JP2001167694A - Electron emission element, electron source and image forming device and method of fabricating the electron emission element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron emission element, realizing an improvement in electron orbit binding and electron emission efficiency and also realizing in an inhibition of a potential drop of an upper electrode. SOLUTION: The electron emission element includes a convex structure, which has an insulating layer 3 on a substrate 1 and a high potential electrode 4 extended from the upper surface portion to the sidewall of the insulating layer 3; a low potential electrode 2; and paired electron emission portions 5a and 5b formed on the sidewall of the convex structure while intervening a gap G therebetween. The high potential electrode 4 has a buried electrode 4b having a more thick thickness than that of an upper electrode 4b on the sidewall of the convex structure.

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 display device using the same, and a method of manufacturing the electron-emitting device.

[0002]

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

As an example of the FE type, W. P. Dyke &
W. W. Dolan, "FieldEmission",
Advance in Electron Physi
cs, 8, 89 (1956) or C.I. A. Spin
dt, PHYSICAL PROperties of
thin-film field emission
cathodes with molebdenium
cones ", J. Appl. Phys., 47, 5
248 (1976) and the like are known.

As an example of the MIM type, C.I. A. Mead,
“Operation of Tunnel-Emis
sion 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.

An example of the surface conduction type is disclosed in JP-A-8-26.
No. 4,112, JP-A-3-20941, JP-A-9-82214, JP-A-7-235256, and the like.

[0007]

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

Therefore, in such an electron-emitting device, it is necessary to control the trajectory of electrons more precisely to obtain a higher-definition beam, and to prevent a decrease in efficiency related to trajectory control in technical development. Has become an issue.

As a conventional technique for obtaining a high-definition beam diameter, for example, Japanese Patent Application Laid-Open No.
No. 714, an electron emission electrode,
In addition to the electron extraction electrode, an electrode for converging electrons is arranged above the emission section to converge the electron trajectory, or as disclosed in Japanese Patent Application Laid-Open No. 9-63461, the converging electrode is used to emit electrons. Although a structure or the like arranged on the same plane as the part has been proposed, there have been problems with the complexity of the manufacturing method, an increase in the element area, a decrease in the electron emission efficiency described later, and the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to realize convergence of electron orbits and improvement of electron emission efficiency. An object of the present invention is to provide an electron-emitting device that can suppress a voltage drop of an electrode. Another object of the present invention is to provide an electron source and an image forming apparatus using the electron-emitting device.

[0011]

In order to achieve the above object, according to the present invention, there is provided an insulating layer and a first layer disposed on the substrate so as to reach the side wall from the upper surface of the insulating layer. A convex structure portion having a first electrode and a second electrode, and disposed on the side wall portion of the convex structure portion so as to form a pair so as to form a pair, and the first electrode or the second electrode is respectively provided. An electron-emitting device comprising an electron-emitting portion connected to an electrode, wherein the first
Wherein the electrode has a portion having a thickness greater than the thickness of the side wall of the convex structure.

[0012] It is also preferable that the thick portion of the first electrode is buried in the insulating layer.

When the width of the gap between the pair of electron emitting portions is D, and the distance between the upper and lower ends of the electron emitting portion on the side wall of the convex structure of the first electrode is T1, T1 < 20
0D is also suitable.

An anode is provided above the first electrode for capturing electrons. The width of the first electrode is W, the distance from the upper surface of the substrate to the anode is H, and the first electrode and the first electrode are connected to each other. 2
When the applied voltage between the electrodes is Vf and the applied voltage between the second electrode and the anode is Va, the width W becomes HVf /
It is also preferable that the ratio is set to be equal to or more than 1/2 times and equal to or less than 15 times of (circumference π × Va).

It is also preferable that there is no overlapping portion between the first electrode and the second electrode when viewed from vertically above the plane of the substrate.

In the electron source, a plurality of the above-described electron-emitting devices are arranged on a substrate.

An image forming apparatus has the above-described electron source and a phosphor, and forms an image by irradiating the emitted phosphor from the electron source to the opposing phosphor. And

In addition, a convex structure having an insulating layer, a first electrode disposed so as to reach a side wall from an upper surface of the insulating layer, and a second electrode is provided on the substrate; On the side wall portion of the convex structure portion, arranged with a gap so as to form a pair,
A method of manufacturing an electron-emitting device having an electron-emitting portion connected to the first electrode or the second electrode, wherein a step of forming a recess separated from the second electrode by the insulating layer; Forming a buried electrode to be a portion having a large thickness of the first electrode; and forming an upper electrode of the first electrode reaching the side wall of the insulating layer on the insulating layer and the buried electrode. Forming a film.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the characteristic structure and operation of the present invention, a description will be given of a technique which is a premise of an electron-emitting device having a convex structure and a movement of electrons.

