JP2003051243A - Electron discharging element, electron source and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron discharging element, in which spread of electron beams are suppressed, and realize an imaging device where a high precision displaying is possible. SOLUTION: An extraction electrode 2 and a cathode electrode 3 are arranged on the substrate 1 separated by a distance d. An electron discharge material 4 is arranged on the cathode electrode 3. If the width, to be contacted with a gap of the drawing out electrode 2 of the cathode electrode side, is taken as L1 and the width to be contacted with a gap of the electron discharging material 4 of the extraction electrode side is taken as L2, sizes of the cathode electrode 2 and the electron discharge material 4 are set so that L1<L2.

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 and an image forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus such as a display device,
Flat panel display devices using liquid crystal have become popular in place of CRTs, but since they are not self-luminous, they have problems such as having a backlight, and self-luminous display devices have been desired.

As an electron source for an image forming apparatus, a field emission type (FE type) electron-emitting device that emits electrons from a metal surface by applying a strong electric field of 10 ⁶ V / cm or more to a metal is one of cold electron sources. It is attracting attention as one. If a FE-type cold electron source is put into practical use, a thin self-luminous image display device will be possible, which will contribute to reduction in power consumption and weight.

As a general example of the FE type electron-emitting device, as shown in FIG. 16, an emitter 165 has a conical or quadrangular pyramid shape in a substantially vertical direction from a substrate 161, and is surrounded by an insulating layer 163. There is a so-called vertical FE in which the gate electrode 164 is arranged. For example, CASpindt, "Phy
sical Properties of thin-film field emission catho
des with molybdenum cones ", J.Appl.Phys., 47,5248 (1
This is the one disclosed in 976) (hereinafter Spindt type). The principle of operation is that when a positive voltage is applied to the gate electrode with respect to the emitter, electric field concentration occurs at the sharpened tip of the emitter, and electrons are emitted.

In recent years, an electron-emitting device using a material, such as diamond or carbon fiber (including carbon nanotube, graphite nanofiber, etc.), which requires a low voltage for emitting electrons as an emitter, has been actively developed. . For example, an example of a structure in which the emitter of the Spindt-type electron-emitting device is replaced with an aggregate of carbon fibers, or as shown in FIG. 17, the emitter 175 is formed in parallel with the substrate 171, and the tip of the carbon fiber 175 is sharpened by processing. , The cathode faces the facing gate electrode 174, and the collector 176 is formed in a direction orthogonal to the direction in which electrons are extracted.
A horizontal FE having a structure (referred to as an anode in this case) is disclosed (USP4728851 etc.).

[0006]

In recent years, an image forming apparatus such as a self-luminous image display device is required to have a higher resolution, and an electron beam from each electron-emitting device is transferred to an anode having a phosphor. The reachable area needs to be smaller.

The operation principle of an image forming apparatus using a general Spindt FE type electron-emitting device will be described with reference to FIG. In FIG. 16, 161 is a substrate, 162 is a gate electrode, 163 is an insulating layer, 164 is a cathode electrode, and 165 is an emitter. Generally, the operating voltage (voltage between the emitter and the electrode that gives a positive potential to the emitter) Vf of the element is Fowler with the electric field at the tip of the emitter guided by the Poisson equation and the electric field and the work function of the emitter as parameters. -Nordh
It is determined by the current density of the electron emission current according to the relational expression called eim's equation.

The electric field necessary for electron emission corresponds to the tip of the emitter and an electrode that gives a positive potential to the emitter (a gate electrode in a three-electrode configuration of a cathode, an anode, and a gate. In the case of the configuration, the smaller the distance D to the anode electrode) and the smaller the radius r of the emitter tip, the larger the electric field obtained.

The beam shape of the conventional configuration will be described with reference to FIG. In the case of the Spindt type described above, the emitter 16
When Vf is loaded between the gate 5 and the gate 162, the electric field at the tip of the protrusion of the emitter is increased and electrons are taken out into the vacuum from the vicinity of the tip of the cone.

Since the electric field at the tip of the emitter is formed with a certain finite area along the shape of the tip of the emitter, the electrons to be taken out are extracted from the finite area of the tip of the emitter in the vertical direction with respect to the potential. . At this time, electrons with various angles are also emitted. As a result, electrons having a large angular component are eventually extracted toward the gate.

As a result, when the circular gate is formed, the electron distribution obtained on the anode 166 in the figure has a substantially circular beam shape 167. That is, the shape of the obtained beam is closely related to the shape of the gate to be extracted and the distance from the emitter.

Considering the virtual shape of the gate, considering that the area surrounding the cone is reduced by making a notch in the gate from the shape surrounding the emitter, the direction in which electrons are extracted is gradually reduced from 360 degrees. I understand.

In the electron beam obtained on the anode
The maximum size Xd in the X direction (for example, the maximum reach distance from the center of the circular beam shape 167 in FIG. 16) is expressed in a form proportional to √ (Vf / Va) in a simple calculation, which is clear from this relationship. Thus, the beam diameter increases as Vf increases toward the positive potential side. Further, the electrons that are drawn out toward the gate and reach the gate electrode cause a current loss, which leads to an increase in power consumption.

Since the resolution of the image forming apparatus using the field emission type electron-emitting device is limited by the width of the electron beam reaching the anode, a problem arises in the conventional structure in which the electron beam spreads. In order to suppress the spread of the electron beam, the image forming apparatus using the cold cathode is
Some have a focusing electrode (giving an appropriate negative potential to the gate) for narrowing the electron beam between the gate and the anode, but the cold cathode, the gate electrode, and the focusing electrode need to be aligned. The method becomes complicated.

