JP2003045325A - Manufacturing method of field emission type electron source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a field emission type electron source which realizes easiness of manufacturing, high reliability and lower cost. SOLUTION: A structure as shown in Fig. (d) is obtained by a process of forming recessed portions 6c with a mask material layer 9 on the main surface of an conductive n-type silicon substrate 1 as a mask. Then, a structure as shown in Fig. (e) is obtained by depositing using a PCVD method silicon microcrystals of nanometer-size microparticles on the recessed portions 6c. Portions 5a in Fig. (e) are layers of microcrystals of silicon microcrystals filling the recessed portions 6c. A plurality of drift sections 6a are formed by an insulation layer forming process which forms a silicon oxide film as an insulation film on the surface of the silicone microcrystals forming a layer of microcrystals. Then, a structure as shown in Fig. (f) is obtained by forming a surface electrode 7 on a strong electric field drift sections 6 composed of drift sections 6a and heat radiation sections 6b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a field emission type electron source which emits an electron beam by field emission.

[0002]

2. Description of the Related Art Conventionally, as a field emission type electron source, there is a so-called Spindt type electrode disclosed in, for example, US Pat. No. 3,665,241. This Spindt-type electrode has a substrate on which a large number of minute conical emitter chips are arranged, and a gate layer which has a radiation hole for exposing the tip end of the emitter chip and is arranged in a manner insulated from the emitter chip. By providing a high voltage with the emitter tip serving as a negative electrode with respect to the gate layer in a vacuum, an electron beam is emitted from the tip of the emitter tip through the emission hole.

However, the Spindt-type electrode has a complicated manufacturing process, and it is difficult to form a large number of conical emitter chips with high accuracy. For example, when the Spindt-type electrode is applied to a flat light emitting device or a display, the area of the Spindt type electrode becomes large. There was a problem that it was difficult. In addition, the Spindt-type electrode is
Since the electric field is concentrated on the tip of the emitter tip, when the vacuum around the tip of the emitter tip is low and residual gas exists, the emitted gas ionizes the residual gas into positive ions, and the positive ions Since it collides with the tip of the tip, the tip of the emitter tip is damaged (for example, damaged by ion bombardment), current density and efficiency of emitted electrons become unstable, and the life of the emitter tip is shortened. There is a problem that it will end up. Therefore, in the Spindt-type electrode, in order to prevent the occurrence of this kind of problem, a high vacuum (about 10 ⁻⁵ Pa to about 10 ^{−6) is used.}
However, there is a problem that it is necessary to use it in Pa), the cost becomes high, and the handling becomes troublesome.

In order to improve this kind of problem, MIM
(Metal Insulator Metal) method and MOS (Metal Oxid)
A field emission electron source of the e Semiconductor) type has been proposed. The former is a plane-type field emission electron source having a laminated structure of metal-insulating film-metal and the latter metal-oxide film-semiconductor. However, in order to increase the electron emission efficiency (in order to emit many electrons) in this type of field emission electron source, it is necessary to reduce the film thickness of the insulating film and the oxide film. If the thickness of the insulating film or the oxide film is too thin, there is a risk of causing dielectric breakdown when a voltage is applied between the upper and lower electrodes of the laminated structure. There is a problem that the electron emission efficiency (drawing efficiency) cannot be made so high because there is a restriction on thinning of the insulating film and the oxide film.

On the other hand, as a field emission type electron source capable of improving electron emission efficiency, a single crystal semiconductor such as a silicon substrate has recently been disclosed in, for example, Japanese Patent Laid-Open No. 8-250766. Using a substrate, one surface of the semiconductor substrate is anodized to form a porous semiconductor layer (porous silicon layer), and a surface electrode made of a metal thin film (conductive thin film) is formed on the porous semiconductor layer. Then, a field emission type electron source (semiconductor cold electron emission device) configured to apply a voltage between a semiconductor substrate and a surface electrode to emit electrons has been proposed.

However, the above-mentioned Japanese Patent Laid-Open No. 8-2507
In the field emission electron source described in Japanese Patent Publication No. 66, a so-called popping phenomenon is likely to occur at the time of electron emission, and the amount of emitted electrons is likely to be uneven. There is a problem called.

Therefore, the inventors of the present application filed Japanese Patent Application No. 10-2.
No. 72340 and Japanese Patent Application No. 10-272342,
We propose a field emission electron source composed of a porous polycrystalline silicon layer obtained by oxidizing a strong electric field drift layer in which electrons injected from the conductive substrate drift between the conductive substrate and a metal thin film (surface electrode). did. This field emission electron source 1
0'is a conductive substrate n as shown in FIG.
A strong electric field drift layer 6 ″ made of an oxidized porous polycrystalline silicon layer is formed on the main surface side of the shaped silicon substrate 1, and a surface electrode 7 made of a metal thin film is formed on the strong electric field drift layer 6 ″. An ohmic electrode 2 is formed on the back surface of the silicon substrate 1. Although the non-doped polycrystalline silicon layer 3 is interposed between the n-type silicon substrate 1 and the strong electric field drift layer 6 ″ in the example shown in FIG. A configuration in which a strong electric field drift layer 6 ″ is formed on a silicon substrate is also proposed.

A field emission type electron source 10 'having the structure shown in FIG.
In order to emit electrons from the surface electrode 7, a collector electrode 21 arranged opposite to the surface electrode 7 is provided, and the surface electrode 7 is placed in a vacuum state between the surface electrode 7 and the collector electrode 21. A DC voltage Vps is applied between the surface electrode 7 and the n-type silicon substrate 1 so that the electrode 2) is on the higher potential side (positive electrode), and the collector electrode 2
A DC voltage Vc is applied between the collector electrode 21 and the surface electrode 7 so that 1 is on the high potential side with respect to the surface electrode 7. If the DC voltages Vps and Vc are appropriately set, the electrons injected from the n-type silicon substrate 1 drift in the strong electric field drift layer 6 ″ and are emitted through the surface electrode 7 (note that the chain line in FIG. A flow of electrons e ⁻ emitted through the surface electrode 7 is shown.) A material having a small work function (for example, gold) is adopted for the surface electrode 7, and the film thickness of the surface electrode 7 is set to about 10 nm to 15 nm. There is.

A field emission type electron source 1 having the above-mentioned structure.
At 0 ′, the current flowing between the surface electrode 7 and the ohmic electrode 2 is called the diode current Ips, and the collector electrode 21
If the current flowing between the surface electrode 7 and the surface electrode 7 is called an emission current (emission electron current) Ie (see FIG. 9), the emission current I with respect to the diode current Ips
The larger the ratio of e (= Ie / Ips), the higher the electron emission efficiency. In the field emission electron source 10 ′, the DC voltage V applied between the surface electrode 7 and the ohmic electrode 2
The electrons can be emitted even when ps is set to a low voltage of about 10 to 20V.

In this field emission type electron source 10 ', the degree of vacuum dependence of electron emission characteristics is small, and the popping phenomenon does not occur during electron emission, and electrons can be emitted stably with high electron emission efficiency.