When an anode is formed at a distance H above an electron-emitting device composed of a pair of electrodes facing each other with a gap on the order of nm, an electrode to which a high potential is applied is selected from the pair of electrodes. In a configuration in which the potential difference between the electrodes to which the low potential is applied is Vf and the voltage Va applied between the low potential electrode and the anode is applied, the SID 98Dig
est, Okuda, et. al (p185 to p18
According to 8), when Vf is applied to this element, electrons are emitted from the tip of the low potential electrode toward the opposite high potential electrode, and the electrons are isotropically scattered at the tip of the high potential electrode. I have.

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

Here, Xs is substantially equal to HVf / (πVa), for example, Va = 10 (KV), Vf = 15 (V),
When H = 2 (mm), it is about 1 μm.

The efficiency is such that the electrons due to multiple scattering have the characteristic distance Xs
In the meantime, the number of electrons is governed by a decrease in the number of electrons due to partial absorption by the high potential electrode due to multiple scattering.

It is estimated that the ratio β which is scattered by the electron scattering of about several tens eV (although there is a part which is not clear) is about 0.1 to 0.5 each time.

Since β is equal to or less than 1 in such a scattering mechanism, it can be seen that the amount of electrons taken out in vacuum decreases by a power.

Thereafter, the electrons extracted in a vacuum reach the anode along a trajectory affected by the potential formed between the anode and the element.

According to the present invention, not only the number of times of the scattering of electrons to the high potential electrode (the first electrode) due to the scattering (the number of times of drop) is reduced, but also the emitted electrons reflect the arrangement and the potential of the electrodes. The convergence effect of changing the trajectory under the influence of the applied potential distribution has been earnestly studied so as to be realized with a simple configuration so as to reach the anode.

From the above, in order to prevent a decrease in the number of electrons due to multiple scattering, that is, to prevent a decrease in efficiency, the distance from the gap position to the upper portion of the high potential electrode (first electrode) should be as small as possible. With this configuration, it is possible to prevent a decrease in the number of electrons due to multiple scattering. Therefore, it is possible to prevent a decrease in efficiency by configuring the high-potential electrode as thin as possible and making the gap position as close as possible to the high-potential electrode.

However, a high-potential electrode (first electrode)
If the film thickness is too thin, the electric resistance increases, and when a drive voltage is applied, a greater voltage drop occurs farther from the power supply, so that the characteristics of electron emission may vary from place to place. In the present invention, the thickness of the high-potential electrode on the side wall portion having the gap is reduced to prevent a decrease in the number of electrons due to multiple scattering, and the thickness of the high-potential electrode other than the side wall portion having the gap is increased. As a result, it is possible to suppress an increase in the electric resistance and suppress a variation in the characteristic of electron emission depending on a place.

The characteristic structure of the present invention will be described below with reference to the drawings.

First, the configuration of an example of the electron-emitting device 101 of the present invention will be described with reference to the drawings. FIG. 1A is an explanatory view of a cross-sectional configuration of an electron-emitting device 101 of the present invention, and FIG.
Is a top view. In FIG. 1, reference numeral 1 denotes a substrate, 2 denotes a low-potential electrode (second electrode), 3 denotes an insulating layer, 4 denotes a high-potential electrode (first electrode), and 4a denotes an end of the high-potential electrode 4. The upper electrode 4b, which is a part, is a buried electrode that is buried in the insulating layer 3 and is a part of the base side of the high-potential electrode 4 that is a part having a large thickness.

Reference numeral 5a denotes an electron emission portion electrically connected to the upper electrode 4a, and 5b denotes an electron emission portion electrically connected to the low potential electrode 2.

As shown in FIG. 1B, the width of the upper electrode 4a of the high-potential electrode 4 is W, the length is L1, and the length of the electron-emitting portions 5a and 5b is L2. Next, a case where the electron-emitting device 101 of the present invention is provided with an anode for capturing electrons in the upper part in a vacuum vessel will be described with reference to FIG.

In FIG. 2, 21 is an anode, 22 is a vacuum vessel, Vf is a voltage applied between the high-potential electrode 4 and the low-potential electrode 2, If is a device current flowing at this time, and Va is a voltage applied to the low-potential electrode 2. The voltage applied between the anode 21 and Ie is an electron emission current. H is the distance between the low potential electrode 2 and the anode 21.

FIG. 3 is an enlarged view of an electron emitting portion (S1 portion in FIG. 2) in such an arrangement. 3, D is the distance of the gap G between the high-potential electrode 4 and the low-potential electrode 2, and T1 is the distance between the top and bottom of the side wall 5a1 of the high-potential region HET including the upper electrode 4a of the high-potential electrode 4. is there.

