JP2002124176A - Electron-emitting element, electron source and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron-emitting element having a still smaller electron beam diameter realized, and an electron source as well as an image forming device with a good color quality and high resolution equipped with the electron- emitting element. SOLUTION: A side wall laminated with at least an insulation layer 3 and gate electrodes 4a, 4b is provided facing an electron-emitting film 5, with regions partially different heights (t1, t2).

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 such 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 source and a cold cathode electron source, are known. Field emission type (hereinafter referred to as FE type) cold metal electron sources, metal / insulating layer /
There are a metal type (hereinafter, referred to as an MIM type) and a surface conduction electron-emitting device.

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. Spindt, “PHYSICAL Proper
ties ofthin-film field em
issue cathodes with molly
bdenium cones ", J. Appl. Phys.
s. , 47, 5248 (1976).

As an example of the MIM type, C.I. A. Mead,
“Operation of Tunnel-Emis
site Devices, ”J. Apply. Phys.
s. , 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 and the like 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. Examples of the surface conduction type device include a device using an SnO ₂ thin film, a device using an Au thin film described in the above-mentioned report of Elinson, and (G. Dittmer. Thin Solid).
Films, 9, 317 (1972)), In ₂ O ₃ / S
nO ₂ thin film (M. Hartwell and
C. G. FIG. Fonstad, IEEE Trans. ED
Conf. , 519 (1983)).

[0007] In order to apply the electron-emitting device to an image forming apparatus, an emission current for causing the phosphor to emit light with sufficient luminance is required. Further, in order to increase the definition of the display, it is required that the diameter of the electron beam applied to the phosphor be small. And it is important that it is easy to manufacture.

[0008]

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

The conventional MIM type has a structure in which an insulator is arranged between a lower electrode and an upper electrode, and a voltage is applied between both electrodes to extract electrons. The direction of the internal electric field matches the direction of the emitted electrons, and there is no distortion in the potential distribution on the emitting surface.Thus, a small electron beam diameter can be achieved.However, since the scattering of electrons occurs between the insulating layer and the upper electrode, It is generally inefficient.

A Spindt type electron-emitting device is an example of a conventional FE type. In the Spindt type, a microchip is generally formed as an emission point and electrons are emitted from the tip thereof. When the emission current density is increased to emit light from the phosphor, thermal destruction of the electron emission portion is caused. And the life of the FE element is limited. Further, the electrons emitted from the tip tend to spread due to the electric field formed by the gate electrode, and thus have a disadvantage that the beam diameter cannot be reduced.

In order to overcome such disadvantages of the FE element, various examples have been proposed as individual solutions.

As an example of preventing the spread of the electron beam, there is an example in which a focusing electrode is arranged above the electron emitting portion. In this case, the emitted electron beam is generally narrowed by the negative potential of the focusing electrode. However, the manufacturing process is complicated and the manufacturing cost is increased.

As another example of reducing the electron beam diameter, there is a method of not forming a microchip such as a Spindt type. For example, there are those described in JP-A-8-096903 and JP-A-8-096904. FIG. 1 shows an electron-emitting device disclosed in Japanese Patent Application Laid-Open No. 8-097044.
5 is shown.

This has the advantage that a flat equipotential surface is formed on the electron emission surface and the spread of the electron beam is reduced, since electrons are emitted from the thin film disposed in the hole.

Further, by using a material having a low work function as an electron-emitting substance, electrons can be emitted without forming a microchip, and a low driving voltage can be achieved. Another advantage is that the manufacturing method is relatively simple.

Further, since the electron emission is performed on the surface,
The electric field is not concentrated, the chip is not broken, and the life is long.

In such a structure, generally, a gate electrode is arranged above the fine hole so as to surround the electron emission film. The size of the fine hole is related to the beam size, and the size is several μm to several μm. It is common to make it smaller. The production of such micropores becomes more difficult as the pores become smaller.

In addition, Japanese Patent Application Laid-Open Nos. Hei 8-115654, Hei 8-293244, Hei 10-125215, and
U.S. Pat. No. 5,473,328.

Japanese Patent Application Laid-Open No. H11-32930 discloses an example in which a similar structure is used to further converge a beam.
There is No. 8. This is one in which a focusing electrode is provided inside the gate electrode.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an electron-emitting device which realizes a further smaller electron beam diameter.
Another object of the present invention is to provide a high-definition electron source and an image forming apparatus having good image quality and including the electron-emitting device.

[0021]

In order to achieve the above object, according to the present invention, there is provided a cathode electrode disposed on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, An electron-emitting device electrically connected to the cathode electrode; and an electron-emitting device including: a side wall that is stacked with at least the insulating layer and the gate electrode facing the electron-emitting film; The side wall is characterized by comprising regions having different heights partially.

