JPH0765701A - Manufacture of electron emission element and emitter for electron emission element - Google Patents

Abstract

PURPOSE:To provide an emitter for electron emission element which has high electron emission property and stability and in which the performance does not deteriorate for a long period by having a diamond thin film, whose surface is thermally performed as an emitter. CONSTITUTION:The surface of a silicon wafer substrate 2 is treated for damage with compound diamond particles and ultrasonic waves, and it is coated with spin-on-glass. Next, it is spin-coated with photoresist, and pattern is introduced with a mask analyzer. The pattern is 5mm in diameter, and the cover in this section is exfoliated. A diamond film 3 about 1 mum thick is selectively formed in the exfoliation part by microwave plasma CVD method, and then it is thermally reformed by heat treatment by current application under proper condition. After formation of an insulating layer 4 of polymide resin around the thin film 3, the film 3, which fuctions as an emitter, is so arranged on a layer 4 as to be caught, using a p-type silicon substrate as a collector 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electron-emitting device and an emitter for an electron-emitting device, and more particularly, it has high electron-emitting characteristics and stability and its performance does not deteriorate for a long period of time. , Cold cathode, flat CRT,
Manufacture of an electron-emitting device that can be preferably used in a wide field including electric and electronic fields such as an electron gun and a high-frequency device, and an emitter for an electron-emitting device for easily and simply manufacturing the electron-emitting device. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, a display, an electron beam drawing apparatus,
Electron-emitting devices used in vacuum tubes, electron beam printers, etc.
It was formed of a material such as silicon, molybdenum, SiC, SiN ₄ . However, these materials do not have sufficient oxidation resistance, sputtering resistance, stability, etc., and the conventional electron-emitting device formed of these materials cannot emit electrons stably for a long period of time. Had.

By the way, diamond has a negative electronegativity, thermal conductivity, oxidation resistance, sputtering resistance,
It has the characteristics of excellent stability. In addition, (11
1) It has a unique crystal structure having a face. Recently, there have been proposed some electron-emitting devices in which the diamond is applied to an emitter to solve the conventional problems.

For example, US Pat. No. 4,943,7
No. 20 discloses an emitter in which a diamond thin film is coated on the tip of a steel rod-shaped substrate whose tip is cut into a conical shape to form a diamond tip.
However, in this case, since the angle of the tip of the diamond tip is large and not sharp, there is a problem that electrons cannot be efficiently and stably emitted. Further, Japanese Patent Laid-Open No. 4-67527 proposes a semiconductor electron emitting device using diamond for a p-type semiconductor layer.
However, this semiconductor electron-emitting device is a device that emits electrons by a specific amplification mechanism called avalanche amplification, and differs from a normal electron-emitting device in the principle of emitting electrons. In this device, the unique crystal structure of diamond having the (111) plane is not effectively utilized. Therefore, these electron-emitting devices still have problems, and an electron-emitting device without such a problem is desired.

The present invention has high electron emission characteristics and stability, its performance is not deteriorated for a long period of time, and is applied to the electric and electronic fields such as cold cathodes, flat CRTs, electron guns, and high frequency devices. An object of the present invention is to provide an electron-emitting device that can be preferably used in a wide field, and a method for manufacturing an electron-emitting device emitter for easily and simply manufacturing the electron-emitting device.

[0006]

The invention according to claim 1 for solving the above-mentioned problems is an electron-emitting device characterized by having a diamond thin film whose surface is thermally modified as an emitter. The invention according to claim 2 forms a diamond thin film on the surface of a substrate by a vapor phase synthesis method,
A method for manufacturing an emitter for an electron-emitting device, which comprises forming an emitter by thermally modifying the diamond thin film at 200 to 1,150 ° C. The invention according to claim 3,
A diamond thin film is formed on the surface of the substrate by a vapor phase synthesis method, and the diamond thin film is subjected to a sputtering treatment.
A method for manufacturing an emitter for an electron-emitting device, characterized in that the emitter is formed by thermal modification at 00 to 1,150 ° C.

The electron-emitting device according to the present invention will be described in detail below along with a method of manufacturing an emitter for an electron-emitting device.