In the above-described field emission electron source 10 ', the strong field drift layer 6 "is formed by depositing a non-doped polycrystalline silicon layer on the n-type silicon substrate 1 which is a conductive substrate, and then depositing the polycrystalline silicon layer. Is formed by anodic oxidation treatment, and the polycrystallized silicon layer (porous polycrystallized silicon layer) which has been made porous is oxidized at a temperature of, for example, 900 ° C. by a rapid heating method.
As the electrolytic solution used for the anodizing treatment, a solution prepared by mixing an aqueous solution of hydrogen fluoride and ethanol at a ratio of about 1: 1 is used. Further, in the step of oxidizing by the rapid heating method, a lamp annealing apparatus is used and the substrate temperature is raised from room temperature to 900 ° C. in dry oxygen, and then the substrate temperature is set to 900 ° C.
It is oxidized by maintaining it for a time, and then the substrate temperature is lowered to room temperature.

As shown in FIG. 10, the strong electric field drift layer 6 ″ formed as described above has at least a columnar polycrystalline silicon grain 51 and a thin silicon oxide film formed on the surface of the grain 51. 52 and grain 51
Intervening nanometer-order silicon microcrystals 63
And a silicon oxide film 64 which is an oxide film formed on the surface of the silicon microcrystal 63 and having a film thickness smaller than the crystal grain size of the silicon microcrystal 63. That is, in the strong electric field drift layer 6 ″, it is considered that the surface of each grain contained in the polycrystalline silicon layer before the anodization treatment is made porous and the crystalline state is maintained in the central portion of each grain. Therefore, most of the electric field applied to the strong electric field drift layer 6 ″ is concentrated on the silicon oxide film 64, and the injected electrons are accelerated by the strong electric field applied to the silicon oxide film 64 and the grains 5
1 drifts toward the surface in the direction of the arrow in FIG. 10 (upward direction in FIG. 10), so that the electron emission efficiency can be improved. The electrons that have reached the surface of the strong electric field drift layer 6 ′ are considered to be hot electrons, and easily tunnel through the surface electrode 7 and are emitted into a vacuum. By the way, in the above-mentioned field emission electron source 10 ′, it is possible to stably emit electrons with high electron emission efficiency without generating popping noise, but this is generated in the strong electric field drift layer 6 ″ during operation. It is considered that this is because the heat is radiated to the outside through the grain 51 and the temperature rise is suppressed.

In the above-mentioned field emission type electron source 10 ', an n-type silicon substrate is used as a conductive substrate.
As shown in FIG. 1, a field emission electron source 10 ″ using a conductive substrate 12 formed on one surface of an insulating substrate 11 made of a glass substrate has also been proposed. The same components as those of the source 10 'are designated by the same reference numerals and the description thereof will be omitted.

A field emission type electron source 1 having the structure shown in FIG.
In order to emit electrons from 0 ″, the collector electrode 21 arranged opposite to the surface electrode 7 is provided, and the surface electrode 7 is formed on the conductive layer 12 with a vacuum between the surface electrode 7 and the collector electrode 21. On the other hand, a DC voltage Vps is applied between the surface electrode 7 and the conductive layer 12 so as to be on the high potential side (positive electrode), and the collector electrode 21 is on the high potential side with respect to the surface electrode 7. A DC voltage Vc is applied between the electrode 21 and the surface electrode 7. By appropriately setting each DC voltage Vps, Vc, the electrons injected from the conductive layer 12 drift in the strong electric field drift layer 6 "and the surface Emitted through the electrode 7 (note that the chain line in FIG. 11 indicates the flow of the electrons e ⁻ emitted through the surface electrode 7). In the field emission electron source 10 ″ having the above-mentioned configuration, Flow between the conductive layer 12 The current flowing between the collector electrode 21 and the surface electrode 7 is called an emission current (emission electron current) Ie.
(Refer to FIG. 11), the diode current I
Ratio of emission current Ie to ps (= Ie / Ips)
Is larger, the electron emission efficiency is higher. The field emission electron source 10 ″ can emit electrons even when the DC voltage Vps applied between the surface electrode 7 and the conductive layer 12 is a low voltage of about 10 to 20V.

However, the field emission type electron source 1 in which the strong electric field drift layer 6 "is formed by utilizing the anodic oxidation treatment.
0 ′ and 10 ″ are the anodizing process being a wet process and the thickness of the porous region and the size and distribution of the silicon microcrystals become non-uniform in the plane, resulting in the strong electric field drift layer. Since the size and distribution of the silicon microcrystals 63 in 6 "become non-uniform, an in-plane distribution is generated in the electron emission characteristics (current density of emission current, electron emission efficiency, etc.) or a local defect occurs. As a result, dielectric breakdown occurs and the life is shortened, and it is difficult to increase the area in terms of in-plane uniformity.

On the other hand, a field emission type electron source having a structure shown in FIG. 12 has been proposed which can be manufactured without utilizing the anodizing process and which can suppress the occurrence of popping at the time of electron emission (Japanese Patent Application Laid-Open No. 2000-242242). 2001-68012). The field emission electron source having the configuration shown in FIG. 12 includes a strong electric field drift portion 6 ′ formed on one surface side of the n-type silicon substrate 1 which is a conductive substrate, and the strong electric field drift portion 6 ′ is The heat dissipation portion 6b 'having high thermal conductivity and the embedding hole 6
The drift portion 6a 'includes a large number of nanometer-sized conductive fine particles filled in c'and an insulating film covering each conductive fine particle. In this field emission electron source, the electrons injected into the drift portion 6a ′ of the strong electric field drift portion 6 ′ drift in the drift portion 6a ′ and are emitted through the surface electrode 7.

By the way, the strong electric field drift portion 6'in the field emission type electron source having the structure shown in FIG. 12 radiates heat by forming an embedded hole 6c 'on one surface side of the n-type silicon substrate 1 by an etching process. Forming the portion 6b ′, and then dispersing conductive fine particles whose surface is covered with an insulating film in a solvent such as an organic solvent and filling the embedded hole 6c ′ by spin coating, and then removing the solvent by drying. Drift part 6
a'is formed.

[0018]

However, in the method of manufacturing the field emission electron source having the structure shown in FIG. 12, the drift portion 6a 'has a film thickness of a solution (a conductive surface whose surface is covered with an insulating film). A solution in which fine particles are dispersed in an organic solvent)
The film thickness of the drift portion 6a ′ cannot be controlled by process parameters such as film formation time that are easy to control, because it is determined by the viscosity of the film and the rotation speed during spin coating. Since it becomes slightly thin, it is necessary to fill it in consideration of that amount.
It is difficult to control the film thickness of the device, the characteristics of each device vary greatly, the yield decreases, and as a result, it becomes difficult to reduce the cost.

Further, when the above solution is spin-coated, due to the effect of surface tension, the embedding hole 6c 'formed in the central portion of the n-type silicon substrate 1 and the embedding hole 6 formed in the peripheral portion thereof.
Since the filling amount of the above solution differs from that of c ′, the electron emission amount (current density of emission current) and electron emission efficiency vary within the plane, and when applied as an electron source for a display, etc. There was a problem that the brightness varied.

Further, it is difficult to cover the surface of the conductive fine particles with a thin and uniform insulating film, which causes a problem that the manufacturing is difficult.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing a field emission electron source which is easy to manufacture, has high reliability, and can be manufactured at low cost. It is in.