In the above-mentioned regions having different heights,
It is also preferable that the thickness of the gate electrode is partially different.

In the regions where the heights are partially different,
It is also preferable that the thickness of the insulating layer is partially different.

In the above-mentioned areas having different heights,
It is also preferable that the thickness of the cathode electrode is partially different.

It is preferable that the side wall is provided substantially linearly.

It is also preferable that a part of the cathode electrode is exposed by being surrounded by the side wall and an opening having the electron emission film therein is provided.

A cathode electrode disposed on the substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and a part of the cathode electrode exposed through the insulating layer and the gate electrode. An electron-emitting device provided in the opening and an electron-emitting film provided in the opening and electrically connected to the cathode electrode, wherein at least the insulating layer and the gate electrode face the opening; And a side wall, which is characterized in that the side wall includes regions having partially different heights.

Preferably, the opening has a substantially slit shape, and the height of the side wall forming one long side of the substantially slit shape is different from the height of the side wall forming the other long side.

The opening is provided in a substantially ring shape, and the height of the side wall disposed on the inner diameter side of the substantially ring-shaped opening is
It is also preferable that the height be smaller than the height of the side wall disposed on the outer diameter side of the substantially ring-shaped opening.

The electrons emitted from the electron-emitting film provided in the substantially ring-shaped opening, and emitted from opposing positions on the periphery of the electron-emitting film, It is also preferable to determine the length of the inner diameter of the opening so that the opening reaches substantially above the center of the portion.

It is also preferable that the electron emission film is diamond or diamond-like carbon having a low work function.

An electron source comprising a plurality of the above-described electron-emitting devices, wherein the gate electrode is connected to a gate electrode wiring, and the cathode electrode is connected to a cathode wiring in a matrix wiring.

An image forming apparatus includes the above-described electron source, and an image forming member that forms an image using electrons emitted from the electron source.

It is also preferable that the image forming member is a phosphor which 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.

FIG. 1 is a schematic view showing an electron-emitting device according to the present invention. FIG. 1 (a) is a sectional view, and FIG. 1 (b) is a plan view.

In FIG. 1, 1 is a substrate, 2 is a cathode electrode, 3 is an insulating layer, 4a and 4b are gate electrodes, and 5 is an electron emission film.

The electron emission film 5 is formed in a stripe shape having a width of w1 and a length of L1.

A second gate 4b is laminated on the first gate electrode 4a only on one side from the center of the slit as an opening where the electron emission film 5 is provided. Therefore, in the present device, on one side, the insulating layer 3 and the first gate electrode 4a have a height t1 on the side wall, and on the other side, the insulating layer 3, the first gate electrode 4a, and the second gate electrode 4b have a high height. T
2 constitutes a side wall.

A drive voltage Vg is applied between the cathode electrode 2 and the gate electrode 4 by a power supply 6.

Reference numeral 7 denotes an anode electrode which is arranged above the electron-emitting device with only H separated therefrom. An anode voltage Va is supplied from a high-voltage power supply 8. The position of the element at the distance H between the anode electrode and the element may be usually based on the position of the cathode electrode 2.

At the anode electrode 7, electrons are captured, and an electron emission current Ie is detected.

FIG. 2 is a diagram showing an example of an equipotential surface and an electron beam trajectory when this element is driven.

Immediately above the electron emission film 5, an equipotential surface is substantially symmetrical with respect to the slit, but the equipotential surface is also asymmetric near the gate electrode. Thereby, the electron orbit is bent as shown in FIG. The trajectory on the side where the second gate electrode 4b is stacked is more affected.

FIG. 3 is a diagram showing an example of the height t2 / t1 and the electron beam diameter.

As can be seen from the electron orbits shown in FIG. 2, the beam diameter is reduced by making the side wall height asymmetrical as shown in the present invention.

One example is the effect of electrons colliding with the gate electrode. When the number of colliding electrons increases, some of the electrons are scattered, and as a result, the beam diameter increases.

In the electron-emitting device of the present invention, the electron-emitting layer 5
Is formed substantially flat, a relatively small distortion is formed between the electron emission layer 5 and the anode electrode 7, and the spread of the electron beam is relatively small. And no extreme asymmetry is desired.

Further, by selecting a material having a low work function as the material of the electron emission layer 5, the device driving voltage can be reduced.

FIG. 4 is a view for explaining an example of a method for manufacturing the electron-emitting device of the present invention shown in FIG.

Hereinafter, an example of a method for manufacturing an electron-emitting device according to the present invention will be described with reference to FIG.

As shown in FIG. 4 (a), a quartz glass, a glass having a reduced content of impurities such as Na, a blue plate glass, a silicon substrate or the like is coated with SiO 2 by sputtering, etc. _The cathode electrode 2 is laminated on the substrate 1 by using any one of the laminated body obtained by laminating ₂ and the insulating substrate made of ceramic such as alumina.

