevent a decrease in the efficiency related to the trajectory control. It is in.

A conventional example for obtaining a high-definition beam diameter is disclosed in, for example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent No. 6714, a technique for arranging an electron converging electrode in the upper part of the emitting part in addition to the electron emitting electrode and the electron anode to converge the electron trajectory,
As disclosed in US Pat. No. 3,461, a structure in which a focusing electrode is arranged on the same plane as an electron emitting portion has been proposed.
There have been problems such as the complexity of the manufacturing method, an increase in the element area, and a decrease in the electron emission efficiency described later.

Further, US Pat. No. 5,382,218 discloses an FE type electron-emitting device having an edge emitter structure.
5, US Pat. No. 5,584,740, which discloses a manufacturing method for adding a focusing electrode and the like.

As for the surface conduction type device, a reduction in the size of the electron-emitting device has been proposed in JP-A-3-20941, and a higher efficiency has been proposed in JP-A-9-82214. It was not sufficient to realize an image forming apparatus. Furthermore, as a device for increasing the convergence, Japanese Patent Laid-Open No.
-112125.

As the surface conduction type device, there has been a vertical type electron emission device having a gap on a side wall of an insulating layer between electrodes (see, for example, JP-A-4-13732).
8).

FIG. 17 shows an example of this conventional example.
2001 is a substrate, 2002 and 2003 are electrodes, 2004
Is a step forming material, 2005 is a conductive film, and 2006 is a gap.

This configuration is considered to be an excellent configuration for reducing the size of the electron-emitting device and simplifying the fabrication process when used as an electron source.

Further, as a configuration similar to the present case,
235256 and the like. However, all of them aim at a simple arrangement of the electron-emitting devices and do not have any convergence action.

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 capable of simultaneously improving the electron-emitting efficiency and converging the electron orbit and an electron-emitting device. An object of the present invention is to provide a high-definition electron source and an image forming apparatus used.

[0030]

According to the present invention, there is provided an electron-emitting device comprising: a first electrode disposed on a substrate and having a projection in a partial region; And an insulating layer disposed on a region other than the upper surface region of the convex portion of the first electrode, and the first layer so as to form a pair on the insulating layer via the convex portion. A second electrode having a gap between the electrodes and disposed on the insulating layer,
It is characterized by having.

[0031] It is also preferable to provide a voltage applying means for applying a higher potential to the first electrode than to the second electrode.

It is also preferable that the first and second electrodes have first and second conductive films, respectively, and the gap is provided between the first and second conductive films.

[0033] It is also preferable that the projection of the first electrode is disposed so as to be sandwiched or surrounded by the second electrode.

[0034] It is also preferable that the projection of the first electrode is located above the second electrode disposed on the region other than the projection of the first electrode via the insulating layer. is there.

An electron-emitting device as described above, and an anode provided above the electron-emitting device for capturing electrons, wherein the width of the upper surface region of the convex portion of the first electrode is W, The distance to the anode is H, the first electrode and the second
When the voltage applied between the electrodes is Vf and the voltage applied to the anode is Va, the width W is equal to or more than 1/2 times (H × Vf) / (pi π × Va), It is also preferable that the value be twice or less.

[0036] It is also preferable that the gap is provided on the insulating layer disposed substantially on the same plane as the upper surface region of the projection of the first electrode.

It is preferable that the gap is provided on the insulating layer disposed on a side wall of the projection of the first electrode.

An electron-emitting device as described above, and an anode provided above the electron-emitting device to capture electrons.
The distance from the second electrode to the anode is H,
When the voltage applied between the first electrode and the second electrode is Vf, and the voltage applied to the anode is Va, the side wall of the convex portion is located between both ends of the first electrode and the substrate in the vertical direction. It is also preferable that the length is not more than 1/2 of (H × Vf) / (pi π × Va).

In an electron source having a plurality of electron-emitting devices, the electron-emitting devices are the above-described electron-emitting devices.

The upper wiring and the lower wiring arranged above and below the insulating layer are arranged in a matrix, and the lower wiring and the first electrode, and the upper wiring and the second electrode are respectively arranged. It is also preferable that they are connected.

An image forming apparatus is provided with the above-mentioned electron source and an image forming member for forming an image by the electrons emitted from the electron source.

It is also preferable that the image forming member is provided immediately above the electron-emitting device.

[0043]

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 material, the shape, and the relative arrangement thereof should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions, and are not intended to limit the scope of the invention to the following embodiments.

Hereinafter, the mechanism of the electron-emitting device according to the present invention will be described. FIG. 1 is a view showing an example of an electron-emitting device according to the present invention. FIG.
FIG. 1B is a plan view. 2 to 4 are views showing one example of a method for manufacturing an electron-emitting device according to the present invention. FIGS. 5 and 6 are diagrams for explaining the effect of the electron-emitting device according to the present invention.

In FIG. 1, 1 is a substrate, 2 is a first electrode (first electrode), 3 is an insulating layer, 4 is a second electrode (second electrode), 5 is a conductive film (5b is a first electrode). Conductive film of 5a, 5
c is a second conductive film), 6 is a gap, 7 is an anode electrode (anode), 8 is a power supply (voltage applying means) for applying a voltage between the first electrode and the second electrode, and 9 is a voltage applied to the anode electrode. It is a power supply to apply.

Hereinafter, an example of the manufacturing method will be sequentially described with reference to FIGS.

A laminate obtained by laminating SiO ₂ by sputtering or the like on quartz glass, glass having a reduced content of impurities such as Na, blue plate glass, blue plate glass, a Si substrate, etc. The first electrode 2 is laminated on an insulating substrate 1 made of ceramics such as alumina (FIG. 2A).

A resist pattern 21 is formed in a desired portion of the first electrode 2 by a photolithography process.
(B)).

Next, a projection is formed on the first electrode along the resist pattern 21 by etching.
(C)). In this step, an etching method may be appropriately selected in accordance with an electrode material.

The resist is peeled off after the etching.

Next, the insulating layer 3 and the second electrode 4 are laminated by a general vacuum film forming technique such as an evaporation method and a sputtering method (FIG. 2D).

Further, a resist is applied to the entire surface (FIG. 2)
(E)).

After that, the resist is removed only at the upper bottom (upper surface region) of the projection. This method can be formed in a self-aligned manner by adjusting the viscosity of the resist, etc., and applying the upper bottom resist thinner than other portions (FIG. 2 (f)).

Thereafter, the second electrode 4 and the insulating layer 3 laminated on the upper bottom of the projection are removed by etching (FIG. 2).
(G)).

The resist is further stripped to form a basic convex structure. The length L1 of the convex structure is arbitrary, but is designed to be larger than the length L2 of the emission part.

In the steps up to this point, a general photolithography step and an etching step were used, but the method of forming the convex structure may be another method.

As a material of the first electrode 2 and the second electrode 4, a general conductor material is used.
Cr, Au, Mo, W, Pt, Ti, Al, Cu, Pd
Metals or alloys such as Pd, Au, RuO ₂ ,
It is appropriately selected from a printed conductor composed of a metal such as Pd-Ag or a metal oxide and glass, a transparent conductor such as In ₂ O ₃ —SnO ₂ , and a semiconductor material such as polysilicon.

The thickness of the first electrode 2 and the second electrode 4 is several nm.
Is set within a range of several millimeters.

The shape of the first electrode 2 to be processed into a convex portion may be a structure in which the convex portion continues in one direction (ridge shape), a structure in which the convex portion is formed two-dimensionally (pillar shape), or The one whose shape is deformed or the like can be selected.

It is desirable that the side wall of the first electrode 2 to be processed into a convex portion is as flat as possible in order to improve the film quality of a film to be subsequently laminated. The cross-sectional shape of the projection is desirably trapezoidal or rectangular. Most preferred is a rectangle, the inclination of which is preferably close to 90 degrees.

The length w0 of the convex portion is determined according to the distance (width W of the upper surface region of the convex portion of the first electrode) w1 of the high potential region required in the present invention.

The processing height h0 of the convex portion is determined depending on the step coverage of each layer in the subsequent process and the film thickness of each layer. Height h1 and gap positions T1 and T3 described later.

