JPH0343932A - Electron emitting apparatus - Google Patents

Abstract

PURPOSE:To obtain a highly reliable electron emitting apparatus without peeling liable to occur between a film and a substrate at the time of use and with high electron emission rate by providing a good thermally conductive insulating member, a dense resistor film with high film density, an insulating protective film, a porous reducing member with film density lower than the resistor film and an electron emitting member. CONSTITUTION:A protective film 5 formed to cover a resistor film 3 protects the resistor film 3 against external atmosphere as well as functions to suppress peeling of the resistor film 3 from an insulating member 4 during use. By forming a reducing member 2 of a porous body, it can conform with an electron emitting member 1 provided on the reducing member 2 while the electron emitting member 1 partly enters the reducing member 2 thereby enhancing efficiency of electron emission. Thus peeling of the dense resistor film 3 from the insulating member 4 can be suppressed thereby realizing high efficiency of electron emission as well as obtaining a highly reliable electron emitting apparatus with long service life and high performance.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to 1000'C electron guns for cathode ray tubes, etc.
This invention relates to the structure of a stacked electron emitting device that efficiently emits electrons at moderately high temperatures.

[Prior Art] Conventionally, when manufacturing a flat layered electron emitting device with a cathode material layer, a so-called thick film method such as screen printing is used, as described in Japanese Patent Publication No. 55-24846. It was manufactured using circuit formation technology. FIG. 2 is a cross-sectional configuration diagram showing a conventional electron emitting device manufactured in this manner. First, raw materials are prepared to take over the Nanau Misoku substrate (10), and a heating element layer (11) in a desired pattern is formed on the belt by extrusion or casting printing technology, which is passed between rolls. An insulator <1> is placed on the substrate (10) on which this heating element layer (11) is formed.
2) is formed, and furthermore, a cathode material layer (13), a cutter 1 layer (14), and a heat metal layer (15) are formed on this insulator layer (12) by the same printing method. A radiating device is formed.These heating element layers (1
Each layer including 1) is formed by screen printing Pase I, which is a mixture of materials with a baking aid added, on the substrate (10) one after another.
000-2000°C) to form an electron emitting device.

This method involves a high temperature treatment process during manufacturing, so if the heater is used at a temperature below 7m degrees, it is expected that the heater will have long-term stability at high temperatures, such as small changes in resistance over time, and at the same time, the cathode will also have long-term stability at high temperatures. was expected.

However, the pattern accuracy obtained by screen printing is low, and it is difficult to control the thickness of the heating element (thinning it), resulting in high power consumption.Moreover, there is large variation in resistance between multiple heaters, so the cathode electron The radiation also varied widely and was unreliable. Therefore, PVD and CV are methods that can form patterns with high precision.
Development of a film forming method using D was in progress.

FIG. 3 shows a conventional electron emitting device using a thin film formation method.

First, a resistor (heating element) film <17) for a heater is placed on a smooth seven-layer substrate <lO>, and then the opposite (11)
A base metal (reducing member) film (18) is formed in a negative shape, then a desired heater pattern and cathode pattern are formed by etching, and an electron emitting member (19) is applied on the base metal film. However, an electron emitting device was realized by connecting a lead wire (20) to the heater side.

[Invention or problem to be solved] As described above, the electron emitting device using the film forming method is IJ-
A voltage is applied to the lead wire to heat the heater, and the ceramic
・During use, peeling occurs between the film and the substrate by heating Ka-F and emitting electrons through the Nox substrate (lO). Peeling occurs between the resistor film <10> and the resistor film <17) or the seven Minox substrate <10> and the base metal film (18). This is mainly due to the fact that the adhesion of the film to the substrate was originally weak, that the internal stress balance CJ changed due to the thermal history during use, and that the thermal expansion coefficients of the film and the substrate were different. . As a result, the heat capacity changes due to peeling, the resistance value as a heater fluctuates (), the wire breaks in the heater, and the amount of electrons emitted from the cathode fluctuates due to the change in heat capacity. Furthermore, base metal (reducing member) film <18)
The compatibility with the cathode material was poor, and the electron emission characteristics were poor.As a result, both the heater and the cathode were unstable, lacked long-term reliability, and their performance was far from satisfactory.

In this way, for electron emitting devices, there are two choices: to use thick film circuit formation technology to provide a porous film that is stable at high temperatures on both sides, or to use thin film formation technology to create a film that is dense, has low adhesion, and has good pattern accuracy. It is one of the few that has been formed using only one method, and its performance is not fully demonstrated.