The cathode electrode 2 generally has conductivity, and is formed by a general vacuum film forming technique such as an evaporation method or a sputtering method, or a photolithography technique. The material of the cathode electrode 2 is, for example, Be, Mg, Ti, Zr, H
f, V, Nb, Ta, Mo, W, Al, Cu, Ni, C
metal or alloy material such as r, Au, Pt, Pd, Ti
Carbides such as C, ZrC, HfC, TaC, SiC, WC, etc., HfB ₂ , ZrB ₂ , LaB ₆ , CeB ₆ , YB ₄ , G
dB boride such as _4, appropriately selected TiN, ZrN, nitrides such as HfN, Si, a semiconductor such as Ge, an organic polymer material, amorphous carbon, graphite, diamond-like carbon, diamond from dispersed carbon and carbon compounds etc. Is done. The thickness of the cathode electrode 2 is set in the range of several tens nm to several mm, and preferably several hundred n.
It is selected in the range of m to several μm.

Next, following the cathode electrode 2, the insulating layer 3,
A first gate electrode 4a is deposited.

The insulating layer 3 is formed by a general vacuum film forming technique such as a sputtering method, a CVD method and a vacuum evaporation method, and its thickness is set in a range from several nm to several μm, preferably It is selected from the range of tens nm to several hundred nm. Desirable materials include SiO ₂ , SiN, Al ₂ O ₃ , CaF
For example, a material having a high withstand voltage that can be cut off by a high electric field, such as a high electric field, is desirable.

The gate electrode 4a is similar to the cathode electrode 2.
Has conductivity and is commonly used for vapor deposition, sputtering, etc.
Formed by vacuum deposition technology and photolithography technology
It is. The material of the gate electrode 4a is, for example, Be, Mg,
Ti, Zr, Hf, V, Nb, Ta, Mo, W, Al,
Metals such as Cu, Ni, Cr, Au, Pt, Pd
Gold material, TiC, ZrC, HfC, TaC, SiC, W
Carbides such as C, HfB _Two, ZrB_Two, LaB₆, CeB₆,
YB_Four, GdB_FourBoride such as TiN, ZrN, HfN, etc.
Nitrides, semiconductors such as Si and Ge, organic polymer materials, etc.
Selected as appropriate.

Next, as shown in FIG. 4B, a second gate electrode 4b is partially formed.

The second gate electrode 4b may be made of the same material or different material as 4a, and may be formed by the same method or different method.

Next, as shown in FIG. 4C, a mask pattern 41 is formed by photolithography.

Further, as shown in FIG. 4D, a laminated structure is formed in which a part of each of the layers 3, 4a, 4b is removed from the cathode electrode 2. However, this etching step may be stopped on the cathode electrode 2 or a part of the cathode electrode 2 may be etched.

However, the cathode electrode 2 itself is shown in FIG.
It is necessary to avoid being etched by the step reflecting the step shape of the above.

For this purpose, it is necessary to select an etching method in the etching step according to the material of each of the layers 2, 3, and 4.

Next, as shown in FIG. 4E, an electron emission layer 5 is deposited on the entire surface.

The electron emission layer 5 is formed by a general film forming technique such as a vapor deposition method, a sputtering method, a plasma CVD method and the like. It is preferable to select a material having a low work function for the material of the electron emission layer 5. For example, it is appropriately selected from amorphous carbon, graphite, diamond-like carbon, carbon in which diamond is dispersed, and a carbon compound. Preferably, a diamond thin film, diamond-like carbon, or the like having a lower work function is used. The thickness of the electron emission layer 5 is set in the range of several nm to several hundred nm, and is preferably selected in the range of several nm to several tens nm.

The electric field required to emit electrons from these electron emission films 5 should be as low as possible.
Drive voltage can be reduced. If it is not more than 5 × 10 ⁵ V / m, the driving voltage can be reduced to about several tens of V, which is preferable.

Next, as shown in FIG. 4F, the mask pattern 41 is peeled off to complete the device as shown in FIG.

The difference between the heights of the side walls is set in the range of several tens of nm to several tens of μm, and preferably about several hundreds of nm. As shown in FIG. Is selected.

In this case, the asymmetric direction, ie, x
The beam diameter in the direction becomes smaller.

In the cross section of the side wall, the positions of the side walls of the gate electrode, the insulating layer, and the cathode electrode do not necessarily have to coincide with each other. However, in the case where the inclination is extremely large or the position of the second gate electrode is largely retreated, The effect of the present invention is reduced.