Up to now, the Spindt type FE type element has been described, but in the case where a carbon fiber is used for the convex emitter 165 in the element as shown in FIG. 16 (including an aggregate of fine carbon fibers). Is also the same.
This is also the case when the convex emitter is replaced with an apparently flat film-like emitter (including an aggregate of fine carbon fibers), and electrons are extracted in the direction of the gate electrode. In the case of a flat film-like emitter structure, the electric field tends to be stronger in the part closer to the gate electrode of the film-like emitter, and it is difficult to control the electron emission region. As described above, it is understood that the vertical FE structure in which the emitter is arranged in the hole formed in the gate electrode is disadvantageous for realizing a high-definition image forming apparatus.

On the other hand, in the lateral FE type as shown in FIG. 17, the direction of extraction of the electron beam is relatively uniform, so that the spread of the electron beam is smaller than in the Spindt type.
Further, according to the knowledge of the applicants, the emission voltage is lowered by using a material having a low emission voltage for the emitter, and the position of the emission point, the electric field applied between the emitter and the gate electrode, and the application between the emitter and the anode are applied. By adjusting the electric field, it is known that the electrons colliding with the gate electrode can be controlled and the spread of the electron beam can be reduced.

However, also in the lateral FE type, the shape of the electron beam is greatly influenced by the arrangement of the extraction electrode with respect to the cathode region. For example, a conventional horizontal FE as shown in Fig. 18
With the configuration of (Japanese Patent Laid-Open No. 8-77916 as an example), the electron beam extracted from the convex portion of the cathode by the peripheral extraction electrode spreads in the Y direction as well, and a high-definition image forming apparatus is provided. It is a problem when manufacturing.

The present invention has been made in order to solve the problems of the prior art, and an object thereof is to provide an electron-emitting device in which spread of an electron beam is suppressed, and high-definition display is possible. It is to realize an image forming apparatus.

[0019]

In order to solve the above-mentioned problems, the present invention has a pair of electrodes facing each other on a substrate with a gap therebetween, the pair of electrodes being relatively positive and negative. A first electrode and a second electrode to which a potential is applied,
The second electrode includes an electron emitting portion that emits electrons, and the width of the first electrode is larger than the width of the first electrode on the side facing the second electrode through the gap when viewed from above the substrate. The electron-emitting device is characterized in that the width of the electron-emitting portion on the side facing the first electrode via a gap is large.

It is preferable that the second electrode includes an electrode member provided on the substrate and an electron emitting member that is laminated on the electrode member and forms an electron emitting portion.

It is preferable that the electron emitting member is formed not only on the electrode member but also in a gap between the electrode member and the first electrode.

The electron emitting portion is preferably made of a material containing carbon as a main component.

The material containing carbon as a main component is preferably an aggregate of fibrous carbon.

The fibrous carbon is preferably made of any one of graphite nanofibers, carbon nanotubes and amorphous carbon, or a mixture thereof.

The material containing carbon as a main component preferably contains at least one selected from diamond, tetrahedral amorphous carbon, metal and semiconductor.

Further, according to the present invention, a plurality of any one of the electron-emitting devices are arranged in parallel and connected to each other, and at least one or more device lines are provided to face the device line. It can be configured as an electron source including an anode that accelerates the emitted electrons.

Wirings for driving the electron-emitting devices may be arranged in a matrix.

Further, according to the present invention, any one of the electron sources, an image forming member for forming an image by the electrons accelerated by the anode, and an electron emitting device emitting an electron in response to an input information signal. The image forming apparatus may include a driving device that controls the amount of electrons.

It is preferable that the image forming member includes a phosphor that emits fluorescence upon collision of electrons.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION (Principle of Operation of Electron-Emitting Element) Prior to detailed description of embodiments of the present invention, the principle of operation of the electron-emitting element of the present invention will be illustratively described in detail with reference to the drawings. .

FIG. 1 (a) is a plan view of the electron-emitting device of the present invention, FIG. 1 (b) is a sectional view taken along the line AA 'in FIG. 1 (a), and FIG.
Shows the BB 'cross section in FIG. 1 (a). As shown in the figure, the extraction electrode and the cathode electrode (the electrode that gives a negative potential to the extraction electrode) are arranged electrically independently on the insulating substrate, and the electron emission material is arranged on a part of the cathode electrode. There is. Here, the arrangement of the electron emission layer material on the cathode electrode is set so that L2> L1 when the width of the electron emission layer on the gate electrode side is L2 and the width of the extraction electrode on the electron emission layer side is L1. There is.

Such an element structure is installed in a vacuum apparatus as shown in FIG. 6, and the anode is placed at a height L4 from the substrate.
If an anode (hereinafter referred to as an anode) is provided and a positive voltage Vf at the extraction electrode is applied to the cathode electrode and a positive voltage Va at the anode is applied to the cathode electrode for driving, for example, equipotential lines 63 are as shown in the figure. In this case, the point where the electric field is most concentrated in the electron emission material is the XZ plan view (Fig. 2 (a)).
Seen in FIG. 2, the electron emission material shown in FIGS. 2A and 6 is located closest to the anode and on the anode side (E2A). When viewed from the YZ plan view (FIG. 2 (b)) from the side of the extraction electrode, the place where the electric field is concentrated is near the width L1 where the extraction electrode is formed, as shown in FIG. 2 (b). Therefore, in the electron-emitting material, the place where electron emission easily occurs is near the electric field concentration point.

First, referring to FIG. 2 (b), regarding an electric field in which electrons are taken out in the Y-axis direction (here, referred to as Y-direction electric field for convenience) and an electric field toward the anode (here, referred to as Z-direction electric field). Think When Vf is increased, electron emission starts from the region where electron emission easily occurs, and the electron emission region is expanded as Vf increases. The emission current density J at a certain point of the electron emission material is determined by the electric field E applied to the point and the work function φ, and according to the Fowler-Nordheim equation, the electric field E causes the emission current density J to change exponentially. The electric field E is Vf and the distance D from the extraction electrode,
It is determined by the electric field amplification factor β (due to the atomic level unevenness on the surface of the electron emission material and the macroscopic shape effect of the electron emission material such as the tip of the Spindt-type emitter), and between these, E = β There is a relationship of (Vf / D). If the work functions φ and β in the electron-emitting material used here are the same, the electron emission depends on the distance D from the extraction electrode.