The insulating layer 3 is formed by a general vacuum film forming method such as a vapor deposition method and a sputtering method, a thermal oxidation method, an anodic oxidation method and the like. The material of the insulating layer 3 is preferably SiO ₂ , and a material having a high withstand voltage that can withstand a high electric field, such as other oxides and nitrides, is selected.

Further, even when the insulating layer 3 is laminated on the side wall of the first electrode 2, a high-quality material and a film forming method capable of obtaining a sufficient withstand voltage are required.

The thickness of the insulating layer 3 is from several nm to several tens μm.
, Preferably from several tens nm to several μm.
m.

Next, a step of forming a gap 6 between the first electrode 2 and the second electrode 4 and forming an electron emitting portion is performed. For this purpose, a conductive film 5 is further deposited.
(H)).

The material of the conductive film 5 is Pd, Pt, Ru,
Ag, Au, Ti, In, Cu, Cr, Fe, Zn, S
metals such as n, Ta, W, Pb, Pt-Pd, Pd-Ag
Alloys such as PdO, SnO ₂ , In ₂ O ₃ , PbO, Sb ₂
Oxide such as O ₃ , boride such as HfB ₂ , ZrB ₂ , LaB ₆ , carbide such as TiC, ZrC, SiC, WC, Ti
It is appropriately selected from nitrogen such as N, ZrN, and HfN, semiconductors such as Si and Ge, organic polymer materials, carbon and carbon compounds such as amorphous carbon, graphite, and diamond-like carbon.

The thickness of the conductive film 5 ranges from several Å to several hundreds n.
m, but is designed with resistance and step coverage. The length L2 of the conductive film substantially corresponds to the length of the emission portion.

Further, a voltage is applied between the first and second electrodes to perform a step called an energization forming step.
A gap 6 is formed (FIG. 2 (i)).

In the present invention, the gaps 6 are usually formed on both sides of the projection. After the formation of the gap, the conductive film 5 is separated into those 5b connected to the first electrode 2 and those 5a and 5c connected to the second electrode 4.

In the energization forming, the voltage waveform is preferably a pulse waveform. The energization forming may be performed in a vacuum atmosphere as in the subsequent activation step. The energization forming process is terminated when a voltage is applied to the extent that the conductive film 5 is not broken during the pulse interval, the current is measured, the resistance is detected, and the resistance value becomes 1 MΩ or more. You.

The forming step is not limited to the energization forming but includes a process of forming a local high resistance state on the conductive film 5.

Further, there is a case where the electron-emitting device manufactured as described above is placed in a vacuum vessel 30, evacuated to a vacuum atmosphere, and then subjected to an activation and stabilization step (FIG. 3).

The activation step is a step of significantly changing the device current If and the emission current Ie to form a shape capable of emitting electrons at a low voltage. And depositing on the periphery thereof to cover the deposited layer 32.

In the activation step, for example, an organic gas is introduced into the vacuum vessel from an organic gas supply source 31, and the first electrode 2 and the second electrode 4 are placed in an atmosphere containing an organic substance gas.
Voltage.

FIG. 4 shows an example of the voltage waveform. FIG. 4 (a)
FIG. 4B shows a method of continuously applying a pulse having a pulse crest value at a constant voltage, and FIG. 4B shows a method of applying a voltage pulse while increasing the pulse crest value. FIG.
There are a case where the polarity is repeated on one side as in (a) and (b), and a case where the polarity is both sides as shown in FIG. 4 (c).

The preferable gas partial pressure of the organic substance in producing the carbon varies depending on the form of the carbon, the shape of the vacuum vessel, the type of the organic substance, and the like, and is appropriately set depending on the case.

Suitable organic substances include alkane, alkene aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, aldehydes, ketones, amines, phenols, carboxyls, organic acids such as sulfonic acids, and the like. Specifically, saturated hydrocarbons represented by C _n H _{2n + 2} such as methane, ethane and propane; unsaturated hydrocarbons represented by a composition formula such as C _n H _2n such as ethylene and propylene; benzene , Toluene, methanol, ethanol, formaldehyde, acetaldehyde, acetone, methyl ethyl ketone, methylamine, ethylamine, phenol, formic acid, acetic acid, propionic acid and the like.

Further, after the activation step, a process called a stabilization step is performed. In this step, the organic substance in the vacuum vessel is exhausted.
It is preferably at most 10 × 10 ⁻⁵ Pa, particularly preferably at most 1 × 10 ⁻⁶ Pa. When the inside of the vacuum vessel is evacuated, a vacuum evacuation system using no oil, such as a sorption pump or an ion pump, is preferable so that oil or the like generated from the apparatus is mixed and does not affect the element characteristics.

Further, when the vacuum vessel is evacuated, it is preferable to heat the entire vacuum vessel so that the organic substance molecules adsorbed on the inner wall of the vacuum vessel and the electron-emitting device can be easily evacuated. The heating temperature at this time is preferably from 80 ° C. to 200 ° C. for 5 hours or more, but is not particularly limited to this condition.
It is appropriately selected depending on the size and shape of the vacuum vessel, the configuration of the electron-emitting device, and the like.

The operation of the electron-emitting device according to the present invention will be described with reference to FIGS.

In FIG. 5, the same members as those in FIG. 1 are denoted by the same reference numerals. 1 is a substrate, 2 is a first electrode, 3 is an insulating layer, 4 is a second electrode, 5 and 5a, 5b, 5c are conductive films, 6 is a gap, 7 is an anode electrode, 8 is a first electrode and a second
A power supply 9 for applying a voltage to the electrode, and 9 is a power supply for applying a voltage to the anode electrode.

The electron-emitting device of the present invention is a surface-conduction type electron-emitting device in which electrons are emitted from the gap 6 by a voltage applied between a pair of electrodes, a first electrode and a second electrode. The first electrode 2 and the second electrode 4 are separated by an insulating layer,
An electron-emitting device in which a gap 6 exists on the insulating layer 3.

In the present invention, the gap 6 is formed by the conductive film 5
Through the first electrode 2 or the second electrode 4.

Further, in the present invention, the first electrode 2 is connected to a high potential to form a high potential region, and the second electrode 4
Are connected to a low potential to form a low potential region. When the element portion is viewed from the anode electrode 7 side, the high potential region is formed so as to be sandwiched or surrounded by the low potential region. The feature is that it is done.

When the low potential region is sandwiched between the high potential regions, the length of the high potential region is expressed as w1.

In the present invention, a high potential is applied to the first electrode 2 and a low potential, that is, the driving voltage Vf is applied to the second electrode 4 by the power supply 8 for applying a voltage between the first electrode and the second electrode. As a result, the element current If flows. Further, an anode voltage Va is given by a power supply 9 for applying a voltage to the anode electrode 7. The electrons emitted from the gap 6 are captured by the anode electrode 7 arranged at a distance H, and the emission current Ie flows.

In the electron-emitting device of the present invention, the drive voltage Vf is set to several volts to several tens volts. The drive voltage largely depends on the gap width D, and the larger the gap width D, the higher the drive voltage Vf.

In the electron source and the image forming apparatus using the electron-emitting device according to the present invention, the anode voltage Va and the distance H between the anode electrodes are appropriately designed. In the case of an electron source or an image forming apparatus, the smaller the distance H between the anode electrodes and the larger the anode voltage Va, the smaller the beam diameter, which is advantageous. However, on the other hand, there is a problem in terms of discharge and difficulty in manufacturing the device. Accordingly, a practical anode voltage Va exists in accordance with the distance H between the anode electrodes.

The distance H between the anode electrodes of the electron-emitting device according to the present invention is from several tens of μm to several tens of mm, preferably from several hundred μm to several mm. Further, the anode voltage Va corresponding thereto is several tens of volts to several tens of kV.
And preferably several hundreds of volts to several tens of kV.

First, the efficiency and the beam size in the conventional planar type will be described with reference to FIG. 16, and then the device of the present invention will be described.