[0022]

In order to achieve the above-mentioned object, the invention of claim 1 is a conductive substrate, a strong electric field drift portion formed on one surface side of the conductive substrate, and a strong electric field drift portion. A high electric field drift part having a surface electrode formed on the upper part, a heat dissipation part having a high thermal conductivity in which a recess is formed along the thickness direction of the conductive substrate, and a large number of nanometer-order fine particles filled in the recess. And a drift portion including a large number of insulating films covering the surfaces of the respective fine particles. Electrons injected from the conductive substrate are applied to the drift portion by applying a DC voltage with the surface electrode serving as a positive electrode with respect to the conductive substrate. A method of manufacturing a field emission electron source that drifts and is emitted through a surface electrode, comprising a processing step of forming a recess on one surface side of a conductive substrate, and a deposition step of depositing a large number of fine particles in the recess, Characterized in that it comprises an insulating film forming step of forming an insulating film on the surface of each of the fine particles deposited in the portion, because it is possible to deposit a large number of nanometer-sized fine particles in the recess using a thin film forming technique, Fine particles can be filled in the recesses without performing processes such as anodic oxidation treatment and spin coating, which makes it easy to control the film thickness in the drift portion and forms an insulating film on the surface of each fine particle deposited in the recesses. Since it is formed in the process, the insulating film can be formed relatively easily as compared with the conventional case where the insulating film is formed on the surface of the fine particles in advance, and the manufacturing is easy and the reliability is high. It is possible to provide a field emission electron source capable of cost reduction.

According to the invention of claim 2, in the invention of claim 1, since the fine particles are made of nanocrystal Si or nanocrystal SiC, they are widely used as a raw material for forming the fine particles in a general semiconductor manufacturing process. The materials used can be adopted, and the cost can be reduced.

According to a third aspect of the invention, in the first or second aspect of the invention, the deposition step is plasma CVD.
Method, ECR-CVD method, or cluster beam method, the fine particles are deposited. Therefore, by controlling process parameters such as power, gas flow rate, and gas pressure at the time of film formation in the deposition step, nanometer size The fine particles of can be easily obtained.

According to the invention of claim 4, in the invention of claims 1 to 3, since the thickness of the drift portion does not exceed 2 μm, scattering of electrons injected into the drift portion is relatively small. As a result, the electron emission amount is increased, so that the emission current can be increased.

According to a fifth aspect of the invention, in the first to fourth aspects of the invention, the drift portion includes a first fine particle layer containing fine particles of a first size and a second fine particle layer containing fine particles of a second size. In the deposition step, the first fine particle layer and the second fine particle layer are alternately formed, so that the fine particle having the largest size of the first fine particle layer and the second fine particle layer is formed. Inclusively acts as an electrode equivalently, and an electric field is uniformly applied to the entire drift portion, so that the electron emission efficiency is improved.

According to a sixth aspect of the present invention, in the first to fifth aspects of the invention, the processing step is a reactive ion etching method, an electron beam processing method, a sandblast processing method,
Since the recess is formed by a method selected from the stamping method, the recess can be formed with a processing accuracy on the order of sub-μm.

According to a seventh aspect of the invention, in the first to sixth aspects of the invention, the conductive substrate is single crystal Si, polycrystalline Si, amorphous Si, single crystal SiC, or polycrystalline S.
Since it is selected from iC and amorphous SiC, the recess can be easily formed in the conductive substrate with high processing accuracy.

According to an eighth aspect of the invention, in the first to seventh aspects of the invention, the insulating film is an oxide film, and the insulating film forming step is a step of electrochemically oxidizing in an electrolytic solution. Therefore, it becomes possible to form the insulating film at a lower temperature than the case where the insulating film is formed by thermal oxidation.
Since the process temperature becomes low, restrictions on the material of the conductive substrate are reduced, and it is easy to increase the area and cost.

The invention of claim 9 comprises a conductive substrate, a strong electric field drift portion formed on one surface side of the conductive substrate, and a surface electrode formed on the strong electric field drift portion. A heat-dissipating portion having a high thermal conductivity in which a concave portion is formed along the thickness direction of the conductive substrate, a large number of nanometer-order fine particles filled in the concave portion, and an oxide film or a nitride film covering the surface of each fine particle. A drift portion including an insulating film made of an oxynitride film is used.By applying a DC voltage with the surface electrode serving as a positive electrode with respect to the conductive substrate, electrons injected from the conductive substrate drift in the drift portion and pass through the surface electrode. A method of manufacturing a field emission electron source to be emitted, comprising a processing step of forming a recess on one surface side of a conductive substrate, and an oxidizing species or a nitriding species or an oxidizing species and a nitriding species. And a deposition step of depositing the fine particles in the recesses in an ambient atmosphere, wherein a large number of nanometer-sized fine particles whose surfaces are covered with an insulating film can be deposited in the recesses using a thin film forming technique. Therefore, it is possible to fill the concave portion with the fine particles whose surface is covered with the insulating film without performing a process such as anodizing treatment or spin coating, which facilitates the control of the film thickness of the drift portion, and the fine particles are not required in advance as in the conventional case. Provided is a field emission type electron source capable of forming an insulating film relatively easily as compared with the case where the insulating film is formed on the surface of the substrate, being easy to manufacture, having high reliability, and being capable of cost reduction. can do. In addition, the number of steps can be reduced as compared with the case where an insulating film forming step such as an oxidizing step, a nitriding step, or an oxynitriding step is performed after the deposition step, which leads to an improvement in yield and cost reduction. It is possible to reduce the variation in the film thickness of the insulating film, improve the film quality, and reduce the in-plane variation in the emission characteristics.

According to a tenth aspect of the invention, in the first to ninth aspects of the invention, the surface of the drift portion and the surface around the drift portion of the strong electric field drift portion are flush with each other. The disconnection of the surface electrode on the strong electric field drift portion can be prevented, and the reliability is improved.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 4A shows a schematic configuration diagram of a field emission electron source 10 of the present embodiment, and FIG. 1 illustrates a method of manufacturing the field emission electron source 10. The main process sectional drawing of is shown. In this embodiment, a single crystal n-type silicon substrate 1 (for example, a (100) substrate having a resistivity of approximately 0.1 Ωcm) having a resistivity relatively close to that of a conductor is used as the conductive substrate. .

In the field emission electron source 10 of the present embodiment, as shown in FIG. 4A, the strong electric field drift portion 6 is formed on the main surface side (one surface side) of the n-type silicon substrate 1 and the strong electric field drift portion 6 is formed. A surface electrode 7 made of a conductive thin film (for example, a gold thin film) is formed on the electric field drift portion 6. An ohmic electrode 2 is formed on the back surface of the n-type silicon substrate 1.

In this field emission type electron source 10, the surface electrode 7 is arranged in a vacuum, and a collector electrode (not shown) is arranged so as to face the surface electrode 7 and the surface electrode 7 is arranged with respect to the ohmic electrode 2. Electrons injected from the n-type silicon substrate 1 into the strong electric field drift portion 6 are applied by applying a direct current voltage as the positive electrode and a direct current voltage with the collector electrode to the surface electrode 7 as the positive electrode. And is emitted through the surface electrode 7. Here, as in the conventional example shown in FIG. 9, the current flowing between the surface electrode 7 and the ohmic electrode 2 is called a diode current, and the current flowing between the collector electrode and the surface electrode 7 is called an emission current. Then, the larger the ratio of the emission current to the diode current, the higher the electron emission efficiency. The field emission electron source 1 of the present embodiment
At 0, electrons can be emitted even if the DC voltage between the surface electrode 7 and the ohmic electrode 2 is set to a low voltage of about 10 to 20V.