Here, the high potential electrode 4 refers to the upper electrode 4a,
All the electrodes including the buried electrode 4b and the electron emission portion 5a electrically connected to the high potential side, that is, the high potential region HET, and the low potential region LET is similarly connected to the low potential electrode 2 and the electron emission portion. Means all electrodes including the portion 5b (hereinafter, the high potential electrode 4 is used as the upper electrode 4a itself or the high potential region HET, and the low potential electrode 2 is used as the low potential electrode 2 itself or the low potential electrode, as appropriate. Used in the meaning of the area LET).

When Vf is applied to this element, electrons 31 are emitted from the tip of the low potential electrode 2 (the tip of the electron emitting portion 5b) to the opposing high potential electrode 4 (the lower end of the electron emitting portion 5a) in FIG. The electrons are isotropically scattered again at the tip of the high potential electrode 4. As described above, many of the electrons 32 emitted from the high-potential electrode 4 are repeatedly subjected to elastic scattering (multiple scattering) several times by the high-potential electrode 4 (electron emitting portion 5a).

At this time, the high-potential region H including the high-potential electrode 4
By configuring the distance T1 between the upper and lower ends of the side wall 5a1 of the ET such that the characteristic distance Xs is as small as possible, it is possible to prevent a decrease in the number of electrons due to multiple scattering.

Here, the flying distance of the scattered electrons is estimated to be at most 200 times the width D of the gap G. Therefore, in order to suppress the scattering of electrons, at least T1 <2
00D is required. Since D is several nm, it is necessary to set at least Tl <1 μm in the case of 5 nm.

As described above, by making the upper electrode 4a of the high-potential electrode 4 as thin as possible, it is possible to prevent the efficiency from decreasing as much as possible.

However, if the film thickness of the upper electrode 4a is too thin, the electric resistance increases, and when a drive voltage is applied, a greater voltage drop occurs farther from the power supply (voltage application unit). The thickness of the upper electrode 4a at the position corresponding to the portion 5a1 is reduced, and as shown in FIG. 1B, a buried electrode 4b serving as a portion having a large film thickness is formed to suppress an increase in electric resistance. By forming a part of the upper electrode 4a, a decrease in the number of electrons due to multiple scattering can be prevented, an increase in electric resistance can be suppressed, and a variation in electron emission characteristics depending on the location can be suppressed.

As shown in FIG. 1 (b), the high potential electrode 4 and the low potential electrode 2 have a structure in which there is no overlap when viewed from above. There are advantages of high withstand voltage and small capacitance.

When the insulating layer is SiO ₂ , the breakdown voltage is 10 ⁶ V
/ Cm, the driving voltage can be secured by embedding the buried electrode 4b of the high-potential electrode 4 in the insulating layer 3 so that both electrodes are separated by 150 nm or more when driven at 15V.

With the configuration shown in FIGS. 2 and 3, a characteristic potential distribution mainly related to convergence is formed according to the width W and H, Vf, Va of the upper electrode 4a. The electrons are affected by this potential and their orbits (emitted electrons 3
2) is changed to reach the anode 21.

According to the electron-emitting device 101 of the present invention, the convergence of the beam largely changes because of the beam diameter Dx in the X direction.
And the beam diameter Dy in the Y direction does not change much. This is because the electron-emitting device 101 has a linear shape extending in the Y direction. Therefore, a potential for bending the electron trajectory is formed in the X direction, but no bending potential is formed in the Y direction. This is because the same potential is formed even when the current is cut off.

The condition that the beam diameter of the electrons reaching the anode 21 is reduced is such that the width W of the upper electrode 4a is obtained by performing a numerical calculation of the potential using Vf, Va, and H as parameters.

From the relationship between the width W of the upper electrode 4a and the beam diameter and efficiency shown in FIG.
A small beam diameter and high efficiency can be achieved when having a size of 以上 to 15 times s.

Hereinafter, an example of an embodiment of the electron-emitting device 101 according to the present invention will be described.

In FIG. 1, the insulating substrate 1 includes:
Quartz glass, whose surface has been sufficiently cleaned, reduced the content of impurities such as Na, and partially substituted with K, etc., blue plate glass, silicon substrate, etc., by sputtering or the like.
Examples include a laminate in which O ₂ is laminated, and an insulating substrate made of ceramics such as alumina.

The low potential electrode 2 has conductivity, and is formed by a general vacuum film forming technique such as a vapor deposition method and a sputtering method, and a photolithography technique. The material is, for example, B
e, Mg, Ti, Zr, Hf, V, Nb, Ta, Mo,
It is appropriately selected from metals or alloy materials such as W, Al, Cu, Ni, Cr, Au, Pt, and Pd. The thickness of the low potential electrode 2 is set in a range from several tens of nm to several mm.

The insulating layer 3 is formed by a general vacuum film forming method such as a sputtering method, a thermal oxidation method, an anodic oxidation method or the like, and its thickness is set in a range from several nm to several tens μm. Preferably, it is selected from the range of several tens nm to several μm. Desirable materials include SiO ₂ , SiN, Al ₂ O ₃ , Ca
It is desirable to use a material having a high withstand voltage that can be cut off by a high electric field, such as F.