SID '98 Digest, Okud
According to a and et al, there is a gap 315 on the order of nm between opposing electrodes, and when a driving voltage Vf is applied to this element, electrons are emitted from the tip of the low potential electrode to the opposing high potential electrode (or through the substrate). It is known that electrons are isotropically scattered again at the tip of the high potential electrode (assuming that electrons are emitted isotropically from the tip of the high potential electrode). Experiments and numerical calculations have been found to be consistent.

Most of the electrons emitted from the low potential electrode are repeatedly elastically scattered (multiple scattering) several times on the high potential electrode, and electrons exceeding the characteristic distance Xs reach the anode electrode.

The characteristic distance Xs is expressed as follows: Xs = D / 2√ ｛1+ (2H ・ Vf / π ・ Va ・ D) ・ 2｝｝ (H ・ Vf) / (π ・ Va) 1) It is expressed by the following equation. 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 approximation of the above equation (1) is Vf / D
It is satisfied in the case of ≫Va / H (which is sufficiently satisfied in the case of a normal surface conduction electron-emitting device).

As shown in FIG. 16, the characteristic distance Xs is, as shown in FIG. 16, the distance from the gap 315 to the point where the surface of the same potential as the high potential electrode crosses the high potential electrode on the equipotential surface appearing in vacuum. Expressed as distance.

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 315 are partially absorbed by the high potential electrode by multiple scattering until the electrons exceed the Xs. Although the ratio (scattering coefficient) β scattered by the collision of electrons of about several tens eV is not clear, it is estimated to be about 0.1 to 0.5 per one scattering. Since β is equal to or less than 1 in such a scattering mechanism, it can be seen that the amount of electrons extracted in a vacuum decreases with a power as the number of scattering increases.

Therefore, in the conventional surface conduction electron-emitting device shown in FIG. 16, electrons emitted from the gap 315 are scattered at least once on the high potential electrode opposed in the Xs and many electrons are scattered a plurality of times. Therefore, the number of electrons that are taken into the high-potential electrode and disappear is increased, and the electron emission efficiency is reduced.

Since the electron-emitting device of the present invention has the same emission mechanism as the conventional device, the anode electrode 7
Is the same as the important parameter that affects the efficiency.

However, according to the electron-emitting device of the present invention, the three-dimensional potential configuration means that
The potential distribution near the gap and on the electron orbit is different. In particular,
The configuration size (for example, the height h1 of the convex portion, the width w0 of the convex portion)
) Approaches the size of Xs with respect to the flat type equation (1), the potential distribution changes in a complicated manner, and the efficiency becomes more complicated than in the case of the flat type.

However, it is known that there are conditions under which the efficiency is higher than that of the planar type due to the three-dimensional configuration.

One of them is to arrange the position of the high potential electrode above the low potential electrode.

Further, the position of the gap is further provided on the side wall portion,
It has also been found that it is important to minimize the distance of the side wall from the gap to the high potential electrode.

In such a configuration, the number of times of electron scattering is reduced, and an improvement in efficiency can be expected.

Next, the shape and beam size of the electron beam of the conventional surface conduction electron-emitting device will be described.

FIG. 16 shows the arrival position of electrons in a conventional electron-emitting device. As shown in FIG. 16, when the beam reaches the characteristic distance Xs above the element, it largely shifts from the emission position, and largely shifts due to the distorted electric field above.

The beam diameter is almost equal to the amount of displacement from immediately above the emission part to the main arrival position of the beam. Therefore, the beam diameter is SID '98 Digest, O
From kuda and et al, Lh ≒ 4 ・ Kh ・ H√ (Vf / Va) (2) Equation Lw） 2 ・ Kw ・ H√ (Vf / Va) (3) Equation (3) It is known that it can be done.

Here, Lh indicates the size of the beam in the vertical direction (y direction), and Lw indicates the size of the beam in the horizontal direction (x direction). Kh and Kw may vary slightly depending on the element structure, but are in the range of 0.8 to 1.0, and can be approximated by 1 in most cases.

Next, the beam shape of the electron-emitting device according to the present invention will be described with reference to FIG. In the present invention,
The beam diameter in the x direction was Lx, and the beam diameter in the y direction was Ly.

In the present invention, the high potential region is sandwiched or surrounded by the low potential region when viewed from the anode electrode 7 side. Therefore, by setting the size w1 of the high potential region to a size affected by the surrounding low potential, the electron trajectory changes, and a configuration can be obtained in which the spread of electrons is suppressed to some extent. Therefore, it can be seen that the effect of reducing the beam size in the present invention largely depends on the width w1 of the high potential region.

FIG. 6 shows a typical example of the width w1 of the high potential region and the beam shape of the electron-emitting device in FIG.

In FIG. 1, the electron-emitting device has a structure in which the emission portions are present in two linear shapes having a length L1, and the emission portions are sandwiched between low potential regions.

When w1 is large, the beam is considered to have been emitted as a respective beam from each linear emitter, and generally has two peaks. Also,
At a certain distance, the two beams may be approximately one point. However, in this case, the conditions are the same for each beam, but they are not converged.

Assuming that the outermost circumference of these two beams is a beam diameter, when w1 is large, Lx = 2 × (w
1/2 + Lw), and Ly = Lh + L2 (Lh, Lh)
w is based on the equations (2) and (3).

Further, when w1 is reduced, the influence of low potential outside each high potential appears.

Due to the influence of the surrounding low potential, the arrival position of the beam is changed, and the beam diameter in the x direction is somewhat deviated toward the central portion toward the emission portion, not according to the equation (3).
Also, as the position of this beam begins to change, so does the efficiency. This is because the surrounding low potential constitutes a deceleration potential, and a force for moving electrons toward the high potential electrode acts, so that the number of scattering increases and the efficiency decreases.

Further, when w1 becomes smaller, the beam becomes
Surrounded by low potentials on both sides, it folds back in it, making the beam smaller. In such a size region, the electron beam is limited not only in the x direction but also in the y direction, even though the size change of w1 is a change in the x direction, and an effect of reducing the beam in the y direction occurs. . However, the width corresponding to the emission length L1 remains.

Further, when w1 is reduced, the beam diameter is further reduced, but the efficiency is significantly reduced, and almost no electrons reach the anode electrode.

Therefore, in order to reduce the beam size in the present invention, the required efficiency must be taken into consideration,
It is necessary to reduce the size of the projections as much as possible for beam reduction.

As a result of examining these size effects, w1
It can be seen that the characteristic is almost normalized depending on how many times the size of Xs becomes. As w1 expected to reduce the beam diameter, 15 times or less of Xs, and w1 for which the efficiency is secured to some extent (for example, up to 1/10 of the efficiency when w1 is ∞) Xs
It was found that the ratio was 1/2 or more.

Therefore, by appropriately selecting w1,
It can be seen that an element having a desired beam diameter and efficiency can be obtained.

However, if the width of the projection is made too small, a problem may occur. One is the problem of rising resistance. The other is a method of taking out an electrode.

For example, Va = 10 kV, Vf = 15
Assuming that V and H = 2 mm, Xs = 0.95 μm ≒ 1 μm
And the upper limit of w1 in the present invention is w1 = 1
5 μm, and the lower limit is w1 = 0.5 μm.

When the lower limit w1 = 0.5 μm, L
When the length of 1 is about 100 μm, when the electrodes are taken out from both ends, the parasitic resistance may be several kΩ. In this case, at the center of the element, due to the voltage drop,
Since the driving voltage Vf = 15 V cannot be applied, the efficiency is reduced.

However, as in the present invention, the parasitic resistance can be reduced as much as possible by taking out from the lower part of the electrode arranged on the entire surface of the element portion. Therefore, even when w1 is small, the parasitic resistance can be reduced, and the efficiency as the electron-emitting device can be secured.

In the case of an element having a two-dimensional structure, the extraction of the electrodes becomes a further problem. Usually, a method of taking out from below the electrode by using a contact hole or the like formed in the central portion of the element can be considered, but in this case, if the electrode becomes several μm, a problem of alignment accuracy occurs. Therefore, when the electrodes have a convex structure as in the electron-emitting device of the present invention, the electrodes can be easily taken out.

In the electron-emitting device of the present invention, the potential distribution on the high-potential electrode is important in terms of its characteristics. In this configuration, the problem of such deformation is easily solved.