The strong electric field drift portion 6 in this embodiment.
Is a heat dissipating portion 6b having a high thermal conductivity in which a concave portion (embedding hole) 6c is formed along the thickness direction of the n-type silicon substrate 1 which is a conductive substrate, and a drift portion 6a which is filled in the concave portion 6c and drifts the electrons. Consists of. Here, the heat dissipation portion 6b is configured by a part of the n-type silicon substrate 1, and the cross section orthogonal to the thickness direction of the n-type silicon substrate 1 is formed in a lattice shape (mesh shape). In short, the drift portion 6a is filled in the mesh of the heat dissipation portion 6b, and n
The silicon substrate 1 is formed in a prism shape parallel to the thickness direction. The heat dissipation portion 6b has higher thermal conductivity than the drift portion 6a.

By the way, the drift portion 6a is shown in FIG.
As shown in FIG. 3, the crystal grain size is composed of a large number of nanometer-sized silicon microcrystals (nanocrystal Si) 63, and a large number of silicon oxide films 64 covering the surfaces of the respective silicon microcrystals 63. In other words, the drift portion 6a is composed of a set of silicon microcrystals 63 whose surface is covered with the silicon oxide film 64. Here, the film thickness of the silicon oxide film 64 is set smaller than the crystal grain size of the silicon microcrystal 63. In this embodiment, the silicon microcrystals 63 form fine particles, and the silicon oxide film 64 forms an insulating film. Although nanocrystal Si (nanometer-sized silicon microcrystal) is used as the fine particles in the present embodiment, nanocrystal SiC may be used.

In the drift portion 6a, however, the electrons injected from the n-type silicon substrate 1 do not collide with the silicon microcrystal 63 but are accelerated by the electric field applied to the silicon oxide film 64 and drift, and the drift portion 6a. Since the heat generated in 1 is radiated through the heat radiating portion 6b, the popping phenomenon does not occur during electron emission, and electrons can be emitted stably and with high efficiency.

In this embodiment, the n-type silicon substrate 1 is used as the conductive substrate, but the conductive substrate is not limited to the n-type silicon substrate 1, and an insulating material such as a glass substrate may be used. A substrate in which a conductive film (chrome film or ITO film) is formed on one surface of the substrate, a metal substrate, or the like may be used, and a larger electron source than the case where a semiconductor substrate such as the n-type silicon substrate 1 is used. Area reduction and cost reduction are possible. In the present embodiment, the surface electrode 7 is composed of a gold thin film, but the material of the surface electrode 7 is not limited to gold, and any material having a small work function may be used. The surface electrode 7 may be composed of at least two thin film electrode layers stacked in the thickness direction. When the thin film electrode layer is composed of two layers, for example, gold or the like is used as the material of the upper thin film electrode layer, and as the material of the lower thin film electrode layer (thin film electrode layer on the strong electric field drift portion 6 side), for example, Chromium, nickel, platinum, titanium, iridium or the like may be adopted.

Hereinafter, a method for manufacturing the above-mentioned field emission electron source 10 will be described with reference to FIG.

First, the structure shown in FIG. 1A is obtained by forming the ohmic electrode 2 on the back surface of the n-type silicon substrate 1. Then, a thermal oxidation method or a plasma CVD method (hereinafter referred to as PCVD) is applied to the main surface side of the n-type silicon substrate 1.
By forming the mask material layer 9 made of a silicon oxide film by the abbreviated method), the structure shown in FIG. 1B is obtained. As the mask material layer 9, a silicon nitride film may be formed by the PCVD method instead of the silicon oxide film.

Next, a photoresist layer (not shown) is formed by coating on the mask material layer 9, and the photoresist layer is patterned into a grid pattern using a photomask M as shown in FIG. By using the photoresist layer as a mask, the exposed portion of the mask material layer 9 is etched by using a reactive ion etching (RIE) device or the like, and thereafter, the photoresist layer is removed, whereby the photoresist layer shown in FIG. The structure shown in is obtained. Although the photoresist mask M is configured so that the planar shape of the opening of the photoresist is a minute and substantially square shape, the planar shape of the opening of the photoresist layer is a minute polygonal shape other than a square shape and a minute shape. It may be configured to have a circular shape, a minute star shape, or the like.

Next, using the mask material layer 9 as a mask, the n-type silicon substrate 1 is anisotropically etched to a predetermined depth using a reactive ion etching device or the like to form a vertical hole along the thickness direction of the n-type silicon substrate 1. The structure shown in FIG. 1D is obtained by performing the processing step of forming the recessed portion 6c made of. Here, 6b in FIG. 1 (d) shows a heat radiating portion formed of a part of the n-type silicon substrate 1. This heat dissipation part 6
In b, the cross section orthogonal to the thickness direction of the n-type silicon substrate 1 (the vertical direction in FIG. 1D) is formed in a lattice shape.
The depth from the surface of the mask material layer 9 to the bottom of the recess 6c may be set appropriately within a range not exceeding 2 μm.

Then, a structure shown in FIG. 1E is obtained by performing a deposition step of depositing silicon microcrystals, which are fine particles of nanometer size, in the recesses 6c by, for example, the PCVD method. Here, reference numeral 5a in FIG. 1 (e) indicates a microcrystal layer made up of a large number of silicon microcrystals filled in the recess 6c. As an example of the conditions for forming the microcrystalline layer by the PCVD method, the substrate temperature is 250 ° C., the SiH ₄ gas flow rate is 0.02 L / min (20 sccm) in the standard state, and H _{2 is}
The gas flow rate is 2 L / min (2000 scc
m) and the discharge power density may be 0.28 W / cm ² . The deposition process for forming the microcrystalline layer is not limited to the PCVD method, but may be performed by ECR (Electron Cyclotron Resonance).
-Silicon microcrystals may be deposited by a CVD method, a cluster beam method, or the like. In addition, ECR-CV
To deposit silicon microcrystals by the D method, an ECR-CVD apparatus as shown in FIG. 3 may be used. The ECR-CVD apparatus shown in FIG. 3 has a plasma generation chamber 32 in which the microwave of 2.45 GHz generated in the magnetron oscillator 22 is introduced through the waveguide 23 and a source gas is introduced through the gas introduction port 31, and a plasma generation chamber. Room 32
, A magnet coil MC for generating a magnetic field of 875 Gauss, and a reaction chamber 33 in which the substrate support 34 is housed and the plasma generated in the plasma generation chamber 32 is drawn out through a plasma outlet 36.
AC bias voltage can be applied to the substrate support table 34 from the substrate through the matching box 35. As film forming conditions, the flow rate of SiH ₄ gas is 0.0 in the standard state.
01 L / min (1 sccm), the flow rate of H ₂ gas is 0.02 L / min (20 sccm) in the standard state, the magnet current flowing through the magnet coil MC is 155 A, and the power density of the AC bias applied to the substrate support 34 is 0. 5
It should be 6 W / cm ² .

