JP2632883B2 - Electron-emitting device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold-cathode type electron-emitting device, and more particularly to an electron-emitting device that emits electrons by passing a current through the surface of the device.

[Conventional technology]

Conventionally, as an element that can obtain electron emission with a simple structure,
For example, published by Elinson et al. (Radio Eng. Ele
ctron.Rhys.10.1290.1965) Cold cathode devices are known.

This utilizes a phenomenon in which electron emission occurs when a current flows through a small-area thin film formed on a substrate in parallel with the film surface, and is generally called a surface conduction electron-emitting device (surface-emitting device). The name of the conduction type emission element is based on the description of the thin film handbook).

As the surface conduction electron-emitting device, in addition to the above-mentioned example of Elinson using a SnO ₂ (Sb) thin film, a device using an Au thin film or (GD
ittmar: Thin Solid Films 9, 317 (1972)), using ITO thin film (M. Hartwell and CGFonstad: IEEE Trans.ED)
Conf. 519 (1975)), and those using a carbon thin film (Hisashi Araki et al .: Vacuum, Vol. 26, No. 1, P-22 (1983)) and the like have been reported.

A typical device configuration of these surface conduction electron-emitting devices is the eighth device.
Shown in the figure. 21 and 22 are electrodes for obtaining an electrical connection, 23
Denotes a thin film formed of an electron emission material, 24 denotes a substrate, and 26 denotes an electron emission portion.

Conventionally, in these surface conduction electron-emitting devices, a process called forming is performed before electron emission. That is, by applying a voltage between the electrode 21 and the electrode 22, the thin film 23 is energized, and the thin film 23 is locally destroyed, deformed or deteriorated by the generated Joule heat, and has a high electrical resistance. This is to obtain the electron emitting section 25 in the state.

The above-mentioned electrical high resistance state means that 0.5 μ
A discontinuous film having a crack of m to 5 μm and having a so-called island structure inside the crack. In general, the island structure has fine particles having a diameter of several tens angstroms to several microns on the substrate 24, and each fine particle is a spatially discontinuous and electrically continuous film.

Conventionally, in the surface conduction electron-emitting device, electrons are emitted from the fine particles by applying a voltage to the high-resistance discontinuous film by the electrodes 21 and 22 and flowing a current to the surface of the device.

[Problems to be solved by the invention]

As described above, the conventional surface conduction electron-emitting device requires a forming step in manufacturing, and therefore has the following disadvantages.

(1) Since it is impossible to design an island structure serving as an electron emitting portion in the forming by the electric heating, it is difficult to improve the elements, and variations among the elements are likely to occur.

(2) The life of the island structure is short and unstable. In addition, the element is easily destroyed by external electromagnetic noise.

(3) Since an island is formed by the forming process, the degree of freedom in selecting an island constituent material is small.

(4) In the forming step, local heat concentration is required, so that the element shape is limited.

(5) The substrate is easily broken due to local heat concentration.

Due to the above-mentioned problems, the surface conduction electron-emitting device has not been actively used in industry, despite the advantage that the device structure is simple.

[Object of the invention]

The present invention has been made in order to eliminate the disadvantages of the conventional example as described above, and has a quality equal to or higher than that of an electron-emitting device obtained by a forming process without performing a process called the conventional forming as described above. It is an object of the present invention to provide an electron-emitting device having a novel structure that has small variations in characteristics, can control characteristics, and can control the position of an electron-emitting portion.

[Means (and action) for solving the problem]

The electron-emitting device according to the present invention is characterized in that a plurality of polycrystalline fine particles are dispersedly arranged on the insulator surface between the electrodes so as to be spaced apart from adjacent polycrystalline fine particles.

Conventionally, in a surface conduction electron-emitting device, electron emission is obtained by forming a thin film provided between electrodes into an island structure by a forming process.

However, the present inventors have conducted intensive studies on the forming process and its structure and electron emission characteristics. As a result, the forming process is performed by selectively positioning the fine particles of the polycrystalline material between the electrodes having minute intervals. It has been found that an electron emission function equivalent to or higher than that of the conventional surface conduction type element can be obtained without using the same.

Specifically, the present invention is characterized by an electron-emitting device having polycrystalline fine particles obtained by crystal growth between electrodes.

In other words, the fine particles of the polycrystalline material are selectively formed on the electrodes by utilizing the difference in the nucleation density of the deposition material depending on the type of the deposition surface material.

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view showing an embodiment of an electron-emitting device according to the present invention, and FIG. 2 is a schematic cross-sectional view taken along the line AB in FIG. In FIGS. 1 and 2, opposing electrodes 1 and 2 are provided on an insulator 5 such as glass, and fine particles 3 made of a polycrystalline material are dispersed and arranged therebetween to form an electron emitting portion 4. I have. Although not shown, electrodes are provided on the upper surface of the electron-emitting portion at intervals to extract emitted electrons. When a voltage is applied between the electrodes 1 and 2 in the vacuum vessel (this voltage is Vf), current flows between the electrodes (If), and the voltage is applied with the extraction electrode set to the + side. The electrons are emitted substantially perpendicularly to the element structure substrate 1 (this electron emission current is defined as Ie).