According to the present invention, it is possible to avoid such a problem that the display quality is degraded due to the parasitic resistance and the problem of taking out the electrodes.

Next, an electron source obtained by arranging a plurality of the above-described electron-emitting devices and an image forming apparatus using the same will be described with reference to FIGS. 7, 8, 9 and 10. FIG.

FIG. 7 shows an example of a configuration in which the electron-emitting device of FIG. 1 is used as an electron source. In FIG. 7, reference numeral 61 denotes an interlayer insulating layer, and 62 denotes a wiring electrode. FIG. 7A is a plan view of one electron-emitting device. 7B and FIG.
(C) is an AA 'sectional view and BB' sectional view in the plan view (a), respectively.

FIG. 8 is a diagram of an image forming apparatus in which a large number of the above-described electron-emitting devices are arranged in an m × n matrix and the formed electron source is used. In the image forming apparatus of the present invention, the above-described electron-emitting devices are generally arranged in a simple matrix arrangement.

That is, a plurality of electrodes are arranged in a matrix in the X direction and the Y direction, and one of the electrodes of the plurality of electron-emitting devices arranged in the same row is commonly connected to the wiring in the X direction, and arranged in the same column. The other of the electrodes of the plurality of electron-emitting devices is commonly connected to a wiring in the Y direction.

In the X direction, m X-direction wirings 72 (Do
x1, Dox2... Doxm) are arranged alternately, and in the Y direction, n Y-direction wirings 73 (Doy1, Doy2, D
oy3... Doyn).

The first electrode 2 constituting the electron-emitting device has Y
It is electrically connected to the direction wiring 73. The first electrode 4 is connected to the wiring electrode 62 and is electrically connected to the X-direction wiring 72.

An arrangement other than the simple matrix arrangement can be adopted. For example, connection is made at both ends of a plurality of electron-emitting devices arranged in parallel, a large number of rows of electron-emitting devices are arranged (row direction), and the electron-emitting devices are arranged in a direction perpendicular to the wiring (column direction). Control electrode (grid electrode) placed above
There is also a ladder-like arrangement for controlling and driving electrons from the electron-emitting device.

The X-direction wiring and the Y-direction wiring are formed by vacuum evaporation,
It can be made of a conductive metal or the like formed by using a printing method, a sputtering method, or the like. The material, thickness and width of the wiring are appropriately designed.

The interlayer insulating layer 61 may be the same as the insulating layer 3 between the first electrode 2 and the second electrode 4 of the electron-emitting device, but may be a simple matrix using a plurality of electron-emitting devices as an electron source. In the case of driving in an arrangement, it is desirable to provide and stack the insulating layer 3 separately from the insulating layer 3 in order to reduce the capacitance between wirings. As the interlayer insulating layer 61, a vacuum deposition method, a printing method,
SiO ₂ or the like formed by using a sputtering method or the like is selected. The thickness and the shape are appropriately set so as to be able to withstand a potential difference at an intersection between the wirings.

Electrons emitted from the electron-emitting device according to the present invention can be controlled by the peak value and the width of the pulse-like voltage applied between the electrodes when the electrons are below the threshold voltage. On the other hand, when the voltage is equal to or lower than the threshold voltage, almost no light is emitted.

According to this characteristic, even when a large number of electron-emitting devices are arranged, if a pulse-like voltage is appropriately applied to each of the devices, the electron-emitting device is selected according to the input signal and the amount of electron emission Can be controlled. Therefore, in the above configuration, individual elements can be selected and driven independently using simple matrix wiring.

Next, an image forming apparatus using the above-described electron source will be described.

In FIG. 8, reference numeral 71 denotes an electron-emitting device;
Denotes an electron source substrate having a plurality of electron-emitting devices, 91 denotes a rear plate to which the electron source substrate 81 is fixed, and 96 denotes a glass substrate.
3 is a face plate in which a fluorescent film 94 and a metal back 95 are formed on the inner surface. Reference numeral 92 denotes a support frame, and a rear plate 91 and a face plate 96 are connected to the support frame 92 using frit glass or the like.

The envelope (panel) 98 is composed of the face plate 96, the support frame 92, and the rear plate 91 as described above. Since the rear plate 91 is provided mainly for the purpose of reinforcing the strength of the substrate 81, if the substrate 81 itself has sufficient strength, the separate rear plate 91 can be omitted. May be an integral member.

The phosphor film 94 of the support frame 92 and the metal back 9
5 is disposed on the inner surface thereof, frit glass is applied to an adhesive surface where the face plate 96, the rear plate 91, and the support frame 92 are joined, and the face plate 96, the support frame 92, and the rear plate 91 are moved to a predetermined position. , Fix, heat, bake and seal.

The heating means for firing and sealing can employ various means such as lamp heating using an infrared lamp or the like and a hot plate, but is not limited to these.

Further, the bonding material for heating and bonding the plurality of members constituting the envelope is not limited to frit glass, and any bonding material that can form a sufficient vacuum atmosphere after the sealing step may be used. Materials can be adopted.

The above-described envelope is one embodiment of the present invention, and is not limited, and various types can be adopted.

As another example, the support frame 92 is directly mounted on the substrate 81.
And the envelope 98 may be constituted by the face plate 96, the support frame 92, and the base 81. Further, by providing a support (not shown) called a spacer between the face plate 96 and the rear plate 91, an envelope 98 having sufficient strength against atmospheric pressure can be formed.

FIGS. 9A and 9B are schematic views of the fluorescent film 94 formed on the face plate 96. FIG. The fluorescent film 94 can be composed of only the phosphor 85 in the case of monochrome. In the case of a color fluorescent film, the black stripe shown in FIG.
Alternatively, it can be composed of a black conductive material 86 called a black matrix shown in FIG.

The purpose of providing the black stripes and the black matrix is to make the color separation between the phosphors 85 of the necessary three primary color phosphors black in the case of color display so that color mixing and the like become inconspicuous. The object of the present invention is to suppress a decrease in contrast caused by external light reflection at 94. As a material for the black stripe, a material which is conductive and has little light transmission and reflection can be used in addition to a commonly used material mainly containing graphite.

As a method of applying the phosphor on the glass substrate 93, a precipitation method, a printing method, or the like can be adopted regardless of monochrome or color.

A metal back 95 is usually provided on the inner side of the fluorescent film 94. The purpose of providing the metal back is to convert the light emitted from the phosphor toward the inner surface into the face plate 96.
Improving the brightness by specular reflection to the side,
The purpose is to function as an electrode for applying an electron beam acceleration voltage, and to protect the fluorescent film 94 from damage due to collision of negative ions generated in the envelope.

After the fluorescent film is formed, the metal back 95 is subjected to a smoothing treatment (usually “filming”) on the inner surface of the fluorescent film.
Called. ) And then depositing Al using vacuum evaporation or the like.

The face plate 96 is further provided with a fluorescent film 9.
A transparent electrode (not shown) may be provided on the outer surface side of the fluorescent film 94 in order to increase the conductivity of No. 4.

In the present invention, since the electron beam reaches just above the electron-emitting device 71, the electron beam is positioned and arranged so that the fluorescent film 94 is arranged directly above the electron-emitting device 71.

Next, the envelope (panel) subjected to the sealing step
Next, a vacuum sealing step for sealing is described.

In the vacuum sealing step, the envelope (panel) 98 is heated and maintained at 80 to 250 ° C., and exhausted through an exhaust pipe (not shown) by an exhaust device such as an ion pump or a sorption pump. After the atmosphere is made sufficiently low in organic substances, the exhaust pipe is heated and melted with a burner and sealed. To maintain the pressure after the envelope 98 is sealed, a getter process may be performed.

This is arranged at a predetermined position (not shown) in the envelope 98 by heating using resistance heating, high-frequency heating, or the like immediately before or after the envelope 98 is sealed. In this process, the getter is heated to form a deposited film. The getter is usually composed mainly of Ba or the like, and maintains the atmosphere in the envelope 98 by the adsorption action of the deposited film.

In the image forming apparatus constructed by using the electron sources of the simple matrix arrangement manufactured by the above steps, the external terminals Dox1 to Doxm, Dox
By applying a voltage via y1 to Doyn, electron emission occurs.

