JPH02247938A - Electron emission element - Google Patents

Abstract

PURPOSE:To make an electron emission element to be independent from the environment, with less dispersion of the characteristics and to have a stable longer lifetime under low degree of vacuum by coating at least the surface of a field irradiated with electrons with organic compound having fluorine. CONSTITUTION:At least the surface of a range 5 irradiated with electrons is coated with organic compound containing fluorine. As for the organic compound containing fluorine, fluororesin such as polytetrafluoroethylene, fluorine random copolymer compound containing perfluoroalkyl group, fluorine surface active agent on the market and fluorine lubricating oil, etc. The amount of the applied organic compound 15 including fluorine is the amount not causing degradation of electron emission characteristics. The film thickness is less than 150Angstrom .

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron-emitting device, and particularly to an electron-emitting device that can obtain a stable emission current.

[Prior Art] Conventionally, as an element that can emit electrons with a simple structure,
For example, M.I. Ellingson (M, I.

A cold cathode device announced by John Elinson et al. is known. [Radio Engineering Electron Physics (Radio Hug, Elect
Ron.

Pbya, ) Volume 10, pp. 1290-129B,
11385] This device utilizes the phenomenon that electrons are emitted when a current is passed through a small-area thin film formed on a substrate parallel to the film surface, and is generally called a surface conduction electron-emitting device. It is.

This surface conduction type electron-emitting device includes one using a 5nOz (Sb) thin film developed by Ellingson et al., and one using an Au thin film [G.
Solid Films” (G, former ttmar: “Th1
n 5 solid Films”), volume 9, page 317,
(1972)], ■↑Thin film [M. Hartwell and C.G.
7 (M, Hartwell and C, G, F
onstad: IEEE Trans, ED Co
n? , ” ) 519 pages, (1975)], by carbon thin film [Hisashi Araki et al.: “Vacuum”.

Vol. 26, No. 1, p. 22 (1983)].

A typical device configuration of these surface conduction type electron-emitting devices is shown in FIG. 2. In FIG. 2, l and 2 are electrodes for obtaining electrical connection, and 3 is a thin film formed of an electron-emitting material. , 4 is an insulating substrate, and 5 is an electron emitting part.

Conventionally, in these surface conduction type electron-emitting devices, an electron-emitting portion is formed in advance by an electrical heating process called forming before electron emission. That is, by applying a voltage between the electrode 1 and the electrode 2, the thin film 13 is energized, and the Joule heat generated thereby causes the thin film 3 to be locally destroyed, deformed, or altered, resulting in a high electrical resistance. The electron emitting function is obtained by forming the electron emitting portion 5 in the state.

As mentioned above, the electrically high resistance state is 0.51 in a part of the thin film 3.
It refers to a discontinuous state film that has ~51 cracks and has a so-called island structure within the crack.The island structure is generally a structure in which fine particles with a diameter of several tens to a few centimeters are located on the substrate 4, and each fine particle has a space. A film that is electrically discontinuous and electrically continuous.

Conventionally, a surface conduction type electron-emitting device is one in which a voltage is applied to the above-mentioned high-resistance discontinuous film through an electrode 1.2, and a current is caused to flow across the surface of the device, thereby causing the above-mentioned fine particles to emit electrons.

[Problems to be Solved by the Invention] However, in the electron-emitting device manufactured by the conventional forming process using electric heating as described above, it is impossible to design an island structure that becomes the electron-emitting part, so it is difficult to improve the device. However, the position and characteristics of the electron-emitting portion tend to vary between manufactured devices, resulting in instability and poor reproducibility.

Therefore, as methods to create the above island structure without using forming, methods have been proposed such as a method of dispersing fine particles, a method of utilizing local precipitation phenomenon by heat treatment, and a method of directly spraying fine particles and depositing them on the island structure. has been done.

However, even when electron-emitting devices fabricated using these methods are exposed to an environment containing water or oxygen,

It was found that the characteristics varied, were unstable, and had poor reproducibility. This makes it difficult to control the characteristics when applying or manufacturing the device. Due to these problems, conventional surface conduction electron-emitting devices have not been actively applied in industry, despite having the advantage of a simple device structure, and are environmentally friendly. I was hoping for an element that was not easily affected.