The upper electrode 4a of the high-potential electrode 4 and the buried electrode 4b are appropriately selected from the same candidates as those of the low-potential electrode 2, and may be the same material as the low-potential electrode 2 or a different material. The upper electrode 4a and the buried electrode 4b of the high potential electrode 4 may be made of the same material or different materials.

The upper electrode 4a of the high-potential electrode is preferably made of a heat-resistant material because electrons collide and cause an impact, and the thickness is preferably as thin as described above. The thickness is several nm.

The buried electrode 4b is set in the range of several nm to several μm, and is preferably a low-resistance metal material for wiring.

The electron emitting portions 5a and 5b may be formed by a general vacuum film forming method such as a sputtering method, a thermal oxidation method, an anodic oxidation method, or the like, or may be formed by the above-described activation.

In the former case, the same material as the material of the low potential electrode 2 or a different material may be used. Preferably, W, Ta, Mo,
Heat-resistant materials such as TiC, ZrC, HfC,
Carbides such as TaC, SiC and WC, HfB ₂ , ZrB ₂ ,
Borides such as LaB ₆ , CeB ₆ , YB ₄ and GdB ₄ , Ti
Nitride such as N, ZrN, HfN, etc., semiconductors such as Si, Ge, etc., organic polymer materials, amorphous carbon, graphite, diamond-like carbon, carbon and carbon compounds in which diamond is dispersed, and the like are preferable.

On the other hand, the latter case is formed by a step called an activation step. Prior to this step, the above-described forming step is generally used.

In this step, carbon and a carbon compound are formed as the electron emission portions 5a and 5b. Carbon and carbon compounds include, for example, graphite (so-called HOP
HOPG including G ′, PG (GC) has a crystal structure of almost perfect graphite, PG has a crystal grain of about 20 nm and has a slightly disordered crystal structure, and GC has a crystal grain of about 2 nm and has a crystal structure of about 2 nm. Refers to things that have become even more disruptive. ), Amorphous carbon (refers to amorphous carbon and a mixture of amorphous carbon and the aforementioned microcrystals of graphite)
The thickness is preferably in the range of 50 nm or less, more preferably in the range of 30 nm or less.

An application example of the electron-emitting device 101 to which the present invention can be applied will be described below. By arranging a plurality of electron-emitting devices 101 to which the present invention can be applied on a substrate, for example, an electron source or an image forming apparatus can be configured.

Hereinafter, an electron source substrate in which a plurality of electron-emitting devices to which the present invention is applied is arranged on a substrate will be described with reference to FIG. In FIG. 5, reference numeral 51 denotes an electron source base, 52 denotes an X-direction wiring, and 53 denotes a Y-direction wiring. Reference numeral denotes an electron-emitting device to which the present invention is applied (having the same configuration as the electron-emitting device 101), and reference numeral 55 denotes a connection.

When the capacitance of the elements increases due to the arrangement of a plurality of elements, when a short pulse accompanying the pulse width modulation is applied to the matrix wiring shown in FIG. There are problems such as inability to remove.

For this reason, as shown in FIG. 6, a thick interlayer insulating layer 61 is arranged immediately on the side of the electron-emitting device 54 to reduce an increase in capacitance component other than the electron-emitting portion (electron-emitting device 54). Adopted structure. Reference numeral 62 denotes an upper wiring connected to the upper electrode 4a. FIG. 6A is a top view, and FIG. 6B is a cross-sectional configuration diagram.

In FIG. 5, m X-direction wirings 52 are DX
, DX2,... DXm, and is formed 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 material, thickness, and width of the wiring are appropriately designed.

The Y-direction wiring 53 has a thickness of 0.5 μm and a width of 10 μm.
... DYn, and are formed in the same manner as the X-direction wiring 52. Between these m X-directional wirings 52 and n Y-directional wirings 53,
An interlayer insulating layer (not shown) having a thickness of about 1 μm is provided.
Both are electrically separated (m and n are both positive integers).

An interlayer insulating layer (not shown) is an insulating layer formed by using a sputtering method or the like. For example, the X-direction wiring 52
Are formed in a desired shape on the entire surface or a part of the electron source substrate 51 on which the X-direction wiring 52 and the Y-direction wiring 53 are formed.
It is set appropriately. The X direction wiring 52 and the Y direction wiring 53
Each is drawn out as an external terminal.

A pair of electrodes (not shown) constituting the electron-emitting device 54 of the present invention are composed of m X-directional wires 52 and n Y wires.
The directional wiring 53 is electrically connected to a connection 55 made of a conductive metal or the like.