The metal back 95 via the high voltage terminal 97,
Alternatively, a high voltage is applied to a transparent electrode (not shown) to accelerate the electron beam.

The accelerated electrons collide with the fluorescent film 94,
Light emission occurs to form an image.

FIG. 10 is a block diagram showing an example of a drive circuit for performing display in accordance with an NTSC television signal.

Scan Circuit FIG. 10 will be described. This circuit includes M switching elements inside (in the drawing, S1 to Sm are schematically shown). Each switching element selects either the output voltage of the DC voltage source Vx or 0 [V] (ground level),
The display panel 1301 is electrically connected to terminals Dox1 to Doxm.

Each of the switching elements S1 to Sm operates based on the control signal Tscan output from the control circuit 1303, and can be configured by combining switching elements such as FETs.

In the case of the present embodiment, the DC voltage source Vx uses a drive voltage applied to an unscanned element based on the characteristics (electron emission threshold voltage) of the electron emission element of the present invention. It is set to output a constant voltage that is equal to or lower than the voltage.

The control circuit 1303 has a function of matching the operation of each unit so that appropriate display is performed based on an image signal input from the outside. The control circuit 1303
The synchronization signal Tsy sent from the synchronization signal separation circuit 1306
Tscan and Tsf for each part based on nc
The control signals t and Tmry are generated.

The synchronizing signal separating circuit 1306 is a circuit for separating a synchronizing signal component and a luminance signal component from an NTSC television signal input from the outside, and uses a general frequency separating (filter) circuit or the like. Can be configured.

The synchronization signal separated by the synchronization signal separation circuit 1306 is composed of a vertical synchronization signal and a horizontal synchronization signal, but is shown here as a Tsync signal for convenience of explanation. The luminance signal component of the image separated from the television signal is referred to as a DATA signal for convenience. The DATA signal is input to the shift register 1304.

A shift register 1304 is for serially / parallel converting the DATA signal input serially in time series for each line of an image, and is based on a control signal Tsft sent from the control circuit 1303. (Ie, the control signal Tsft can be said to be a shift clock of the shift register 1304).

The serial / parallel-converted data for one line of the image (corresponding to drive data for N electron-emitting devices) is output by the shift register 1304 as N parallel signals Id1 to Idn.

A line memory 1305 is a storage device for storing data for one line of an image for a required time only, and stores the contents of Id1 to Idn as appropriate according to a control signal Tmry sent from a control circuit 1303. The stored contents are output as Id′1 to Id′n and input to the modulation signal generator 1307.

Modulated signal generator 1307 outputs image data I
A signal source for appropriately driving and modulating each of the electron-emitting devices of the present invention according to each of d'1 to Id'n, and an output signal of the signal source is provided in the display panel 1301 through the terminals Doy1 to Doyn. Are applied to the electron-emitting devices.

As described above, the electron-emitting device of the present invention has the following basic characteristics with respect to the emission current Ie. That is, the electron emission has a clear threshold voltage Vth,
Electron emission occurs only when a voltage greater than th is applied.
For a voltage equal to or higher than the electron emission threshold, the emission current also changes according to the change in the voltage applied to the device.

From this, when a pulse-like voltage is applied to the present element, for example, when a voltage lower than the electron emission threshold is applied, no electron emission occurs, but when a voltage higher than the electron emission threshold is applied, An electron beam is output. At that time, the intensity of the output electron beam can be controlled by changing the pulse peak value Vm. Further, by changing the pulse width Pw, it is possible to control the total amount of charges of the output electron beam.

Therefore, as a method of modulating the electron-emitting device according to the input signal, a voltage modulation method, a pulse width modulation method, or the like can be employed. When performing the voltage modulation method, a circuit of the voltage modulation method that generates a voltage pulse of a fixed length and modulates the peak value of the pulse appropriately according to input data is used as the modulation signal generator 1307. be able to.

When implementing the pulse width modulation method,
As the modulation signal generator 1307, a pulse width modulation type circuit that generates a voltage pulse having a constant peak value and appropriately modulates the width of the voltage pulse according to input data can be used.

The shift register 1304 and the line memory 1
305 can be a digital signal type or an analog signal type. This is because the serial / parallel conversion and storage of the image signal may be performed at a predetermined speed.

When the digital signal type is used, it is necessary to convert the output signal DATA of the synchronization signal separation circuit 1306 into a digital signal.
An A / D converter may be provided at the output unit 6. In this connection, the circuit used for the modulation signal generator 1307 is slightly different depending on whether the output signal of the line memory 1305 is a digital signal or an analog signal. That is, in the case of the voltage modulation method using a digital signal, the modulation signal generator 13
For 07, for example, a D / A conversion circuit is used, and an amplification circuit and the like are added as necessary.

In the case of the pulse width modulation system, the modulation signal generator 1307 includes, for example, a high-speed oscillator, a counter for counting the number of waves output from the oscillator, and a comparison between the output value of the counter and the output value of the memory. A circuit in which a comparator (comparator) is combined is used. If necessary, an amplifier for amplifying the pulse width modulated signal output from the comparator to the drive voltage of the electron-emitting device of the present invention can be added.

In the case of the voltage modulation method using an analog signal, an amplification circuit using, for example, an operational amplifier can be used as the modulation signal generator 1307, and a level shift circuit and the like can be added as necessary. In the case of the pulse width modulation method, for example, a voltage controlled oscillator (VCO)
And, if necessary, an amplifier for amplifying the voltage up to the driving voltage of the electron-emitting device of the present invention can be added.

The configuration of the image forming apparatus described here is an example of an image forming apparatus to which the present invention can be applied, and various modifications can be made based on the technical concept of the present invention. As for the input signal, the NTSC system has been described, but the input signal is not limited to this, and PAL, SECAM system, etc.
A TV signal composed of a large number of scanning lines (for example,
A high-definition TV system such as the MUSE system can also be adopted.

In addition to the display device, the present invention can also be used as an image forming apparatus as an optical printer constituted by using a photosensitive drum or the like.

[0182]

The present invention will be described in more detail with reference to the following examples.

Example 1 FIG. 1 shows a plan view and a cross-sectional view of an electron-emitting device manufactured according to the first example, and FIG. 2 shows an example of a method for manufacturing the electron-emitting device of this example.

Hereinafter, the manufacturing process of the electron-emitting device of this embodiment will be described in detail.

(Step 1) After sufficiently cleaning the substrate 1 using quartz, the first electrode 2 having a thickness of 8 was formed by sputtering.
Deposit 00 nm of Ta.

(Step 2) Thereafter, in a photolithography step, spin coating of a positive type photoresist (AZ1500 / manufactured by Clariant), exposure and development of a photomask pattern were performed, and the mask pattern was transferred. Thereafter, the patterned photoresist was used as a mask.

(Step 3) Further, the first electrode 2 was etched by 300 nm (h0 = 0.3 μm) by dry etching using CF ₄ gas, and w0 = 1 μm, 5 μm, and 10 μm.
Five types of devices having convex portions of m, 50 μm, and 250 μm were produced. L1 was all 200 μm. The resist mask was then peeled off.

(Step 4) The insulating layer 3 having a thickness of 1
SiO ₂ is deposited in nm, thickness 1 as the second electrode 4
00 nm of Ta was deposited.

(Step 5) Thereafter, in a photolithography step, a positive photoresist (AZ1500 / manufactured by Clariant) was spin-coated. Thereafter, when the photoresist was etched by ion milling, the resist on only the upper and lower portions of the projections was quickly lost.

(Step 6) Further, using the remaining resist as a mask, the second electrode 4 and the insulating layer 3 were dry-etched using CF ₄ gas. After the etching, the resist was peeled off.

(Step 7) Next, a 5 nm-thick Pt-Pd
A conductive film 5 was deposited on part of the structure. At this time, Pt
The length L2 where Pd was deposited was 100 μm. The P
The t-Pd conductive film was masked using photolithography and selectively deposited by ion sputtering.

