JP3603682B2 - Field emission electron source - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a field emission type electron source that emits an electron beam by field emission.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a field emission electron source, there is a so-called Spindt electrode disclosed in, for example, US Pat. No. 3,665,241. This Spindt-type electrode has a substrate on which a number of minute triangular pyramid-shaped emitter chips are arranged, a gate layer having a radiation hole for exposing the tip of the emitter chip, and being arranged insulated from the emitter chip. And applying a high voltage with the emitter tip as a negative electrode to the gate layer in a vacuum to emit an electron beam from the tip of the emitter tip through a radiation hole.
[0003]
However, the Spindt-type electrode has a complicated manufacturing process, and it is difficult to accurately configure a large number of triangular pyramid-shaped emitter chips. For example, it is difficult to increase the area when applied to a flat light emitting device or a display. There was a problem. In the Spindt-type electrode, the electric field is concentrated at the tip of the emitter tip, so if the degree of vacuum around the tip of the emitter tip is low and residual gas exists, the emitted gas turns the residual gas into positive ions. Since the positive ions are ionized and collide with the tip of the emitter tip, the tip of the emitter tip is damaged (for example, damage due to ion bombardment), and the current density and efficiency of emitted electrons become unstable, There is a problem that the life of the chip is shortened. Therefore, in a Spindt-type electrode, a high vacuum (about 10^-5Pa to about 10^-6Pa), there is a problem that the cost increases and the handling becomes troublesome.
[0004]
In order to improve this kind of problem, a MIM (Metal Insulator Metal) system and a MOS (Metal Oxide Semiconductor) type field emission electron source have been proposed. The former is a flat field emission type electron source having a metal-insulating film-metal structure, and the latter is a metal-oxide film-semiconductor stacked structure. However, in order to increase the emission efficiency of electrons in this type of field emission electron source (to emit a large number of electrons), it is necessary to reduce the thickness of the insulating film and the oxide film. If the thickness of the insulating film or the oxide film is too thin, dielectric breakdown may occur when a voltage is applied between the upper and lower electrodes of the laminated structure, and in order to prevent such dielectric breakdown, Since the thickness of the insulating film or the oxide film is limited, the electron emission efficiency (drawing efficiency) cannot be increased.
[0005]
In recent years, as disclosed in JP-A-8-250766, a single-crystal semiconductor substrate such as a silicon substrate is used, and one surface of the semiconductor substrate is anodized to form a porous semiconductor layer (porous semiconductor layer). A field emission electron source (semiconductor) configured to form a silicon thin film, form a metal thin film on the porous semiconductor layer, and apply a voltage between the semiconductor substrate and the metal thin film to emit electrons. Cold electron-emitting devices) have been proposed.
[0006]
However, the field emission type electron source described in Japanese Patent Application Laid-Open No. 8-250766 has a problem that it is difficult to increase the area and reduce the cost because the substrate is limited to a semiconductor substrate. Further, in the field emission type electron source described in JP-A-8-250766, a so-called popping phenomenon is apt to occur during electron emission, and the amount of emitted electrons tends to be uneven. There is a problem that can be done.
[0007]
In view of this, the inventors of the present application have disclosed in Japanese Patent Application Nos. 10-272340 and 10-272342 that a porous polycrystalline semiconductor layer (for example, a polycrystalline silicon layer made porous) is subjected to rapid thermal oxidation (RTO). ) Rapid thermal oxidation by the technology formed a strong electric field drift layer (strong electric field drift portion) between the conductive substrate and the metal thin film (surface electrode), in which electrons injected from the conductive substrate drift. A field emission electron source was proposed. In this field emission type electron source, the electron emission characteristics have a small dependence on the degree of vacuum and can stably emit electrons without a popping phenomenon during electron emission. In addition, a single-crystal silicon substrate or the like is used as a conductive substrate. In addition to the semiconductor substrate described above, a substrate in which a conductive film (for example, an ITO film) is formed on a glass substrate or the like can be used. Therefore, a porous semiconductor layer in which a semiconductor substrate is made porous as in the related art is used. As compared with the case and the Spindt-type electrode, the area of the electron source can be increased and the cost can be reduced.
