JP2003016915A - Electron source, electron source assembly, image forming apparatus, and method of manufacturing electron source - Google Patents

Abstract

(57) [Problem] To provide an electron source having a small electron beam diameter, and to provide a high-definition image forming apparatus with good image quality using the electron source. SOLUTION: A cathode electrode 2 arranged on a substrate 1
And a plurality of electron emission films 5 formed by electrically connecting the gate electrode 4 stacked on the cathode electrode 2 via the insulating layer 3 and the cathode electrode 2. The upper surfaces of the cathode electrode 2 and the gate electrode 4 are made concave.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron source, an electron source assembly in which a plurality of the electron sources are arranged, an image forming apparatus configured by using the electron source assembly, and a method of manufacturing the electron source. It is a thing.

[0002]

2. Description of the Related Art Conventionally, there are known two types of electron-emitting devices, a thermoelectron device and a cold cathode device. The cold cathode 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 emission device, and the like.

As an example of the FE type, W. P. Dyke
& W. W. Dolan, "Field Emissi
on ", Advance in Electron P
hysics, 8, 89 (1956), or C.I.
A. Spindt, "PHYSICAL Proper
ties of thin-film field em
ision cathodes with molly
bdenium cones ", J. Appl. Phy
s. , 47, 5248 (1976) and the like are known.

An example of the MIM type is C.I. A. Mea
d, "Operation of Tunnel-Em
"Ission Devices", J. Apply. P
hys. , 32,646 (1961) and the like are known.

In a recent example, Toshiaki.
Kusunoki, "Fluctuation-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
theode luminescent display
s ", IDW'96, (1996) pp. 529 and the like have been studied.

[0006] As an example of the surface conduction type, as reported by Elinson (MI Elinson Radio Eng. E.
electron Phys. , 10 (1965)) and the like. In this surface conduction electron-emitting device, electrons are emitted by passing a current through a thin film of a small area formed on a substrate in parallel to the film surface. It utilizes the phenomenon. As the surface conduction type element, one using the SnO ₂ thin film described in the above-mentioned report of Erinson, one using an Au thin film, (G. Dittmer. Thin Solid
Films, 9, 317 (1972)), In ₂ O ₃ / S
nO ₂ thin film (M. Hartwell and
C. G. Fonstad, IEEE Trans. ED
Conf. , 519 (1983)) and the like have been reported.

By the way, in order to apply the electron-emitting device to the image forming apparatus, an emission current for causing the phosphor to emit light with sufficient brightness is required. Further, in order to improve the definition of the display, it is required that the diameter of the electron beam with which the phosphor is irradiated is small. And it is important to be easy to manufacture.

An example of the conventional FE type is a Spindt type electron-emitting device. In the Spindt type, a microchip is generally formed as an emission point, and electrons are emitted from the tip of the microchip. When the emission current density is increased to cause the phosphor to emit light, the electron emission part is thermally destroyed. Will be induced and the life of the FE element will be limited. Further, the electrons emitted from the tip tend to spread due to the electric field formed by the gate electrode, and there is a drawback that the beam diameter cannot be reduced.

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

As an example of preventing the spread of the electron beam, there is an example in which a focusing electrode is arranged above the electron emitting portion. But,
In this method, the emitted electron beam is generally focused by the negative potential of the focusing electrode, but there is a problem that the manufacturing process is complicated and the manufacturing cost is increased.

Another example of reducing the electron beam diameter is a method of forming no microchip, such as the Spindt type. For example, there are those described in JP-A-8-096703 and JP-A-8-096704.

Since these emit electrons from the thin film arranged in the holes, there is an advantage that a flat equipotential surface is formed on the electron emission surface and the spread of the electron beam is reduced. Further, by using a low work function constituent material as the electron emitting substance, electrons can be emitted without forming a microchip, and a low driving voltage can be achieved. Further, since the electron emission is performed on the surface, the electric field is not concentrated, no breakdown occurs, and the life is long.

Further, as a method of reducing the electron beam diameter and suppressing the drive voltage, there is an example using a method of improving the shape of the cathode electrode. For example, JP-A-8-2932
44, Japanese Unexamined Patent Publication No. 10-125215, Japanese Unexamined Patent Publication No. 2000-67736, and USP 5473218. These improve the beam diameter and the driving voltage by forming the cathode electrode in a concave shape and forming an electron emission material in the groove.

[0014]

As described above, various attempts have been made to reduce the diameter of the electron beam of each electron-emitting device, but an electron source is manufactured by using a plurality of such electron-emitting devices. In this case, the following problems also occur.

In the present specification, the "electron source" means
It is a unit for forming one pixel (sub pixel) at the time of image formation, and is an assembly of elements including a plurality of electron-emitting devices. Therefore, for example, in the case of an image forming apparatus that forms a color image with three color phosphors of RGB, one electron source (three picture elements) corresponding to each color of RGB constitutes one pixel. .

Such an electron source is generally constituted by several to several hundreds of electron-emitting devices. In this case, even if the beam diameter of each electron-emitting device is reduced,
The diameter of the electron beam formed by the entire electron source has a certain spread.

FIG. 15 and FIG. 16 show schematic sectional views of conventional electron sources. FIG. 15 is an enlarged schematic view of the electron-emitting device included in the electron source.

As shown in FIG. 15 and FIG. 16, the electron source is a cathode electrode 102 arranged on a substrate 101.
A gate electrode 104 stacked on the cathode electrode 102 via the insulating layer 103; a plurality of openings penetrating the insulating layer 103 and the gate electrode 104 to expose a partial region of the cathode electrode 102; It is composed of an electron emission film 105 as a plurality of electron emission portions formed on the region by being electrically connected to the cathode electrode 102.

In this structure, when a driving voltage is applied between the cathode electrode 102 and the gate electrode 104 by the power supply 106, electrons are emitted from the electron emission film 105.
The emitted electrons are accelerated by the acceleration voltage applied by the power supply 108 and reach the anode electrode 107.
At this time, the emitted electrons orbit along a direction substantially perpendicular to the equipotential surface formed between the cathode electrode 102 and the gate electrode 104. Therefore, the electrons emitted from the center of the electron emission film 105 are directed to the anode electrode 107 directly above, but the electrons emitted from the peripheral portion of the electron emission film 105 are
The orbit is taken in a direction away from the center of the electron emission film 105.

Looking at this as an entire electron source, FIG.
As shown in FIG. 6, the electron beam emitted from the electron-emitting device arranged near the center of the electron source is the anode electrode 107.
To reach the approximate center (the approximate center of the picture element). However, the electron beam emitted from the electron-emitting device arranged in the peripheral portion of the electron source reaches a position deviated from the central portion of the anode electrode 107, resulting in widening the beam diameter of the entire electron source. It will be.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object thereof is to propose an electron source having a small electron beam diameter, and further utilize the electron source. And to provide a high-definition image forming apparatus with good image quality.

[0022]

To achieve the above object, an electron source of the present invention comprises a cathode electrode arranged on a substrate, and a gate electrode laminated on the cathode electrode via an insulating layer. In an electron source including a plurality of electron emitting portions formed on the cathode electrode and electrically connected to the cathode electrode, an upper surface of at least one of the cathode electrode and the gate electrode has a concave shape. Characterized by presenting.