In view of the above points, the present invention has been made to eliminate the above-mentioned problems of the conventional technology.5 Surface conduction type electron-emitting devices are not influenced by the environment by modifying the surface of the electron-emitting portion. The object of the present invention is to provide an electron-emitting device that has little variation in characteristics, is stable even in low vacuum, and has a long life.

[Means and effects for solving the problems] The present invention provides a surface conduction type electron-emitting device in which at least the surface of the region where electrons are emitted in the electron-emitting portion is covered with an organic compound containing fluorine. The present invention relates to a characteristic electron-emitting device.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is an explanatory diagram showing one embodiment of the electron-emitting device of the present invention. In FIG. 1, 4 is an insulating substrate, 1 and 2 are a pair of electrodes made of a low-resistance material for voltage application, 6 is an island-like structure formed of an electron-emitting material, and electrodes 1.2 The electron emitting section 5 is arranged at a minute interval between the two electrodes.

Further, at least the electron emitting portion on this element is covered with an organic compound film 7 containing fluorine.

The island-like structure referred to in the present invention is formed by fine particles or aggregation of fine particles with a particle size of several tens of amps to several micrometers, and an interval between each fine particle in the range of several tens of microns to 0.5 micrometers. good,
As the electron-emitting material used in this island-like structure, almost all conductive materials such as ordinary metals, semimetals, and semiconductors can be used in a very wide range. Among them, ordinary cathode materials with low work function, high melting point, and low vapor pressure, thin film materials that form surface conduction electron-emitting devices through conventional forming processing, and materials with high secondary electron emission coefficients. is suitable.

A desired electron-emitting device can be formed by selecting an appropriate material from these materials depending on the required purpose and using it as fine particles.

Specifically, LaBa, CeBs, YB4. Gd
Borides such as B4, Tic, ZrC, HfC, TaC,
Carbide such as SiC, WC, 7iN, zrN, HfN
Nitrides such as Nb, Mo, Rh, Hf.

Ta, W, Re, Ir, Pt, Ti, Au
, Ag, Cu, Cr, AR.

Go, Ni, Fe, Pb, Pd, Cs, B
Metals such as a, I n *Os *5nOx, Sb*
Examples include metal oxides such as Os, semiconductors such as Si and Ge, carbon, and AgMg. still,
The present invention is not limited to the above materials.

The electrode material is a common conductive material, Au.

In addition to metals such as Pt and Ag, oxide conductive materials such as SnO and ITO can also be used. In Figure 1, the appropriate thickness of the electrodes is from several hundred meters to several four meters, but it is not limited to this value, and the electrode spacing is approximately several hundred meters thick.
0 to several 100 I&m, and the width W dimensions are suitably from several ILm to several III, but are not limited to these L and W dimensions.

Organic compounds containing fluorine include so-called fluororesins such as polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoroethylene, tetrafluoroethylene-ethylene copolymer, polyvinyl fluoride, or fluorine-based random. Copolymer resins, copolymers containing perfluoroalkyl groups as one component, such as graft copolymer acrylic resins in which the main chain is perfluoroalkyl methacrylate and the branch chains are PMMA, and for those with lower molecular weight, perfluoroalkyl Compounds containing a group (Rf) (e.g. general formula RfCO
OH and its salt, CH! =CHC00CHsRf.

RfCHICHfiSi-(OCHI)l, RfCf
iH40H, RfCH=CH1, etc.), commercially available fluorine-based surfactants (e.g. perfluoroalkyl sulfonate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl trimethylammonium salt, perfluoroalkyl phosphate ester, etc.), commercially available fluorine Lubricating oil (
For example, perfluoropolyethers such as Fufubulin (product name: Monte Fluos), Krytox (Dupont), fluorinated oils, fluorinated glycols, etc.
Examples include sulfur, fluorine-based oligomer compounds, and the like.

The amount of the organic compound containing fluorine to be applied is preferably an amount that does not impair the electron emission characteristics. Although it depends on the electron-emitting material and the shape of the electron-emitting part, the film thickness is preferably 150 A or less.