[0008]
However, in the field emission type electron source proposed in the above-mentioned Japanese Patent Application Nos. 10-272340 and 10-272342, the oxidation temperature of rapid thermal oxidation cannot be increased beyond the heat resistance temperature of the conductive substrate. There is a problem that the material of the substrate and the material of the ITO film are limited, and the increase in the diameter (larger area) of the substrate is restricted.
[0009]
In view of this, the present inventors have proposed in Japanese Patent Application No. 11-108632 a field emission electron source in which a strong electric field drift layer is formed by oxidizing a porous polycrystalline silicon layer with an acid.
[0010]
[Problems to be solved by the invention]
However, even with the field emission type electron source proposed in Japanese Patent Application No. 11-108632, a process of 600 ° C. or more is required to form polycrystalline silicon, so that expensive quartz glass is used as a conductive substrate. In this case, a conductive film must be formed, or a single-crystal silicon substrate must be used, which limits the increase in the diameter of the conductive substrate (increase in area). For example, it is difficult to realize a large-area display. Was.
[0011]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a field emission type electron source that can be easily made large in size and low in cost, and a method of manufacturing the same.
[0012]
[Means for Solving the Problems]
According to an 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 conductive thin film formed on the strong electric field drift portion. A field emission type in which electrons injected from the conductive substrate drift through the strong electric field drift portion and are emitted through the surface electrode by applying a voltage with the surface electrode being a positive electrode with respect to the conductive substrate. Electron source, the strong electric field drift partA drift section in which the cross section perpendicular to the thickness direction of the conductive substrate is formed in a mesh shape and the electrons drift, and a column-shaped heat radiating section having better thermal conductivity than the drift section filled in the mesh, The drift part is made of oxidized porous amorphous silicon or a porous amorphous silicon compound, and the heat radiation part is made of oxidized amorphous silicon or an oxidized amorphous silicon compound.The process temperature is lower than in the case where the strong electric field drift portion is formed of porous polycrystalline silicon, the restriction of the conductive substrate is reduced, and the area and the area are reduced. Cost reduction becomes easy.
Moreover, strong electric field driftSince the Joule heat generated in the drift part is radiated through the heat radiating part in the part, it is possible to prevent the popping phenomenon from occurring at the time of electron emission, and it is stableTo emit electrons with high efficiencyAnd stability with time is improved.
[0015]
In addition, the source of the strong electric field driftSince it is made of rufus silicon or an amorphous silicon compound, it is possible to use a manufacturing apparatus such as a thin film transistor or a solar cell and to use a process.. In addition, the control of the electrical characteristics of the strong electric field drift portion is also facilitated.
[0019]
Claim2The invention of claimOneIn the invention,The above drillThe lift portion has semiconductor microcrystals in the order of nanometers, and the surface of the semiconductor microcrystals is covered with an insulating film having a thickness smaller than the crystal grain size of the semiconductor microcrystals. And the electron emission efficiency is improved.
[0020]
Claim3The invention of claim2In the present invention, since the insulating film is formed of an oxide film, the insulating film can be easily formed.
[0021]
Claim4The invention of claim 1 to claim 13In the invention of the above, since the strong electric field drift portion is formed by a low-temperature process of 450 ° C. or less, a conductive substrate having a conductive film formed on one surface side such as an inexpensive glass substrate or a resin substrate may be used. It can be used, and cost reduction and large area can be achieved.
[0022]
Claim5The invention of claim 1 to claim 14In the invention, the conductive substrate is composed of a glass substrate and a conductive film formed on one surface of the glass substrate, and the electric field drift portion is formed on the conductive film. And the process can be utilized.