(Step 8) Next, a pulse voltage of 10 V to 17 V as shown in FIG. 4B (ON time: 1 msec / OFF time: 9 msec) is applied to the first electrode 2 and the second electrode 4.
(c unipolar) to apply a current to the Pt-Pd conductive film 5 to form a gap 6 by the forming step. The forming was terminated when the resistance between the upper and lower electrodes became 10 MΩ.

(Step 9) Next, the device was placed in a vacuum vessel, and after evacuation, BN (benzonitrile), 2 ×
A pulse voltage of 12 V to 15 V (ON time: 1 msec / OFF time: 9 msec both electrodes) as shown in FIG. 4C is applied to the first electrode 2 and the second electrode 4 in a 10 ⁻⁵ Pa atmosphere. Carbon was produced in the gap. The activation step was completed when the current flowing during the activation step was saturated. As a result, the gap 6 was formed only in the region where the Pt-Pd film was deposited.

When the gap position was confirmed by an electron microscope after driving the device, it was found that the gap was located above the insulating layer 3 and almost at the center of the insulating layer 3 as shown in FIG.

The device fabricated as described above was evacuated again to 5 × 10 ⁻⁵ Pa or more in the same vacuum vessel,
After maintaining at 0 ° C. and heating for 3 hours or more, the temperature was returned to room temperature. At that time, the degree of vacuum was 1 × 10 ⁻⁶ Pa.

The device was driven in a vacuum vessel.

The driving voltage was set to Vf = 15 V, and 15 V was applied to the first electrode and 0 V was applied to the second electrode.

The anode voltage was 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 a phosphor-coated anode electrode. Here, the electron beam diameter refers to the outer diameter of a region having a luminance of 10% with respect to the peak luminance of the emission pattern of the phosphor.

Table 1 shows the characteristics of each device.

[0200]

[Table 1]

In these devices, a beam could be observed just above the device.

In the present embodiment, the characteristic distance Xs = 0.95 μm obtained from the driving conditions and the like can be calculated. In the present structure, the length w1 of the high potential region is such that the elements 1 to 3 are effective in the present invention. 1 / Xs, which is the applicable range of w1
It is 2 or more and 15 or less. Therefore, element 4,
5, the electron-emitting device has a smaller beam diameter.

In the element 1, although w1 is small, it can be confirmed that electrons are emitted over the entire emission portion.
No deterioration of characteristics due to parasitic resistance was observed.

(Embodiment 2) FIG. 11 is a diagram showing a second embodiment of the present invention.

In the present embodiment, the configuration of the second electrode is slightly different from that of the first embodiment in that the gap is located on the side wall of the projection.

FIGS. 11A and 11B are different in the position of the gap 6.

The steps were slightly changed in order to produce the respective structures of FIGS. 11 (a) and 11 (b).

(Step 1) Using quartz for the substrate 1 and sufficiently cleaning it, the first electrode 2 having a thickness of 8 was formed by sputtering.
Deposit 00 nm of Ta.

(Step 2) Thereafter, in a photolithography step, spin coating of a positive photoresist (AZ1500 / manufactured by Clariant), exposure and development of a photomask pattern were performed, and the mask pattern was transferred. Thereafter, the patterned photoresist was used as a mask.

(Step 3a) Further, dry etching was performed using CF ₄ gas, and the first electrode 2 was etched by 300 nm (h0 = 0.3 μm) to produce an element having a convex portion of w0 = 5 μm. L1 was set to 200 μm. The resist mask was then peeled off.

(Step 4a) Subsequently, SiO ₂ having a thickness of 100 nm was deposited as the insulating layer 3.

(Step 5a) Thereafter, in a photolithography step, a positive photoresist (AZ1500 / manufactured by Clariant) was spin-coated. Thereafter, when the photoresist was etched by ion milling, the resist on only the upper and lower portions of the projections was quickly lost.

(Step 6a-1) Further, using the remaining resist as a mask, the insulating layer 3 was dry-etched using CF ₄ gas.

(Step 6a-2) Further, after depositing Al by 1 μm, the resist mask left in (Step 6a-1) was lifted off.

As a result, an Al mask was formed only on the upper bottom.

(Step 6a-3) The second electrode 4 having a thickness of 1
00 nm of Ta was deposited. At this time, since the Al mask is thick and its shape has a somewhat inverted tapered structure,
Ta did not accumulate on the side wall, but only on the periphery.
Thereafter, the Al mask was peeled off.

(Step 7a) Next, the Pt-Pd conductive film 5
Was deposited on a portion of the structure. At this time, the length L2 where Pt-Pd was deposited was 100 μm. The Pt-Pd conductive film was masked by using a photolithography technique and selectively deposited by an ion sputtering method.

At this time, the thickness of the Pt-Pd conductive film 5 was 7 nm in (a) and 3 nm in (b).

(Step 8a) When forming was performed in the same manner as in Example 1, a gap was formed at substantially the center of the side wall portion in (a), and a gap was formed at the upper bottom edge portion in (b).

In (b), since the film thickness is small, (Step 7)
It is considered that the film thickness at the edge portion was thin at the time of a).

In this embodiment, when the same driving as that of the first embodiment was performed, the beam diameter was almost the same as that of the element 2 of the first embodiment. On the other hand, the efficiency was 0.5% in (a) and 0.7% in (b), and the efficiency was higher than that of Example 1 in each case.

FIG. 12 is a diagram for explaining the number of scattering times of the electron-emitting device according to the present invention, and FIG. 13 is a graph showing the effect of the shape factor on the efficiency.

In the electron-emitting device of the present invention, the emitted electrons are scattered on the conductive film 5 formed on the high-potential side from the gap 6 and on the high-potential electrode by the first electrode 2 and then to the anode electrode 7. Heading. However, since the distance T1 to the top of the high-potential electrode (the length between the both ends of the first electrode in the direction perpendicular to the substrate on the side wall of the projection) is short, electrons are low at a high potential electrode near the electron-emitting device. It is possible to escape from the region of the potential distribution dominated by the electric field of the potential electrode with a small number of scatterings, thereby improving the electron emission efficiency.

Further, when the distance T1 from the gap 6 to the top of the high-potential electrode is shorter than the flight distance of the electrons, the electrons can reach the upper part of the element without being scattered, and the electron emission efficiency is greatly improved. Here, the flying distance of the scattered electrons is estimated to be at most about 200 times the gap width D. By setting T1 in this range, the efficiency is improved.

Xs indicates a range in which scattering occurs, and is a numerical value related to the flight distance. Therefore, by setting T1 to an appropriate range for Xs, an improvement in efficiency is expected. After a detailed study,
It has been found that an improvement in efficiency can be expected by setting T1 to １ ／ or less of Xs.

Further, the distance T3 from the gap 6 to the bottom of the low potential region is also significantly related to electron scattering. T
When 3 is small, the scattering on the side wall increases in many cases, but by increasing T3, the scattering on the side wall is suppressed.

The effect of the shape factors of T1 and T3 at a constant w1 on the efficiency is shown in the graph of FIG.

From the graph, it is desirable that the distance of the high-potential region T1 is as thin as possible and that T3 is as large as possible. However, at T3 → ∞, the line becomes a constant straight line, and the effect is saturated.

Therefore, the present embodiment is generally more efficient than the first embodiment. Further, in (a), T1 ≒ 50 nm is T3 ≒ 50 nm, and in (b), T1 ≒ 50 nm
1 ≒ 3 nm and T3 ≒ 100 nm, and it is considered that (b) is more efficient than (a).

(Embodiment 3) FIG. 14 shows Embodiment 3 of the present invention. FIG. 14A is a sectional view, and FIG. 14B is a plan view. This embodiment is an example in which the protrusions are two-dimensional, that is, pillar-shaped, and the laminated structure is slightly different.

The projection is composed of the wiring electrode 141 and the first electrode 2. The processing height of the projection is controlled by the film thickness of the first electrode 2, and is connected to the wiring electrode 141 at the processing bottom. Further, the insulating layer 142 is buried in the entire lower portion of the insulating layer 3 except for the protrusions.

(Step 1b) After sufficiently cleaning the substrate 1 using quartz, 2 μm of Cu is laminated as the wiring electrode 141 by sputtering, and the thickness of the first electrode 2 is 500 nm.
Of Al is deposited.