After the above-described deposition step, an insulating film forming step of forming a silicon oxide film 64 (see FIG. 4B) as an insulating film on the surface of the silicon microcrystal forming the microcrystalline layer is performed. As a result, a plurality of drift portions 6a are formed (that is, the strong electric field drift portion 6 is formed), and subsequently, the strong electric field drift portion 6 including the drift portion 6a and the heat dissipation portion 6b is formed.
Surface electrode 7 made of a conductive thin film (eg, gold thin film)
Is formed by, for example, a vapor deposition method.
The structure shown in (f) is obtained. Here, it is considered that the drift portion 6a is composed of a large number of nanometer-order silicon microcrystals 63 and a silicon oxide film 64 covering the surface of each silicon microcrystal 63, as shown in FIG. 4B.

In the insulating film forming step in this embodiment, the silicon oxide film 64 is formed on the surface of the silicon microcrystal 63 by the rapid thermal oxidation method. However, as the insulating film forming step, the silicon oxide film 64 is electrochemically formed in the electrolytic solution. The silicon oxide film 64 may be formed by adopting the step of oxidizing the silicon oxide film. By adopting the process of electrochemically oxidizing the silicon oxide film 64 as described above, the silicon oxide film 64 can be formed at a lower temperature than the case where the silicon oxide film 64 is formed by the rapid thermal oxidation method, and the process temperature becomes low. As a result, there are less restrictions on the material of the conductive substrate, and it is easy to increase the area and cost. In addition, a conductive thin film that becomes the surface electrode 7 (for example,
The method for forming the gold thin film is not limited to the vapor deposition method, and for example, the sputtering method may be used.

In the field emission type electron source 10 manufactured by the above manufacturing method, the emission current changes little with time, there is no popping noise, and electrons are stably emitted with high electron emission efficiency. Further, this field emission type electron source 10
Has little dependence of electron emission characteristics (emission current, electron emission efficiency, etc.) on the degree of vacuum, and good electron emission characteristics were obtained even at a low degree of vacuum, so there is no need to use it in a high vacuum as in the past. In addition, the cost of the device using the field emission electron source 10 can be reduced and the handling becomes easy.

By the way, in the strong electric field drift portion 6 of the field emission electron source 10 of this embodiment, after the concave portion 6c is formed by anisotropic etching using the mask material layer 9 as a mask, the silicon microcrystal 63 is introduced into the concave portion 6c. And then the silicon oxide film 64 is formed on the surface of the silicon microcrystal 63.
Since the drift portion 6a is formed by forming
The pattern shape of the drift portion 6a and the heat radiating portion 6b can be controlled by the pattern of the mask material layer 9, and the popping phenomenon does not occur during electron emission, and electrons can be stably emitted with high electron emission efficiency. The field emission electron source 10 can be realized at low cost, and in view of controllability of electrical conductivity and structural and thermal stability, the entire main surface side of the single crystal silicon substrate is different from the conventional one. It is considered that they have better properties than the strong electric field drift layer obtained by making the porous.

In the field emission electron source 10 of this embodiment,
It is considered that electron emission occurs in the following model. The DC voltage applied to the surface electrode 7 as a positive electrode with respect to the n-type silicon substrate 1 (ohmic electrode 2) is a predetermined value (critical value)
Then, electrons are injected into the strong electric field drift portion 6 from the n-type silicon substrate 1 side by thermal excitation. On the other hand, in the drift portion 6a of the strong electric field drift portion 6, there are many silicon microcrystals 63 which are fine particles having a crystal grain size of nanometer size (for example, about 10 nm), and the silicon microcrystals 63 are on the surface of each silicon microcrystal 63. Since the silicon oxide film 64, which is an insulating film having a film thickness smaller than the crystal grain size of 63, is formed, the electric field applied to the strong electric field drift portion 6 is almost the same as the silicon oxide film formed on the surface of the silicon oxide film 63. Since the electrons are applied to the film 64, the injected electrons can
4 is accelerated by a strong electric field applied to the drift part 6a
The inside drifts toward the surface electrode 7. Since the crystal grain size of the silicon microcrystal 63 is sufficiently smaller than the mean free path of electrons (the mean free path of electrons in silicon is said to be about 50 nm), the electrons almost collide with the silicon microcrystal 63. Without reaching the surface of the drift portion 6a. In short, the electrons injected into the drift portion 6 a are accelerated by the electric field applied to the silicon oxide film 64 on the surface of the silicon microcrystal 63 without scattering due to collision, and the electrons on the surface of the next silicon microcrystal 63 are scattered. The energy increases as the phenomenon of plunging into the silicon oxide film 64 is repeated. Therefore, the electrons that have reached the surface of the drift portion 6a are hot electrons, and since the hot electrons have energy of several kT or more than in the thermal equilibrium state, they easily tunnel through the surface electrode 7 and are emitted into a vacuum. Further, in the present embodiment, since the thickness of the drift portion 6a is set so that the thickness of the drift portion 6a does not exceed 2 μm, the scattering of electrons injected into the drift portion 6a can be made relatively small. As a result, the amount of electron emission increases, so that the emission current can be increased.

By the way, in the field emission type electron source 10 of the present embodiment, electrons can be emitted with high efficiency and stability without the occurrence of popping phenomenon. It is considered that this is because the heat generated in the drift portion 6a of No. 6 is conducted to the heat radiating portion 6b and is radiated to the outside to suppress the temperature rise.

In summary, the strong electric field drift section 6
Has a semi-insulating property in which a strong electric field can exist, has a small drift of electrons, has a large drift length, and has thermal conductivity enough to suppress thermal runaway of the diode current. Is believed to be able to be released.

Therefore, according to the method of manufacturing the field emission electron source 10 of the present embodiment, the processing step of forming the concave portion 6c on the one surface side of the conductive substrate and the silicon microcrystal which is a large number of fine particles in the concave portion 6c. Deposition process for depositing 63, and the recess 6
Since a step of forming an insulating film, which is an insulating film, is formed on the surface of each of the silicon microcrystals 63 deposited in c, a large number of nanometer-sized fine particles are deposited in the recess 6c by using a thin film forming technique. Therefore, the recess 6c can be filled with the fine particles without performing a process such as anodizing or spin coating, the thickness of the drift portion 6a can be easily controlled, and each fine particle deposited in the recess can be controlled. Since the insulating film is formed on the surface in the insulating film forming step, the insulating film can be formed relatively easily as compared with the conventional case where the insulating film is formed on the surface of the fine particles in advance, and the manufacturing is easy. It is possible to provide the field emission electron source 10 that is easy, reliable, and low in cost. In addition, the surface of the drift portion 6 a and the mask material layer 9
Since the surfaces of the surface electrodes are aligned on the same plane, disconnection of the surface electrodes on the strong electric field drift portion 6 can be prevented, and reliability is improved.

In the present embodiment, the reactive ion etching method is used in the processing step of forming the recess 6c, but a sand blast processing method, a stamping method or the like may be used. Can be formed with a processing accuracy on the order of sub-μm. Further, in the present embodiment, single crystal Si is adopted as the material of the conductive substrate, but polycrystalline Si, amorphous Si, single crystal SiC, polycrystalline SiC, amorphous SiC or the like may be adopted, and any one of them may be adopted. Also in the case, the recess 6c is formed in the conductive substrate.
Can be formed easily and with high processing accuracy.