An electron source according to another invention is a cathode electrode arranged on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and an electric source connected to the cathode electrode on the cathode electrode. In the electron source including a plurality of electron-emitting portions formed by electrically connecting each other, the normal line in the vicinity of the electron-emitting portion on the upper surface of at least one of the cathode electrode and the gate electrode is the center of the electron source. It is characterized by being inclined in the direction.

Further, an electron source of another invention is a cathode electrode arranged on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and the cathode electrode electrically connected to the cathode electrode. In an electron source including a plurality of electron emission portions formed by electrically connecting each other, the height from the substrate upper surface to the cathode electrode upper surface is higher in the electron source peripheral portion than in the electron source central portion. Is characterized by.

Here, it is preferable that the cathode electrode is thicker in the electron source peripheral portion than in the electron source central portion.

It is also preferable that the cathode electrode is arranged on the substrate via an underlayer having a larger film thickness in the electron source peripheral portion than in the electron source central portion.

As a result, the height from the upper surface of the substrate to the upper surface of the cathode electrode becomes higher in the peripheral portion of the electron source than in the central portion of the electron source.

Furthermore, it is preferable that the height from the upper surface of the substrate to the upper surface of the cathode electrode continuously increases from the central portion of the electron source toward the peripheral portion of the electron source.

An electron source according to another invention is a cathode electrode arranged on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and an electric source connected to the cathode electrode on the cathode electrode. In the electron source including a plurality of electron emitting portions that are connected to each other, the height from the cathode electrode upper surface to the gate electrode upper surface is higher in the electron source peripheral portion than in the electron source central portion. It is characterized by

Here, it is preferable that the gate electrode is thicker in the peripheral portion of the electron source than in the central portion of the electron source. As a result, the height from the upper surface of the cathode electrode to the upper surface of the gate electrode becomes higher in the electron source peripheral portion than in the electron source central portion.

Further, it is preferable that the height from the upper surface of the cathode electrode to the upper surface of the gate electrode continuously increases from the central portion of the electron source toward the peripheral portion of the electron source.

Further, each of the electron sources described above is provided with a plurality of openings penetrating the insulating layer and the gate electrode to expose a partial region of the cathode electrode, and the electron emission portion is provided in the opening. Therefore, it is preferable that it is formed on the exposed region of the cathode electrode.

At this time, it is preferable that the opening shape of the opening is any of a circle, an ellipse, a rectangle and a polygon.

In each of the above electron sources, the material of the electron emitting portion preferably contains diamond or diamond-like carbon.

Further, the electron source assembly of the present invention comprises a plurality of any one of the above electron sources, and a plurality of cathode wirings connected to the cathode electrode and a plurality of gate wirings connected to the gate electrode. It is characterized in that the plurality of electron sources are wired in a matrix.

The image forming apparatus of the present invention is characterized by including the electron source assembly and an image forming member for forming an image by the electrons emitted from the electron source assembly.

Here, it is preferable that the image forming member is a phosphor that emits light by collision of electrons.

In the electron source manufacturing method of the present invention, a step of stacking a cathode electrode on a substrate, a step of stacking a gate electrode on the cathode electrode via an insulating layer, and the cathode electrode And a step of electrically connecting the cathode electrode to form a plurality of electron emission portions, the method comprising the steps of: stacking the cathode electrode or the gate electrode, and then chemically mechanical polishing the upper surface thereof. It is characterized by including a step of processing into a concave shape by (CMP) processing.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions of the components described in this embodiment,
Unless otherwise specified, the material, the shape, the relative arrangement, and the like are not intended to limit the scope of the present invention thereto.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a schematic diagram showing a line type electron source according to the embodiment of FIG.

As shown in the figure, the line type electron source of the present embodiment comprises a plurality of electron emitting portions formed on the substrate 1. The line type electron source is a line in which a plurality of electron emitting portions are linearly arranged (in the Y direction),
A plurality of electron sources are arranged side by side (in the direction). The electron beam emitted from each line forms a substantially elliptical or substantially rectangular beam spot on the anode electrode 7 arranged to face the electron source.

Since the structure of the electron emitting portion in the ZX cross section of the line type electron source is substantially the same regardless of the position in the Y direction, the following description will be focused on the ZX cross section. To do.

FIG. 2 is a schematic diagram showing a ZX cross section of the line type electron source according to the present embodiment.

As shown in the figure, the electron source is roughly composed of a cathode electrode 2 arranged on a substrate 1, a gate electrode 4 laminated on the cathode electrode 2 via an insulating layer 3, and a cathode electrode 2. And an electron emission film 5 which is a plurality of electron emission portions electrically connected to the upper surface.

The electron source has a plurality of openings penetrating the insulating layer 3 and the gate electrode 4 to expose a partial region of the cathode electrode 2, and the electron emission film 5 has a cathode electrode in each opening. It is formed on two exposed areas.

In the present embodiment, by changing the film thickness of the cathode electrode 2 formed on the substrate 1 in the X direction,
The upper surface of the cathode electrode 2 is a concave curved surface.

That is, by making the thickness of the cathode electrode 2 thicker in the electron source peripheral portion than in the electron source central portion,
The height from the upper surface of the substrate 1 to the upper surface of the cathode electrode 2 is set such that the electron source peripheral portion (height T1) is higher than the electron source central portion (height T2).
It is set to be high in.

At this time, from the upper surface of the substrate 1 to the cathode electrode 2
It is preferable that the height to the upper surface is continuously increased from the central portion of the electron source toward the peripheral portion of the electron source. This is because the shape in which the upper surface of the cathode electrode 2 is smoothly curved is easier to manufacture, and the electron beam convergence is also excellent.

On the cathode electrode 2 thus formed, the insulating layer 3 and the gate electrode 4 are formed with a substantially constant film thickness. Therefore, the upper surfaces of the insulating layer 3 and the gate electrode 4 are also
Like the cathode electrode 2, it has a concave curved surface.

With such a structure, the normal line in the vicinity of the electron emitting portion on the upper surfaces of the cathode electrode 2 and the gate electrode 4 is
It tilts toward the center of the electron source. The equipotential surface 9 formed when a voltage is applied between the cathode electrode 2 and the gate electrode 4 is a surface that is substantially orthogonal to the normal direction of both electrodes,
As shown in FIG. 2, the cathode electrode 2 and the gate electrode 4 have a concave shape corresponding to the curvature.

As described above, the electrons emitted from the electron emission film 5 take a trajectory substantially perpendicular to the equipotential surface 9 formed between the cathode electrode 2 and the gate electrode 4. Therefore, in the configuration of the present embodiment, each electron emission film 5
Electrons emitted from the electron source are given a directivity toward the center of the electron source, and the electron beam can be converged (the beam diameter can be reduced) as the entire electron source.

Next, with reference to FIGS. 3 and 4, the structure and operation of the electron emitting portion will be described in more detail.

FIG. 3 is a schematic diagram showing an electron emitting portion of the line type electron source according to the present embodiment, and FIG.
An X sectional view and FIG. 3B are XY plan views.

FIG. 3 is an enlarged schematic view of one of the plurality of openings (electron emission film 5) provided in the electron source. The portion shown in FIG. 3, that is, the substrate 1, the cathode electrode 2, the insulating layer 3, the gate electrode 4, the opening and the electron emitting film 5 near the opening are referred to as an "electron emitting device".