The electron-emitting device according to the present invention can be manufactured by the following method. The electron-emitting device is
1) a step of forming a diamond thin film on the surface of a substrate (hereinafter referred to as a diamond thin film forming step), 2) a step of thermally modifying the diamond thin film (hereinafter referred to as a thermal modifying step), and 3 ) A process including a step of forming a collector on a substrate on which a diamond thin film is formed (hereinafter referred to as an element forming step). further,
In addition to these, a step of sputtering the diamond thin film (hereinafter, referred to as a sputtering step) may be included prior to the 2) thermal reforming step.

1) Diamond thin film forming step In this diamond thin film forming step, a diamond thin film having a desired shape is selectively formed on the surface of the substrate.

In order to selectively form the diamond thin film having the desired shape, a diamond thin film selective forming method can be adopted.

The selective formation method of the diamond is not particularly limited and may be a method known per se. For example, a diamond thin film is formed after a pretreatment for forming a pattern on the surface of the substrate. I can list the method to do.

-Substrate- The material of the substrate is not particularly limited, but is, for example, silicon, gallium-arsenic, SiC, SiO.
₂ , Si ₃ N ₄ , SrTiO ₃ , MgO, alumina, A
Examples thereof include substrates that can be used as semiconductor substrates such as 1N, ceramics, sapphire, and cemented carbide. Of these, a silicon substrate is preferable. In the present invention, a silicon wafer can be preferably used as the substrate. Further, the substrate may be a P-type or N-type semiconductor. The specific resistance of the substrate is usually 10 ⁻⁶ to 10 ³ Ω · cm.

-Pretreatment-For the pretreatment, for example, a pretreatment for forming a pattern by a carbon film or a resist material and then performing a scratch treatment, a pretreatment for forming a pattern by a masking material and then performing an electric field plasma treatment, After forming the pattern by the resist material, the non-mask part is made porous by the anodization method and thermally oxidized to become SiO ₂ , and then the pretreatment for performing the electric field treatment or the scratch treatment, and the heat treatment after forming the pattern by the diamond-like carbon Pretreatment, after forming a pattern by the resist material containing diamond particles, the diamond particles remaining in the non-patterned portion are removed by ultrasonic cleaning, a pretreatment for etching the non-patterned portion, after coating with SiO _2. A pattern is formed by the resist material, and a non-pattern Of SiO ₂ emissions portion was dissolved in a solvent, it can be given pretreatment such as dissolving the pattern portion with a solvent.

As the carbon film, for example, a film made of carbon such as diamond-like carbon (DLC), glassy carbon, graphite and amorphous carbon,
Polyethylene, polystyrene, polypropylene, ABS
Membrane composed of carbon and hydrogen such as resin, polycarbonate, polyester, ethylene-vinyl acetate copolymer (E
VA resin), ethylene-ethyl acrylate copolymer (E
EA resin), polymethylmethacrylate resin, novolac resin, and other films composed of carbon, hydrogen, and oxygen.

Examples of the resist material include photoresists and resists for electron beams and X-rays.

The photoresist may be a negative photoresist or a positive photoresist. In addition to the commonly used resists, various known resin-based or rubber-based photoresists can be used.

Examples of commercially available negative photoresists include LMR-33 manufactured by Fuji Yakuhin Kogyo Co., Ltd. and OMR-83 and OMR-85 manufactured by Tokyo Ohka Kogyo Co., Ltd. Further, as the commercially available product of the positive photoresist, OFPR- manufactured by Tokyo Ohka Kogyo Co., Ltd. is used.
2 and OFPR-800.

As the masking material, for example, SiO
Examples thereof include carbides, oxides, and nitrides of transition metals such as ₂ , Si ₃ N ₄ , and SiC.

Here, specifically, the pretreatment of coating the surface of the substrate with SiO ₂ to form a pattern by the resist material, dissolving the non-patterned portion of SiO ₂ with a solvent, and dissolving the patterned portion with a solvent will be described in detail. explain.

[0020] covering the SiO ₂ on the surface of the substrate, an SiO ₂ film-forming coating material using a spinner or the like is applied to the surface of the substrate can be carried out by heat treatment.