By the way, in the present embodiment, as described above, the portion on the main surface side of the n-type silicon substrate 1 which is a conductive substrate constitutes the heat dissipation portion 6b.
You may form the heat dissipation part which consists of this high heat conductive layer by forming a high heat conductive layer which consists of a single crystal silicon layer or a polysilicon layer and has high heat conductivity on it, and forms a recessed part in this high heat conductive layer.

(Embodiment 2) The basic structure and manufacturing method of the field emission electron source 10 of this embodiment are substantially the same as those of Embodiment 1, and as shown in FIG. 5, the structure of the drift portion 6a and its manufacture. Only the process is different. The drift portion 6a in the present embodiment includes a first fine particle layer 6a1 containing silicon microcrystals that are fine particles of a first size and a second fine particle layer 6a containing silicon microcrystals that are fine particles of a second size.
2 and 2 are alternately laminated in the thickness direction of the n-type silicon substrate 1. That is, the first fine particle layer 6
The a1 and the second fine particle layer 6a2 are composed of a large number of silicon microcrystals and a large number of silicon oxide films which are insulating films covering the surfaces of the respective silicon microcrystals, and the silicon microcrystals contained in the first fine particle layer. And the crystal grain size of the silicon microcrystals contained in the second fine particle layer are made different.

In order to form such a drift portion 6a, the first fine particle layer and the second fine particle layer may be alternately formed while appropriately changing the film forming conditions in the deposition process described in the first embodiment. .

In the field emission electron source 10 of this embodiment, however, one of the first fine particle layer and the second fine particle layer which contains the silicon microcrystal 63 having a larger size serves as an electrode equivalently. Since the electric field is uniformly applied to the entire drift portion 6a, the electron emission efficiency is improved.

(Embodiment 3) The field emission type electron source 10 of the present embodiment has substantially the same basic structure as that of Embodiment 1, except that the conductive substrate is an insulating substrate 11 made of glass as shown in FIG. And the lower electrode 12 made of a conductive material formed on one surface of the insulating substrate 11 is different. Here, the lower electrode 12 is formed in a portion corresponding to the vicinity of the interface between the n-type silicon substrate 1 and the drift portion 6a in the first embodiment. Therefore, the lower electrodes 12 are arranged in a matrix. The same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

In the field emission electron source 10 of this embodiment, as shown in FIG. 6, the strong electric field drift portion 6 is formed on the one surface side of the insulating substrate 11 having the lower electrode 12 formed on the one surface. The surface electrode 7 made of a conductive thin film (for example, a gold thin film) is formed on the strong electric field drift portion 6.

In the field emission electron source 10 of this embodiment,
The front surface electrode 7 is arranged in a vacuum, and a collector electrode (not shown) is arranged so as to face the front surface electrode 7.
By applying a DC voltage to the lower electrode 12 as a positive electrode and applying a DC voltage to the surface electrode 7 with the collector electrode as a positive electrode, electrons injected from the lower electrode 12 into the strong electric field drift portion 6 are generated. The strong electric field drift portion 6 drifts and is emitted through the surface electrode 7. Here, the current flowing between the front surface electrode 7 and the lower electrode 12 is called a diode current, and the current flowing between the collector electrode and the front surface electrode 7 is called an emission current. The larger the ratio, the higher the electron emission efficiency. In the field emission electron source 10 of this embodiment, the surface electrode 7 and the lower electrode 1 are
Electrons can be emitted even if the DC voltage between the two is set to a low voltage of about 10 to 20V.

Strong electric field drift portion 6 in this embodiment.
Is a heat dissipation portion 6 formed of a high thermal conductive layer (for example, a polysilicon layer or an amorphous silicon layer) having a high thermal conductivity in which a concave portion 6c is formed along the thickness direction of the conductive substrate.
b and a drift portion 6a filled in the recess 6c. Here, in the heat dissipation portion 6b, a cross section orthogonal to the thickness direction of the insulating substrate 11 is formed in a lattice shape (mesh shape). In short, the drift portion 6a is filled in the mesh of the heat dissipation portion 6b and is formed in a prismatic shape. The heat dissipation portion 6b has higher thermal conductivity than the drift portion 6a.

By the way, the drift portion 6a is the same as in the first embodiment.
As shown in FIG. 4B, it has the same structure as the above, and is composed of a silicon microcrystal 63 having a crystal grain size of nanometer size and a silicon oxide film 64 covering the surface of the silicon microcrystal 63.

In the drift portion 6a, the electrons injected from the lower electrode 12 of the conductive substrate are accelerated by the electric field applied to the silicon oxide film 64 which is an insulating film without colliding with the silicon microcrystal 63 which is a fine particle. Since the heat generated by the drift portion 6a is radiated through the heat radiating portion 6b, the popping phenomenon does not occur at the time of electron emission, and electrons can be stably emitted with high electron emission efficiency.

The manufacturing method will be described below with reference to FIGS. 7 and 8.

First, by forming the lower electrode 12 made of a conductive material patterned in a predetermined shape on one surface of the insulating substrate 11 made of glass, the structure shown in FIG.
The structure shown in is obtained. After that, a high thermal conductive layer 4 made of a polysilicon thin film is formed on the entire surface on the one surface side of the insulating substrate 11, so that the structure shown in FIG. 7B is obtained. An amorphous silicon thin film may be formed instead of the polysilicon thin film.

Next, after a mask material layer 9 made of a silicon oxide film is formed on the high thermal conductive layer 4, a photoresist layer (not shown) is applied and formed on the mask material layer 9 and, as shown in FIG. After patterning the photoresist layer into a grid pattern using a photomask M as shown, exposed portions of the mask material layer 9 using a reactive ion etching (RIE) device or the like using the photoresist layer as a mask. By etching and then removing the photoresist layer, the structure shown in FIG. 7C is obtained. In the present embodiment, the photomask M
Is configured such that the opening of the photoresist layer is located on the lower electrode 12. A silicon nitride film may be formed as the mask material layer 9 instead of the silicon oxide film.

Next, the high thermal conductive layer 4 is anisotropically etched to a depth reaching the surface of the lower electrode 12 by using the reactive ion etching device or the like with the mask material layer 9 as a mask, and the thickness direction of the insulating substrate 11 is measured. By performing the processing step of forming the concave portion 6c formed of the vertical hole along the line, the heat dissipation portion 6b formed of the high thermal conductive layer 4 is formed, and the structure shown in FIG. 7D is obtained. Here, in the heat dissipation portion 6b, a cross section orthogonal to the thickness direction of the insulating substrate 11 is formed in a lattice shape.

Then, a structure shown in FIG. 8A is obtained by performing a deposition step of depositing silicon microcrystals, which are fine particles of nanometer size, in the recesses 6c by, for example, the PCVD method. Here, reference numeral 5a in FIG. 8 (a) indicates a microcrystal layer made up of a large number of silicon microcrystals filled in the recess 6c. The conditions for forming the microcrystalline layer by the PCVD method are the same as those in the first embodiment. In addition, the deposition step of forming the microcrystalline layer is not limited to the PCVD method, but silicon microcrystals may be deposited by the ECR-CVD method or the cluster beam method.