In the figure, the interval between the electrodes 1 and 2 is several hundreds to several tens.
μm is appropriate. The material of the fine particles used in the present invention is very wide, and almost any polycrystalline conductive material such as a normal metal, semimetal or semiconductor can be used. Among them, a normal cathode material having a property of a high melting point and a low vapor pressure with a low work relationship, a material for forming an electron-emitting device by a conventional forming process, and a polycrystal of a material having a high secondary electron emission efficiency are preferable. .

Specifically, borides such as LaB ₆ , CeB ₆ , YB ₄ and GdB ₄ . T
Carbides such as iC, ZrC, HfC, TaC, SiC, WC. Nitride such as TiN, ZrN, HfN. Nb, Mo, Rh, Hf, Ta, W, Re, Ir, Pt, Ti, Au, Ag, Cu, Cr, A
Metals such as l, Co, Ni, Fe, Pb, Pd, and Cs. In ₂ O ₃ , SnO ₂ , Sb ₂ O ₃
Such as metal oxides. Semiconductors such as Si and Ge, carbon AgMg
And the like can be cited as an example.

 Note that the present invention is not limited to the above materials.

Furthermore, in the present invention, different substances may be selected from the above-mentioned materials, and polycrystalline fine particles of two or more different substances may be formed according to the purpose.

As a method of forming polycrystalline fine particles on a substrate with good position controllability, there is a crystal growth method utilizing a difference in nucleation density of a desired material on an element constituting substrate. According to this method, after a region having a high nucleation density for a desired material is provided in advance on a substrate and crystal growth is performed, polycrystalline fine particles having a desired particle size can be formed at a desired position. it can. by this,
Since the island structure can be formed freely and more precisely, the variation in the electron emission characteristics can be suppressed and controlled.

As a method for forming the region having a high nucleation density, an evaporation method, an ion implantation method, or the like can be applied, and an optimum material and method can be selected for a desired material.

After the polycrystalline fine particles are formed, a counter electrode is formed at a position where the fine particles fall within a minute interval to complete the element.

In the electron-emitting device according to the present invention, a current flows through the surface, and is not affected by the substrate material. Therefore, the selection range of the material used for the substrate is wide.

 Hereinafter, the present invention will be described in detail using embodiments.

Embodiment 1 FIG. 3 is a schematic partial sectional view showing an embodiment of the electron-emitting device of the present invention.

As shown in the same drawing, the pressure was reduced on a clean # 7059 glass substrate (manufactured by Corning) 5 which had been subjected to cleaning and chemical etching.
A 500 nm Si ₃ N ₄ layer was deposited by CVD. Next, the Si ₃ N ₄ layer was patterned using ordinary photolithography to form circular Si ₃ N ₄ layers 6 having a diameter of about 5 μm at intervals of 5 μm.

Subsequently, Si was selectively grown on the substrate 5 using SiH ₄ as a raw material and a mixed gas of HCl and H ₂ as a carrier gas. At this time, the substrate temperature is ~ 600 ° C and the pressure is ~ 100 Torr.

Si ₃ N provided on a glass substrate 5 with a growth time of about several tens of minutes
Polycrystalline Si particles 3 grew around a material 6 different from the fine 5 of ₄ . The diameter of the polycrystalline Si fine particles 3 is approximately 5 μm
Met.

The thus obtained glass substrate on which the polycrystalline Si fine particles were grown was coated with Ni by photolithography and vacuum deposition so that the fine particles entered between the gaps as shown in FIG.
Electrodes 1 and 2 were formed (thickness: 1000 mm) to complete the device.

The device resistance of the electron-emitting device thus obtained is approximately
It had a high resistance of 1M ohm.

Next, the device according to the present invention was placed in a vacuum container of ~ 10 ^-5 Torr, a DC voltage was applied between the Ni electrodes 1 and 2, and 1 KV was applied to an extraction electrode provided at a position 5 mm away from the device, As a result of measuring the electron current, it was confirmed that electron emission occurred. In addition, the emission current is stable, and the element applied voltage Vf =
At 20 V, If was 0.1 mA and emission current Ie = 2.5 μA was obtained.

No difference was observed in the shape and arrangement of the fine particles before and after electron emission. Further, the variation in the electron emission characteristics between the respective devices was suppressed to within approximately 5%, and the reproducibility of the devices obtained through the same process was better than that of the conventional electron-emitting devices formed by the forming.

Example 2 As shown in FIG. 5, an amorphous SiO ₂ layer 8 was formed on a clean Si substrate by the CVD method at a thickness of about 1000 °. Next, using a focused ion beam apparatus, divalent Si ions were implanted on the SiO ₂ layer at an acceleration voltage of 40 KV to form regions 9 having a high nucleation density at intervals of 10 μm. At this time, the Si ion beam diameter was almost 0.2.
μm, the area where implantation was performed was a square area of 5 μm square,
The injection amount on the O ₂ surface is 1 × 10 ¹⁸ (ions / cm ² ). On the substrate thus formed, Si was applied in the same manner as in the first embodiment.
Using a mixed gas of H ₄ , HCl, and H ₂ , polycrystalline silicon fine particles were grown in the Si injection region by a CVD method. At this time, the growth time is 60 minutes, and the diameter of the fine particles is approximately 10 μm.
Met.