In order to obtain the effect of the present invention, it is desirable that the side wall positions of the insulating layer and the gate electrode substantially coincide with each other, and that the side wall is substantially perpendicular to the substrate 1.

The diameter w1 of the slit is a factor which largely depends on the electron emission characteristics of the device. The characteristics of the material constituting the device, particularly the work function and the film thickness of the electron emission layer, the driving voltage of the device, It is set appropriately according to the shape of the electron emission beam to be emitted. Usually, w1 is selected from the range of several hundred nm to several tens of μm.

The planar shape of the slit is not particularly limited. However, in some cases, a rectangular shape or a ring shape is most preferable in terms of the structure of the element.

The length L1 of the slit is a factor that depends on the amount of emitted electrons and is set as appropriate.

Further, after patterning of the cathode electrode 2, an electron emitting layer 5 is formed on the entire surface, and in an etching step,
Etching may be stopped on the upper surface of the electron emission layer 5, or a diamond thin film, diamond-like carbon, or the like may be selectively deposited at a desired location.

Further, the device of the present invention has a very simple structure in which lamination is repeated, the manufacturing process is easy, and the device can be manufactured with a high yield.

An application example of the electron-emitting device to which the present invention can be applied will be described below. By arranging a plurality of the electron-emitting devices of the present invention on a substrate, for example, an electron source or an image forming apparatus can be configured.

Various arrangements of electron-emitting devices are employed. As an example, a plurality of electron-emitting devices 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 a wiring in the X direction, and the same column is connected. There is a simple matrix arrangement in which the other of the electrodes of the plurality of electron-emitting devices arranged in the above is commonly connected to the wiring in the Y direction. Hereinafter, the simple matrix arrangement will be described in detail.

5 and 6, reference numerals 51 and 61 denote electron source substrates, 52 and 62 denote X-direction wirings, and 53 and 63 denote Y-direction wirings. Reference numeral 64 denotes an electron-emitting device of the present invention.

The m X-direction wirings 62 are Dx1, Dx
2,... Dxm, and can be made of a conductive metal or the like formed by a vacuum deposition method, a printing method, a sputtering method, or the like. The material, thickness, and width of the wiring are appropriately designed. Y
The direction wiring 63 is composed of n wirings Dy1, Dy2,... Dyn, and is formed similarly to the X-direction wiring 62. An interlayer insulating layer (not shown) is provided between the m X-directional wirings 62 and the n Y-directional wirings 63, and electrically separates them (m and n are: Both are positive integers).

The interlayer insulating layer (not shown) is made of SiO ₂ or the like formed by using a vacuum deposition method, a printing method, a sputtering method, or the like. For example, the base 61 on which the X-direction wiring 62 is formed
Is formed in a desired shape on the entire surface or a part thereof. In particular, the film thickness, material, and manufacturing method are appropriately set so as to withstand the potential difference at the intersection of the X-directional wiring 62 and the Y-directional wiring 63. The X-direction wiring 62 and the Y-direction wiring 63 are led out as external terminals.

The m X-directional wires 62 constituting the electron-emitting device 64 may function as the cathode electrode 2, the n Y-directional wires 63 may function as the gate electrode 4, and the interlayer insulating layer may be In some cases, the insulating layer 3 may be used.

The X-direction wiring 62 is connected to a scanning signal applying means (not shown) for applying a scanning signal for selecting a row of the electron-emitting devices 64 arranged in the X-direction. On the other hand, Y
The direction wiring 63 has electron emitting elements 64 arranged in the Y direction.
(Not shown) for modulating each of the columns according to the input signal. The driving voltage applied to each electron-emitting device is supplied as a difference voltage between a scanning signal and a modulation signal applied to the device.

In the above configuration, individual elements can be selected and driven independently using simple matrix wiring. An image forming apparatus configured using such an electron source having a simple matrix arrangement will be described with reference to FIG. FIG. 7 is a schematic diagram illustrating an example of a display panel of the image forming apparatus.

In FIG. 7, reference numeral 71 denotes an electron-emitting device;
Denotes an electron source substrate on which a plurality of electron-emitting devices are arranged, 91 denotes a rear plate on 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.

As described above, the envelope (panel) 98 includes the face-plate 96, the support frame 92, and the rear plate 91.
It consists of. 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 fluorescent 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 thereto.

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

The above-described envelope is an 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.

FIG. 8 is a schematic diagram showing the fluorescent film 94 formed on the face plate 96. 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, a black conductive material 86 called a black stripe, a black matrix, or the like is used.
And the phosphor 85.

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 color display so that color mixing and the like are 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.