In the present embodiment, the opening shape of the opening is formed in a substantially rectangular shape (slit shape), and the electron emission film 5 is also formed in a substantially rectangular shape (slit shape) having a width W1 and a length L1.
Is formed in. The opening shape of the opening and the shape of the electron emission film 5 are not limited to the rectangular shape, but may be, for example, a circular shape, an elliptic shape,
It may be polygonal. In addition, the opening shape is formed in a ring shape (donut shape), and the ring shape (doughnut shape) is formed in the opening shape.
A configuration in which the electron emission film 5 is provided is also suitable.

Reference numeral 7 denotes an anode electrode which is arranged above the electron source and is separated by a distance H. An anode voltage (accelerating voltage) Va is applied to the anode electrode 7 by a high voltage power supply 8. Note that the position of the element when defining the anode electrode-element distance H may normally be based on the position of the cathode electrode 2. At this time, the distance H between the anode electrode and the element differs for each electron-emitting device in the electron source, but the difference can be ignored as compared with the distance H between the anode electrode and the element.

In the electron-emitting device having the above structure, when the driving voltage Vg is applied between the cathode electrode 2 and the gate electrode 4 by the driving power supply 6, electrons are emitted from the electron-emitting film 5. The emitted electrons are accelerated by the anode voltage Va applied to the anode electrode 7 and captured by the anode electrode 7. Thereby, the electron emission current Ie is detected.

FIG. 4 is a diagram schematically showing an equipotential surface and electron beam trajectories when this electron-emitting device is driven.

Regarding one electron-emitting device arranged in the peripheral portion of the electron source, the cathode electrode 2 and the gate electrode 4 thereof have a substantially parallel layer structure, and both have an inclined surface inclined toward the center of the electron source. ing. Therefore, the equipotential surfaces 9 formed between the cathode electrode 2 and the gate electrode 4 are formed with a substantially equal density, and their normal direction is inclined toward the electron source center direction.

Since the electrons emitted from the electron emission film 5 take a trajectory substantially perpendicular to the equipotential surface 9, the electron trajectory is bent toward the center of the electron source as shown in FIG. Since the inclination angle of the cathode electrode 2 increases from the central portion of the electron source toward the peripheral portion thereof, the electron orbit of the electron emitting element arranged near the peripheral portion of the electron source becomes more curved.

As described above, according to the structure of the present embodiment, by making the upper surface of the cathode electrode 2 of the electron source concave, the electrons emitted from each electron-emitting device (electron emitting portion) It is possible to give directivity toward the center of the source and to condense the beam of the entire electron source.

FIG. 5 is a diagram showing the relationship between the electron beam diameter and the ratio of the height T1 from the upper surface of the substrate 1 to the upper surface of the cathode electrode 2 in the central portion of the electron source to the height T2 in the peripheral portion of the electron source. is there.

As described above, the height T1 of the cathode electrode 2 in the peripheral portion of the electron source is equal to the height T1 in the central portion of the electron source.
The electron beam diameter can be reduced by increasing T1 / T2 as compared with T2.
If 1 / T2 is made too large, inconvenience occurs.

The cause is considered to be the influence of electrons colliding with the gate electrode 4. It is considered that when the number of collision electrons increases, a part of the electrons are scattered, and as a result, the beam diameter increases. Therefore, the concave shape of the cathode electrode 2 may be set to a shape that minimizes the beam diameter based on the graph of FIG.

Although one embodiment in which the present invention is applied to a line-type electron source is shown here, the present invention also applies to an electron source or the like in which a plurality of electron emitting portions are arranged concentrically or radially. It can be applied suitably. Further, in the present embodiment, the height of the cathode electrode 2 is changed only in the X direction to form the concave surface. However, the height is changed not only in the X direction but also in the Y direction to form a bowl-shaped concave surface. By doing so, not only the X direction but also the Y direction beam can be converged.

As the material of the electron emission film 5, a device having a low work function such as diamond or diamond-like carbon can be selected to lower the device driving voltage.

6 and 7 are views for explaining an example of a method of manufacturing the electron source of this embodiment.

An example of the method of manufacturing the electron source of this embodiment will be described below with reference to FIGS.

As shown in FIG. 6 (a), the surface of the glass is thoroughly cleaned in advance, and quartz glass, glass with a reduced content of impurities such as Na, soda lime glass, silicon substrate, etc. are deposited by sputtering or the like. Any one of a laminated body in which ₂ is laminated and an insulating substrate made of ceramics such as alumina is used as the substrate 1, and the cathode electrode 2 is laminated on the substrate 1.

Next, in order to separate each electron source (picture element), a separator 50 is formed by a general vacuum film forming technique such as a vapor deposition method and a sputtering method, and a photolithography technique.
This separation body 50 is provided after the chemical mechanical polishing (Chemical Mechanical Po
Any material may be used as long as it has a higher hardness or a higher chemical resistance than the cathode electrode material in order to effectively perform the lightening (hereinafter referred to as “CMP”) treatment. The thickness of the separator 50 is set in the range of several tens nm to several mm, preferably selected in the range of several hundred nm to several μm, and its width is set in the range of several tens nm to several mm. And is preferably selected in the range of several hundred nm to several μm. The distance between the separators is set in the range of several tens nm to several mm, and preferably selected in the range of several hundreds nm to several μm.

Next, the cathode electrode 2 is formed by a general vacuum film forming technique such as a vapor deposition method and a sputtering method, and a photolithography technique. The cathode electrode 2 has conductivity. For example, Be, Mg, Ti, Zr, Hf, V, N
b, Ta, Mo, W, Al, Cu, Ni, Cr, Au,
Metal or alloy material such as Pt, Pd, TiC, ZrC,
Carbides such as HfC, TaC, SiC, WC, HfB ₂ ,
_{ZrB 2, LaB 6, CeB 6} , YB 4, GdB borides such as _4, TiN, ZrN, nitrides such as HfN, Si, such as Ge semiconductor, an organic polymer material, amorphous carbon, graphite, diamond-like carbon, It is appropriately selected from carbon and carbon compounds in which diamond is dispersed. The thickness of the cathode electrode 2 is several tens nm to several meters.
It is set in the range of m, and is preferably selected in the range of several hundred nm to several μm.

Next, CMP treatment is performed to process the cathode electrode 2 sandwiched by the separator 50 into a concave shape. The shape of the curve at this time can be changed by changing the abrasive, the polishing cloth, and the rotation speed described below.

Chemical Mechanical Polishing (CMP)
Is to perform polishing by utilizing a chemical etching action due to a chemical component contained in the polishing material and a mechanical polishing action originally possessed by the polishing agent. As an example of chemical mechanical polishing (CMP), a reaction product generated by a chemical reaction between a chemical component contained in an abrasive and a sample to be polished is mechanically polished and removed using an abrasive and a polishing cloth. You can think of something to do. As the process of CMP,
After the sample to be polished to be polished is attached to a rotatable polishing head, polishing is performed by pressing the surface of the sample to be polished against a rotating platen (polishing platen). A pad (polishing cloth) is attached to the surface of the platen, and polishing is performed by the slurry (polishing material) to which the pad is attached.

Various types of CMP devices are commercially available, and in the present invention, those devices can be used appropriately.

As a CMP apparatus, AVANTI472
(Manufactured by IPEC / PLANAR), CMP-II (manufactured by Speedfam), EPO-113, EPO-114.
(Manufactured by EBARA CORPORATION), MIRRA (APPLIED MA
TERIALS, 6DS-SP (STRASBA)
UGH) and the like.