Next, a method for manufacturing an electron-emitting device according to the present invention will be explained. In Fig. 1, a thin film that will become an electrode material is first formed on an insulating substrate made of cleaned glass, quartz, etc. by vapor deposition, sputtering, plating, etc. Next, micro-intervals that will become electron-emitting regions are formed by photolithography. Then, island structures of electron emitting material are formed. Methods include direct deposition by spraying fine particles, dispersion of fine particles,
One example is a method that utilizes local precipitation phenomena caused by heat treatment. Note that a thin film of the electron-emitting material is first formed, then an electrode material is deposited using a mask to form a pattern, and a voltage is applied between the electrodes to locally destroy and deform the thin film of the electron-emitting material using gel heat. Alternatively, a forming type element as shown in FIG. 2, in which the electron emission region is formed in an electrically high resistance state by alteration, is also possible. On the surface of at least the electron-emitting region of the electron-emitting region thus formed, a dry coating of an organic compound containing fluorine is formed by EB evaporation, resistance heating, ion, or vacuum evaporation such as brating, or a solvent is applied. Coating can be performed using known wet coating techniques such as dipping, barcoding, reverse roll coating, rod coating, spin-coating, and the like. At this time, parts outside the electron-emitting material may also be covered with this fluorine-containing organic compound, but with the coating thickness of the present invention, this does not pose a problem in most cases, and in some cases, the electrode surface may be masked. It is also possible to apply it using a method.

By covering the surface of the region where electrons are emitted with the fluorine-containing organic compound of the present invention, variations in characteristics are reduced.
Although the details of why they are stable and have a long lifespan are unknown, organic compounds containing fluorine have high water repellency and low surface energy, making it difficult for polar gas molecules, especially oxygen and water, to be adsorbed. This is thought to be because surface alteration of the island-like structure is avoided, preventing changes in characteristics.

[Example J] Hereinafter, the present invention will be explained in detail by way of examples based on the drawings.

First, an old electrode 3000A is formed on a clean quartz substrate by a vacuum evaporation method, and an electrode pattern as shown in FIG. 1 is formed using a photolithography method. L in Figure 1 is 30th grade,
The zero-order sample substrate with W set to 40 Gpm was set in the vacuum apparatus shown in FIG. The device shown in FIG.
The sample element 1G is set at position 10 in the figure. The degree of vacuum in the exhaust system 11 is 5 x 1G-'To
After exhausting to rr, the introduced Ar gas 12 is introduced into the particle generation chamber 7.
The zero-order conditions were as follows: pressure in the particle generation chamber 7 was 5 x 10-2 Torr, pressure in the particle deposition chamber 8 was I x 10-' Torr, nozzle diameter was 5φ, and distance between nozzle and substrate was 150 layers. P was produced by evaporating Pd from the evaporation source 13 of a carbon crucible under the above conditions.
d Fine particles are blown out from the nozzle 9 and deposited in a predetermined amount by opening and closing the shutter 14. At this time, the deposition thickness of the Pd fine particles was 100 A. Although the fine particles are placed over the entire surface of the sample, there is no problem with the Pd fine particles other than the formed electron emitting part because no voltage is substantially applied to them.The diameter of the Pd fine particles is about 50 to 200 A, and the center particle size is 100A
, scattered in islands on the substrate.

Next, apply FEP (tetrafluoroethylene-67) on the same sample.
Polypropylene copolymerization) resin is EB-deposited in vacuum.
The deposition rate of FEP was approximately 3.0 Al5et.

A thickness of 150 A was deposited using a mask near the electron emitting part.

After exposing this sample to an atmospheric environment with a temperature of 30°C and a humidity of 70% RH for 24 hours, I
The extraction electrode was set at a position 5 sam away from the device in the vertical direction of the substrate under vacuum, and the electrode 1. in FIG.
The measurement was performed with an applied voltage of 15 V between 2 and 3. As a result, stable electron emission was obtained with an average emission current of 0.9 pm and an emission current stability of ±9%. - Also, the reproducibility between elements was good, and the variation in characteristics (stability) was 5 to 17%. It is also possible to operate with a repeated electron emission life of 100 hours or more.