The method of applying the phosphor on the glass substrate 93 can employ a precipitation method, a printing method, or the like irrespective of monochrome or color. Usually, a metal back 95 is provided on the inner surface side of the fluorescent film 94. The purpose of providing a metal back is
Light emitted to the inner surface side of the light emitted from the phosphor is transferred to the face plate 9.
Improving the brightness by specular reflection to the 6th side, acting as an electrode for applying an electron beam accelerating voltage, and protecting the fluorescent film 94 from damage due to the collision of negative ions generated in the envelope. And so on. The metal back 95 can be manufactured by performing a smoothing process (usually called “filming”) on the inner surface of the fluorescent film after manufacturing the fluorescent film, 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 directly above the electron-emitting device 71, the electron beam is positioned and arranged so that the fluorescent film 94 is disposed immediately 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) of an exhaust device such as an ion pump and a sorption pump. Then, after the atmosphere is made sufficiently low in organic substances, the exhaust pipe is heated with a burner to be dissolved and sealed. To maintain the pressure after the envelope 98 is sealed, a getter process may be performed. This is the envelope 98
Immediately before or after sealing, a getter disposed at a predetermined position (not shown) in the envelope 98 is heated by heating using resistance heating, high-frequency heating, or the like, to form a vapor-deposited film. Processing. 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.

The image forming apparatus constructed by using the electron sources of the simple matrix arrangement manufactured by the above-described processes has the structure in which each of the electron-emitting devices has external terminals Dx1 to Dxm and Dy1 to Dx1 to Dx1.
By applying a voltage via Dyn, 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. 9 is a block diagram showing an example of a driving circuit for performing display according to an NTSC television signal.

The scanning circuit 1302 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), and is electrically connected to the terminals Dox1 to Doxm of the display panel 1301. S1
Each of the switching elements Sm 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.

The DC voltage source Vx is set based on the characteristics of the electron-emitting device.

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.

A synchronization signal separation circuit 1306 is a circuit for separating a synchronization signal component and a luminance signal component from an NTSC television signal input from the outside, and uses a general frequency separation (filter) circuit or the like. Can be configured. The synchronizing signal separated by the synchronizing signal separating circuit 1306 includes a vertical synchronizing signal and a horizontal synchronizing 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 data of one line of the serial / parallel-converted image (corresponding to drive data for N electron-emitting devices) is output from the shift register 1304 as N parallel signals Id1 to Idn.

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

Modulation 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.

When a pulse-like voltage is applied to this element,
For example, when a voltage lower than the electron emission threshold is applied, electron emission does not occur, but when a voltage higher than the electron emission threshold is applied, an electron beam is output. At this time, the pulse peak value V
By changing m, the intensity of the output electron beam can be controlled. 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, the output signal DATA of the synchronization signal separation circuit 1306 needs to be converted into a digital signal.
What is necessary is just to provide a D converter. 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, for example, a D / A conversion circuit is used as the modulation signal generator 1307, and an amplification circuit and the like are added as necessary.
In the case of the pulse width modulation method, 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 comparator for comparing the output value of the counter with the output value of the memory. (Comparator) is used. If necessary, an amplifier for voltage-amplifying the pulse-width-modulated signal output from the comparator to the driving 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, the modulation signal generator 1307 can employ, for example, an amplifier circuit using an operational amplifier or the like, and can add a level shift circuit or the like 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 idea 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.

[0118]

Embodiments of the present invention will be described below in detail.

[Embodiment 1] FIG. 1 shows Embodiment 1 of the present invention. FIG. 4 shows an example of the manufacturing method. Hereinafter, the manufacturing method will be described.

(Step 1) First, as shown in FIG. 4A, the substrate 1 is made of quartz and sufficiently washed, and then a 800 nm thick Al is formed as the cathode electrode 2 by sputtering.
Was formed.

Next, a 600 nm thick S
iO ₂ and 100 nm thick Ta were deposited in this order as the gate electrode 4a.

(Step 2) Further, as shown in FIG. 4B, a 300 nm-thick Ta was partially formed as a gate electrode 4b via a mask pattern.

(Step 3) Next, as shown in FIG. 4 (c), spin coating of a positive photoresist (AZ1500 / manufactured by Clariant), photomask pattern exposure and development by photolithography The pattern 41 was formed.

(Step 4) As shown in FIG. 4D, using the mask pattern 41 as a mask, the gate electrode 4 of Ta
a, 4b and the insulating layer 3 are each dry-etched using CF ₄ gas, stopped at the cathode electrode 2 and the width w1
Formed an opening having a width of 1 μm and a width L1 of 100 μm.

(Step 5) Subsequently, as shown in FIG. 4E, an electron emission layer 5 of diamond-like carbon was deposited on the entire surface to a thickness of about 100 nm by a plasma CVD method. The reaction gas used was CH ₄ gas.

(Step 6) As shown in FIG. 4F, the mask pattern 41 was completely removed to complete the electron-emitting device of the first embodiment.