As the slurry, MS manufactured by Rodel
W-1000, XJFW-8048H, XJFW-80
97B, XJFW-8099, SEM manufactured by Cabot
I-SPERSE W-A355, SEMI-SPER
SE FE-10, PLANERL made by FUJIMI
ITE-5101, PLANERITE-RD-93
034, PLANERLITE5102, PLANER
LITE-RD-93035, PLANERLITE-
5103, PLANERITE-RD-93036
STI's KLEBOSOL-20H12, KLEB
OSOL-30H25, KLEBOSOL-30H5
0, KLEBOSOL-30N12, KLEBOSOL
-30N25, KLEBOSOL-30N50 and the like can be used.

As the polishing cloth, IC-made by Rodel Co.
1000, IC-1400, IC-60, IC-53,
IC-50, IC-45, IC-40, Suba 40
0, Suba 400H, Suba 500, Suba
600, Suba 800, MH S15A, MH
S24A, MH C14A, MH C14B, MHC1
5A, MH C26A, MH N15A, MH N24
A, Supreme RN-H, Supreme RN-
R, Whitex WH, Whitex W-S, UR
-100, XHGM-1158, XHGM-1167,
FUJIMI's Surfin XXX-5, Sur
fin 100, Surfin 260S, Surfin
000, Surfin 194, Surfin 19
1, Surfin 192, Surfin 2-X, S
urfin 018-3, Surfin 018-0,
Surfin 018, Surfin 200, Sur
fin 026, Surfin 024, Polite
x, Politex DG, Politex Supr
em, Unicorfam, Teijin SBL135,
SBD1014, 6ZP09, RP3010P5, GQ
8785, GQ9810, GQ9806, GQ981
3, GQ1070, GQ1110, GQ1300, NA
1000,1000R, 1200,12 made by PCON
00R, 1300, 1400, 2000, 2010, 2
020,4100,4300,4400,4500,4
600, 4800, 4900, 5100, 5400 etc. can be used.

As described above, by using materials having different easiness of polishing, the cathode electrode 2 having a different thickness is formed in the portion sandwiched by the separators 50 as shown in FIG. 6C. .

Next, as shown in FIGS. 6D and 6E, the insulating layer 3 and the gate electrode 4 are deposited.

The insulating layer 3 is formed by a general vacuum film forming method such as a sputtering method, a CVD method, or a vacuum vapor deposition method, and the thickness thereof is set in the range of several nm to several μm, preferably several. It is selected from the range of 10 nm to several hundred nm. As a desirable material, a material having a high withstand voltage such as SiO ₂ , SiN, Al ₂ O ₃ , and CaF that can withstand a high electric field is desirable.

The gate electrode 4 has conductivity like the cathode electrode 2, and is formed by a general vacuum film forming technique such as a vapor deposition method or a sputtering method, or a photolithography technique. The material of the gate electrode 4 is, for example, Be, Mg, T
i, Zr, Hf, V, Nb, Ta, Mo, W, Al, C
Metal or alloy material such as u, Ni, Cr, Au, Pt, Pd, TiC, ZrC, HfC, TaC, SiC, WC
Carbides such as HfB ₂ , ZrB ₂ , LaB ₆ , CeB ₆ , Y
B _4, GdB borides such as _4, TiN, ZrN, nitrides such as HfN, Si, a semiconductor such as Ge, are appropriately selected from organic polymeric material.

Next, a method of manufacturing the opening and the electron emission film 5 will be described with reference to FIG. FIG. 7 shows A of FIG.
It is an enlarged view of the part.

As shown in FIG. 7A, after a mask pattern 51 is formed by a photolithography technique, etching is performed to form holes (openings) as shown in FIG. 7B. At this time, the etching may be stopped at the cathode electrode 2, or a part of the cathode electrode 2 may be etched. However, in the etching process, it is necessary to select an etching method according to the material of each layer (cathode electrode 2, insulating layer 3, gate electrode 4).

Next, as shown in FIG. 7C, the electron emission film 5 is deposited on the entire surface.

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

The electric field required to emit electrons from these electron emitting films 5 should be as low as possible.
The drive voltage can be reduced. For example, if it is 5 × 10 ⁵ V / m or less, the driving voltage can be reduced to about a dozen V, which is preferable.

Next, as shown in FIG. 7D, the mask pattern 51 is peeled off to complete the electron source of this embodiment.

Difference T between the height of the peripheral portion of the electron source and the height of the central portion T
1-T2 is set in the range of several tens nm to several tens μm,
It is preferably about several hundreds nm, and as shown in FIG.
The condition that minimizes the beam diameter is selected.

In this case, the beam diameter in the direction in which the thickness of the cathode electrode 2 is different, that is, in the X direction becomes small.

The diameter of the hole is a factor that largely depends on the electron emission characteristics of the device, and the characteristics of the material forming the device, particularly the work function and film thickness of the electron emission film, the drive voltage of the device, and the necessary at that time It is appropriately set according to the shape of the electron emission beam. Usually, the diameter of the pores is selected from the range of several hundred nm to several tens of μm.

The plane shape of the hole is not particularly limited. The length of the hole is a factor that depends on the electron emission amount and is set appropriately.

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

The electron source described here has a very simple structure in which stacking is repeated, and the processing of the cathode electrode or the gate electrode is a self-forming manufacturing method using the CMP method. The process is easy and it can be manufactured with high yield.

Next, application examples of the electron source according to the embodiment of the present invention will be described below.

FIG. 8 is a plan view schematically showing the structure of an electron source assembly having a plurality of the above electron sources. In addition, FIG.
FIG. 9 is a perspective view schematically showing the configuration of an image forming apparatus using the electron source assembly of FIG. 8.

Various arrangements of electron sources in the electron source assembly are adopted. In FIG. 8, as an example, a plurality of electron sources are arranged in a matrix in the X direction and the Y direction, and cathode electrodes of the plurality of electron sources arranged in the same row are shown as X electrodes.
A simple matrix arrangement is shown, in which gate electrodes of a plurality of electron sources arranged in the same column are commonly connected to wirings in the direction (cathode wiring) and are commonly connected to wirings in the Y direction (gate wiring). The simple matrix arrangement will be described in detail below.

In FIGS. 8 and 9, 61 is an electron source substrate,
62 is an X-direction wiring and 63 is a Y-direction wiring. Reference numeral 64 denotes an electron source according to the embodiment of the present invention.

The m number of X-direction wirings 62 are Dx1 and Dx.
, ..., 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 63 includes Dy1, Dy2, ...
It is composed of n Dyn wirings and is formed similarly to the X-direction wirings 62. An interlayer insulating layer (not shown) is provided between the m X-direction wirings 62 and the n Y-direction wirings 63 to electrically separate the two (m and n are: Both are positive integers).

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

M number of X-direction wirings 6 constituting the electron source 64
2 may also serve as the cathode electrode 2, n Y-direction wirings 63 may serve as the gate electrode 4, and the interlayer insulating layer may serve as the insulating layer 3.

A scanning signal applying means (not shown) for applying a scanning signal for selecting a row of the electron sources 64 arranged in the X direction is connected to the X-direction wiring 62. On the other hand, the Y-direction wiring 63 is connected to a modulation signal generating means (not shown) for modulating each column of the electron sources 64 arranged in the Y direction according to an input signal. The driving voltage applied to each electron source is supplied as a difference voltage between the scanning signal and the modulation signal applied to the element.