In the device of the present invention, as shown in FIG. 1 (a), the width L2 of the formation region of the electron-emitting material is made wider than the width L1 of the extraction electrode, so that the YZ plane can be obtained as shown in FIG. , The equipotential surface bends in the formed electron-emitting material and causes distortion of the electric field in the Y direction. The distance between the end portion E or E'of the electron-emitting material and the extraction electrode is increased to weaken the electric field at that portion, and the end portion is weakened. Suppresses electron emission from the E or E'part. As shown in Fig. 2 (b), electron emission is caused only in the vicinity of the extraction electrode width L1 where there is no Y-direction electric field distortion in the YZ plan view, and the emission electron beam is prevented from spreading in the Y direction. You can do it. When L2 is narrower than L1 as shown in Fig. 3, or when L2 and L1 are approximately the same, electrons emitted from the edge of the electron-emitting material (region where the Y-direction electric field is distorted) are It will spread in the Y direction along with the distortion. In addition, since a macroscopic shape effect works at the edges of the electron emitting material and electrons are more easily emitted than in other regions, the influence of the electrons emitted from the edges on the electron beam shape cannot be ignored, which is not preferable. .

Next, referring to FIGS. 2 (a) and 6, an electric field for ejecting electrons in the X-axis direction, which is the direction of the extraction electrode (referred to as X-direction electric field), and an electric field directed to the anode (referred to as Z-direction electric field). think about.

The electrons emitted from the electron-emitting material are initially
After being extracted by the X-direction electric field and heading toward the extraction electrode, the Z-direction electric field pulls up and reaches the anode.

At this time, the intensity ratio between the X-direction electric field and the Z-direction electric field and the relative position of the electron emission point are important.

When the electric field in the X direction is stronger than the electric field in the Z direction by an order of magnitude, most of the extracted electrons have their orbits gradually bent by the radial potential formed by the electric field in the X direction, and head toward the extraction electrode. Take a trajectory. Electrons that collide with the extraction electrode are emitted again due to scattering, and while repeating the scattering while reducing the number of electrons by themselves, drawing an orbit similar to an ellipse and spreading over the gate until it is captured by the electric field in the Z direction. Becomes In the electron-emitting device of the present invention, by making the X-direction electric field and the Z-direction electric field to be approximately the same, although the orbit of the extracted electron is bent by the radial potential, the binding by the electric field becomes loose and the gate electrode becomes It is possible to make electron trajectories captured by the electric field in the Z direction appear without collision.

Further, when the X-direction electric field and the Z-direction electric field are almost the same, when the electron emission point position is raised from the plane to which the extraction electrode belongs to the plane side to which the anode belongs (as shown in FIG. 6), the emitted electrons are emitted. Without hitting the gate at all, Z
It is possible to draw a trajectory that can be captured by a directional electric field.

With the above effects, according to the electron-emitting device of the present invention, it is possible to reduce the spread of the electron beam.

(Embodiment) An electron-emitting device according to the present invention, which follows the above-described principle of operation, will be described in detail below with reference to the accompanying drawings. However, the dimensions, materials, shapes of the components described in this embodiment,
The relative arrangement and the like are not intended to limit the scope of the present invention thereto unless otherwise specified.

FIG. 1 (a) is a schematic view showing an example of an electron-emitting device according to the present invention, FIG. 1 (b) is a sectional view taken along the line AA ′ of FIG. 1 (a), and FIG. 1 (c) is a drawing.
FIG. 1B is a sectional view taken along line BB ′ of 1 (a). In the figure, 1 is an insulating substrate, 2 is a lead electrode (gate electrode) as a first electrode, 3 is a cathode electrode (second electrode and electrode member), 4
Indicates an electron emitting material (electron emitting portion and electron emitting member).

An example of a method of manufacturing an electron-emitting device of the present invention
Explain along line 4.

Quartz glass, the surface of which is thoroughly washed,
As the substrate 1, a substrate in which the content of impurities such as Na is reduced and partially replaced with K, soda lime glass, a laminated body in which SiO2 is laminated on a silicon substrate or the like by a sputtering method, or an insulating substrate of ceramics such as alumina is prepared. (Figure 4 (a)).

On top of that, the extraction electrode 2 and the cathode electrode 3
Are electrically divided and arranged at a certain distance d. The extraction electrode 2 and the cathode electrode 3 have conductivity, and are formed by a general vacuum film forming technique such as a vapor deposition method and a sputtering method, and a photolithography technique. The material of the device electrode is appropriately selected from, for example, carbon, metal, metal nitride, metal carbide, metal boride, semiconductor, and semiconductor metal compound. The thickness of the extraction electrode 2 and the cathode electrode 3 is set in the range of several tens of nm to several tens of μm, and is preferably a heat resistant material of carbon, metal, metal nitride, or metal carbide. In particular, when fibrous carbon is grown as the electron-emitting material, conductive silicon, for example, doped polysilicon is preferable.

When there is a fear of potential drop due to the thin electrode, or when this element is used in a matrix arrangement, a low resistance metal material for wiring does not participate in electron emission as necessary. Sometimes used in parts (Fig. 4 (b)).

Next, the electron emitting material 4 is placed on a part of the cathode electrode. The electron emission material 4 is formed by processing a film deposited by a general vacuum film forming method such as a sputtering method into a convex shape which is advantageous for electron emission using a method such as RIE, and a CVD method.
Thin film using nucleus growth in, and growth of needle crystals,
Growth of whiskers may be used. Convex shape control is performed in the case of RIE by using the type of substrate, type of gas,
It depends on gas pressure (flow rate), etching time, energy for forming plasma, and the like. On the other hand, in the formation method by CVD, the type of substrate, the type of gas, the flow rate, and the growth temperature are controlled. The electron emitting material is preferably W, T
Heat resistant materials such as a, Mo, etc., or TiC, ZrC, HfC, Ta
Carbides such as C, SiC, WC, HfB2, ZrB2, LaB6, CeB6, YB
4, boride such as GdB4, nitride such as TiN, ZrN, HfN, Si, Ge
Such as semiconductors, organic polymer materials, amorphous carbon,
Graphite, diamond-like carbon, carbon and carbon compounds in which diamond is dispersed, or fibrous carbon such as carbon nanotubes and graphite nanofibers are preferable (FIG. 4 (c)).