[0023]
Claim6The invention of claim5According to the invention, since the glass substrate is made of a non-alkali glass substrate, the cost and the area can be further reduced.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
(Reference Example 1)
In FIG.In this reference exampleFIGS. 2A to 2D are schematic cross-sectional views of the field emission electron source 10 and main process cross-sectional views in a method of manufacturing the field emission electron source 10.In this reference exampleUses a substrate composed of a glass substrate 1a and a conductive film 2 formed on one surface of the glass substrate 1a as the conductive substrate 1, so that a single crystal silicon substrate is used as the conductive substrate 1. As compared with the above, the area of the electron source can be increased and the cost can be reduced.
[0025]
In this reference exampleIn the field emission type electron source 10, as shown in FIG. 1, a strong electric field drift portion 6 made of oxidized porous amorphous silicon is formed on one surface side of a conductive substrate 1, and a conductive material is formed on the strong electric field drift portion 6. A surface electrode 7 made of a conductive thin film (for example, a gold thin film) is formed. In addition,In this reference exampleIn the field emission electron source 10, electrons that reach the surface of the strong electric field drift section 6 by applying an electric field to the strong electric field drift section 6 are considered to be hot electrons, and are emitted from the surface of the surface electrode 7 by a tunnel effect. Is done. Therefore, a material having a small work function may be used as the surface electrode 7. Also,In this reference exampleAlthough the strong electric field drift portion 6 is made of oxidized porous amorphous silicon, the strong electric field drift portion 6 may be made of an oxidized porous amorphous silicon compound.
[0026]
In this field emission type electron source 10, as shown in FIG. 3, the surface electrode 7 is disposed in a vacuum, a collector electrode 21 is disposed opposite to the surface electrode 7, and the surface electrode 7 is connected to the conductive film 2. By applying a voltage as a positive electrode and applying a DC voltage with the collector electrode 21 as a positive electrode to the surface electrode 7, electrons injected from the conductive substrate 1 drift in the strong electric field drift portion 6 and Released through Here, the current flowing between the surface electrode 7 and the conductive film 2 is called a diode current, the current flowing between the collector electrode 21 and the surface electrode 7 is called an emission electron current, and the emission electron current with respect to the diode current is The larger the value, the higher the electron emission efficiency. In addition,In this reference exampleIn the field emission type electron source 10, electrons can be emitted even when the DC voltage between the surface electrode 7 and the conductive film 2 is set to a low voltage of about 10 to 20V.
[0027]
Hereinafter, the manufacturing method will be described with reference to FIG.
[0028]
First, a non-doped amorphous silicon layer 3 having a predetermined thickness (for example, 1.5 μm) is formed (deposited) on the main surface of the conductive substrate 1 (on the conductive film 2), as shown in FIG. The structure as shown is obtained. Here, since the amorphous silicon layer 3 is deposited by the plasma CVD method, it can be formed by a low-temperature process of 450 ° C. or less.
[0029]
After the non-doped amorphous silicon layer 3 is formed, a platinum electrode (see FIG. 1) is used by using an anodic oxidation treatment tank containing an electrolytic solution consisting of a mixture of a 55 wt% aqueous solution of hydrogen fluoride and ethanol in a ratio of about 1: 1. (Not shown) as a negative electrode and the conductive substrate 1 (conductive film 2) as a positive electrode, the porous silicon layer 4 is formed by performing anodizing treatment under predetermined conditions while irradiating the amorphous silicon layer 3 with light. As a result, a structure as shown in FIG. 2B is obtained. put it here,In this reference exampleAlthough the conditions of the anodizing treatment were such that the light power applied to the surface of the amorphous silicon layer 3 was constant and the current density was constant during the anodizing treatment, these conditions may be changed as appropriate (for example, The density may be changed).
[0030]
After the above-described anodizing treatment is completed, the electrolytic solution is removed from the anodizing treatment tank, and an acid (for example, about 10% diluted nitric acid, about 10% diluted sulfuric acid, aqua regia, etc.) is added to the anodizing tank. ), And then using the anodizing tank containing the acid, a platinum electrode (not shown) is used as a negative electrode, and the conductive substrate 1 (conductive film 2) is used as a positive electrode. By oxidizing the amorphous silicon layer 4, the structure shown in FIG. 2C is obtained. In FIG. 2C, reference numeral 6 denotes a strong electric field drift portion formed by oxidizing the porous amorphous silicon layer 4 with an acid. In short, the strong electric field drift portion 6 is made of a porous amorphous material.