In the above structure, individual elements can be selected and driven independently by using simple matrix wiring. An image forming apparatus configured by using an electron source having such a simple matrix arrangement will be described with reference to FIG. FIG. 9 is a schematic diagram showing an example of a display panel of the image forming apparatus.

In FIG. 9, 71 is an electron source, 81 is an electron source substrate on which a plurality of electron sources are arranged, 91 is a rear plate on which the electron source substrate 81 is fixed, 96 is a fluorescent film 94 and a metal back on the inner surface of a glass substrate 93. It is a face plate on which 95 and the like are formed. 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.

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

Fluorescent film 94 of support frame 92 and metal back 9
Frit glass is applied to the bonding surface where the face plate 96 having the inner surface 5 and the rear plate 91 and the support frame 92 are joined, and the face plate 96, the support frame 92, and the rear plate 91 are placed at predetermined positions. , Fix, heat and bake to seal.

As the heating means for firing and sealing, various means such as lamp heating using an infrared lamp and a hot plate can be adopted, but the heating means is not limited to these.

Further, the adhesive material for heat-bonding a plurality of members constituting the envelope is not limited to frit glass, and various adhesives can be used as long as they can form a sufficient vacuum atmosphere after the sealing step. Materials can be adopted.

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

As another example, the support frame 92 is directly attached to the substrate 81.
Alternatively, the face plate 96, the support frame 92, and the base body 81 may be sealed to form the envelope 98. Further, by installing a support body (not shown) called a spacer between the face plate 96 and the rear plate 91, it is possible to configure the envelope 98 having sufficient strength against atmospheric pressure.

FIG. 10 is a schematic view showing the fluorescent film 94 formed on the face plate 96. In the case of monochrome, the phosphor film 94 can be composed of only the phosphor 85. In the case of a color fluorescent film, it can be composed of a black conductive material 86 called a black stripe (FIG. 1A), a black matrix (FIG. 2B) and the like and a phosphor 85.

The purpose of providing the black stripes and the black matrix is to make the mixed colors and the like inconspicuous by making the coating portions between the phosphors 85 of the three primary color phosphors necessary for color display inconspicuous. This is to suppress the decrease in contrast due to external light reflection at 94. As the material of the black stripe, in addition to a commonly used material containing graphite as a main component, a material having conductivity and having little light transmission and reflection can be used.

As a method for applying the fluorescent substance to the glass substrate 93, a precipitation method, a printing method or the like can be adopted regardless of monochrome or color. A metal back 95 is usually provided on the inner surface side of the fluorescent film 94. The purpose of providing a metal back is
Of the light emitted from the phosphor, the light to the inner surface side
To improve the brightness by mirror-reflecting to the 6 side, to act as an electrode for applying an electron beam acceleration voltage, and to protect the fluorescent film 94 from damage due to collision of negative ions generated in the envelope. Etc. The metal back 95 is subjected to a smoothing process (generally called “filming”) on the inner surface of the fluorescent film after the fluorescent film is produced.
And then depositing Al using vacuum deposition or the like.

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

In the present embodiment, the electron-emitting device 7
Since the electron beam reaches just above 1, the electron-emitting device 7
1, the fluorescent film 94 is aligned and configured so as to be arranged immediately above.

Next, an enclosure (panel) which has been subjected to a sealing step.
The vacuum sealing step of sealing the will be described.

In the vacuum sealing step, the envelope (panel) 98 is heated and kept at 80 to 250 ° C., and exhausted through an exhaust pipe (not shown) by an exhaust device such as an ion pump or a sorption pump. Then, after the atmosphere is made sufficiently low in organic substances, the exhaust pipe is heated by a burner to melt and seal. A getter process may be performed to maintain the pressure after the envelope 98 is sealed. This is the envelope 98
Immediately before or after the sealing of (1), by heating using resistance heating, high frequency heating, or the like, the getter arranged at a predetermined position (not shown) in the envelope 98 is heated to form a vapor deposition film. Processing. The getter usually has Ba or the like as a main component, and maintains the atmosphere in the envelope 98 by the adsorption action of the deposited film.

In the image forming apparatus constructed by using the electron sources of the simple matrix arrangement manufactured by the above steps, the outside-container terminals Dx1 to Dx are attached to each electron-emitting device of each electron source.
Electrons are emitted by applying a voltage through m and Dy1 to Dyn.

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

The accelerated electrons collide with the fluorescent film 94,
Light emission occurs and an image is formed.

FIG. 11 is a block diagram showing an example of a drive circuit for displaying according to an NTSC television signal.

The scanning circuit 1302 will be described. The circuit includes M switching elements (schematically shown by S1 to Sm in the drawing) inside. Each switching element selects either the output voltage of the DC voltage source Vx1 or the voltage source Vx2 and is electrically connected to the terminals Dx1 to Dxm of the display panel 1301. Each switching element of S1 to Sm is a control circuit 1
It operates based on the control signal Tscan output by 303, and can be configured by combining switching elements such as FETs.

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

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

The sync signal separation circuit 1306 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 1306 includes a vertical sync signal and a horizontal sync signal, but it is shown 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. This DATA signal is a shift register 1304
Entered in.

The shift register 1304 is for serially / parallel converting the DATA signals serially input in time series for each line of the image, and is based on the control signal Tsft sent from the control circuit 1303. It can be said that the control signal Tsft is the shift clock of the shift register 1304. The serial / parallel converted image data for one line (corresponding to drive data for N electron emission elements) is output from the shift register 1304 as N parallel signals Id1 to Idn.

The line memory 1305 is a storage device for storing data for one line of an image for a required time, and stores the contents of Id1 to Idn as appropriate in accordance with the control signal Tmry sent from the control circuit 1303. The stored contents are output as I′d1 to I′dn and input to the modulation signal generator 1307.

The modulation signal generator 1307 is a signal source for appropriately driving and modulating each of the electron-emitting devices according to each of the image data I'd1 to I'dn, and the output signal thereof is from the terminals Doy1 to Doy1. Display panel 1 through Doyn
It is applied to an electron source (electron emitting device) in 301.

When a pulsed voltage is applied to this element,
For example, no electron emission occurs even if a voltage below the electron emission threshold is applied, but an electron beam is output when a voltage above the electron emission threshold is applied. At that time, the peak value V of the pulse
It is possible to control the intensity of the output electron beam by changing m. It is also 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 implementing the voltage modulation method, a circuit of the voltage modulation method is used as the modulation signal generator 1307, which generates a voltage pulse of a fixed length and appropriately modulates the peak value of the pulse according to the input data. be able to.

In implementing the pulse width modulation method,
As the modulation signal generator 1307, 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 1304 and the line memory 1
A digital signal type or an analog signal type can be used as the 305. 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 sync signal separation circuit 1306 into a digital signal.
A D converter may be provided. In connection with this, the circuit used for the modulation signal generator 1307 is slightly different depending on whether the output signal of the line memory 1305 is a digital signal or an analog signal. That is, in the case of the voltage modulation method using a digital signal, for example, a D / A conversion circuit is used for the modulation signal generator 1307, and an amplification circuit or the like is added if necessary. In the case of the pulse width modulation method, the modulation signal generator 13
As the circuit 07, for example, a circuit in which a high-speed oscillator, a counter that counts the number of waves output from the oscillator, and a comparator that compares the output value of the counter with the output value of the memory is used. If necessary, an amplifier for voltage-amplifying the pulse-width-modulated modulation signal output from the comparator up to the driving voltage of the electron-emitting device can be added.