Further, as shown in FIG. 5, ion implantation is performed again on the same substrate to form a region 11 having a high nucleation density.
The nucleus growth of Si was performed again by the CVD method for 10 minutes. As a result, two types of polycrystalline Si fine particles having different sizes were formed on the same substrate by controlling the position. Finally, as shown in FIG. 6, Ni electrodes 1 and 2 are formed by vapor deposition (thickness of 1000) so that two kinds of fine particles, large and small, are both contained inside the gap.
Ii) The device was completed.

The electron-emitting characteristics of the electron-emitting device thus obtained were much more stable than those of the conventional device requiring forming, and the fluctuation range of the current was within approximately 5%.

In the device in which the size and the interval of the fine particles were constant, the reproducibility of various characteristics was good.

Example 3 FIG. 7-a shows a top view of an electron-emitting device formed of a thin film having a laminated structure. In the figure, 5 is a substrate constituting an element, 13 and 13 'are insulating layers, 14 is an altered region having a high nucleation density, 15 is polycrystalline fine particles grown from 14, 1,
Reference numeral 2 denotes an element driving electrode.

FIG. 7-b shows a cross-sectional view along AA 'in FIG. 7-a, and FIG. 7-c shows a cross-sectional view along BB' in FIG. 7-a.

The lower comb-shaped electrode 1 was formed on a normal # 7059 glass substrate (manufactured by Corning Incorporated) 5 using ordinary vacuum evaporation and photolithography techniques. Next, after protecting the comb-shaped electrode 1 with a photoresist, an SiO ₂ insulating film 13 is formed at a thickness of 1000 ° by the CVD method, and then, as shown in FIG.
The Si ₃ N ₄ layer 14 was formed to a thickness of about 200 μm by the CVD method, and was formed into a stripe shape having a width of 0.5 μm by chemical etching. Further, after forming an SiO ₂ layer 1000 ° similarly to the SiO ₂ insulating film 13 ′, the upper comb-shaped electrode 2 was formed, and the resist was lifted off to complete the device.

The device thus obtained has a layered structure composed of SiO ₂ , Si ₃ N ₄ and upper and lower electrodes, and the end faces of each layer are exposed as shown in FIG. 7-c. Therefore, selective nucleus growth of Si was performed on the end face portion by using the same method as in Example 1, and Si polycrystalline fine particles were grown only on the Si ₃ N ₄ portion.

As a result of measuring the electron emission characteristics of the electron-emitting device thus obtained, the same good results as those of the first and second embodiments were obtained.

〔The invention's effect〕

As described above, by forming an element structure in which a plurality of polycrystalline fine particles are dispersedly arranged on the insulator surface between the electrodes at a distance from the adjacent polycrystalline fine particles, the surface which conventionally required the forming process is formed. The following effects are obtained as compared with the conduction electron-emitting device.

1. Stable electron emission can be obtained because the polycrystalline fine particles can be fixed on the substrate.

2. Easy to optimize device structure.

3. Good reproducibility of element characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing one embodiment, FIG. 2 is a schematic cross-sectional view taken along the line AB in FIG. 1, and FIG. 3 is a cross-sectional view showing one embodiment according to the present invention. 4, FIG. 4 is a top view of FIG. 3, FIG. 5 is a top view showing one embodiment in which the size of fine particles is controlled, FIG. 6 is a top view of the element shown in FIG. 5, FIG. 7, FIG. 7-b and FIG. 7-c are schematic views of a device implemented by applying the present invention, and FIG. 8 is a plan view of a conventional electron-emitting device. 1,2 Ni electrode 3,10,12 Polycrystalline fine particles 4 Electron emission part 5,7 Device substrate 6 ... Si ₃ N ₄ micro thin film 8,13 Insulating thin film 9,11 ... Si ion implanted layer 21,22 ... Electrode 23 ... Thin film 24 ... Substrate 25 ... Emitting part

Continuing on the front page (72) Inventor Yoshikazu Banno 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hidetoshi Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kojiro Yokono 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-63-207028 (JP, A) JP-A-59-69495 (JP, A) JP-A-64-107440 (JP, A) JP-B-53-25632 (JP, B2)

Claims (5)

(57) [Claims] 1. An electron-emitting device wherein a plurality of polycrystalline fine particles are dispersedly arranged on an insulator surface between electrodes so as to be spaced apart from adjacent polycrystalline fine particles. 2. The electron-emitting device according to claim 1, wherein said polycrystalline fine particles are obtained by crystal growth. 3. The electron-emitting device according to claim 2, wherein said polycrystalline fine particle growth site is a region where nucleation density is sufficiently higher than a non-growth site. 4. The electron-emitting device according to claim 1, wherein said electrodes are arranged side by side along said insulator surface. 5. The electron-emitting device according to claim 1, wherein said electrodes are stacked with said insulator interposed therebetween.