[0031]
After 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 strong electric field drift portion 6 by, for example, vapor deposition, so that the structure shown in FIG. The field emission type electron source 10 is obtained. In addition,In this reference exampleAlthough the thickness of the surface electrode 7 is set to 15 nm, the thickness is not particularly limited, and may be any thickness as long as electrons passing through the strong electric field drift layer 6 can tunnel. Also,In this reference exampleIn the above, a conductive thin film to be the surface electrode 7 is formed by vapor deposition, but the method of forming the conductive thin film is not limited to vapor deposition, and for example, a sputtering method may be used.
[0032]
In this reference exampleIn the manufacturing method, the amorphous silicon layer 3 is formed by a low-temperature process such as a plasma CVD method, the porous amorphous silicon layer 4 is oxidized with an acid, and the surface electrode 7 is formed by a vapor deposition method, a sputtering method, or the like. Since the film is formed, the field emission electron source 10 can be manufactured by a low-temperature process of 450 ° C. or less. Therefore, an inexpensive substrate such as non-alkali glass, which can have a large area, and an inexpensive substrate, such as a resin substrate, can be used as the conductive substrate 1. The area and cost can be reduced.
[0033]
The field emission electron source manufactured by the above-described manufacturing method is similar to the field emission electron source proposed by the present inventors in Japanese Patent Application Nos. 10-272340 and 10-272342. The electron emission characteristics are less dependent on the degree of vacuum, and electrons can be emitted stably without generating a popping phenomenon during electron emission.
[0034]
In addition,In this reference exampleIs a silicon oxide film in which the strong electric field drift portion 6 has nanometer-order silicon microcrystals 63 as shown in FIG. 4, and the surface of the silicon microcrystals 63 has a thickness smaller than the crystal grain size of the silicon microcrystals 63. The electron e injected into the strong electric field drift portion 6 because it is covered with the insulating film 64 made of⁻Is accelerated by the strong electric field applied to the insulating film 64 and drifts in the direction of arrow A in FIG. 4, and since the drift length of the electrons is much larger than the grain size of the silicon microcrystals, almost no collision occurs. Since the electrons reach the surface of the strong electric field drift portion 6 without any problem, the electron emission efficiency is improved.
[0035]
Also, In FIG.Although the strong electric field drift portion 6 is formed over substantially the entire surface of the conductive substrate 1, if the strong electric field drift portion 6 is formed in a columnar shape substantially orthogonal to the one surface of the conductive substrate 1, Heat dissipation is improved, and electrons can be more stably and efficiently emitted.
[0036]
(Reference Example 2)
Reference Example 1The field emission type electron source 10 of FIG. 1 was produced under the following conditions by the method of manufacturing the field emission type electron source 10 described with reference to FIG.
[0037]
As the conductive substrate 1, a substrate in which a conductive film 2 made of an ITO film was formed on one surface of a glass substrate 1a made of non-alkali glass was used. The formation of the amorphous silicon layer 3 (see FIG. 2A) was performed by a plasma CVD method, and the substrate temperature was set to 270 ° C.
[0038]
In the anodic oxidation, an electrolytic solution obtained by mixing a 55 wt% aqueous solution of hydrogen fluoride and ethanol at a ratio of about 1: 1 was used. The anodic oxidation is performed such that only the area of the surface of the amorphous silicon layer 3 having a diameter of 10 mm is in contact with the electrolytic solution, and the other portions are sealed so as not to contact the electrolytic solution. While irradiating the amorphous silicon layer 3 with a constant light power using a tungsten lamp, a predetermined current was passed using the platinum electrode as a negative electrode and the conductive substrate 1 (conductive film 2) as a positive electrode. Here, the current density is 2.5 mA / cm²And the anodic oxidation time was about 10 seconds.