The height t1 of the side wall is 500 nm, and t2 is 80
It became 0 nm.

The electron-emitting devices manufactured as described above were arranged with H = 2 mm as shown in FIG. Va =
10 kV and Vg = 15 V.

Here, as Comparative Example 1, an element having a symmetrical side wall height was fabricated by forming only the first gate electrode without laminating the second gate electrode 4b, and simultaneously driving.

Here, the size of the electron beam was observed using an electrode coated with a phosphor as the anode electrode 7. The electron beam size referred to here is a size up to a region of 10% of the peak luminance of the emitted phosphor.

As a result, in Comparative Example 1, the beam shape was symmetric, and in this embodiment, the beam shape was asymmetric in the x direction. However, in Comparative Example 1, the beam diameter was (x × y) = 150 μm ×
220 μm, and 130 μm × 220 μm in the present embodiment, and the beam diameter was reduced in the y direction.

[Embodiment 2] FIG. 10 shows Embodiment 2 of the present invention.

In this embodiment, the cathode electrode is composed of two layers, a part of the side wall is also formed of the cathode electrode, and the electron emission film 5 is formed below the upper surface of the cathode electrode on the side wall. In the present embodiment, the electron orbit is different from that of the first embodiment.

Hereinafter, a manufacturing method will be described.

(Step 1) First, as shown in FIG. 4A, a substrate 1 is made of quartz and sufficiently cleaned, and then a 500 nm thick A is formed as a cathode electrode 2a by sputtering.
1. Ta having a thickness of 150 nm was formed as the cathode electrode 2b.

Next, a 500 nm thick S
iO ₂ and 100 nm thick Ta were deposited in this order as the gate electrode 4a.

(Step 2) Further, as shown in FIG. 4B, a 300 nm-thick Ta was partially formed as a gate electrode 4a via a mask pattern.

(Step 3) Next, as shown in FIG. 4C, spin coating of a positive photoresist (AZ1500 / manufactured by Clariant), photomask pattern exposure, and development by photolithography The pattern 41 was formed.

(Step 4) As shown in FIG. 4D, the gate electrode 4 of Ta is
a, 4b, the insulating layer 3, and the cathode electrode 2 were each dry-etched using CF ₄ gas and stopped at the cathode electrode 2a as shown in FIG.
An opening having a width L1 of 100 μm was formed.

(Step 5) Subsequently, as shown in FIG. 4E, an electron emission layer 5 of diamond-like carbon was deposited on the entire surface to a thickness of about 100 nm by a plasma CVD method. The reaction gas used was CH ₄ gas.

(Step 6) As shown in FIG. 4F, the mask pattern 41 was completely removed to complete the electron-emitting device of Example 1.

The height t1 of the side wall is 650 nm, and t2 is 95
It became 0 nm.

The electron-emitting devices manufactured as described above were arranged with H = 2 mm, as in Example 1. V
a = 10 kV and Vg = 15 V.

Here, as Comparative Example 2, an element having only a first gate electrode without a second gate electrode 4b and having a symmetrical height was simultaneously driven.

As a result, the beam shape in Comparative Example 2 was symmetric and the beam shape in this example was asymmetric, but the beam diameter was 130 μm × 220 μm in Comparative Example 2 and 110 μm × 220 μm in this Example. The diameter has shrunk.

The beam diameter of the present embodiment is smaller than that of the first embodiment because the electron trajectory is different. In the trajectory of the present embodiment, since the electron emission film 5 is lower than the cathode electrode 2 on the side wall, the equipotential surface immediately above the electron emission film 5 is concave downward, reflecting its shape. For this reason, electrons emitted from the left side of the center of the electron emission film reach the right side, and electrons emitted from the right side of the center of the electron emission film cross the upper side of the opening to reach the anode electrode 7. Due to the influence of this intersection, the beam diameter is slightly reduced.

[Embodiment 3] FIG. 11 shows Embodiment 3 of the present invention. FIG. 11A is a sectional view, and FIG. 11B is a plan view.

This embodiment is an arrangement example in which the electron-emitting device of Embodiment 2 is effectively used, and a ring-shaped electron-emitting film is formed. Since the manufacturing method is the same as that of the second embodiment, the description is omitted. The inner side wall of the ring is low and the outer side wall of the ring is high.

The gate electrode 4a inside the ring is connected to the gate electrode 4a outside the ring at a connection portion formed in a part of the ring.
It is connected to the. This connecting portion may have the same configuration as that in the ring, or may have a different configuration. The connection direction may be one or more. However, in the structure of the present embodiment, if the structure portion is larger than the ring, the electron trajectory is affected.

Further, the connection portion may be connected below the side wall via a contact hole.