In the case of the voltage modulation method using an analog signal, the modulation signal generator 1307 can employ an amplifier circuit using, for example, an operational amplifier, and a level shift circuit or the like can be added if necessary. In the case of the pulse width modulation method, for example, a voltage control type oscillation circuit (VCO)
Can be adopted, and an amplifier for amplifying the voltage up to the driving voltage of the electron-electron-emitting device can be added if necessary.

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. As for the input signal, the NTSC system is mentioned, but the input signal is not limited to this, and PA
In addition to the L and SECAM systems, a TV signal (for example, a high-definition TV including the MUSE system) system having a larger number of scanning lines than these systems can be adopted.

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

Next, examples of the electron source and the image forming apparatus according to this embodiment will be described in detail.

[Example of Electron Source] The following will describe a preferable method of manufacturing an electron source as an example of the electron source according to the present embodiment. It should be noted that here, as shown in FIG.
A description will be given with reference to FIGS. 6 and 7.

(Step 1) Quartz was used for the substrate 1 and after thorough cleaning, a plasma SiN film was deposited to a thickness of 1000 nm (not shown). The plasma SiN film was dry-etched using CF ₄ and patterned as shown in FIG. 6A to form a separator 50. At this time, the space between the separators 50 is
It was 30 μm.

(Step 2) Next, as shown in FIG. 6B, a cathode electrode 2 having a thickness of 10 is formed by a sputtering method.
00 nm Ta was formed.

(Step 3) Next, as shown in FIG. 6C, the surface of the cathode electrode 2 was processed into a concave shape by the CMP method. The polishing amount was such that the difference between the height of the SiN separator 50 and the height of the cathode electrode 2 in the central portion of the electron source was 0.4 μm. CMP processing was performed by Ebara Corporation EPO-114 as a CMP apparatus, and polishing cloth manufactured by Rodel SUP.
REMERN-H (D51), FUJIMI for slurry
It was performed using PLNERLITE5102 manufactured by the company.

(Step 4) Next, as shown in FIGS. 6 (d) and 6 (e), as the insulating layer 3, plasma SiO _{2 is used} for 500 times.
As the gate electrode 4, Ta was deposited by 100 nm by sputtering.

(Step 5) Next, as shown in FIG. 7A, spin coating of a positive photoresist (AZ1500 / Clariant) and a photomask pattern are exposed by photolithography, developed, and masked. The pattern 51 was formed.

(Step 6) As shown in FIG. 7B, using the mask pattern 51 as a mask, the Ta gate electrode 4 and the insulating layer 3 are dry-etched with CF ₄ gas, respectively, and stopped at the cathode electrode 2. The width in the X direction is 1μ
A hole (opening) having a length of 100 μm in the m and Y directions was formed. At this time, the distance between the opening and the opening in the X direction (hereinafter,
The pitch) was 3 μm.

(Step 7) Subsequently, as shown in FIG. 7C, an electron emission film 5 of diamond-like carbon was deposited on the entire surface by about 60 nm by the rf plasma CVD method. As the film forming gas at that time, CH ₄ + Ar gas was used.

(Step 8) As shown in FIG. 7D, the mask pattern 51 was completely removed, and the electron-emitting device of this example was completed.

The electron source manufactured as described above was arranged with a distance H between the anode electrode and the element being 1 mm. Va
= 5 kV and Vg = 15 V.

As a comparative example, the width of the openings in the X direction is 1 μm, the length in the Y direction is 100 μm, and the pitch is 3 μm.
An electron source was prepared in which the cathode electrode 2 had a uniform thickness of 1 μm. Then, these two electron sources are simultaneously driven for comparison. The insulating layer 3 of the comparative example,
The film thickness of the gate electrode 4 is similar to that of the embodiment.

An electrode coated with a phosphor was used as the anode electrode 7, and the sizes of the electron beams of the two electron sources were observed. Here, the size of the electron beam is the size up to a region of 10% of the peak brightness of the phosphor that has emitted light.

As a result, in the electron source of this example, as compared with the comparative example, an electron beam having a shape converged in the central portion of the electron source was obtained. The decrease in the beam diameter in the X direction at this time was -14.4% with respect to the comparative example.

[Example of Image Forming Apparatus] An image forming apparatus was produced using the electron source of the above example.

The electron sources of the examples were arranged in a 10 × 10 simple matrix. The electron source is 100 μm in width and 100 in length.
It was arranged at a pitch of μm. A phosphor was placed above the electron source at a distance of 1 mm. A voltage of 5 kV was applied to the phosphor as an acceleration voltage. Electron source drive voltage is V
It was set to g = 15V.

As a result, a high definition image forming apparatus could be formed.

(Second Embodiment) FIGS. 12 and 13
Shows an electron source according to the second embodiment of the present invention.

In the first embodiment described above, the cathode electrode and the gate electrode both have a concave shape, but in the present embodiment, the cathode electrode has a planar shape and the gate electrode has a concave shape. .

Except that the layer structure is different, the second embodiment is substantially the same as the first embodiment. Therefore, the common components are designated by the same reference numerals and the description thereof will be omitted. Here, the different portions will be mainly described. explain.

FIG. 12 is a schematic diagram showing a ZX cross section of the line type electron source according to the present embodiment.

As shown in the figure, the electron source is roughly composed of a cathode electrode 2 arranged on a substrate 1, a gate electrode 4 laminated on the cathode electrode 2 via an insulating layer 3, and a cathode electrode 2. And an electron emission film 5 which is a plurality of electron emission portions electrically connected to the upper surface.

The electron source has a plurality of openings penetrating the insulating layer 3 and the gate electrode 4 to expose a partial region of the cathode electrode 2, and the electron emission film 5 has a cathode electrode in each opening. It is formed on two exposed areas.

In this embodiment, the film thicknesses of the cathode electrode 2 and the insulating layer 3 are made substantially uniform over the entire electron source. Then, by changing the film thickness of the gate electrode 4 laminated on the insulating layer 3 in the X direction, the upper surface of the gate electrode 4 is formed into a concave curved surface.

That is, by making the film thickness of the gate electrode 4 thicker in the peripheral portion of the electron source than in the central portion of the electron source, the height from the upper surface of the cathode electrode 2 to the upper surface of the gate electrode 4 is
The height is higher in the peripheral portion of the electron source than in the central portion of the electron source.

At k, it is preferable that the height from the upper surface of the cathode electrode 2 to the upper surface of the gate electrode 4 continuously increases from the central portion of the electron source toward the peripheral portion of the electron source. This is because the shape in which the upper surface of the gate electrode 4 is smoothly curved is easier to manufacture, and the electron beam convergence is also excellent.

With such a structure, the normal line on the upper surface of the gate electrode 4 in the vicinity of the electron emission portion is inclined toward the center of the electron source. The equipotential surface 9 formed when a voltage is applied between the cathode electrode 2 and the gate electrode 4 is a surface that is substantially orthogonal to the normal direction of both electrodes, and the curvature of the gate electrode 4 as shown in FIG. Will have a concave shape.

As described above, the electrons emitted from the electron emission film 5 take a trajectory substantially perpendicular to the equipotential surface 9 formed between the cathode electrode 2 and the gate electrode 4. Therefore, in the configuration of the present embodiment, each electron emission film 5
Electrons emitted from the electron source are given a directivity toward the center of the electron source, and the electron beam can be converged (the beam diameter can be reduced) as the entire electron source.