[0039]
About 10% diluted nitric acid was used as an acid for oxidizing the porous amorphous silicon layer 4. The surface electrode 7 was formed by a vapor deposition method using a gold thin film having a thickness of 15 nm.
[0040]
This reference exampleThe field emission type electron source 10 is introduced into a vacuum chamber (not shown), and a collector electrode 21 (emission electron collecting electrode) is arranged at a position facing the surface electrode 7 as shown in FIG. 5 × 10 vacuum inside^-5As Pa, a DC voltage Vps is applied between the surface electrode 7 (positive electrode) and the conductive film 2 (negative electrode), and a DC voltage Vc of 100 V is applied between the collector electrode 21 and the surface electrode 7. , A diode current Ips flowing between the surface electrode 7 and the conductive film 2, and electrons e radiated from the field emission type electron source 10 through the surface electrode 7.⁻FIG. 5 shows the result of measurement of the emission electron current Ie flowing between the collector electrode 21 and the surface electrode 7 by the dashed line in FIG. Here, the horizontal axis of FIG. 5 shows the value of the DC voltage Vps, and the vertical axis shows the current density.○ is this reference exampleOf the diode current Ips of FIG.● This reference exampleShows the emission electron current Ie.
[0041]
Incidentally, the electron emission efficiency is represented by a ratio Ie / Ips of the emission electron current Ie to the diode current Ips.This reference exampleIn the field emission type electron source 10 described above, a higher electron emission efficiency is obtained as compared with each of the above conventional examples.
[0042]
Note that a case where part or all of the above-described amorphous silicon layer 3 is crystallized during the manufacturing process may be considered, but there is no particular problem.
[0043]
(Embodiment)
In FIG.Of this embodimentFIGS. 7A to 7C are cross-sectional views of main steps in a method for manufacturing the field emission electron source 10. In addition,In this embodimentUses a substrate composed of a glass substrate 1a and a conductive film 2 formed on one surface of the glass substrate 1a as the conductive substrate 1, so that a single crystal silicon substrate is used as the conductive substrate 1. As compared with the above, the area of the electron source can be increased and the cost can be reduced.
[0044]
Of this embodimentAs shown in FIG. 6, in the field emission type electron source 10, a strong electric field drift portion 6 is formed on the main surface side of the conductive substrate 1, and a conductive thin film (for example, a gold thin film) is formed on the strong electric field drift portion 6. The surface electrode 7 is formed.
[0045]
In this field emission type electron source 10,, Reference Example 1Similarly to the above, the surface electrode 7 is arranged in a vacuum, a collector electrode (not shown) is arranged opposite to the surface electrode 7, and a DC voltage is applied with the surface electrode 7 as a positive electrode with respect to the conductive film 2. By applying a DC voltage using the collector electrode as a positive electrode with respect to the surface electrode 7, electrons injected from the conductive substrate 1 into the strong electric field drift portion 6 drift in the strong electric field drift portion 6 and are emitted through the surface electrode 7. You.
[0046]
In this embodimentThe strong electric field drift portion 6 has a cross section orthogonal to the thickness direction of the conductive substrate 1 formed in a mesh shape, and the drift portion 61 in which the electrons drift, and a thermal conductivity higher than that of the drift portion 61 filled in the mesh. And a heat radiating section 62 having a good quality. In short, the heat radiating portion 62 is formed in a prism shape parallel to the thickness direction of the conductive substrate 1. Here, the drift part 61 is made of oxidized porous amorphous silicon, and the heat radiation part 62 is made of oxidized amorphous silicon. In the strong electric field drift portion 6, the heat radiating portion 62 may be formed in the above-described mesh shape, and the drift portion 61 may be formed in the above-described prism shape.
[0047]
AndOf this embodimentIn the field emission electron source 10, since the heat generated in the drift portion 61 is radiated through the heat radiation portion 62, the electron can be stably and efficiently emitted without generating a popping phenomenon at the time of electron emission.