As the coating material for forming the SiO ₂ film,
There is no particular limitation, but a silicon compound {general formula R _n S
It can be represented by i (OH) _4-n . However, n is a number of 4 or less. } And additives (for example, impurities for diffusion, glass forming agents and organic binders) dissolved in an organic solvent (for example, a solvent containing alcohol as a main component and optionally an ester and a ketone mixed therein). _{A 2} type film forming coating is preferred. S like this
A commercially available product can be used as the coating material for forming the iO ₂ film. Examples of the commercially available product include OCD (Type-1, Type-2, Type-) manufactured by Tokyo Ohka Kogyo Co., Ltd.
3, Type-7). SiO
_The thickness for applying ₂ is usually 0.05 μm or more and 0.
It is 5 μm or less. If the thickness is less than 0.05 μm, selective formation of diamond may not be sufficiently performed. If the thickness exceeds 0.5 μm, the SiO ₂ may not be easily removed by the solvent treatment performed later.

The pattern formation by the resist material is
It can be performed as follows.

That is, first, the above resist material is applied onto the SiO ₂ by using a method such as spraying, spinner, dipping, brush coating, etc., and dried,
A resist layer having a thickness of about 0.5 to 10 μm is obtained. Then, the resist layer is irradiated with light such as ultraviolet rays through a photomask having a light-shielding portion having the same shape as the pattern of a desired shape or an inverse shape, and the resist layer is exposed, developed, and rinsed. it can. Examples of the exposure method include a contact exposure method, a proximity exposure method, and a projection exposure method.

To dissolve the non-patterned portion with a solvent,
It can be performed using a solvent capable of dissolving SiO ₂ . The solvent is not particularly limited, and examples thereof include commercially available buffer hydrofluoric acid and a dilute solution of hydrofluoric acid (50%).

To dissolve the pattern portion with a solvent, a solvent capable of dissolving the resist material can be used. The solvent is not particularly limited, and a commercially available solvent for dissolving resist can be used, for example.

From the above, the Si on the surface of the substrate is
A pattern of O ₂ that is the same as or opposite to the desired pattern can be formed. When this pretreatment is adopted, the SiO ₂ may be removed using a solvent such as the buffer hydrofluoric acid after forming the diamond thin film described later.

-Formation of Diamond Thin Film- The diamond thin film can be formed by various diamond vapor phase formation methods known per se.

Examples of the diamond vapor phase forming method include a CVD method, a PVD method, a PCVD method, and a method combining these. Among these, various hot filament methods including the normal EACVD method, and various direct current plasma CVD including the thermal plasma method
Method, various alternating current including thermal plasma method (50Hz, 60H
z, 13.5 MHz, etc.) Plasma CVD method, microwave plasma CVD method including thermal plasma method and the like can be preferably mentioned.

Examples of the carbon source gas used in the diamond vapor phase formation method include paraffin hydrocarbons such as methane, ethane, propane and butane; olefin hydrocarbons such as ethylene, propylene and butylene; acetylene;
Acetylene-based hydrocarbons such as arylene; Diolefin-based hydrocarbons such as butadiene and allene; Alicyclic hydrocarbons such as cyclopropane, cyclobutane, cyclopentane and cyclohexane; Aromatic such as cyclobutadiene, benzene, toluene, xylene and naphthalene Hydrocarbons; Ketones such as acetone, diethyl ketone, benzophenone; Alcohols such as methanol, ethanol; Other oxygen-containing hydrocarbons; Amines such as trimethylamine and triethylamine; Other nitrogen-containing hydrocarbons; Carbon dioxide gas, one Carbon oxide,
Carbon peroxide etc. can be mentioned.

Among these, paraffin hydrocarbons such as methane, ethane and propane, alcohols such as ethanol and methanol, ketones such as acetone and benzophenone, amines such as trimethylamine and triethylamine, carbon dioxide and carbon monoxide. Carbon monoxide is particularly preferable. Incidentally, these may be used alone,
Alternatively, two or more kinds may be used together as a mixed gas or the like.

Further, these may be used as a mixture with an active gas such as hydrogen or an inert gas such as helium, argon, neon, xenon or nitrogen.