This invention was made in order to solve the above-mentioned problems, and aims to provide a highly reliable electron emitting device that is less likely to cause separation between the film and the substrate during use, and has high electron emission efficiency. The purpose is

[Means for Solving the Problems] An electron emitting device according to the present invention includes an insulating member with good thermal conductivity, and one surface of the insulating member formed into a predetermined shape using a high melting point and good electrical conductivity material. A dense resistor film with high film density, an insulating protective film formed to cover the resistor film, and a good heat conductive reducing material formed into a predetermined shape on the other surface of the insulating member, It is equipped with a porous reducing member having a low film density than the resistor film, and an electron emitting member formed on the reducing member by partially penetrating into the pores of the reducing member.

[Function] In the present invention, the protective film formed to cover the resistor film protects the resistor film from the external atmosphere and acts to prevent the resistor film from peeling off from the insulating member during use. do. In addition, by forming the reducing member with a porous material, it is better compatible with the electron emitting member provided on the reducing member, and since the electron emitting member partially penetrates into the reducing member, the electron emission is increased. It affects efficiency.

[Example] An example of the present invention will be described below based on the drawings. FIG. 1 is a cross-sectional configuration diagram showing an electron emitting device according to an embodiment of the present invention. In the figure, <1) is an electron emitting member, (2> is a reducing member (base metal) made of a porous material with a low film density that reduces the electron emitting member (1),
The - part of the electron emitting member (1) has entered the hole of the reducing member (2)., (3) heats the cathode consisting of the electron fraction i'4' (1) and the reducing member <2). This is a dense resistor film with a high film density for heaters, and is formed into a predetermined shape using a high melting point and electrically conductive material. (4)
is interposed between the reducing member (2) and the heater resistor film <3>, electrically insulating the two and transferring the heat generated from the heater resistor film (3) to the reducing member (2). An insulating member <5> made of raw electrical insulation material for efficient conduction, <5>, is formed to cover the heater resistor film <3>, and the resistor film <3> is connected to the outside. It is a protective film to protect from the atmosphere.

For example, the following properties are required for each material. The insulating member (4) corresponding to the substrate, which is the structure of the electron emitting device, has good thermal conductivity.
Thermal expansion coefficient or heater resistor film <3) and reducing member <2
It is similar to that of 〉, has a long edge, is prone to dielectric breakdown at high temperatures, and is smooth. Therefore, considering availability, 8IN, A1.203, etc. are considered. For the resistor film for heaters (3), the vapor pressure in the high temperature range should be low and the electrical characteristics should be stable in the high temperature range. Therefore, Mo
, W, Pt, TaTiN, TiC, T1CN, etc. can be considered. In particular, TiN, TiC, and T1C, which have a high recrystallization temperature and good stability at high temperatures, have a high recrystallization temperature.
N is suitable. For the protective film 5>, diffusion at high temperatures should be small, the softening point or melting point should be higher than the operating temperature, and the film should have a long edge. Therefore, 5i02.
Possible materials include Al2O3, which has a high softening point and high melting point, and is stable and glassy, and ceramic materials such as 8IN and 13N. For example, 5102 has a softening point of 1710°C (quartz), a melting point of 1470°C (crystalline), and A ]-203 has a melting point of 2
030°C. It may also contain substances that are scattered outside during firing, such as Cab, Y2O3, etc.

The reducing member (2) must have low vapor pressure in a high temperature range, stable electrical properties in a high temperature range, and an electron emitting member <1
) has a high reducing property, and the porous membrane has good compatibility with the electron emitting member <1).

In view of the above conditions, a single-crystal sapphire substrate (81.203) is used as the insulating part 4), and powder W is sintered on the sapphire substrate as the reducing part 2).
As the heater resistor film <3>, TiN was formed by the sputtering method, and as the insulating protective film <5), 8IN was formed by the sputtering method, and electrons were deposited on the W of the reducing member (2). Radiating member (
1) A method for manufacturing an electron emitting device coated with (Ba, Sr, Ca) CO3 will be described. The reference photograph shows a surface photograph of the porous W film used as the reduction subassembly (2) in the example. In the photo, 0067 is the film number, +5. O
KV is the accelerating voltage of the scanning electron microscope, X2.000 is the magnification of 2000 times, and 10 μm is the length of the line directly above it is 10 μm.
represents that it corresponds to

First, prepare a sapphire substrate 4 with mirror-polished finish on only one side, screen print the desired cathode pattern on the non-mirror-finished surface using W paste containing an organic solvent and baking aid, and then (1000-180
0 °C). Since the pattern on the cathode side is relatively simple, the accuracy can be satisfied even if the surface is not mirror-finished. Next, a mask with a desired heater pattern is set on the mirror-finished surface, and a TiN film (3) of a desired thickness (several μm to 10 μm) is formed by sputtering.

Next, an AIN film (5) is formed by sputtering on the surface on which the heater pattern is formed, and a heater resistor film (3) is formed thereon.