[0048]
The drift portion 61 may be made of an oxidized porous amorphous silicon compound, and the heat radiation portion 62 may be made of an oxidized amorphous silicon compound.
[0049]
Hereinafter, the manufacturing method will be described with reference to FIG.
[0050]
First, a non-doped amorphous silicon layer 3 having a predetermined thickness (for example, 1.5 μm) is formed (deposited) on the main surface of the conductive substrate 1 (on the conductive film 2), and then formed on the amorphous silicon layer 3. By applying a photoresist and patterning the photoresist using a photomask M as shown in FIG. 8, a resist mask 30 is formed to obtain a structure as shown in FIG. 7A. Here, since the amorphous silicon layer 3 is deposited by the plasma CVD method, it can be formed by a low-temperature process of 450 ° C. or less. Further, the photomask M is configured such that the planar shape of the resist mask 30 is a minute (for example, on the order of 0.1 μm) substantially square, but the planar shape of the resist mask 30 is a minute polygon other than the square. It may be configured to have a shape, a minute circle, a minute star, or the like.
[0051]
Next, a platinum electrode (not shown) was connected to a negative electrode by using an anodizing treatment tank containing an electrolytic solution composed of a mixture of a 55 wt% hydrogen fluoride aqueous solution and ethanol in a ratio of about 1: 1. Using the substrate 1 (conductive film 2) as a positive electrode and performing anodizing treatment under predetermined conditions (for example, constant current) while irradiating light to the main surface side of the amorphous silicon layer 3, the main surface of the amorphous silicon layer 3 is formed. Portions of the front side that are not covered with the resist mask 30 are made porous to form the porous amorphous silicon layer 11, and the structure shown in FIG. 7B is obtained. Here, reference numeral 12 in FIG. 7B denotes an amorphous semiconductor layer formed by a part of the amorphous silicon layer 3. This amorphous semiconductor layer 12 is formed in a quadrangular prism shape. In addition,In this embodimentMeans that the current density is 10 mA / cm²The anodic oxidation time was set to 30 seconds, and the main surface side of the amorphous silicon layer 3 was irradiated with light by a 500 W tungsten lamp during the anodic oxidation. However, this condition is an example and is not particularly limited. Absent.
[0052]
After the above-described anodizing treatment is completed, the electrolytic solution is removed from the anodizing treatment tank, the resist mask 30 is removed, and then an acid (for example, about 10% diluted nitric acid, about 10 % Diluted sulfuric acid, aqua regia, etc.), and then, using an anodizing tank containing the acid, a platinum electrode (not shown) is used as a negative electrode, and a conductive substrate 1 (conductive film 2) is used. As a positive electrode, a strong electric field drift portion 6 is formed by flowing a constant current to oxidize the porous amorphous silicon layer 11 and the amorphous semiconductor layer 12, and then a conductive thin film (for example, a gold thin film) is formed on the strong electric field drift portion 6. 7) is obtained by forming, for example, by vapor deposition. Here, 61 in FIG. 7C indicates the oxidized porous amorphous silicon layer 11 corresponding to the drift portion 61 described above, and 62 indicates the oxidized amorphous semiconductor layer 12 which corresponds to the heat dissipation portion 62 described above. Corresponding. That is, the drift part 61 and the heat radiation part 62 in FIG. 7C constitute the strong electric field drift part 6. The thickness of the surface electrode 7 is set to approximately 15 nm, but the thickness is not particularly limited, and the method of forming a conductive thin film (for example, a gold thin film) serving as the surface electrode 7 is also limited to vapor deposition. Instead, for example, a sputtering method may be used. The field emission electron source 10 has a diode in which the surface electrode 7 is a positive electrode (anode) and the conductive film 2 is a negative electrode (cathode). The current flowing when a DC voltage is applied between the positive electrode and the negative electrode is a diode current.