Ratio 10 Egami Samples were prepared and evaluated in the same manner as in Example 1, except that the FEP resin was not deposited in Example 1.

As a result, the average emission current was 1.0 μI, and the stability of emission current ±
37%, the variation is ±12 to 73%, and the variation is extremely large.The repeated life of electron emission is 20 to 73%.
It was 62 hours.

Instead of depositing the FEP resin in Example 1, a graft copolymerized acrylic resin containing a perfluoroalkyl group as one component (comb-shaped polymer LF-40 manufactured by Soken Kagaku ■) was deposited in toluene/ MEK = 1: It was dissolved in 1, applied by a spin code method, and dried at 80'CI for 5 minutes. The adhesion thickness was approximately 85A in terms of weight. Other than that,
It was processed and evaluated in the same manner as in Example 1. As a result, the average emission current was 1.2 μA, the stability of the emission current was ±11%, and the variation thereof was ±6 to 14%. The repeat life of electron emission was also 100 hours or more.

1 cliff crossing 1 Instead of Pd fine particles in Example 1, primary particle size 80-20O
A (7) S1102 dispersion (SnO2: i g p solvent: MEK/cyclohexanone = 3/1 10
00cc, butyral: lr) was spin-coated and heat-treated at 250°C to form OOH.
It was applied by a spin code method and dried at 80° C. for 10 minutes. The deposition thickness was approximately 12 OA. The rest was treated and evaluated in the same manner as in Example 1. As a result, the average emission current was 0.7
pA, stability of emission current is 5%, variation is ±4 to 12
%, and the repetition life of electron emission was 100 hours or more.

11A As shown in Fig. 2, a thin film 3 made of In2O3 with a film thickness of 1000A and a film thickness 1 are deposited on an insulating substrate 4 made of a white glass plate.
Electrodes 1 and 2 consisting of Aj) of 000 A were formed using a photolithography method. Then, a voltage of about 30 V was applied between the electrodes 1 and 2, electricity was applied to the thin wJ3, and the Joule heat generated thereby caused a thin film. 3 is locally made into an electrically high-resistance state to form an electron-emitting region, and a thermosetting fluororesin (Lumiflon manufactured by Asahi Glass Co., Ltd.) is applied to the surface of the electron-emitting region.
Dissolved in a solvent with a mixing ratio of xylene: methyl isobutyl ketone: incyanate (curing agent) = l: 1: 0.3,
It was spin coated onto the sample and cured at 230°C for 5 minutes. The deposition thickness at this time was about 40A.

The electron emission characteristics of the electron-emitting device obtained in this way are I
As a result of measurement under the condition of X 1O-5Torr, 15
At an applied voltage of v, an average emission current of 0.8 path A was obtained, stability of the emission current was about ±9%, and its variation was 7 to 20%.

The repeat life of electron emission was also 100 hours or more.

[Effects of the Invention] As explained above, in the electron-emitting device of the present invention, at least the surface of the region where electrons are emitted in the electron-emitting part is covered with an organic compound containing fluorine, so that the degree of vacuum, This element has the following effects: it can obtain a stable emission current with little fluctuation, regardless of the gaseous environment present in the air, has a long life, has little variation from element to element, and has good reproducibility. It is expected that this technology will contribute to extremely reliable products when applied industrially.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the electron-emitting device of the present invention, FIG. 2 is a schematic diagram of a forming-type electron-emitting device showing another embodiment of the electron-emitting device of the present invention, and FIG. FIG. 2 is a diagram of an embodiment of a vacuum apparatus for depositing fine particles between electrodes. 1.2... Electrode, 3... Thin film. 4... Insulating substrate, 5... Electron emission part. 6... Island-like structure, 7... Fine particle generation chamber, 8
...Particle deposition chamber, 9...Nozzle, lO...
Sample element, 12... Introduced Ar gas, 14... Shutter 11... Exhaust system, 13... Evaporation source. 15...Organic compound film.

Claims (2)

[Claims] (1) An electron-emitting device of surface conduction type, characterized in that at least the surface of a region from which electrons are emitted is covered with an organic compound film containing fluorine. (2) The electron-emitting device according to claim 1, wherein the film thickness of the fluorine-containing organic compound is 150 Å or less.