FIG. 13 is a schematic diagram showing the structure of the electron-emitting device according to this embodiment. This figure shows one electron-emitting device arranged around the electron source.

As shown in the figure, the cathode electrode 2 and the insulating layer 3 are formed with a uniform film thickness, but the film thickness of the gate electrode 4 formed on the insulating layer 3 is larger than that in the central portion of the electron source. Also becomes thicker on the peripheral side of the electron source, and the upper surface of the gate electrode 4 is an inclined surface inclined toward the center of the electron source. Therefore, the equipotential surface formed between the cathode electrode 2 and the gate electrode 4 becomes dense in the central portion of the electron source and rough in the peripheral portion of the electron source in the opening, and their normal direction is the cathode electrode. It becomes gradually inclined toward the center of the electron source from 2 toward the gate electrode 4.

Since the electrons emitted from the electron emission film 5 take a trajectory substantially perpendicular to the equipotential surface 9, the electron trajectory is bent toward the center of the electron source as shown in FIG. Since the inclination angle of the gate electrode 4 increases from the central portion of the electron source toward the peripheral portion thereof, the electron orbit of the electron-emitting device arranged near the peripheral portion of the electron source becomes larger.

As described above, according to the structure of the present embodiment, since the upper surface of the gate electrode 4 of the electron source is made concave, each electron-emitting device (electron-emitting portion) is formed in the same manner as in the first embodiment. ), The directivity toward the center of the electron source can be imparted to the electrons emitted from (1), and the beam of the entire electron source can be converged.

[Example] A preferred method of manufacturing an electron source will be described below as an example of the electron source according to the present embodiment.

(Step 1) Quartz is used for the substrate 1, and after sufficiently washing, the cathode electrode 2 is formed by the sputtering method.
A Ta layer having a thickness of 1000 nm was formed.

(Step 2) Next, as the insulating layer 3, plasma SiO ₂ was deposited to a thickness of 500 nm.

(Step 3) Next, a plasma SiN film is formed by 10
00 nm was deposited. CF plasma SiN film _FourUsing
Dry etching, patterning, and the separator 50.
And The distance between the SiN separators 50 at this time is 30 μm.
m. Then, as the gate electrode 4, Ta is 100
It was deposited by 0 nm sputtering.

(Step 4) The gate surface was processed into a concave shape by the CMP method. At this time, the difference between the maximum and the minimum film thickness of the gate electrode was 0.4 μm.

(Step 5) Next, by photolithography,
Spin coating of a positive photoresist (AZ1500 / Clariant) and a photomask pattern were exposed and developed to form a mask pattern.

(Step 6) Using the mask pattern as a mask
The Ta gate electrode 4 and the insulating layer 3 were each dry-etched using CF ₄ gas and stopped at the cathode electrode to form an opening having a width of 1 μm in the X direction and a length of 100 μm in the Y direction. The pitch between the openings at this time is 3 μm
And

(Step 7) Next, 60 is formed on the entire surface of the diamond-like carbon electron emission film 5 by the rf plasma CVD method.
The thickness was about nm. The film forming gas at that time is CH ₄ + A
r gas was used.

(Step 8) The mask pattern was completely removed, and the electron source of this example was completed.

The electron source manufactured as described above was arranged with the distance H between the anode electrode and the element being 1 mm. Va
= 5 kV and Vg = 15 V.

As a comparative example, the width of the openings in the X direction is 1 μm, the length in the Y direction is 100 μm, and the pitch is 3 μm.
An electron source was prepared in which the gate electrode 4 had a uniform thickness of 1 μm. Then, these two electron sources are simultaneously driven for comparison. The film thicknesses of the cathode electrode 2 and the insulating layer 3 of the comparative example are the same as those of the example.

An electrode coated with a phosphor was used as the anode electrode 7, and the sizes of the electron beams of the two electron sources were observed. Here, the size of the electron beam is the size up to a region of 10% of the peak brightness of the phosphor that has emitted light.

As a result, in the electron source of this example, an electron beam having a shape converged in the central part of the electron source was obtained as compared with the comparative example. The decrease in beam diameter in the X direction at this time was -7.51% with respect to the comparative example.

(Third Embodiment) FIG. 14 shows an electron source according to a third embodiment of the present invention.

In the above-described first embodiment, the cathode electrode and the gate electrode are formed to have a concave upper surface by making the cathode electrode thicker in the electron source peripheral portion than in the electron source central portion. In the above configuration, the upper surface of the cathode electrode and the gate electrode is made concave by interposing an underlayer having a thickness larger in the electron source peripheral portion than in the electron source central portion between the cathode electrode and the substrate. .

Except that the layer structure is different, the second embodiment is substantially the same as the first embodiment. Therefore, the common components are denoted by the same reference numerals, and the description thereof will be omitted. explain.

FIG. 14 is a schematic diagram showing a ZX cross section of the line type electron source according to the present embodiment.

As shown in the figure, the electron source is roughly the cathode electrode 2 arranged on the substrate 1 with the underlayer 121 interposed therebetween.
And a gate electrode 4 stacked on the cathode electrode 2 with an insulating layer 3 interposed therebetween, and an electron emission film 5 serving as a plurality of electron emission portions electrically connected to the upper surface of the cathode electrode 2. Composed.

The electron source has a plurality of openings penetrating the insulating layer 3 and the gate electrode 4 to expose a partial region of the cathode electrode 2, and the electron emission film 5 has a cathode electrode in each opening. It is formed on two exposed areas.

In this embodiment, the film thickness of the base layer 121 laminated on the substrate 1 is changed in the X direction. And
By stacking the cathode electrode 2 on the surface of the underlying layer 121 with a substantially uniform film thickness, the upper surface of the cathode electrode 2 is formed into a concave curved surface.

On the cathode electrode 2 thus formed, the insulating layer 3 and the gate electrode 4 are formed with a substantially constant film thickness. Therefore, the upper surfaces of the insulating layer 3 and the gate electrode 4 are also
Like the cathode electrode 2, it has a concave curved surface.

With this structure, the same effect as that of the first embodiment can be obtained.

[Example] A preferred method of manufacturing an electron source will be described below as an example of the electron source according to the present embodiment.

(Step 1) Quartz was used for the substrate 1 and after thorough cleaning, a plasma SiN film was deposited to a thickness of 1000 nm. The plasma SiN film was dry-etched using CF ₄ and patterned to obtain a separator 50. The distance between the SiN separators 50 at this time was 30 μm. After that, plasma SiO ₂ was deposited to a thickness of 1100 nm.

(Step 2) Plasma Si by CMP method
The O ₂ surface was processed into a concave shape to form a base layer 121. At this time, the difference between the maximum thickness and the minimum thickness of the underlayer 121 is 400 n.
It was set to m.

(Step 3) The cathode electrode 2 has a thickness of 4
00 nm Ta was formed.

(Step 4) Next, as the insulating layer 3, plasma SiO ₂ was deposited to a thickness of 500 nm.

(Step 5) 1 for Ta as the gate electrode 4
It was deposited by 000 nm sputtering.

(Step 6) Next, by photolithography,
Spin coating of a positive photoresist (AZ1500 / Clariant) and a photomask pattern were exposed and developed to form a mask pattern.