Further, when manufacturing a diamond semiconductor, a doping gas can be mixed with the carbon source gas. As the doping gas, B ₂ H ₆ or the like can be used when obtaining a P-type diamond semiconductor, and PH ₃ or the like can be used when obtaining an n-type diamond semiconductor.

The conditions for forming diamond are not particularly limited, but for example, the reaction pressure is usually 10 ^-6 to 1
It is 0 ³ Torr, preferably 1 to 760 Torr. When the reaction pressure is lower than 10 ⁻⁶ Torr, the diamond formation rate may be slow. On the other hand, if higher than 10 ³ Torr is, 10 ³ Torr
There may be no more effect than the effect obtained at.

The surface temperature of the substrate varies depending on the means for activating the carbon source gas and so cannot be specified unconditionally, but is usually room temperature to 1,200 ° C., preferably room temperature to 1,100. ℃. If the surface temperature of the substrate is lower than room temperature, formation of crystalline diamond may be insufficient. On the other hand, if the temperature exceeds 1,200 ° C., the formed diamond may be easily etched.

The reaction time is not particularly limited, and it is preferable to appropriately set the reaction time according to the diamond formation rate so that the diamond has a desired thickness.

The thickness of the diamond to be formed can be appropriately selected according to the purpose and is usually 0.5 to 10
It is 0 μm, preferably 1 to 50 μm. If the thickness is too thin, it may not be possible to perform uniform heat treatment in the subsequent thermal modification treatment, sputtering treatment, or the like, and stable emitter characteristics may not be obtained. On the other hand, if it is too thick, the effect corresponding to it is small, and the diamond thin film may be peeled off, so that a good emitter may not be formed.

As described above, the diamond thin film is selectively formed on the surface of the substrate with high dimensional accuracy.

2) Thermal Modification Step In this thermal modification step, the diamond thin film formed on the surface of the substrate is subjected to a specific heat treatment to thermally modify the diamond thin film.

The heat treatment can be carried out under the conditions of pressure, temperature, time, heating method and the like as follows.

The pressure is usually 2 × 10 ^-3 Tor
r or less, and preferably 5 × 10 ⁻⁴ Torr or less. If the pressure exceeds 2 × 10 ⁻³ Torr, the residual gas may cause contamination.

The temperature is usually 200 to 1,15.
0 ° C., preferably 300 to 900 ° C., especially 400
750 degreeC is preferable. If the temperature is less than 200 ° C, the heat treatment effect may not be sufficiently exhibited. on the other hand,
If the temperature exceeds 1,150 ° C, diamond oxidation may occur.

The time is usually 30 seconds to 1 hour, preferably 5 minutes to 1 hour, and particularly preferably 10 minutes to 1 hour. If the time is less than 30 seconds, the heat treatment effect may not be sufficiently exhibited. On the other hand, if the time exceeds 1 hour, the technical effect commensurate with it may not be obtained.

The heating method is not particularly limited, and examples thereof include a heating method by energization, a heating method by an infrared lamp, and a heating method by a heater. To perform the heating, a heating device known per se can be used.

It is considered that the above-mentioned thermal modification step can expose a surface state having a low work function to the surface of the diamond thin film formed on the surface of the substrate. In any case, the diamond thin film is used as an emitter. Can be modified into a suitable state.

In the present invention, the following sputtering step may be performed prior to the 2) thermal reforming step.

-Sputtering Step-In this sputtering step, the diamond thin film formed on the surface of the substrate is subjected to a sputtering process.

The sputtering process can be carried out by using a sputtering apparatus known per se by RF method, DC method, ion beam method and the like under various conditions such as pressure, gas and time as follows.

As the sputtering apparatus, for example, a 2-pole, DC 2-pole or high-frequency 2-pole sputtering apparatus,
An orthogonal electromagnetic field type sputtering device, a flat plate or coaxial magnetron sputtering device, a sputtering gun sputtering device and the like can be mentioned.

The pressure is usually 2 × 10 ^{-6 to 1} T
orr, preferably 10 ^{−4 to} 0.5 Torr, and particularly preferably 10 ^{−3 to} 0.2 Torr. The pressure is 2
If it is less than × 10 ^-6 Torr, the sputtering efficiency may decrease. On the other hand, if it exceeds 1 Torr, the discharge may become unstable depending on the method.