As described above, the distance d between the extraction electrode 2 and the cathode electrode 3 is determined by comparing the electric field between the electron emission electric field (X direction electric field) of the electron emission material used and the Z direction electric field necessary for image formation. The drive voltage Vf and the interval d may be determined so that the X-direction electric field is about 1 to 50 times the Z-direction electric field. When a phosphor is used for the anode, the required vertical electric field is limited to the range of 10 ^-1 V / μm to 10 V / μm. For example, when 8 kV is applied between the anode and the cathode at an interval of 2 mm, the vertical electric field at this time is 4 V / μm. in this case,
The electron emission electric field of the emitter material to be used is a material having an electron emission electric field larger than 4 V / μm, and its interval and driving voltage may be determined so as to correspond to the selected electron emission electric field. The width L1 of the extraction electrode in FIG. 1 is determined by the width of the region where electrons are desired to be emitted, and may be determined by the use of the device. The formation region L2 of the electron emitting material is determined in consideration of L1 so that the electron emission does not occur from the ends E and E ′ of the electron emitting material at Vf during driving.

As described above, from several V / μm to several tens V / μm
As a material having an electron emission electric field, a material containing carbon as a main component can be mentioned. An example of this is fibrous carbon formed by decomposing hydrocarbon gas using a catalyst as shown in Figs.
Shown in. In each figure, the optical microscope level (~ 1000
2)), the center is a scanning electron microscope (SEM) level (up to 30,000 times), and the right is a transmission electron microscope (T).
The morphology of carbon visible at the (EM) level (up to 1 million times) is schematically shown.

As shown in FIG. 11, graphene has a cylindrical shape (a cylinder having a multi-layered structure is called a multi-walled nanotube) is called a carbon nanotube, and a tube end is particularly open. At that time, the threshold value drops most.

Alternatively, FIG. 12 shows fibrous carbon produced at a relatively low temperature using a catalyst similar to carbon nanotubes. This form of fibrous carbon is composed of a graphene laminate (henceforth referred to as graphite nanofibers, but the proportion of the amorphous structure increases with temperature).

Carbon nanotubes and graphite nanofibers differ depending on the type of catalyst and the decomposition temperature, and in some cases it is possible to select substances having both structures with the same catalyst depending on the temperature, or only one structure is possible. It may not be. Both fibrous carbons have an electric field required for electron emission of about several V to several tens V / μm, and are preferable as the emitter material of the present invention.

As the catalyst material, Fe, Co, etc. are generally used in the formation of carbon nanotubes, but Pd,
Ni can also be used as a nucleus for carbon formation.

In the case of vapor phase growth by thermal decomposition,
With Pd and Ni, it is possible to form graphite nanofibers at low temperatures (450 ° C or higher). Fe,
The production temperature of carbon nanotubes using Co is 800 ℃
From the above requirements, the graphite nanofiber material can be produced using Pd and Ni at a low temperature, which is preferable from the viewpoint of the influence on other members and the manufacturing cost.

Further, in Pd, it is possible to use palladium oxide as a nucleating material by utilizing the property that the oxide is reduced by hydrogen at low temperature (room temperature).

When hydrogen reduction treatment of palladium oxide is performed,
The formation of initial agglomeration nuclei at relatively low temperatures (200 ° C or less) without using thermal agglomeration of metal thin films that have been conventionally used as a general nucleation technique or generation and vapor deposition of ultrafine particles that pose an explosion risk. Became possible.

As the above-mentioned hydrocarbon gas, for example, hydrocarbon gas such as ethylene, methane, propane and propylene, or vapor of an organic solvent such as ethanol and acetone may be used.

The electron-emitting device of the present invention produced as described above was placed in a vacuum apparatus as shown in FIG. 6, and was sufficiently evacuated by a vacuum evacuation apparatus 65 until it reached about 10 ⁻⁴ Pa. A high voltage power source was used to provide an anode 61 at a position with a height L4 of several millimeters from the substrate, and a high voltage Va of several kilovolts was applied. The anode
A phosphor 62 coated with a conductive film is installed at 61. A device voltage If and an electron emission current Ie flowing by applying a pulse voltage of about several tens of V as a driving voltage Vf to the electron emission device were measured.

At this time, the equipotential lines 63 are formed as shown in the figure, and the point where the electric field is most concentrated is the location E2A on the anode side closest to the extraction electrode of the electron emission material shown in FIGS. 6 and 2 (a). Of these, it is in the vicinity of the extraction electrode width L1 of the electron emission material shown in FIG. 2 (b). Electrons are preferentially emitted into the vacuum from the electron emitting material located around the electric field concentration point.

The Ie characteristic of this device was as shown in FIG. That is, Ie rapidly rises from about half of the applied voltage, and If (not shown) was similar to the characteristic of Ie, but its value was sufficiently smaller than that of Ie.

Based on this principle, an image forming apparatus obtained by arranging a plurality of electron-emitting devices to which the present invention can be applied will be described below with reference to FIG. In FIG. 8, 81 is an electron source substrate, 82 is an X-direction wiring, and 83 is a Y-direction wiring. 84 is the electron-emitting device of the present invention, and 85 is a wire connection.