After the above-described deposition step, an insulating film forming step of forming a silicon oxide film 64 (see FIG. 4B) as an insulating film on the surface of the silicon microcrystal forming the microcrystalline layer is performed. As a result, a plurality of drift portions 6a are formed (that is, the strong electric field drift portion 6 is formed), and subsequently, the strong electric field drift portion 6 including the drift portion 6a and the heat dissipation portion 6b is formed.
Surface electrode 7 made of a conductive thin film (eg, gold thin film)
8 is formed by, for example, a vapor deposition method.
The structure shown in (b) is obtained. Here, the drift portion 6a is a large number of silicon microcrystals 6 on the order of nanometers.
3 and a silicon oxide film 64 covering the surface of each silicon microcrystal 63.

In the insulating film forming step of this embodiment, a step of electrochemically oxidizing in an electrolytic solution is adopted to form a silicon oxide film 64 on the surface of the silicon microcrystal 63.
Is formed. Although the thickness of the surface electrode 7 is set to 15 nm, this thickness is not particularly limited, and the method for forming the conductive thin film (for example, a gold thin film) to be the surface electrode 7 is also limited to the vapor deposition method. Instead, for example, a sputtering method may be used.

In the field emission type electron source 10 manufactured by the above-described manufacturing method, the emission current changes little with time, there is no popping noise, and electrons are stably emitted with high electron emission efficiency. Further, this field emission type electron source 10
Has little dependence of electron emission characteristics (emission current, electron emission efficiency, etc.) on the degree of vacuum, and good electron emission characteristics were obtained even at a low degree of vacuum, so there is no need to use it in a high vacuum as in the past. In addition, the cost of the device using the field emission electron source 10 can be reduced and the handling becomes easy.

By the way, in each of the above embodiments, the insulating film in the drift portion 6a is formed of the silicon oxide film 64, but a silicon nitride film or a silicon oxynitride film may be adopted instead of the silicon oxide film 64. When a silicon nitride film is used, instead of the step of forming the silicon oxide film 64 on the surface of the silicon microcrystal 63, a step of forming a silicon nitride film by, for example, rapid thermal nitriding may be adopted. When adopting, the step of forming a silicon oxynitride film by, for example, rapid thermal oxynitridation may be adopted instead of the step of forming the silicon oxide film 64 on the surface of the silicon microcrystal 63.

In each of the above embodiments, the recess 6 is formed after the processing step of forming the recess 6c on the one surface side of the conductive substrate.
The deposition step of depositing the fine particles on c and the insulating film forming step of forming the insulating film on the surface of the fine particles are separately performed. However, the fine particles are present in an atmosphere containing oxidizing species or nitriding species or oxidizing species and nitriding species. You may employ | adopt the deposition process which deposits in the recessed part 6c. If such a deposition process is adopted,
Since a large number of nanometer-sized fine particles whose surfaces are covered with an insulating film can be deposited in the recesses 6c by using a thin film forming technique, the surfaces of the recesses 6c can be formed without performing steps such as anodizing treatment and spin coating. The fine particles covered with the insulating film can be filled, the thickness of the drift portion 6a can be easily controlled, and the insulating film can be compared with the conventional case where the insulating film is previously formed on the surface of the fine particles. It is possible to provide the field emission electron source 10 that can be easily formed, is easy to manufacture, has high reliability, and can be manufactured at low cost. In addition, the number of steps can be reduced as compared with the case where an insulating film forming step such as an oxidizing step, a nitriding step, or an oxynitriding step is performed after the deposition step, which leads to an improvement in yield and cost reduction, and a strong electric field drift portion. It is possible to reduce the variation in the film thickness of the insulating film within 6, improve the film quality, and reduce the in-plane variation in the emission characteristics. Further, the cross-sectional shape of the recess 6c is not limited to the square shape, and may be formed in a linear shape.

[0073]

The invention of claim 1 comprises a conductive substrate, a strong electric field drift portion formed on one surface side of the conductive substrate, and a surface electrode formed on the strong electric field drift portion. The electric field drift portion has a high thermal conductivity in which a concave portion is formed along the thickness direction of the conductive substrate, a large number of nanometer-order fine particles filled in the concave portion, and a large number of insulating films covering the surface of each fine particle. Electrons injected from the conductive substrate drift through the drift electrode and are emitted through the surface electrode by applying a DC voltage with the surface electrode as a positive electrode with respect to the conductive substrate. A method of manufacturing a source, comprising a processing step of forming a recess on one surface side of a conductive substrate, a deposition step of depositing a large number of fine particles in the recess, and a surface of each fine particle deposited in the recess. Since the insulating film forming step of forming the edge film is provided, a large number of nanometer-sized fine particles can be deposited in the concave section by using a thin film forming technique, so that the concave section can be formed without performing steps such as anodizing treatment and spin coating. Can be filled with fine particles, the thickness of the drift portion can be easily controlled, and an insulating film is formed on the surface of each fine particle deposited in the recess in the insulating film forming step. (EN) Provided is a field emission electron source, which allows an insulating film to be formed relatively easily as compared with the case where an insulating film is formed on the surface, is easy to manufacture, has high reliability, and can be manufactured at low cost. The effect is that you can.

According to the invention of claim 2, in the invention of claim 1, since the fine particles are made of nanocrystal Si or nanocrystal SiC, they are widely used as a raw material for forming the fine particles in a general semiconductor manufacturing process. It is possible to use the material that is used, and there is an effect that the cost can be reduced.

According to a third aspect of the invention, in the first or second aspect of the invention, the deposition step is plasma CVD.
Method, ECR-CVD method, or cluster beam method, the fine particles are deposited. Therefore, by controlling process parameters such as power, gas flow rate, and gas pressure at the time of film formation in the deposition step, nanometer size There is an effect that the fine particles can be easily obtained.

According to the invention of claim 4, in the invention of claims 1 to 3, since the thickness of the drift portion does not exceed 2 μm, scattering of electrons injected into the drift portion is relatively small. Therefore, the electron emission amount is increased, so that the emission current can be increased.

According to a fifth aspect of the invention, in the first to fourth aspects of the invention, the drift portion includes a first fine particle layer containing fine particles of a first size and a second fine particle layer containing fine particles of a second size. In the deposition step, the first fine particle layer and the second fine particle layer are alternately formed, so that the fine particle having the largest size of the first fine particle layer and the second fine particle layer is formed. Is equivalent to an electrode, and an electric field is evenly applied to the entire drift portion, so that the electron emission efficiency is improved.

According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the processing step is a reactive ion etching method, an electron beam processing method, a sandblasting method,
Since the recess is formed by a method selected from the stamping method, there is an effect that the recess can be formed with a processing accuracy on the order of sub-μm.

According to a seventh aspect of the present invention, in the first to sixth aspects, the conductive substrate is single crystal Si, polycrystalline Si, amorphous Si, single crystal SiC, or polycrystalline S.
Since it is selected from iC and amorphous SiC, there is an effect that the recess can be easily formed with high processing accuracy in the conductive substrate.