Examples of the gas include rare gases such as He, Ne and Ar, O ₂ gas and N ₂ gas.

The time is usually 10 seconds to 1 hour, preferably 30 seconds to 30 minutes, and particularly preferably 1 to 15 minutes. If the time is less than 10 seconds, the sputtering may not be performed sufficiently. On the other hand, if the time exceeds 1 hour, the effect of increasing the time is not so great, and diamond may be sputtered more than necessary.

It is preferable to carry out the sputtering treatment prior to the step 2) thermal modification step because a lot of surface states having a low work function can be exposed on the surface of the diamond thin film formed on the surface of the substrate.

3) Element forming step In this element forming step, a diamond thin film is used as an emitter, a collector is further formed, and a gate (hereinafter sometimes referred to as a base) is further formed if necessary. Thus, the electron-emitting device is manufactured.

The electron-emitting device may be composed of a tripolar device composed of an emitter, a gate and a collector, or may be composed of a bipolar device composed of an emitter and a collector. The structure may be a point type or a wedge type, and these may be horizontal or vertical. Examples of the vertical type include a planar type, and a non-planar type such as a closed type, an open type, and an FET type.

As the collector, for example, silicon,
Conductive materials such as Al, Au, Pt, Ti, Cr and Mo can be mentioned. The size, shape, etc. of the collector can be appropriately selected according to the size, shape, etc. of the emitter, the type of device, the application, etc.

The collector can be formed, for example, as follows. That is, on the surface of the substrate, around the portion where the diamond thin film is formed,
A layer of an insulating material having a thickness thicker than the diamond thin film is formed. Then, it can be formed by disposing the collector on the surface of the layer made of the insulating material.

As the insulating material, for example, polyimide,
Examples thereof include SiO ₂ and Al ₂ O ₃ . Of these, SiO ₂ is preferable.

In the case of the triode element, the gate is further provided outside the emitter and collector. The material of the gate is Si, Al, Au, Pt, T
i, Cr, Mo, etc. can be mentioned. The gate can be provided at a position between the collector and the diamond thin film, with an appropriately selected size, shape, and the like.

The electron-emitting device can be manufactured by an appropriately selected method known per se.

Here, a manufacturing method of an example of a sandwich type electron-emitting device composed of the bipolar device will be described.
This will be specifically described. In this case, first, an insulating layer made of polyamide resin is formed around the portion of the substrate where the diamond thin film is formed so that the insulating layer is thicker than the diamond thin film. Then, the collector is arranged on the insulating layer made of the polyamide resin so as to cover and seal the diamond thin film. Then,
An electron-emitting device 1 having an emitter of a diamond thin film 3 formed on the surface of a substrate 2 and an insulating layer 4 and a collector 5 formed so as to seal the emitter can be manufactured as shown in FIG. .

[0061]

【Example】

(Example 1) 1) Diamond thin film forming step-Substrate-A 30 mm x 10 mm silicon wafer was used as a substrate.

—Pretreatment— 0.2 g of synthetic diamond particles (Tokyo Diamond IMM) having a particle size distribution of 40 to 60 μm was dispersed in 20 ml of acetone, and the substrate surface was scratched for 15 minutes while being irradiated with ultrasonic waves.

SOG (Spin-On-Gl) is formed on the substrate.
ass) was coated to a thickness of 0.5 μm. This SOG
Is an OCD type 7 made by Tokyo Ohka Kogyo Co., Ltd. on the substrate.
Was spin-coated and annealed in a nitrogen atmosphere while heating at 400 ° C.

Then, a photoresist (Tokyo Ohka Kogyo Co., Ltd., OFPR-800) was spin-coated (3 ×).
A pattern was introduced by a mask aligner (PLA-501, manufactured by Canon Sales Co., Ltd.) with a resist of about 1 μm at 10 ³ rpm.

The pattern is Φ5 mm, and the SOG of this part
Was dissolved and removed with buffer hydrofluoric acid, and then the resist was dissolved and removed with a stripping solution to obtain a substrate for diamond synthesis.