The X-direction wiring 52 is connected to a scanning signal applying means (not shown) for applying a scanning signal for selecting a row of the electron-emitting devices 54 arranged in the X-direction. On the other hand, Y
Electron emitting elements 54 arranged in the Y direction
Are connected to a modulation signal generator (not shown) for modulating each of the columns according to the input signal.

The driving voltage applied to each electron-emitting device 54 is supplied as a difference voltage between a scanning signal and a modulation signal applied to the device. In the present invention, the Y-direction wiring 53 is connected to a high potential and the X-direction wiring 52 is connected to a low potential. By connecting in this way, the feature of the present invention is:
The beam convergence effect was obtained.

In the above configuration, individual electron-emitting devices 54 can be selected and driven independently using simple matrix wiring.

An image forming apparatus 700 configured using such an electron source having a simple matrix arrangement will be described with reference to FIG. FIG. 7 is a diagram illustrating a display panel of an image forming apparatus using soda lime glass as a glass material.

In FIG. 7, reference numeral 711 denotes the electron-emitting device 54.
, 721 is a rear plate to which the electron source substrate 711 is fixed, and 726 is a face plate in which a fluorescent film 724 and a metal back 725 are formed on the inner surface of a glass substrate 723.

Reference numeral 722 denotes a support frame, and a rear plate 721 and a face plate 726 are connected to the support frame 722 using frit glass or the like. Reference numeral 728 denotes an envelope which is sealed in a vacuum by firing at 450 ° C. for 10 minutes.

Reference numeral 714 corresponds to an electron emitting portion. 71
Numerals 2 and 713 are an X-direction wiring and a Y-direction wiring connected to a pair of device electrodes of the electron-emitting device of the present invention.

The envelope 727 includes the face plate 726, the support frame 722, and the rear plate 721 as described above. On the other hand, a supporter (not shown) called a spacer is provided between the face-plate 726 and the rear plate 721 so as to have sufficient strength against atmospheric pressure.

In the image forming apparatus 700 using the electron-emitting device according to the present invention, the phosphor is arranged above the device in alignment in consideration of the emitted electron trajectory.

FIG. 8 is a schematic diagram showing the fluorescent film used for the panel of the present invention.

In the case of a color fluorescent film, the black stripe shown in FIG.
It was composed of a black conductive material 821 called a black matrix or the like shown in FIG.

The purpose of providing the black stripes and the black matrix is to make the color separation between the phosphors 822 of the necessary three primary color phosphors black in color display so that color mixing and the like become inconspicuous. A decrease in contrast due to reflection was suppressed.

As a material for the black stripe, a material mainly containing graphite, which is generally used in the present embodiment, was used.

In FIG. 7, on the inner surface side of the fluorescent film 724,
Usually, a metal back 725 is provided. Metal back 7
No. 25 is manufactured by performing a smoothing process (usually called “filming”) on the inner surface of the fluorescent film 724 after the formation of the fluorescent film 724, and then depositing Al using vacuum evaporation or the like. .

The face plate 726 is provided with a transparent electrode (not shown) on the outer surface of the fluorescent film 724 in order to further enhance the conductivity of the fluorescent film 724.

When performing the above-mentioned sealing, in the case of color, it is necessary to make each color phosphor correspond to an electron-emitting device.
Sufficient alignment is essential. In this embodiment, the corresponding phosphor is disposed right above the electron source.

Scan Circuit FIG. 9 will be described. This circuit includes M switching elements inside (in the figure, S1 to Sm are schematically shown). Each switching element selects either the output voltage of the DC voltage source Vx or 0 (V) (ground level),
The display panel 901 is electrically connected to terminals Dx1 to Dxm. Each of the switching elements S1 to Sm operates based on the control signal Tscan output from the control circuit 903, and can be configured by combining switching elements such as FETs, for example.

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

The control circuit 903 has a function of coordinating the operation of each unit so that an appropriate display is performed based on an image signal manually input from the outside. The control circuit 903 generates control signals Tscan, Tsft, and Tmry for each unit based on the synchronization signal Tsync sent from the synchronization signal separation circuit 906.

The synchronizing signal separating circuit 906 is a circuit for separating a synchronizing signal component and a luminance signal component from an NTSC television signal input from the outside, and uses a general frequency separating (filter) circuit or the like. Can be configured.

The synchronization signal separated by the synchronization signal separation circuit 906 comprises a vertical synchronization signal and a horizontal synchronization signal.
Here, it is illustrated 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 904 in a time-series manner.
A control signal Ts sent from the control circuit 903 for serial / parallel conversion for each line of an image.
ft (ie, the control signal Tsft is
It can also be said that it is a shift clock of the shift register 904. ).

The data for one line of the image that has been subjected to the serial / parallel conversion (corresponding to the drive data for the N-electron emitting elements) is output from the shift register 904 as N parallel signals Id1 to Idn.