The m X-direction wirings 82 are DX1, DX.
2 ,. ． It is made of 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 wiring material, film thickness, and width are appropriately designed.
The Y-direction wiring 83 includes DY1, DY2. ． It is composed of n DYn wirings and is formed similarly to the X-direction wirings 82. Between these m wirings in the X direction 82 and n wirings in the Y direction 83,
An interlayer insulating layer (not shown) is provided to electrically separate the two (m and n are both positive integers). The interlayer insulating layer (not shown) is composed of SiO2 or the like formed by using a vacuum deposition method, a printing method, a sputtering method, or the like. For example, X-direction wiring
It is formed in a desired shape on the entire surface or a part of the base body 81 on which the 82 is formed. In particular, the film thickness, material, and manufacturing method are set so as to withstand the potential difference at the intersection of the X-direction wiring 82 and the Y-direction wiring 83. It is set appropriately. The X-direction wiring 82 and the Y-direction wiring 83 are drawn out as external terminals.

The extraction electrode and the cathode electrode (not shown, hereinafter referred to as device electrode) constituting the electron-emitting device 84 are m X electrodes.
The direction wirings 82, the n Y-direction wirings 83, and the connecting wires 85 made of a conductive metal or the like are electrically connected. The material forming the wirings 82 and 83, the material forming the connection 85, and the material forming the element electrodes may be the same or different in some or all of the constituent elements. These materials are appropriately selected, for example, from the above-mentioned material of the device electrode. When the material forming the element electrode and the wiring material are the same, the wiring connected to the element electrode can also be referred to as an element electrode.

A scanning signal applying means (not shown) for applying a scanning signal for selecting a row of the electron-emitting devices 84 arranged in the X direction is connected to the X-direction wiring 82. On the other hand, the Y-direction wiring 83 is connected to a modulation signal generating means (not shown) for modulating each column of the electron-emitting devices 84 arranged in the Y-direction according to an input signal. The driving voltage applied to each electron-emitting device is supplied as a difference voltage between the scanning signal and the modulation signal applied to the device.

In the above structure, individual elements can be selected and driven independently by using simple matrix wiring.

An image forming apparatus constructed by using such an electron source having a simple matrix arrangement will be described with reference to FIG. FIG. 9 is a schematic view showing an example of a display panel of the image forming apparatus. In FIG. 9, 81 is an electron source substrate having a plurality of electron-emitting devices arranged therein, 91 is a rear plate to which the electron source substrate 81 is fixed, and 96 is It is a face plate in which a fluorescent film 94, a metal back 95 and the like are formed on the inner surface of a glass substrate 93. 92
Is a support frame, and a rear plate 91 and a face plate 96 are connected to the support frame 92 by using frit glass or the like. The envelope 97 is, for example, in the atmosphere, in a vacuum, or
It is sealed and formed by baking in nitrogen at a temperature range of 400 to 500 degrees for 10 minutes or more.

The envelope 97 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 base body 81, if the base body 81 itself has sufficient strength, the separate rear plate 91 can be omitted. That is, the base
Alternatively, the support frame 92 may be directly sealed to the 81, and the face plate 96, the support frame 92, and the base body 81 may constitute the envelope 97. On the other hand, by installing a support body (not shown) called a spacer between the face plate 96 and the rear plate 91,
The envelope 97 having sufficient strength against atmospheric pressure can also be configured.

[0068]

EXAMPLES Examples of the present invention will be described in detail below.

Example 1 FIG. 1 (a) shows the electron-emitting device manufactured according to this example as seen from above the device.
FIG. 1B shows a cross-sectional view taken along the line AA ′ of FIG. Figure 1 (c) is B in Figure 1 (a)
It is a sectional view between -B '. Hereinafter, the manufacturing process of the electron-emitting device of the present embodiment will be described in detail with reference to FIG.

(Step 1) A quartz substrate was used as the substrate 1, and after sufficiently washing, Ti and a thickness of 5 nm (not shown) were used as the extraction electrode 2 and the cathode electrode 3 by the sputtering method.
A 30 nm poly-Si (arsenic doped) was continuously deposited.

Next, in the photolithography process, a positive photoresist (AZ1500 / Clariant) was used to form a resist pattern.

Next, using the patterned photoresist as a mask, a poly-Si (arsenic-doped) layer and a Ti layer are CF ₄
Dry etching is performed using gas, and the distance between electrodes d = 1 μm
The extraction electrode 2 and the cathode electrode 3 were formed (FIG. 4 (a)).

(Step 2) Next, Al is formed as a sacrificial layer 44 on the entire surface by vacuum vapor deposition, and then a resist pattern 42 is formed using a positive photoresist in a photolithography step (FIG. 4 (b)). ).

(Step 3) Then, the patterned photoresist 42 is used as a mask to remove the sacrificial layer 41 in the region to be covered with the electron emission material by wet etching, and then the photoresist 42 is peeled off (FIG. 4 (c)). ).

(Step 4) Subsequently, a heat treatment using a hot filament was performed in a methane stream diluted with H2 to deposit a diamond thin film 44 as an electron emitting material on the entire surface (FIG. 4 (d)).

(Step 5) The unnecessary electron emitting material 44 is removed together with the sacrificial layer 41, and finally L1 = 50 μm and L2 = 120 in FIG.
μ, and an electron-emitting device with d = 1 μm in FIG. 4 was used (FIG. 4 (e)).

This device is installed in a vacuum device 60 as shown in FIG.
2 x 10 by the vacuum exhaust device 62 ^-FiveUntil reaching Pa
L4 = 2 mm from the element, as shown in Fig. 6, fully exhausted at
As the anode (anode) voltage to the remote anode (anode) 61,
Va = 8kV was applied. There is no electron flow to the anode at this point
After confirming that, a pulse with driving voltage Vf = 30V is applied to the device.
Measure the device current If and electron emission current Ie flowing by applying voltage.
I measured it. The If and Ie characteristics of the device are as shown in Fig. 7.
It was. That is, Ie rapidly increases from about half the applied voltage.
When Vf is 30 V, the required electron emission
The flow Ie was measured. On the other hand, If was similar to the characteristics of Ie
However, the value was smaller than Ie by one digit or more.