[0053]
In addition,Of this embodimentIn the field emission electron source 10, it is considered that electron emission occurs in the following model. When the DC voltage applied to the surface electrode 7 as a positive electrode with respect to the conductive substrate 1 (conductive film 2) reaches a predetermined value (critical value), electrons are transferred from the conductive film 2 to the strong electric field drift portion 6 by thermal excitation. Is injected. On the other hand, in the drift portion 61 of the strong electric field drift portion 6, a large number of nanometer-order microcrystalline silicon layers exhibiting a quantum confinement effect are present, and the surface of the microcrystalline silicon layer is smaller than the crystal grain size of the microcrystalline silicon layer. It is considered that a silicon oxide film having a thickness is formed. Therefore, most of the electric field applied to the strong electric field drift portion 6 is applied to the silicon oxide film formed on the surface of the microcrystalline silicon layer, and the injected electrons are accelerated by the strong electric field applied to the silicon oxide film and drift. Drift in the portion 61 toward the surface. Here, the drift length of the electrons reaches the surface of the drift portion 61 with almost no collision because the drift length of the electrons is much larger than the particle diameter of the microcrystalline silicon layer. The electrons that have reached the surface of the drift portion 61 are hot electrons, and the hot electrons have energy of several kT or more as compared with the thermal equilibrium state. It is easily tunneled and released into a vacuum.
[0054]
by the way,Of this embodimentIn the field emission type electron source 10, electrons can be emitted stably with high efficiency without generating popping noise. This is because heat generated in the drift portion 61 of the strong electric field drift portion 6 by application of a voltage. Is transmitted to the outside through the heat radiating portion 62 and the temperature rise is suppressed. Therefore, it is possible to optimize the area ratio between the drift part 61 and the heat radiating part 62 in the strong electric field drift part 6 to improve the electron emission efficiency.
[0055]
In summary, the strong electric field drift portion 6 has a semi-insulating property in which a strong electric field can exist, has a small electron scattering and a large drift length, and has a thermal conductivity sufficient to suppress thermal runaway of the diode current. Therefore, it is considered that electrons can be stably emitted with high efficiency.
[0056]
Of this embodimentIn the manufacturing method, the amorphous silicon layer 3 is formed by a low-temperature process such as a plasma CVD method, the porous amorphous silicon layer 11 is oxidized with an acid, and the surface electrode 7 is formed by an evaporation method, a sputtering method, or the like. Since the film is formed, the field emission electron source 10 can be manufactured by a low-temperature process of 450 ° C. or less. Therefore, an inexpensive substrate such as non-alkali glass, which can have a large area, and an inexpensive substrate, such as a resin substrate, can be used as the conductive substrate 1. The area and cost can be reduced.
[0057]
【The invention's effect】
The invention according to claim 1 includes a conductive substrate, a strong electric field drift portion formed on one surface side of the conductive substrate, and a surface electrode made of a conductive thin film formed on the strong electric field drift portion, A field emission type electron source in which electrons injected from the conductive substrate drift in the strong electric field drift portion and are emitted through the surface electrode by applying a voltage with the surface electrode being a positive electrode with respect to the conductive substrate. The drift partA drift section in which the cross section perpendicular to the thickness direction of the conductive substrate is formed in a mesh shape and the electrons drift, and a column-shaped heat radiating section having better thermal conductivity than the drift section filled in the mesh, The drift part is made of oxidized porous amorphous silicon or a porous amorphous silicon compound, and the heat radiation part is made of oxidized amorphous silicon or an oxidized amorphous silicon compound.The process temperature is lower than in the case where the strong electric field drift portion is formed of porous polycrystalline silicon, the restriction on the conductive substrate is reduced, and the area and cost can be easily reduced. It has the effect of becoming.
Moreover, strong electric field driftSince the Joule heat generated in the drift part is radiated through the heat radiating part in the part, it is possible to prevent the popping phenomenon from occurring at the time of electron emission, and it is stableTo emit electrons with high efficiencyThat the stability with time is improvedeffective.