The line memory 905 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 903. The stored contents are output as I'd1 to I'dn and input to the modulation signal generator 907.

The modulation signal generator 907 outputs the image data I ′
The signal source is a signal source for appropriately driving and modulating each of the electron-emitting devices of the present invention according to each of d1 to I'dn, and the output signal thereof is supplied to the display panel 901 through terminals Doy1 to Doyn. Applied to the emitting element.

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, a clear threshold voltage Vth is required for electron emission.
And electron emission occurs only when a voltage higher than Vth is applied.

For voltages above the electron emission threshold,
The emission current also changes according to the change in the voltage applied to the device.
Therefore, when a pulse-like voltage is applied to the device, 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. Outputs an electron beam.

At this time, the intensity of the output electron beam can be controlled by changing the peak value Vm of the pulse. 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 in accordance with 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 907. be able to.

When implementing the pulse width modulation method,
As the modulation signal generator 907, a pulse width modulation circuit that generates an electron pulse having a constant peak value and appropriately modulates the width of a voltage pulse according to input data can be used.

The shift register 904 and the line memory 90
5 can be a digital signal type or an analog signal type. This is because the serial / parallel conversion and storage of the image signal may be performed at a predetermined speed.

When the digital signal type is used, it is necessary to convert the output signal DATA of the synchronization signal separation circuit 906 into a digital signal. For this purpose, an A / D converter is provided at the output of the synchronization signal separation circuit 906. Just do it.

In connection with this, the circuit used for the modulation signal generator 907 is slightly different depending on whether the output signal of the line memory 905 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 907, and an amplification circuit and the like are added as necessary. In the case of the pulse width modulation method, the modulation signal generator 907 includes, for example, a high-speed oscillator, a counter (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 amplifying the voltage of 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 system using an analog signal, the modulation signal generator 907 can employ an amplifier circuit using, for example, an operational amplifier, and can add a level shift circuit and the like as needed.

In the case of the pulse width modulation method, for example, a voltage controlled oscillation circuit (VCO) can be adopted, and an amplifier for amplifying the voltage up to the driving voltage of the electron-emitting device of the present invention can be added as necessary. Can also.

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.

The image forming apparatus of the present invention can be used not only as a display device for a television broadcast, a display device such as a video conference system or a computer, but also as an image forming device as an optical printer using a photosensitive drum or the like. Can be used.

[0106]

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

Example 1 FIG. 1 shows an example of a sectional view and a plan view of an electron-emitting device 101 manufactured by applying the present invention as an example, and FIG. 10 shows an example of a method for manufacturing an electron-emitting device of the present invention. showed that. Hereinafter, the electron-emitting device 1 of this embodiment will be described.
No. 01 will be described in detail.

(Step 1) After sufficient cleaning was performed using quartz for the substrate 1, 300 nm thick Al to be used for the low potential electrode 2 was deposited by sputtering (FIG. 10).
(A)).

Then, in a photolithography step, a photoresist pattern (not shown), photomask pattern light, development, and a mask pattern were transferred. Thereafter, using the patterned photoresist as a mask, the Al film was wet-etched and patterned (FIG. 10).
(B)).

With the photoresist remaining, SiO ₂ having a thickness of 350 nm was deposited as the insulating layer 3 by sputtering. Remove the photoresist and lift off
The insulating layer 3 was patterned (FIG. 10C).

The width of the insulating layer 3 (SiO ₂ ) is 10 μm,
The height from the film surface is 50 nm. Hereinafter, patterning of a thin film by a photolithography process, film formation, etching, lift-off, or the like is simply referred to as patterning.

Subsequently, a groove having a depth of 350 nm and a width of 5 μm for an embedded electrode is patterned in the insulating layer 3 (FIG. 10).
(D)) The groove was patterned with Ta as an embedded electrode 4b (FIG. 10 (e)). Therefore, the cross-sectional area of the embedded electrode is 0.35 μm × 5 μm = 1.75 μm ² .

Next, Ta having a thickness of 5 nm and a width of 10 μm was patterned as the upper electrode 4a (FIG. 10).
(F)). The cross-sectional area is 0.005 μm × 10 μm = 0.
05 μm ² .

As described above, the sectional area is (1.75 + 0.05) /0.05=36 as compared with the case of only the structure including the upper electrode 4a and the buried electrode 4b.
Therefore, the resistance drop at the time of voltage application becomes 1/36, and the voltage drop becomes small.

[0115] Incidentally, the withstand voltage of the insulating layer 3 (Si0 ₂₎ is 10 ⁶ V
/ Cm, so that when driving at 15V, the embedded electrode 4b is separated from the upper and lower electrodes by 150 nm or more.
Is embedded in the insulating layer 3, the withstand voltage can be ensured. However, in this embodiment, there is no problem with the withstand voltage since the distance is 2.5 μm.