The obtained beam had a substantially rectangular shape which was elongated in the Y direction and short in the X direction.

(Example 2) As Example 2, an example of using an aggregate of fibrous carbon as an electron emitting material will be described. less than,
The manufacturing process of the electron-emitting device of this example will be described in detail with reference to FIG.

(Step 1) A quartz substrate was used as the substrate 1, and after sufficiently cleaning, Ti and thickness 3 with a thickness of 5 nm (not shown) were formed as the extraction electrode 2 and the cathode electrode 3 by the sputtering method.
0 nm poly-Si (arsenic doped) was continuously deposited.

Next, in the photolithography process, a positive photoresist (AZ1500 / Clariant) was used to form a resist pattern.

Next, using the patterned photoresist as a mask, the poly-Si (arsenic-doped) layer and the Ti layer are CF ₄
Dry etching is performed using gas and the distance between electrodes d = 5 μm
The extraction electrode 2 and the cathode electrode 3 were formed (FIG. 13 (a)).

(Step 2) Next, in a photolithography step, a resist pattern is formed using a positive photoresist.
131 was formed. The patterned photoresist 1
Using 31 as a mask, Pd was vapor-deposited by a sputtering method in a region to be covered with the electron emission material as a catalyst 132 for growing the electron emission material described later (FIG. 13 (b)).

(Step 3) After stripping the resist, 300 ° C. in air
Then, heat treatment was performed in order to form Pd as palladium oxide to a thickness of 10 nm (FIG. 13 (c)).

(Step 4) Next, after exhausting the atmosphere, a heat treatment was performed at 200 ° C. in a 2% hydrogen stream diluted with nitrogen. At this stage, fine particles 133 with a diameter of about 10 nm are formed on the device surface.
Was formed. The density of particles at this time is about 10 ¹¹ to 10 ¹² particles /
It was estimated to be cm ² (Fig. 13 (d)).

(Step 5) Subsequently, heat treatment was carried out at 500 ° C. for 30 minutes in a 50% ethylene stream diluted with H 2. Observing this with a scanning electron microscope, the Pd coating area has a diameter of 10 nm to 60 nm.
It was found that a large number of fibrous carbons 134, which were bent and extended into fibrous shapes, were formed to some extent. At this time, the thickness of the fibrous carbon 134 was about 1 μm (Fig. 13
(e)).

If and Ie were measured in the same manner as in Example 1. Although the distance d between the electrodes was increased as compared with Example 1, the voltage Vf required for driving decreased.

The electric field and emission current required for electron emission could be changed by changing the growth conditions. In particular, the average particle size of Pd formed by reduction treatment of palladium oxide is related to the diameter of the fiber formed in the subsequent growth.

When the carbon fiber of this device was observed by a transmission electron microscope, it was found that graphene had a structure in which it was laminated as shown in the right side of FIG.

(Embodiment 3) A sectional view of an electron-emitting device according to Embodiment 3 is shown in FIG. The plan view of the device of this example is shown in FIG.
Same as (a). In this example, an electron-emitting device was manufactured in the same manner as in Example 1 except that the thickness of the cathode electrode 3 in Example 1 was 500 nm, and If and Ie were measured.

According to this element structure, by thickening the cathode electrode, no electron emission occurs from a position corresponding to at least the thickness of the cathode electrode, so that the electron emission position is surely higher than the gate electrode ( Could be the anode side). With this configuration, the number of trajectories of electrons colliding with the gate is reduced, and it is possible to prevent the phenomenon that the efficiency is lowered and the beam diameter is increased.

(Embodiment 4) A sectional view of an electron-emitting device according to Embodiment 4 is shown in FIG. The plan view of the device of this example is shown in FIG.
Same as (a). In this embodiment, the electron emitting material is formed from the cathode electrode 3 to almost the middle position between the gate electrode 2 and the cathode electrode 3.

In this embodiment, the manufacturing method is almost the same as that of the second embodiment, and the only difference from the second embodiment is that the shape of the resist pattern in step 2 is changed. The process is the same as in Example 2 except that Pd, which serves as a catalyst, is formed from the cathode electrode to the quartz substrate.

In this device, the distance between the electrodes is larger than that in the second embodiment.
Since d is small, the electric field between the extraction electrode and the electron emission material is about 2
About twice as strong. Therefore, the driving voltage can be reduced.

Example 5 An image forming apparatus obtained by arranging a plurality of electron-emitting devices to which the present invention can be applied is shown in FIG.
This will be described using 8, 9, and 10. In FIG. 8, 81 is an electron source substrate, 82 is an X-direction wiring, and 83 is a Y-direction wiring. Reference numeral 84 is an electron-emitting device of the present invention, and 85 is a wire connection.

When the capacitance of the element increases due to the arrangement of a plurality of elements, in the matrix wiring shown in FIG. 8, even if a short pulse accompanying the pulse width modulation is applied, the waveform is blunted by the capacitance component, and the expected gradation cannot be obtained. Such problems occur. For this reason, in the present embodiment, as shown in the first embodiment, an interlayer insulating layer is provided immediately next to the electron emitting portion to adopt a structure in which an increase in the capacitive component other than the electron emitting portion is reduced.

In FIG. 8, m wirings in the X direction 82 are DX ₁ ,
DX ₂ ,. ． It is made of DX _m and is made of an aluminum-based wiring material having a thickness of about 1 μm and a width of 300 μm formed by a vapor deposition method. The wiring material, film thickness, and width are appropriately designed.
The Y-direction wiring 83 has a thickness of 0.5 μm, a width of 100 μm, DY ₁ , D
Y ₂ . ． It is composed of _n wirings of DY _n and is formed similarly to the X-direction wiring 82. These m X-direction wires 82 and n Y wires
An interlayer insulating layer (not shown) is provided between the directional wiring 83 and the directional wiring 83 to electrically separate the two (m and n are both positive integers).