(Step 2) Thereafter, in a photolithography step, spin coating of a positive photoresist (AZ1500 / manufactured by Clariant), exposure and development of a photomask pattern were performed, and the mask pattern was transferred. Thereafter, the patterned photoresist was used as a mask.

(Step 3b-1) The first electrode 2 was etched to a thickness of 500 nm by wet etching to form a projection of 5 μm square. When an etchant having selectivity between Al and Cu was used, Cu was not etched.

(Step 3b-2) As the interlayer insulating layer 142, 200 nm of SiO ₂ was deposited. Thereafter, the resist mask was peeled off, and the SiO ₂ at the upper bottom was lifted off.

(Step 4a) Subsequently, SiO ₂ having a thickness of 100 nm was deposited as the insulating layer 3.

(Step 5) Thereafter, in a photolithography step, a positive photoresist (AZ1500 / manufactured by Clariant) was spin-coated. Thereafter, when the photoresist was etched by ion milling, the resist on only the upper and lower portions of the projections was quickly lost.

(Step 6a-1) Further, using the remaining resist as a mask, the insulating layer 3 was dry-etched using CF ₄ gas.

(Step 6a-2) Further, after micron deposition of Al, the resist mask remaining in (step 6a-1) was lifted off.

As a result, an Al mask was formed only on the upper bottom.

(Step 6a-3) The second electrode 4 having a thickness of 1
00 nm of Ta was deposited. At this time, since the Al mask is thick and its shape has a somewhat inverted tapered structure,
Ta did not accumulate on the side wall, but only on the periphery.
Thereafter, the Al mask was peeled off.

(Step 7b) Next, the Pt-Pd conductive film 5
Was deposited on a portion of the structure. At this time, the thickness of the Pt-Pd film was 20 μm. The Pt-Pd conductive film was masked by using a photolithography technique, and was selectively deposited by an ion sputtering method.

At this time, the thickness of the Pt-Pd conductive film 5 was 7 nm.

(Step 8b) When the same forming as in Example 1 was performed, a gap was formed in the side wall.

In this configuration, the processing height h1 is the same as in the second embodiment. However, due to the effect of the interlayer insulating layer 142,
The reduction of the wiring capacitance has been achieved.

When the device of this example was driven in the same manner as in Example 1, the electron emission efficiency Ie / If was 0.40%. However, since the emission length is equivalent to 20 μm, the emission current Ie is the emission length of Example 1 (100 μm × 2 = 200 μm).
m), which is equivalent to 1/10, which is the ratio of m).

The beam diameter is Lx = 160 μm, Ly = 1
60 μm, and the beam diameter was reduced in both the x and y directions. In addition, the beam can be observed just above the element as in Example 1.

FIG. 14B shows the concept of the distance w1 of the high potential region in the two-dimensional structure as in this embodiment.
That is, the diameter w1 of the minimum circumscribed circle of the region of the gap 6
w1 can be substituted for max and the maximum inscribed circle w1min.

That is, w1max is reduced to 15 × Xs or less, w1max
One minute may be set to ×× Xs.

In this embodiment, since the element section is 5 μ square, w
Both 1max and w1min are included in the condition that the beam converges, and it is considered that the beam was observed immediately above the element.

In the electron-emitting device according to the present invention, the projection is
Even in the case of a dimension, that is, a pillar shape, a structure in which the electrode can be easily taken out can be obtained.

(Embodiment 4) Further, in the following fourth embodiment, a description will be given of an embodiment which utilizes these size effects for each region and is effective for further improving the efficiency and reducing the beam diameter.

FIG. 15 is a plan view of the fourth embodiment. In this embodiment, a two-dimensional structure having a cross-shaped shape is employed. As for the size of the cross, all sides are 3 μm.

Further, in (a), the Pt-Pd conductive film 5 was 20 μ square, and in (b), it was 6 μ square. Other configurations are the same as those of the third embodiment.

When the device of this example was driven in the same manner as in Example 1, (a) showed the electron emission efficiency Ie / If.
Was 0.40%. The beam diameter is Lx = 150μ
m and Ly = 150 μm, and a beam could be observed directly above the device.

In (b), the electron emission efficiency Ie / If is:
0.30%. The beam diameter is Lx = 120 μm,
Ly = 120 μm, and a beam could be observed directly above the device.

The cross shape has several effects.

In (a), there is an effect that the emission length can be lengthened. That is, the thickness is 20 μm in the third embodiment, but is 36 μm in the present configuration.

In (b), the potential distribution is distorted by the form factor to form a portion having a high electron emission efficiency or a portion having a high convergence effect. It can be. In the configuration (b), the convergence effect is good at the inside bent portion of the cross, and the beam shape can be reduced by limiting the emission portion to only that portion.

FIG. 15 shows w1min and w1max in this configuration. Both are included within the conditions of convergence.

(Embodiment 5) An embodiment in which an image forming apparatus is constituted by the electron source shown in FIG.

The number of elements of the electron source is m × n, where m = 100, n
= 300.

In the image forming apparatus, the pitch of one pixel was (x, y) = (200 μm, 200 μm).

The manufacturing method is almost the same as that of the first embodiment, but different points will be mainly described.

(Step 1c) After sufficiently cleaning the substrate 1 using quartz, 1 μm thick Ta is deposited as the first electrode 2 by sputtering. The first electrode is a y-direction wiring 73
Also serves as.

(Step 2) Thereafter, in a photolithography step, spin coating of a positive photoresist (AZ1500 / manufactured by Clariant), exposure and development of a photomask pattern were performed, and the mask pattern was transferred. Thereafter, the patterned photoresist was used as a mask.

(Step 3) Further, dry etching was performed using CF ₄ gas, and the first electrode 2 was etched by 300 nm (h0 = 0.3 μm) to form a projection with w0 = 3 μm. L1 was 100 μm. The resist mask was then peeled off.

(Step 3c) An interlayer insulating layer 61 was deposited, and the structure shown in FIG. 7 was produced by a photolithography step and etching. The distance between the interlayer insulating layers 61 is
The thickness was 100 μm.

(Step 4) The insulating layer 3 having a thickness of 1
SiO ₂ is deposited in nm, thickness 1 as the second electrode 4
00 nm of Ta was deposited.

(Step 5) Thereafter, in a photolithography step, a positive photoresist (AZ1500 / manufactured by Clariant) was spin-coated. Thereafter, when the photoresist was etched by ion milling, the resist on only the upper and lower portions of the projections was quickly lost.

(Step 6) Further, using the remaining resist as a mask, the second electrode 4 and the insulating layer 3 were dry-etched using CF ₄ gas. After the etching, the resist was peeled off.

(Step 6c-1) An Al wiring electrode 62 was partially laminated on the second electrode 4 to a thickness of 1 μm.
The second electrode 4 and the wiring electrode 62 constitute an x-direction wiring 72.

(Step 7) Next, a 5 nm-thick Pt-Pd
A conductive film 5 was deposited on part of the structure. At this time, Pt
The length L2 where Pd was deposited was 20 μm.

(Panel Production Step) An electron source substrate (in this embodiment, an electron emission portion is not formed yet) having a plurality of electron-emitting devices produced as described above is used as a rear plate, and a glass substrate is used. A support plate and a face plate having a fluorescent film (corresponding to an image forming member) and a metal pack formed on the inner surface are connected to each other using frit glass,
An envelope was made. This step is performed by baking in a temperature range of 450 ° C. for 10 minutes in a vacuum to seal.

As a color fluorescent film, a black stripe configuration shown in FIG. 9A was used.

The phosphor width was 160 μm, and the black stripe width was 40 μm. In this embodiment, as a material of the black stripe, a material mainly containing graphite as a main component was used.

A metal back 95 was provided on the inner surface side of the fluorescent film. The metal back was formed by performing a smoothing process (usually called “filming”) on the inner surface of the fluorescent film after the fluorescent film was formed, and then depositing Al using vacuum evaporation or the like. The face plate was provided with a transparent electrode on the outer surface side of the fluorescent film in order to further enhance the conductivity of the fluorescent film.

When performing the above-mentioned sealing, in the case of a color, each phosphor must correspond to an electron-emitting device, and sufficient alignment is indispensable.