(Step 2) Next, as shown in FIG. 10 (g), a Pt-Pd conductive thin film of 2 nm (electron emitting portion 5a,
5b) was deposited on one side of the high potential electrode 4. At this time, the length L2 where Pt-Pd was deposited was 30 μm.
And The Pt-Pd conductive thin film was selectively deposited by a sputtering method using a photolithography technique, masking one side of the high-potential electrode with a resist.

In the present embodiment, the deposition of Pt-Pd
Although a fine particle film is formed, a high resistance film is also formed
Is also good. Used for such fine particle film or high resistance film
Materials include Pd, Ru, Ag, Au, Ti, In,
Cu, Cr, Fe, Zn, Sn, Ta, W, Pd, etc.
Metal, PdO, SnO_Two, In_TwoO_Three・ PbO, Sb
_TwoO _ThreeOxides such as, HfB_Two, ZrB_Two, LaB₆, Ce
B₆, YB_Four, GdB_FourBorides such as TiC, ZrC, H
carbides such as fC, TaC, SiC, WC, TiN, Zr
Nitride such as N and HfN, semiconductor such as Si and Ge,
, AgMg, NiCu, Pb, Sn, etc.
The resistance value is 10^Three-10⁷Indicates the sheet resistance value of Ω / □.

(Step 3) Next, as shown in FIG. 10 (h), a pulse voltage of 15 V is applied to the low potential electrode 2 and the high potential electrode 4 (ON time: 1 msec / OFF time: 9 msec).
Was applied to the Pt-Pd conductive thin film, and a gap G was formed by the forming process so as to become the electron-emitting portions 5a and 5b. Forming was terminated when the resistance between the upper and lower electrodes reached 10 MΩ.

(Step 4) Next, the upper and lower electrodes 2 and 3 were placed in an atmosphere of BN (benzonitrile) and 2 × 10 ⁻⁶ Torr.
The same pulse voltage as in the forming step was applied to No. 4 to generate carbon between the cracks in the gap G. The activation step was completed when the current flowing between the cracks was saturated. As a result, the gap G was formed only in the region where the t-Pd conductive thin film was deposited.

The electron-emitting device 1 manufactured as described above
01 is placed in a vacuum container as shown in FIG. 2, and an electrode coated with a phosphor is used as an anode 21 as an anode electrode.
Driven. The driving voltage is Vf = 15V, Va = 10k
V, the distance H between the electron-emitting device 101 and the anode 21 is H = 2
mm.

As a result, according to the present invention, as compared with the case where the buried electrode 4b is not used, the voltage drop is suppressed, the variation due to the position of the element characteristics is eliminated, and an electron beam with a more converged beam diameter is obtained. The efficiency of the device was also higher.

(Example 2) An electron-emitting device was produced in the same process as in Example 1, except that Al was used for the buried electrode 4b instead of Ta, and the other conditions were the same as in Example 1. In the present embodiment, since Al having a resistivity of 2.5 μΩ · Cm is used in place of Ta having a resistivity of 12.5 μΩ · Cm, the resistivity of the embedded wiring is reduced to 、, and the voltage drop can be further suppressed. Therefore, it was possible to obtain an electron-emitting device having no variation in characteristics.

In the first and second embodiments, the embedded electrode 4
Although b is formed by burying the surface of the substrate 1, it is also possible to bury the insulating layer at a certain depth in the insulating layer or to dig the substrate 1 further to bury it deeper.

The same effect can be obtained by forming the upper electrode 4a thicker in a portion other than the side wall portion 5a1 of the upper electrode 4a without affecting the electron trajectory.

The present invention is also applicable to a case where an electron emitting portion is provided only on one side of a convex side wall, or a case where an electron emitting element is provided near a side wall.

Example 3 An electron source substrate and an image forming apparatus were manufactured using the electron-emitting device 101 to which the present invention was applied. As an example, a case where the device is manufactured using the electron-emitting device of Example 1 will be described. In this case, as shown in FIG. 6, in the electron-emitting device 54, the insulating layer in a region other than the high-potential electrode 4 related to the electron emission is formed of SiO _{2 as} thick as 1 μm like the interlayer insulating layer 61 and regulated. The capacity has been reduced to prevent signal delays that occur during matrix driving.

Further, the upper wiring 62 connected to the upper electrode 4a for suppressing the voltage drop due to the wiring resistance is 500 n
It was formed of Al as thick as m. Note that the upper electrode 4a and the upper wiring 62 are connected to each other at an overlapping portion indicated by a broken line in FIG.

As shown in FIG. 5, this device was 10 × 10
Were arranged in a matrix. The wiring was connected to the high potential electrode 4 on the X side and to the low potential electrode 2 on the Y side. The element is horizontal 15
0 μm and a vertical pitch of 300 μm.
1 was completed.