The interlayer insulating layer (not shown) was made of SiO ₂ with a thickness of about 0.8 μm by using the sputtering method or the like. X-direction wiring 82
In this embodiment, in order to withstand the potential difference at the intersection of the X-direction wiring 82 and the Y-direction wiring 83, it is formed in a desired shape on the entire surface or a part of the base body 81 on which the elements are formed. The thickness of the interlayer insulating layer was determined so that the capacitance was 1 pF or less and the device breakdown voltage was 30V. The X-direction wiring 82 and the Y-direction wiring 83 are
Each is pulled out as an external terminal.

The pair of electrodes (not shown) constituting the emitting element 84 of the present invention are m X-direction wirings 82 and n Y-direction wirings.
It is electrically connected to 83 by a connecting wire 85 made of a conductive metal or the like.

A scanning signal applying means (not shown) for applying a scanning signal for selecting the row of the electron-emitting devices 84 of the present invention arranged in the X direction is connected to the X-direction wiring 82. On the other hand, the Y-direction wiring 83 is connected to a modulation signal generating means (not shown) for modulating each column of the electron-emitting devices 84 of the present invention arranged in the Y-direction according to an input signal. The driving voltage applied to each electron-emitting device is supplied as a difference voltage between the scanning signal and the modulation signal applied to the device. In the present invention, the Y-direction wiring is connected to have a high potential and the X-direction wiring is connected to have a low potential.

In the above structure, individual elements can be selected and driven independently by using simple matrix wiring.

An image forming apparatus constructed by using such an electron source having a simple matrix arrangement will be described with reference to FIG. FIG. 9 is a diagram showing a display panel of an image forming apparatus using soda lime glass as a glass substrate material.

In FIG. 9, 81 is an electron source substrate having a plurality of electron-emitting devices, 91 is a rear plate to which the electron source substrate 81 is fixed, and 96 is a glass substrate 93 on which a fluorescent film 94 and a metal back 95 are formed. Face plate. Reference numeral 92 is a support frame, and the rear plate 91 and the face plate 96 are connected to the support frame 92 by using frit glass or the like. 98 is an envelope, in vacuum, in the temperature range of 450 degrees 1
By firing for 0 minutes, it is sealed and configured.

Reference numeral 84 corresponds to the electron emitting portion in FIG. Reference numerals 82 and 83 denote an X-direction wiring and a Y-direction wiring connected to the pair of device electrodes of the electron-emitting device of the present invention.

The envelope 97 is composed of the face plate 96, the support frame 92, and the rear plate 91 as described above. on the other hand,
By installing a support (not shown) called a spacer between the face plate 96 and the rear plate 91, the envelope 98 having sufficient strength against atmospheric pressure was constructed.

The metal back is produced by producing a fluorescent film, smoothing the inner surface of the fluorescent film (usually called “filming”), and then depositing Al using vacuum deposition or the like. Was given.

A transparent electrode (not shown) is provided on the face plate 96 on the outer surface side of the fluorescent film 94 in order to further increase the conductivity of the fluorescent film 94.

When the above-mentioned sealing is performed, in the case of color, it is necessary to associate each color phosphor with the electron-emitting device.
Sufficient alignment is essential.

In this embodiment, since the electron emission from the electron source is emitted to the gate electrode side, when the anode voltage is 8 kV and the distance between the anodes is 2 mm, it is 200 μm, and the phosphor corresponding to the position deviated to the gate side. Was placed.

The drive device of the image forming apparatus of the present invention will be described with reference to FIG.

The scanning circuit 102 will be described. The circuit has M switching elements inside (indicated by S1 to Sm in the figure). Each switching element is the output voltage of the DC voltage source Vx or 0 [V]
One of (ground level) is selected and electrically connected to the terminals Dx1 to Dxm of the display panel 101. Each of the switching elements S1 to Sm operates based on the control signal Tscan output from the control circuit 103, and is, for example, F
It can be configured by combining switching elements such as ET.

In the case of the present example, the direct-current voltage source Vx has a driving voltage applied to an unscanned element based on the characteristics (electron emission threshold voltage) of the electron-electron emitting element of the present invention, and the electron emission threshold is It is set to output a constant voltage that is less than or equal to the value voltage.

The control circuit 103 has a function of matching the operation of each unit so that an appropriate display is performed based on an image signal input from the outside. The control circuit 103 generates control signals Tscan, Tsft, and Tmry for each unit based on the synchronization signal Tsync sent from the synchronization signal separation circuit 106.

The sync signal separation circuit 106 is a circuit for separating the sync signal component and the luminance signal component from the NTSC system television signal input from the outside, and uses a general frequency separation (filter) circuit or the like. Can be configured. The sync signal separated by the sync signal separation circuit 106 is composed of a vertical sync signal and a horizontal sync signal, but is illustrated here as a Tsync signal for convenience of description. The luminance signal component of the image separated from the television signal is represented as a DATA signal for convenience. The DATA signal is input to the shift register 104.

The shift register 104 is for serially / parallel-converting the DATA signal serially input in time series for each line of the image.
It operates based on the control signal Tsft sent from 103 (that is, it can be said that the control signal Tsft is the shift clock of the shift register 104). The serial / parallel converted image data for one line (corresponding to drive data for N electron emission elements) is output from the shift register 104 as N parallel signals Id1 to Idn.

The line memory 105 is a storage device for storing data for one line of the image only for a required time, and stores the contents of Id1 to Idn as appropriate in accordance with the control signal Tmry sent from the control circuit 113. The stored contents are I'd1 through
It is output as I'dn and input to the modulation signal generator 107.

The modulation signal generator 107 is a signal source for appropriately driving and modulating each of the electron electron-emitting devices of the present invention according to each of the image data I'd1 to I'dn, and its output signal is , Terminals Doy1 to Doyn are applied to the electron-electron emitting device of the present invention in the display panel 111.