In this embodiment, since t1 and t2 have the same configuration as in the second embodiment, the electron trajectory shown in the cross-sectional view is almost the same as that in the second embodiment even if it has a ring shape.

Here, the inner diameter w2 of the gate electrode inside the ring is important. That is, if the diameter of w2 is selected so that the electron trajectory emitted from one side of the ring coincides with the electron trajectory from the other side at the anode electrode 7, the same electron beam diameter as that of the second embodiment can be obtained even in a ring shape. As a result, the spread of the beam can be suppressed.

In the present embodiment, when w2 was set to 50 μm, it became 110 μm × 110 μm. This is the same diameter as that of the second embodiment in the x direction, and the same beam diameter in the y direction as in the x direction can be obtained by making the ring shape. In addition, the beam diameter deviation has been eliminated.

Fourth Embodiment FIG. 12 shows a fourth embodiment of the present invention.

This embodiment is a modification of the structure of the electron emission film.

Hereinafter, a manufacturing method will be described. However, the description of the same steps as those in the first embodiment will be omitted.

(Step 1-1) First, the substrate 1 was sufficiently cleaned using quartz, and then W having a thickness of 500 nm was formed as the first cathode electrode 2a by a sputtering method.

(Step 1-2) The electron emission layer 5 of diamond-like carbon was formed on the entire surface by plasma CVD to a thickness of 100 nm.
m. The reaction gas used was CH ₄ gas.

(Step 1-3) Next, 50 nm thick Ta is used as the second cathode electrode 2b, 500 nm thick SiO _{2 is used} as the insulating layer 3, and 10 nm thick is used as the gate electrode 4a.
0 nm of Ta was deposited in this order.

(Step 2) Further, Ta having a thickness of 300 nm was partially formed as a gate electrode 4b via a mask pattern.

(Step 3) Next, as shown in FIG. 4 (c), spin coating of a positive type photoresist (AZ1500 / manufactured by Clariant) and photomask pattern are exposed and developed by photolithography. The pattern 41 was formed.

(Step 4) As shown in FIG. 4D, using the mask pattern 41 as a mask, the Ta gate electrode 4a
4b, the insulating layer 3, and the cathode electrode 2b are each dry-etched using CF ₄ gas to have a width w1 of 0.5 μm,
An opening having a width L1 of 100 μm was formed.

(Step 6) As shown in FIG. 4F, the mask pattern 41 was completely removed to complete the electron-emitting device of this embodiment.

The height t1 of the side wall is 500 nm, and t2 is 80
It became 0 nm.

The electron-emitting devices manufactured as described above were arranged with H = 2 mm as in Example 1. V
a = 10 kV and Vg = 15 V.

In this device, it is necessary to electrically connect the cathode electrodes 2a and 2b in the vicinity of the device so that they have substantially the same potential.

As a result of driving, the beam diameter was 80 μm ×
It was 180 μm. This element has a basic configuration (t1,
t2) is almost the same. In addition, the overall beam diameter was reduced by reducing w1.

[Embodiment 5] FIG. 13 shows Embodiment 5 of the present invention.

This embodiment is an example in which the thickness of the insulating layer is varied to make the side wall asymmetric.

The manufacturing method can be made by changing the laminated structure to the insulating layers 3a and 3b in the process of the second embodiment and changing the order of etching.

In this configuration, by making the thickness of the insulating layer asymmetric, the electric field near the electron emission film also becomes asymmetric as shown by the equipotential surface in FIG.

For this reason, depending on the driving conditions, the electron emission region is biased, and as a result, it is expected that the beam diameter is not small.

[Embodiment 6] FIG. 14 shows a sixth embodiment of the present invention.

This embodiment is an example in which the thickness of the cathode electrode is varied to make the side wall asymmetric.

The manufacturing method can be manufactured by changing the laminated structure to the cathode electrodes 2a and 2b in the process of Embodiment 2 and changing the order of etching.

Also in this configuration, the electric field near the electron emission film in FIG. 13 is asymmetric as in the fifth embodiment.

For this reason, depending on the driving conditions, the electron emission region is biased, and as a result, it can be expected that the beam diameter is not small.

Example 7 An image forming apparatus was manufactured using the electron-emitting devices of Examples 1 to 6. As an example, a case where the device is manufactured using the element of Example 2 will be described. FIG. 5A is a configuration diagram of the device of this embodiment when viewed from above, and FIG.
It is sectional drawing in the AA of (a). In this case, as shown in FIG. 5A, the electron-emitting devices were configured such that the position of the side wall was shifted so that the electron beam came to the center of each device.