According to an eighth aspect of the present invention, in the first to seventh aspects, the insulating film is an oxide film, and the insulating film forming step is a step of electrochemically oxidizing in an electrolytic solution. Therefore, it becomes possible to form the insulating film at a lower temperature than the case where the insulating film is formed by thermal oxidation.
There is an effect that the process temperature becomes low and the restrictions on the material of the conductive substrate are reduced, and it is easy to increase the area and cost.

According to a ninth aspect of the present invention, there is provided a conductive substrate, a strong electric field drift portion formed on one surface side of the conductive substrate, and a surface electrode formed on the strong electric field drift portion. A heat-dissipating portion having a high thermal conductivity in which a concave portion is formed along the thickness direction of the conductive substrate, a large number of nanometer-order fine particles filled in the concave portion, and an oxide film or a nitride film covering the surface of each fine particle. A drift portion including an insulating film made of an oxynitride film is used.By applying a DC voltage with the surface electrode serving as a positive electrode with respect to the conductive substrate, electrons injected from the conductive substrate drift in the drift portion and pass through the surface electrode. A method of manufacturing a field emission electron source to be emitted, comprising a processing step of forming a recess on one surface side of a conductive substrate, and an oxidizing species or a nitriding species or an oxidizing species and a nitriding species. Since the deposition step of depositing the fine particles in the recesses in a dry atmosphere is used, a large number of nanometer-sized fine particles whose surfaces are covered with an insulating film can be deposited in the recesses by using a thin film forming technique. It is possible to fill the recesses with fine particles whose surface is covered with an insulating film without performing a process such as oxidation or spin coating, which makes it easier to control the film thickness of the drift portion and allows the surface of the fine particles to be pre-coated as in the past. It is possible to provide a field emission electron source in which the insulating film can be formed relatively easily as compared with the case where the insulating film is formed, which is easy to manufacture, has high reliability, and can be manufactured at low cost. The effect is that you can do it. In addition, the number of steps can be reduced as compared with the case where an insulating film forming step such as an oxidizing step, a nitriding step, or an oxynitriding step is performed after the deposition step, which leads to an improvement in yield and cost reduction. In this way, it is possible to reduce the variation in the film thickness of the insulating film, improve the film quality, and reduce the in-plane variation in the emission characteristics.

According to a tenth aspect of the present invention, in the strong electric field drift portion, the surface of the drift portion and the surface around the drift portion are aligned on the same plane. The disconnection of the surface electrode on the strong electric field drift portion can be prevented, and the reliability is improved.

[Brief description of drawings]

1A to 1C are sectional views of main steps for explaining a method for manufacturing a field emission electron source according to a first embodiment.

FIG. 2 is a plan view of a photomask for explaining the method of manufacturing the above field emission electron source.

FIG. 3 is a schematic explanatory view of a manufacturing apparatus for explaining the method of manufacturing the above field emission electron source.

FIG. 4 shows the same field emission electron source as in the above, in which (a) is a schematic sectional view and (b) is an explanatory view of a main part.

FIG. 5 is a schematic cross-sectional view of a field emission electron source according to a second embodiment.

FIG. 6 is a schematic cross-sectional view of a field emission electron source according to a third embodiment.

FIG. 7 is a cross-sectional view of main steps for explaining the method for manufacturing the above field emission electron source.

FIG. 8 is a cross-sectional view of main steps for explaining the method for manufacturing the above field emission electron source.

FIG. 9 is an operation explanatory view of a field emission type electron source showing a conventional example.

FIG. 10 is an operation explanatory diagram of the above field emission electron source.

FIG. 11 is an operation explanatory view of a field emission electron source showing another conventional example.

FIG. 12 is a schematic cross-sectional view of a field emission electron source showing another conventional example.

[Explanation of symbols]

1 n-type silicon substrate 2 Ohmic electrodes 6 Strong electric field drift section 6a Drift section 6b Heat dissipation part 6c recess 7 Surface electrode 10 Field emission electron source

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koichi Aizawa             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Yoshiaki Honda             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Yoshifumi Watanabe             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Tsutomu Kagehara             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Toru Baba             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company

Claims (10)

[Claims] 1. A conductive substrate, a strong electric field drift portion formed on one surface side of the conductive substrate, and a surface electrode formed on the strong electric field drift portion, wherein the strong electric field drift portion is conductive. It consists of a heat dissipation part having a high thermal conductivity in which a concave part is formed along the thickness direction of the substrate, and a drift part including a large number of nanometer-order fine particles filled in the concave part and a large number of insulating films covering the surface of each fine particle. A method for manufacturing a field emission electron source, in which electrons injected from a conductive substrate drift in a drift portion and are emitted through the surface electrode by applying a DC voltage with the surface electrode serving as a positive electrode with respect to the conductive substrate. , A processing step of forming a recess on one surface side of the conductive substrate, a deposition step of depositing a large number of fine particles in the recess, and an insulating step of forming an insulating film on the surface of each fine particle deposited in the recess A method of manufacturing a field emission electron source, comprising: a film forming step. 2. The method of manufacturing a field emission electron source according to claim 1, wherein the fine particles are made of nanocrystal Si or nanocrystal SiC. 3. The deposition step is a plasma CVD method, E
The method for producing a field emission electron source according to claim 1 or 2, wherein the fine particles are deposited by a method selected from a CR-CVD method and a cluster beam method. 4. The method of manufacturing a field emission electron source according to claim 1, wherein the thickness of the drift portion does not exceed 2 μm. 5. The first fine particle layer containing fine particles of a first size and the second drift portion containing fine particles of a second size.
The fine particle layer has a structure in which the fine particle layers are alternately laminated, and the depositing step alternately forms the first fine particle layer and the second fine particle layer. A method for manufacturing a field emission electron source according to claim 1. 6. The method according to claim 1, wherein in the processing step, the recess is formed by a method selected from a reactive ion etching method, an electron beam processing method, a sandblast processing method, and a stamping method. A method of manufacturing a field emission electron source according to any one of 1. 7. The conductive substrate is single crystal Si, polycrystalline Si, amorphous Si, single crystal SiC, polycrystalline Si.
7. The method for manufacturing a field emission electron source according to claim 1, wherein C or amorphous SiC is selected. 8. The insulating film is an oxide film, and the insulating film forming step is a step of electrochemically oxidizing in an electrolytic solution. A method for manufacturing the field emission electron source according to. 9. A conductive substrate, a strong electric field drift portion formed on one surface side of the conductive substrate, and a surface electrode formed on the strong electric field drift portion, wherein the strong electric field drift portion is conductive. Consists of a heat radiating portion having a high thermal conductivity with a concave portion formed along the thickness direction of the substrate, a large number of nanometer-order fine particles filled in the concave portion, and an oxide film, a nitride film, or an oxynitride film covering the surface of each fine particle. A field emission in which electrons injected from a conductive substrate drift through the drift electrode and are emitted through the surface electrode by applying a DC voltage with the surface electrode serving as a positive electrode with respect to the conductive substrate. A method of manufacturing a type electron source, comprising: a processing step of forming a recess on one surface side of a conductive substrate; A method of manufacturing a field emission electron source, comprising: a deposition step of depositing fine particles in a recess. 10. The strong electric field drift portion according to claim 1, wherein a surface of the drift portion and a surface around the drift portion are flush with each other. Method for manufacturing field emission electron source.