[0060]
In addition, the source of the strong electric field driftSince it is made of rufus silicon or an amorphous silicon compound, there is an effect that it is possible to divert a manufacturing apparatus such as a thin film transistor or a solar cell and to use a process.. In addition, there is an effect that the control of the electric characteristics of the strong electric field drift portion is facilitated.
[0064]
Claim2The invention of claimOneIn the invention,The above drillThe lift portion has semiconductor microcrystals in the order of nanometers, and the surface of the semiconductor microcrystals is covered with an insulating film having a thickness smaller than the crystal grain size of the semiconductor microcrystals. And the electron emission efficiency can be improved.
[0065]
Claim3The invention of claim2According to the invention, since the insulating film is made of an oxide film, there is an effect that the insulating film can be easily formed.
[0066]
Claim4The invention of claim 1 to claim 13In the invention of the above, since the strong electric field drift portion is formed by a low-temperature process of 450 ° C. or less, a conductive substrate having a conductive film formed on one surface side such as an inexpensive glass substrate or a resin substrate may be used. It can be used, and has an effect that cost reduction and large area can be achieved.
[0067]
Claim5The invention of claim 1 to claim 14In the invention, the conductive substrate is composed of a glass substrate and a conductive film formed on one surface of the glass substrate, and the electric field drift portion is formed on the conductive film. There is an effect that it is possible to divert the manufacturing apparatus and use the process.
[0068]
Claim6The invention of claim5In the invention, since the glass substrate is made of an alkali-free glass substrate, there is an effect that the cost can be further reduced and the area can be increased.
[Brief description of the drawings]
FIG.Reference Example 1FIG.
FIG. 2 is a main process sectional view for explaining the manufacturing method of the above.
FIG. 3 is an explanatory diagram of a principle of measuring characteristics according to the first embodiment;
FIG. 4 is a diagram illustrating the principle of an electron emission mechanism according to the first embodiment;
FIG. 5Reference Example 2FIG. 4 is a voltage-current characteristic diagram.
FIG. 6The embodiment1A is a schematic longitudinal sectional view, and FIG. 1B is a schematic horizontal sectional view.
FIG. 7 is a main process sectional view for explaining the manufacturing method of the above.
FIG. 8 is a plan view of a photomask for describing the manufacturing method according to the embodiment.
[Explanation of symbols]
1 conductive substrate
1a Glass substrate
2 Conductive film
6 Strong electric field drift part
7 Surface electrode
10. Field emission electron source

Claims (6)

A conductive substrate, comprising: a strong electric field drift portion formed on one surface side of the conductive substrate; and a surface electrode formed of a conductive thin film formed on the strong electric field drift portion. a field emission electron source is emitted through the drift surface electrode electrons strong electric field drift part injected from the conductive substrate by applying a voltage as a positive electrode for a high electric field drift part, conductive substrate A cross section orthogonal to the thickness direction of the mesh is formed in a mesh shape, and includes a drift portion in which the electrons drift, and a columnar heat dissipation portion having better thermal conductivity than the drift portion filled in the mesh, and the drift portion is oxidized. The heat radiation part is made of oxidized amorphous silicon or oxidized amorphous silicon compound. Electrolytic emission electron source, characterized in that it consists of. 3. The semiconductor device according to claim 1, wherein the drift portion has semiconductor microcrystals on the order of nanometers, and the surface of the semiconductor microcrystals is covered with an insulating film having a thickness smaller than the crystal grain size of the semiconductor microcrystals. The field emission type electron source according to the above. 3. A field emission type electron source according to claim 2 , wherein said insulating film comprises an oxide film . 4. The field emission type electron source according to claim 1 , wherein the strong electric field drift portion is formed by a low-temperature process of 450 ° C. or lower . Claim the conductive substrate is composed of a formed on one surface of the glass substrate and the glass substrate conductive film, the strong electric field drift part, characterized by comprising formed over the conductive film The field emission electron source according to claim 1 . The field emission type electron source according to claim 5 , wherein the glass substrate is a non-alkali glass substrate .

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