The devices of Example 2 were arranged in a 10 × 10 MTX shape. The devices were arranged at a pitch of 150 μm horizontally and 250 μm vertically. Phosphors were arranged at a distance of 2 mm above the device. A voltage of 10 kV was applied to the phosphor. The drive voltage was Vg = 15V. As a result, a high-definition image forming apparatus was formed.

[0180]

As described above, according to the present invention,
In addition to realizing a smaller electron beam diameter,
It is possible to provide an electron-emitting device that can be easily manufactured and can emit electrons with high efficiency at a low voltage.

Further, when the electron-emitting device according to the present invention is used, it is possible to provide an electron source and an image forming apparatus having good image quality, high definition, and excellent performance.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram illustrating an electron-emitting device according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of a method for manufacturing an electron-emitting device according to an embodiment of the present invention.

FIG. 5 is a diagram showing an example of an electron source according to the embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing an electron source in a simple matrix arrangement.

FIG. 7 is a schematic configuration diagram illustrating an image forming apparatus using an electron source having a simple matrix arrangement.

FIG. 8 is a diagram showing a fluorescent film in the image forming apparatus according to the embodiment of the present invention.

FIG. 9 is a block diagram showing a driving circuit of the image forming apparatus according to the embodiment of the present invention.

FIG. 10 is a diagram showing a second embodiment of the present invention.

FIG. 11 is a diagram showing a third embodiment of the present invention.

FIG. 12 is a diagram showing a fourth embodiment of the present invention.

FIG. 13 is a diagram showing a fifth embodiment of the present invention.

FIG. 14 is a diagram showing a sixth embodiment of the present invention.

FIG. 15 is a diagram schematically showing a conventional electron-emitting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Cathode electrode 3 Insulating layer 4 Gate electrode 5 Electron emission layer 6 Driving power supply 7 Anode electrode 8 High voltage power supply 41 Mask pattern 61, 81 Electron source substrate 62 X direction wiring 63 Y direction wiring 64 Electron emitting element 85 Phosphor 86 Black Conductive material 91 Rear plate 92 Support frame 93 Glass substrate 94 Fluorescent film 95 Metal back 96 Face plate 98 Envelope

Claims (14)

[Claims] 1. A cathode electrode disposed on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and an electron emission film electrically connected to the cathode electrode. In the electron-emitting device, the device has a sidewall facing the electron-emitting film, the sidewall being stacked at least with the insulating layer and the gate electrode, and the sidewall has regions partially different in height. Electron-emitting device. 2. The method according to claim 1, wherein in the areas having different heights,
2. The electron-emitting device according to claim 1, wherein the thickness of the gate electrode is partially different. 3. In the partially different height regions,
3. The electron-emitting device according to claim 1, wherein the thickness of the insulating layer is partially different. 4. The method according to claim 1, wherein in the regions having different heights,
4. The electron-emitting device according to claim 1, wherein the thickness of the cathode electrode is partially different. 5. The electron-emitting device according to claim 1, wherein said side wall is provided substantially linearly. 6. The device according to claim 1, further comprising an opening which exposes a part of the cathode electrode surrounded by the side wall and has the electron emission film therein. An electron-emitting device according to item 13. 7. A cathode electrode disposed on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and a partial region of the cathode electrode passing through the insulating layer and the gate electrode. And an electron emission film provided in the opening and electrically connected to the cathode electrode, wherein at least the insulating layer and the insulating layer face the opening. An electron-emitting device comprising a side wall laminated with a gate electrode, wherein the side wall includes regions having partially different heights. 8. An opening having a substantially slit shape, wherein the height of a side wall forming one long side of the substantially slit shape is different from the height of a side wall forming the other long side. The electron-emitting device according to claim 6, wherein: 9. The opening is provided in a substantially ring shape, and the height of a side wall disposed on the inner diameter side of the substantially ring shaped opening is:
The electron-emitting device according to claim 6, wherein the height is smaller than a height of a side wall arranged on an outer diameter side of the substantially ring-shaped opening. 10. Electrons emitted from the electron-emitting film provided in the substantially ring-shaped opening, and emitted from respective opposing positions on the periphery of the electron-emitting film, 10. The electron-emitting device according to claim 9, wherein the length of the inner diameter of the opening is determined so as to substantially coincide with and reach above the center of the opening. 11. The electron-emitting device according to claim 1, wherein said electron-emitting film is made of diamond or diamond-like carbon having a low work function. 12. An electron source comprising a plurality of the electron-emitting devices according to claim 1, wherein the gate electrode is connected to a gate electrode wiring, and the cathode electrode is connected to a cathode wiring. An electron source characterized by being wired in a matrix. 13. An image forming apparatus, comprising: the electron source according to claim 12; and an image forming member that forms an image by using electrons emitted from the electron source. 14. An image forming apparatus according to claim 13, wherein said image forming member is a phosphor which emits light by collision of electrons.