On the other hand, there is an electron emitting member on the surface of W (2) which is the reducing member.
>, for example, apply (Bn, Sr, Ca)CO3. This completes the electron emitting device. Next, the operation will be briefly explained. A constant voltage is applied to the heater resistor film <3>, and the heater resistor film <3> is heated to a predetermined temperature. The reducing part assembly (2) and the electron emitting member (1) are heated through the insulating part (4), and a voltage is applied between the grid and the cathode to cause the electron emitting member (1) to emit electrons.

For long-term use of such electron emitting devices, the heater resistor film (3) has a high recrystallization temperature and good high-temperature stability, so the change in resistance value is small and it is stable as a heater. Also, since it is covered with the protective film 5), it will not be damaged by the external atmosphere, such as acceleration of corrosion due to residual gas in the atmosphere, and it can also be prevented from peeling off from the substrate <4>. In addition, since the reducing member <2) is formed by sintering on a surface that is not mirror-finished, it has strong adhesion and is stable at high temperatures.Moreover, since it is a porous material, some of the electron emitting member <1> may penetrate. It has good compatibility with the electron emitting member (1) such as iron, and a stable high current density can be obtained.

In addition, after forming the heater and cathode all at once on a large-area insulating member (4), it is possible to divide it into the smallest chips to produce an electron emitting device in large quantities with less variation between products. .

Note that the heater resistor film <3) is TiC or TiN.

The reason for forming T1CN alone or a mixture thereof is as follows.
This is because it has a high recrystallization temperature and high electrical stability at high temperatures. For example, like the reducing member <2>, it is also possible to form it from a general heater material such as W or MO. When these materials are used at high temperatures of about 1000° C., they deprive (reduce) oxygen from the substrate Al2O3, form oxides with high vapor pressure, and scatter. In other words, the heater is quenched and its shape changes. Therefore, the environment where it can be used stably as a heater, such as the substrate (4) material,
Atmosphere and temperature are limited. However, it should be noted that W and Mo can also be used at temperatures below about 800°C.

1 Further, in the above embodiment, T iC is a heater material.

Although the method of forming TiN and T1CN by the sputtering method has been described, it goes without saying that they can also be formed by a so-called PVD method such as ion blasting, electron beam evaporation, or laser PVD method.

In addition, considering the use at high temperatures, TiCl4,
The thermal CVD method using CH4, N83, etc. is considered to be the best in terms of thermal equilibrium. Further, as a film forming method, there is also a plasma CVD method using a similar gas.

Further, in the above embodiment, the insulating member (4) is made of single crystal Al.
A 2O3 substrate was used, but if the leakage current and dielectric strength conditions are not strict, an AIN sintered substrate and an A
A substrate with a 1N film as a bottom film may also be used.

Furthermore, in the above embodiment, the reducing member 2> is W pace).
Although an example using a method of forming the cathode pattern by screen printing has been described, depending on the pattern accuracy, the cathode pattern may be formed by etching a pattern formed by thermal spraying, tardding, etc.

[Effects of the Invention] 2 As described above, according to the present invention, there is provided an insulating member with good thermal conductivity, and a film formed in a predetermined shape using a high melting point and good electrical conductivity material on one surface of the insulating member. A dense and precise resistor film, an insulating protective film formed to cover the resistor film, and a predetermined shape formed using a good heat conductive reducing material on the other surface of the insulating member, Since the resistor film is equipped with a porous reducing member having a lower film density than the body membrane and an electron emitting member formed on the reducing member by partially penetrating the pores of the reducing member, the resistor film is protected from the external atmosphere by the protective film. In addition, by suppressing the peeling of the dense resistor film from the insulating member, it is possible to provide a stable heater for the electron emitting device.Furthermore, by forming the reducing member with a porous material, the This improves the compatibility with the provided electron emitting member, and a portion of the electron emitting member penetrates into the reducing member, making it possible to achieve high efficiency in electron emission, and to achieve long-life, high-performance, and reliable electron emission. This has the effect of providing a radiation device.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an electron emission device according to an embodiment of the present invention, FIG. 2 is a cross-sectional configuration diagram showing a conventional electron emission device formed using thick film circuit technology, and FIG. 3 is a thin film circuit diagram. FIG. 2 is a cross-sectional configuration diagram showing a conventional electron emitting device formed by a forming method. In the figure, 1) is an electron emitting member, (2> is a reducing member, (3> is a heater resistor film, (4) is an insulating member, and (5) is a protective film. Note that the same reference numerals are used in the figure. indicates the same or equivalent part.

Claims (1)

[Claims] An insulating member with good thermal conductivity, a dense resistor film formed in a predetermined shape using a high melting point and good electrical conductivity material on one side of this insulating member, and a dense resistor film covering this resistor film. an insulating protective film formed, a porous reducing member formed into a predetermined shape using a good thermally conductive reducing material on the other surface of the insulating member and having a lower film density than the resistor film; and this reducing member. An electron emitting device comprising an electron emitting member formed by partially penetrating into the hole of the reducing member.