As described above, the electron-emitting device to which the present invention can be applied has the following basic characteristics with respect to the emission current Ie. That is, the electron emission has a clear threshold voltage Vth, and the electron emission occurs only when a voltage higher than Vth is applied. For a voltage equal to or higher than the electron emission threshold value, the emission current also changes according to the change in the voltage applied to the device. Therefore, when a pulsed voltage is applied to this element, for example, electron emission does not occur even if a voltage below the electron emission threshold is applied, but when a voltage above the electron emission threshold is applied, an electron beam is emitted. Is output. At that time, the intensity of the output electron beam can be controlled by changing the peak value Vm of the pulse. Further, it is possible to control the total amount of charges of the electron beam output by changing the pulse width Pw.

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 adopted. When carrying out the voltage modulation method, as the modulation signal generator 107, a voltage modulation method circuit that generates a voltage pulse of a fixed length and appropriately modulates the peak value of the pulse according to the input data is used. be able to.

When implementing the pulse width modulation method,
As the modulation signal generator 107, it is possible to use a circuit of a pulse width modulation system that generates a voltage pulse having a constant peak value and appropriately modulates the width of the voltage pulse according to input data.

The shift register 104 and the line memory 105 are
A digital signal system was used.

In the present embodiment, the modulation signal generator 107 includes
For example, a D / A conversion circuit is used, and an amplification circuit or the like is added if necessary. In the case of the pulse width modulation method, the modulation signal generator 107 includes, for example, a high-speed oscillator and 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. A circuit combining (comparator) was used.

The configuration of the image forming apparatus described here is an example of the 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 method was mentioned, but the input signal is not limited to this, other than PAL, SECAM method, etc.
A TV signal (for example, high-definition TV such as MUSE method) system including a large number of scanning lines can also be adopted.

[0124]

As described above, by using the electron-emitting device according to the present invention, an electron source in which the spread of the electron beam is suppressed can be obtained. Further, since the image forming apparatus is composed of the electron source and forms an image based on an input signal, a higher definition image forming apparatus, for example, a color flat television can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a basic electron-emitting device according to the present invention.

FIG. 2 is a diagram showing how electrons are emitted from an electron-emitting device of the present invention.

FIG. 3 is a diagram showing an electron-emitting device for comparison with the electron-emitting device of the present invention.

FIG. 4 is a drawing for explaining the manufacturing process of the electron-emitting device according to the first embodiment of the present invention.

FIG. 5 is a diagram for explaining a basic manufacturing process according to the present invention.

FIG. 6 is a diagram showing a configuration example when operating an electron-emitting device according to the present invention.

FIG. 7 is a diagram showing an example of operating characteristics of a basic electron-emitting device according to the present invention.

FIG. 8 shows a configuration example of a simple matrix circuit using a plurality of electron sources according to the present invention.

FIG. 9 shows a configuration example of an image forming panel using an electron source according to the present invention.

FIG. 10 shows a circuit example of an image forming panel using an electron source according to the present invention.

FIG. 11 is a schematic diagram showing the structure of carbon nanotubes.

FIG. 12 shows a schematic diagram showing the structure of graphite nanofibers.

FIG. 13 is a drawing for explaining the manufacturing process of the electron-emitting device according to the second embodiment of the present invention.

FIG. 14 is a diagram showing an electron-emitting device according to a third embodiment of the present invention.

FIG. 15 is a diagram showing an electron-emitting device according to a fourth embodiment of the present invention.

FIG. 16 is a diagram showing a conventional FE electron-emitting device.

FIG. 17 is a diagram showing a conventional FE electron-emitting device.

FIG. 18 is a diagram showing a conventional FE electron-emitting device.

[Explanation of symbols]

1 substrate 2 Extraction electrode (gate electrode) 3 cathode electrode 4 Electron emission material 61 Anode 81 Electron source substrate 82 X-direction wiring 83 Y direction wiring 84 Electron-emitting device (electron-emitting portion) 94 Fluorescent film 102 scanning circuit 103 control circuit 107 Modulation signal generator

Claims (11)

[Claims] 1. A pair of electrodes facing each other with a gap interposed on a substrate, wherein the pair of electrodes includes a first electrode and a second electrode to which a positive potential and a negative potential are relatively applied, respectively. The second electrode includes an electron emitting portion that emits electrons, and the width of the first electrode on the side facing the second electrode through the gap when viewed from above the substrate is larger than the width of the first electrode. An electron-emitting device characterized in that the width of the electron-emitting portion on the side facing the first electrode via the gap is large. 2. The second electrode includes an electrode member provided on a substrate, and an electron emitting member that is stacked on the electrode member and forms an electron emitting portion. 1. The electron-emitting device according to item 1. 3. The electron emission member according to claim 2, wherein the electron emission member is formed not only on the electrode member but also in a gap between the electrode member and the first electrode. element. 4. The electron emission portion is made of a material containing carbon as a main component.
An electron-emitting device according to any one of 1. 5. The electron-emitting device according to claim 4, wherein the material containing carbon as a main component is an aggregate of fibrous carbon. 6. The electron emitting device according to claim 5, wherein the fibrous carbon is made of any one of graphite nanofibers, carbon nanotubes and amorphous carbon, or a mixture thereof. 7. The electron emission according to claim 4, wherein the material containing carbon as a main component includes at least one selected from diamond, tetrahedral amorphous carbon, metal and semiconductor. element. 8. At least one of the electron-emitting devices according to claim 1 arranged in parallel and connected.
An electron source comprising: a plurality of rows of elements, and an anode provided to face the rows of elements and accelerating electrons emitted from the electron-emitting devices. 9. The electron source according to claim 8, wherein wirings for driving the electron-emitting devices are arranged in a matrix. 10. The electron source according to claim 8 or 9, an image forming member that forms an image by the electrons accelerated by the anode, and the electron emitting device emits the electron according to an input information signal. An image forming apparatus including: a drive device that controls the amount of electrons. 11. The image forming member includes a phosphor that emits fluorescence upon collision of electrons.
The image forming apparatus according to item 0.