-Formation of Diamond Thin Film- By the microwave plasma CVD method (2.45 GHz), CO / H ₂ was used as a source gas at 10/90 scc each.
A circular diamond thin film having a thickness of about 1 μm and a diameter of 5 mm is obtained by reacting under a condition that the reaction pressure is 40 Torr, the substrate temperature is 900 ° C., and the reaction time is 1 hour. It was selectively formed on the surface of the substrate.

2) Thermal modification step The substrate on which the diamond thin film was formed was subjected to a pressure of 5.7 ×.
The diamond thin film was thermally modified by conducting an electric heating treatment under the conditions of 10 ⁻⁹ Torr or less, a temperature of 700 ° C., and a time of 5 minutes.

3) Element Forming Step An insulating layer made of a polyimide resin having a thickness of 35 μm was formed around the portion where the diamond thin film was formed on the substrate. Next, a p-type silicon substrate was disposed as a collector on the surface of the insulating layer and the diamond thin film functioning as an emitter was sandwiched to form an electron-emitting device composed of two electrodes.

The IV characteristics of the obtained electron-emitting device were measured. Regarding the IV characteristics, a circuit was formed by connecting the substrate on which an emitter was formed to a cathode of a power source and connecting the collector to an anode of a power source, and installing an ammeter and a voltmeter in this circuit. After that, electricity was supplied, the current value and the voltage value were measured, and the measured values were assigned to the Fowler-Nordheim theoretical formula. The results are shown in the graph shown in FIG. 2 and as a white square plot. Note that FIG.
In the graph shown in, A means current and V means voltage. As a result, good electron emission characteristics were observed.

(Comparative Example 1) In Example 1, an electron-emitting device was manufactured in the same manner as in Example 1 except that 2) the thermal reforming step was not performed, and the IV characteristics were measured. The results are shown in the graph shown in FIG. 2 and as a white circle plot. As a result, almost no electron emission was observed.

(Example 2) In Example 1, 2) except that the sputtering step was performed for 5 minutes with argon gas under a pressure of 2 × 10 ^-2 Torr prior to the thermal reforming step.
An electron-emitting device was manufactured in the same manner as in Example 1, and its I-
The V characteristic was measured. The results are shown in the graph shown in FIG. 2 and as a black square plot. As a result, better electron emission characteristics than in Example 1 were observed.

(Comparative Example 2) An electron-emitting device was manufactured in the same manner as in Example 2 except that the thermal reforming step was not performed, and its IV characteristic was measured. The results are shown in the graph shown in FIG. 2 and as a black circle plot. As a result, almost no electron emission was observed.

[0073]

According to the present invention, it has high electron emission characteristics and stability, and its performance is not deteriorated for a long period of time. Therefore, it can be applied to electric and electronic fields such as cold cathodes, flat CRTs, electron guns, and high frequency devices. It is possible to provide an electron-emitting device that can be suitably used in a wide range of fields including the first, and a method of manufacturing an electron-emitting device emitter for easily and simply manufacturing such an electron-emitting device.

[Brief description of drawings]

FIG. 1 is a schematic cross sectional view showing an embodiment of an electron-emitting device according to the present invention.

FIG. 2 is an explanatory diagram showing an example of electron emission characteristics in the electron emitting device of the present invention.

[Explanation of sign]

1 ... Electron emitting device, 2 ... Substrate, 3 ... Diamond thin film, 4 ... Insulating layer, 5 ... Collector,

Claims (3)

[Claims] 1. An electron-emitting device having a diamond thin film whose surface is thermally modified as an emitter. 2. A diamond thin film is formed on a surface of a substrate by a vapor phase synthesis method, and the diamond thin film is formed into a thin film of
A method for manufacturing an emitter for an electron-emitting device, which comprises forming the emitter by thermal reforming at 1,150 ° C. 3. An emitter is formed by forming a diamond thin film on the surface of a substrate by a vapor phase synthesis method, subjecting the diamond thin film to a sputtering treatment, and thermally modifying the diamond thin film at 200 to 1,150 ° C. A method for manufacturing an emitter for an electron-emitting device.