(Step 7) Using the mask pattern as a mask,
The Ta gate electrode 4 and the insulating layer 3 were each dry-etched using CF 4 gas and stopped at the cathode electrode to form an opening having a width of 1 μm in the X direction and a length of 100 μm in the Y direction.

(Step 8) Next, 60 is formed on the entire surface of the diamond-like carbon electron emission film 5 by the rf plasma CVD method.
The thickness was about nm. The film forming gas at that time is CH ₄ + A
r gas was used.

(Step 9) The mask pattern was completely removed, and the electron source of this example was completed.

The electron source manufactured as described above was arranged with the distance H between the anode electrode and the element being 1 mm. Va
= 5 kV and Vg = 15 V.

As a comparative example, the width of the openings in the X direction is 1 μm, the length in the Y direction is 100 μm, and the pitch is 3 μm.
m, the underlayer 121, the cathode electrode 2, the insulating layer 3, and the gate electrode 4 were flat. And these 2
It was decided to drive two electron sources at the same time for comparison. In addition, the cathode electrode 2, the insulating layer 3, and the gate electrode 4 of the comparative example.
The film thickness of is similar to that of the example.

An electrode coated with a phosphor was used as the anode electrode 7, and the sizes of electron beams from two electron sources were observed. Here, the size of the electron beam is the size up to a region of 10% of the peak brightness of the phosphor that has emitted light.

As a result, in the electron source of this example, an electron beam having a shape converged in the central portion of the electron source was obtained as compared with the comparative example. The decrease in the beam diameter in the X direction at this time was -14.50% with respect to the comparative example.

[0204]

As described above, according to the present invention,
It is possible to provide a highly efficient electron emitting device at a low voltage while realizing a further downsizing of the electron beam diameter.

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

[Brief description of drawings]

FIG. 1 is a schematic perspective view of an electron source according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of an electron source according to the first embodiment of the present invention.

3A and 3B are schematic views of an electron-emitting device according to the first embodiment of the present invention, in which FIG. 3A is a Z-X sectional view and FIG.
It is a Y top view.

FIG. 4 is a schematic cross-sectional view of an electron-emitting device according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a change in electron beam diameter when a ratio of heights of cathode electrodes in a central portion and a peripheral portion of an electron source is changed.

FIG. 6 is a schematic cross-sectional view showing the method of manufacturing the electron-emitting device according to the first embodiment of the invention.

FIG. 7 is a schematic cross-sectional view showing the method of manufacturing the electron-emitting device according to the first embodiment of the invention.

FIG. 8 is a schematic plan view showing a configuration of an electron source assembly according to the first embodiment of the present invention.

FIG. 9 is a schematic perspective view showing the configuration of the image forming apparatus according to the first embodiment of the invention.

10 is a schematic view of a fluorescent film suitable for the image forming apparatus of FIG.

11 is a block diagram of a drive circuit suitable for the image forming apparatus in FIG.

FIG. 12 is a schematic sectional view of an electron source according to a second embodiment of the present invention.

FIG. 13 is a schematic cross-sectional view of an electron-emitting device according to a second embodiment of the present invention.

FIG. 14 is a schematic sectional view of an electron source according to a third embodiment of the present invention.

FIG. 15 is a schematic sectional view of a conventional electron-emitting device.

FIG. 16 is a schematic sectional view of a conventional electron source.

[Explanation of symbols]

1 substrate 2 cathode electrode 3 insulating layers 4 gate electrode 5 Electron emission film 6 drive power supply 7 Anode electrode 8 high voltage power supply 9 equipotential surface 50 Separators 51 mask pattern 61 base 62 X-direction wiring 63 Y direction wiring 64 electron sources 71 electron-emitting device 81 electron source substrate 85 phosphor 86 Black conductive material 91 Rear plate 92 Support frame 93 glass substrate 94 Fluorescent film 95 metal back 96 face plate 97 High voltage terminal 98 envelope 121 Underlayer 1301 display panel 1302 scanning circuit 1303 control circuit 1304 shift register 1305 line memory 1306 Sync signal separation circuit 1307 Modulation signal generator

Claims (16)

[Claims] 1. A cathode electrode disposed on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and formed on the cathode electrode electrically connected to the cathode electrode. An electron source comprising a plurality of electron emitting portions, wherein the upper surface of at least one of the cathode electrode and the gate electrode has a concave shape. 2. A cathode electrode disposed on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and formed on the cathode electrode electrically connected to the cathode electrode. In an electron source including a plurality of electron emitting portions, a normal line of the upper surface of at least one of the cathode electrode and the gate electrode in the vicinity of the electron emitting portion is inclined toward the electron source center direction. Characteristic electron source. 3. A cathode electrode arranged on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and formed on the cathode electrode electrically connected to the cathode electrode. In an electron source including a plurality of electron emitting portions, a height from the substrate upper surface to the cathode electrode upper surface is
An electron source characterized in that the peripheral portion of the electron source is higher than the central portion of the electron source. 4. The electron source according to claim 3, wherein the cathode electrode is thicker in a peripheral portion of the electron source than in a central portion of the electron source. 5. The cathode electrode is arranged on the substrate via an underlayer having a larger film thickness in the electron source peripheral portion than in the electron source central portion.
The electron source described in. 6. The height from the upper surface of the substrate to the upper surface of the cathode electrode continuously increases from the central portion of the electron source toward the peripheral portion of the electron source. Electron source. 7. A cathode electrode disposed on a substrate, a gate electrode laminated on the cathode electrode via an insulating layer, and formed on the cathode electrode electrically connected to the cathode electrode. An electron source including a plurality of electron emitting portions, wherein the height from the cathode electrode upper surface to the gate electrode upper surface is higher in the electron source peripheral portion than in the electron source central portion. 8. The electron source according to claim 7, wherein the gate electrode is thicker in a peripheral portion of the electron source than in a central portion of the electron source. 9. The height from the upper surface of the cathode electrode to the upper surface of the gate electrode continuously increases from the central portion of the electron source toward the peripheral portion of the electron source. Electron source. 10. A plurality of openings that penetrate the insulating layer and the gate electrode to expose a partial region of the cathode electrode, wherein the electron emission portion is within the opening and the cathode electrode is formed. The electron source according to claim 1, wherein the electron source is formed on an exposed region. 11. The electron source according to claim 10, wherein the opening shape of the opening is any one of a circle, an ellipse, a rectangle, and a polygon. 12. The electron source according to claim 1, wherein the material of the electron emitting portion contains diamond or diamond-like carbon. 13. An electron source assembly comprising a plurality of electron sources according to claim 1, wherein a plurality of cathode wirings connected to the cathode electrode and the gate electrode are provided. An electron source assembly, wherein the plurality of electron sources are arranged in a matrix by a plurality of gate wirings to be connected. 14. An image forming apparatus, comprising: the electron source assembly according to claim 13; and an image forming member that forms an image by electrons emitted from the electron source assembly. 15. The image forming apparatus according to claim 14, wherein the image forming member is a phosphor that emits light by collision of electrons. 16. A step of laminating a cathode electrode on a substrate, a step of laminating a gate electrode on the cathode electrode via an insulating layer, and a plurality of electrodes electrically connected to the cathode electrode on the cathode electrode. And a step of forming an electron emission part of the same. After the cathode electrode or the gate electrode is laminated, the upper surface thereof is subjected to chemical mechanical polishing (CM).
P) A method of manufacturing an electron source, which comprises a step of processing into a concave shape.