In this embodiment, a phosphor is disposed directly above the electron source, and the thickness of the support frame is adjusted so that the distance between the element portion and the phosphor becomes H = 2 mm. .

(Step 8c) Next, the first embodiment is applied between the first electrode and the second electrode via the x-direction wiring and the y-direction wiring.
Similarly, a pulse voltage of 10 V to 17 V as shown in FIG. 4B (ON time: 1 msec / OFF time: 9 m)
sec unipolar), a current is applied to the Pt-Pd conductive film 5, and a gap 6 is formed by the forming step.

(Step 9) Next, the envelope was evacuated to vacuum using an exhaust pipe (not shown), and after evacuation, BN (benzonitrile) was applied in the y direction in a 2 × 10 ⁻⁵ Pa atmosphere. A pulse voltage of 12 V to 15 V (ON time: 1 msec / OFF time: 9 msec, both poles) as shown in FIG. 4C is applied to the first electrode 2 and the second electrode 4 via the wiring x-direction wiring. And produced carbon in the gap. The activation step was completed when the current flowing during the activation step was saturated. As a result, the gap 6 was formed only in the region where the Pt-Pd film was deposited.

After the device was driven, the gap position was confirmed by an electron microscope.
It was located almost at the center of the insulating layer 3.

The electron source produced as described above was re-evacuated to 5 × 10 ⁻⁵ Pa or more, kept at 150 ° C. in the vicinity of the element, heated for 3 hours or more, and then returned to room temperature. At that time, the degree of vacuum was 1 × 10 ⁻⁶ Pa.

After the envelope was sealed, it was driven in the same manner as in Example 1.

The driving voltage is set to Vf = 15 V, 15 V is applied to the first electrode via the y-direction wiring, and the second driving voltage is applied to the first electrode via the x-direction wiring.
0 V was applied to the electrodes.

The width w1 of the high-potential electrode of the element is 3.
1 μm, and the efficiency of the device was 0.32%. The beam diameter of the element was measured in the same manner as in Example 1, and found to be Lx = 170 μm and Ly = 200 μm.

Therefore, a 200 μm square image forming apparatus of this embodiment can be constructed.

[0288]

As described above, according to the present invention, a first electrode having a projection in a partial region, and an upper surface region of the projection of the first electrode on the first electrode are provided. An insulating layer disposed on a region other than the first electrode and a gap between the insulating layer and the first electrode so as to form a pair on the insulating layer via the protrusion, and disposed on the insulating layer. And the second electrode, the number of electron scattering times can be reduced, and the electron emission efficiency can be improved.

Further, by making it possible to suppress the number of times of scattering, it is possible to minimize the non-uniformity of the electron trajectory due to the isotropic scattering, and it is possible to realize convergence of the electron trajectory.

Further, by improving the electron emission efficiency of the electron-emitting device, it is possible to provide a high-definition, high-definition electron source and an image forming apparatus having excellent performance.

[Brief description of the drawings]

FIG. 1 is a view showing an example of an electron-emitting device to which the present invention is applied, FIG. 1 (a) is a cross-sectional view, and FIG. 1 (b) is a plan view.

FIG. 2 is a process chart showing an example of a method for manufacturing an electron-emitting device to which the present invention is applied.

FIG. 3 is a view showing an activation step in the method for manufacturing an electron-emitting device to which the present invention is applied.

FIG. 4 is a diagram showing a pulse waveform in a method for manufacturing an electron-emitting device to which the present invention is applied.

FIG. 5 is a diagram illustrating an electron beam of the electron-emitting device to which the present invention is applied.

FIG. 6 is a graph for explaining the operation of the electron-emitting device to which the present invention is applied.

FIG. 7 is a configuration example in the case where an electron-emitting device to which the present invention is applied is used as an electron source.

FIG. 8 is a schematic perspective view showing an image forming apparatus formed in a matrix using electron-emitting devices to which the present invention is applied, with a part thereof cut away.

FIG. 9 is a diagram illustrating a fluorescent film used in an image forming apparatus to which the present invention is applied.

FIG. 10 is a block diagram showing a drive circuit for performing display in accordance with an NTSC television signal in an image forming apparatus to which the present invention is applied.

FIG. 11 is a diagram illustrating an electron-emitting device according to a second embodiment.

FIG. 12 is a diagram illustrating the number of scattering times of the electron-emitting device to which the present invention is applied.

FIG. 13 is a diagram illustrating an influence of a shape factor on efficiency.

FIG. 14 is a diagram illustrating an electron-emitting device according to a third embodiment.

FIG. 15 is a diagram illustrating an electron-emitting device according to a fourth embodiment.

FIG. 16 is a schematic view illustrating a conventional electron-emitting device.

FIG. 17 is a schematic view illustrating a conventional electron-emitting device.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 first electrode 3 insulating layer 4 second electrode 5 conductive film 6 gap 7 anode electrode 8, 9 power supply 21 resist pattern 30 vacuum device 31 organic material 32 deposited film 61 interlayer insulating layer 62 wiring electrode 71 electron emitting element 72 x direction wiring 73 y direction wiring 81 electron source substrate 85 phosphor 86 black conductive material 91 rear plate 92 support frame 93 glass substrate 94 fluorescent film 95 metal back 96 face plate 97 high voltage terminal 98 envelope 141 wiring electrode 142 interlayer insulating layer

Claims (13)

[Claims] A first electrode disposed on a substrate and having a convex portion in a partial region; and a region on the first electrode other than an upper surface region of the convex portion of the first electrode. An insulating layer disposed on the insulating layer, and a second electrode disposed on the insulating layer having a gap between the first electrode so as to form a pair on the insulating layer via the protrusion. An electron-emitting device comprising: an electrode; 2. The electron-emitting device according to claim 1, further comprising voltage applying means for applying a higher potential to the first electrode than to the second electrode. 3. The first and second electrodes are each a first electrode.
3. The electron-emitting device according to claim 1, further comprising a second conductive film, and wherein the gap is provided between the first and second conductive films. 4. 4. The electron emission device according to claim 1, wherein the convex portion of the first electrode is arranged so as to be sandwiched or surrounded by the second electrode. element. 5. The method according to claim 1, wherein the convex portion of the first electrode is located above the second electrode disposed on a region other than the convex portion of the first electrode via the insulating layer. The electron-emitting device according to claim 1, 2, 3, or 4, wherein 6. An electron-emitting device according to claim 1, further comprising: an anode provided above the electron-emitting device to capture electrons. When the width of the upper surface region is W, the distance from the electron-emitting device to the anode is H, the applied voltage between the first electrode and the second electrode is Vf, and the voltage applied to the anode is Va The width W is 1 / (H × Vf) / (pi π × Va).
An electron-emitting device characterized by being at least 2 times and not more than 15 times. 7. The semiconductor device according to claim 1, wherein the gap is provided on the insulating layer disposed substantially on the same plane as an upper surface region of the projection of the first electrode. Item 14. The electron-emitting device according to Item 1. 8. The electron emission device according to claim 1, wherein the gap is provided on the insulating layer disposed on a side wall of the projection of the first electrode. element. 9. An electron-emitting device according to claim 8, and an anode provided above the electron-emitting device to capture electrons.
Wherein the distance from the second electrode to the anode is H, the voltage applied between the first electrode and the second electrode is Vf, and the voltage applied to the anode is Va, The length between the both ends of the first electrode in the direction perpendicular to the substrate on the side wall of the portion is (H × Vf) / (pi π
× Va) or less. 10. An electron source in which a plurality of electron-emitting devices are arranged, wherein the electron-emitting devices are any one of claims 1 to 9.
13. An electron source, which is the electron-emitting device according to the above item. 11. An upper wiring and a lower wiring respectively arranged above and below the insulating layer are arranged in a matrix, and the lower wiring and the first electrode, and the upper wiring and the second electrode. 11. The electron source according to claim 10, wherein are connected to each other. 12. An image forming apparatus, comprising: the electron source according to claim 10; and an image forming member that forms an image by using electrons emitted from the electron source. 13. The image forming apparatus according to claim 12, wherein the image forming member is disposed immediately above the electron-emitting device.