Using the electron source substrate 51, an image forming apparatus 700 shown in FIG. 7 was manufactured. Here, the phosphor was arranged at a position 3 mm away from the upper part of the element, with alignment. When driven at Vf = 15 V and Va = 10 kV, an image forming apparatus with high definition and no display variation could be formed.

[0130]

According to the present invention described above, an electron-emitting device which can converge the electron trajectory and can realize high efficiency at the same time is obtained. Further, the thickness of the electrode on the side wall portion of the convex structure portion of the first electrode is formed to be thin to prevent a decrease in the number of electrons due to multiple scattering, and by increasing the thickness of the upper electrode other than the side wall portion, It is possible to suppress an increase in electric resistance and suppress variations in electron emission characteristics depending on the location.

Further, by using the electron-emitting device according to the present invention, a high-definition electron source and an image forming apparatus can be realized.

[Brief description of the drawings]

FIG. 1A shows a cross-sectional configuration of an electron-emitting device.
FIG. 1B is a diagram showing the upper surface.

FIG. 2 is a schematic diagram showing an arrangement state and a driving state of an electron-emitting device in a vacuum vessel.

FIG. 3 is a diagram illustrating an electron-emitting device and an electron trajectory.

FIG. 4 is a diagram illustrating characteristics of a width W of an upper electrode, a beam diameter, and efficiency.

FIG. 5 is a diagram showing electron sources arranged in a matrix using electron-emitting devices.

FIG. 6 is a diagram showing a configuration of an electron-emitting device to be arranged in a matrix.

FIG. 7 is a diagram illustrating an image forming apparatus using an electron source having electron-emitting devices arranged in a matrix.

FIG. 8 is a diagram illustrating a phosphor used in the image forming apparatus.

FIG. 9 is a schematic diagram of a configuration including peripheral circuits necessary for forming an image in the image forming apparatus.

FIG. 10 is a diagram illustrating an example of a method for manufacturing an electron-emitting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Low potential electrode 3 Insulating layer 4 High potential electrode 4a Upper electrode 4b Embedded electrode 5a, 5b Electron emission part 21 Anode 22 Vacuum container 31, 32 Electron 51 Electron source substrate 52 X direction wiring 53 Y direction wiring 54 Electron emitting element 55 connection 61 interlayer insulating layer 62 upper wiring

Claims (8)

[Claims] 1. A convex structure having an insulating layer, a first electrode disposed so as to reach a side wall from an upper surface of the insulating layer, and a second electrode, wherein the second electrode is provided on the substrate. In the electron-emitting device, which is provided on the side wall portion of the convex structure portion with a gap so as to form a pair and has an electron-emitting portion connected to the first electrode or the second electrode, respectively, The electron-emitting device according to claim 1, wherein the electrode has a portion having a thickness greater than a thickness of a sidewall portion of the convex structure. 2. The electron-emitting device according to claim 1, wherein a portion of the first electrode having a large thickness is buried in the insulating layer. 3. When the width of the gap between the pair of electron emitting portions is D, and the distance between the upper and lower ends of the electron emitting portion on the side wall portion of the convex structure portion of the first electrode is T1, T1 <2
The electron-emitting device according to claim 1, wherein the electron-emitting device is 00D. 4. An anode provided above the first electrode to capture electrons, wherein the width of the first electrode is W, the distance from the top surface of the substrate to the anode is H, the first electrode When the applied voltage between the second electrode and the second electrode is Vf, and the applied voltage between the second electrode and the anode is Va, the width W is の of HVf / (ππ × Va). 2. The method according to claim 1, wherein the value is not less than twice and not more than 15 times.
4. The electron-emitting device according to any one of claims 1 to 3. 5. The electron according to claim 1, wherein there is no overlapping portion between the first electrode and the second electrode when viewed from vertically above a plane of the substrate. Emission element. 6. The method according to claim 1, wherein the substrate is provided on a substrate.
13. An electron source, comprising a plurality of the electron-emitting devices described in the above section. 7. An image, comprising: the electron source according to claim 6; and a phosphor, wherein an image is formed by irradiating electrons emitted from the electron source to the opposing phosphor. Forming equipment. 8. A convex structure portion having an insulating layer, a first electrode disposed to reach a side wall portion from an upper surface portion of the insulating layer, and a second electrode, the second electrode being provided on the substrate; A method for manufacturing an electron-emitting device, comprising: an electron-emitting portion disposed on a side wall portion of a convex structure portion with a gap so as to form a pair and connected to the first electrode or the second electrode, respectively. A step of forming a recess separated from the second electrode by an insulating layer; a step of forming a buried electrode to be a portion having a large thickness of the first electrode in the recess; a step of forming the buried electrode in the recess; Forming a film of an upper electrode of the first electrode reaching the side wall of the insulating layer on the substrate.