JP3540445B2 - MIM / MIS electron source and method of manufacturing the same - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a MIM / MIS electron source, and more particularly to a MIM / MIS electron source capable of emitting electrons from an arbitrary pattern area on a substrate.
[0002]
[Prior art]
The MIM electron source is an electron source having a three-layer structure of metal-insulator-metal, and the MIS electron source is a metal-insulator-semiconductor. ) Is an electron source having a three-layer structure. These electron sources have attracted attention as elements having the following advantages: (1) hardly affected by surface contamination, (2) low operating voltage of about 5 to 10 V, and (3) an electron emission region can be formed in an arbitrary pattern. Are gathering. The operating principle is based on the quantum mechanical tunnel effect. That is, two kinds of metals having different Fermi levels or a metal and a semiconductor are joined with an insulating layer interposed therebetween, and electrons that have passed through the insulating layer by tunneling are emitted to the outside.
[0003]
Currently, the mainstream of the proposed MIM / MIS electron source structure is an MIM structure in which a three-layer structure of a metal-insulator-metal thin film is formed on a substrate. For example, the 17th to 21st pages of the 3rd meeting of the Japan Society for the Promotion of Science Vacuum Microelectronics 158th Committee (August 29, 1994), "Non-forming of Metal-Insulator-Metal Type Electron Source" Under the heading "Electron Emission Characteristics in the State", experimental results of trial production of a MIM electron source having a three-layer thin film structure of aluminum-aluminum oxide-gold on a silicon substrate have been reported. In addition, on page 579 of the 55th Federation of Applied Physics-related Lectures, the temperature characteristic of the emission current of the MIM electron source was reported entitled "Temperature dependence of the electron emission characteristic of the MIM electron source" I have. Further, the 42nd Applied Physics-related Lecture Meeting, p. 642, entitled "Emission Characteristics of Cone-Type MIS Electron Source" and "Production of Cone-Type MIS Electron Source with External Electrodes" Research results on electron sources have been reported.
[0004]
[Problems to be solved by the invention]
However, these conventional MIM / MIS electron sources are all experimental, and it is difficult to stably emit uniform electrons in a plane, and the manufacturing process is extremely difficult. There is a problem that it is difficult, and it has not been put to practical use. One of the factors greatly affecting the performance of the MIM / MIS electron source as an element is the quality and thickness of the insulating layer. The insulating layer needs to be thin enough to cause a tunnel effect, and usually has a thickness of only a few nm. For this reason, pinholes and the like easily occur, and it is very difficult to form a high-quality insulating film. It is also technically difficult to form an insulating layer having a uniform thickness. If a defect such as a pinhole or a variation in thickness occurs in the insulating layer, a leakage current is generated, and uniform and stable electron emission is hindered. Further, the state of the interface between the insulating layer and the metal layer (semiconductor layer) is also one of the factors affecting the performance of the MIM / MIS element, and it is very difficult to manufacture an element having an ideal interface. is there.
[0005]
Therefore, an object of the present invention is to provide a MIM / MIS electron source capable of uniformly and stably emitting electrons within a predetermined plane and having a simple manufacturing process, and a method of manufacturing the same.
[0006]
[Means for Solving the Problems]
(1) A first aspect of the present invention relates to a MIM / MIS electron source,
A fine particle layer formed by filling a large number of fine particles made of the first conductive material, the surface of which is covered with an insulating layer; a lower electrode layer formed on the lower surface of the fine particle layer; And the formed upper electrode layer,
The insulating layer has a thickness that allows electrons to pass through due to the tunnel effect,
The upper electrode layer is made of a second conductive material different from the first conductive material, and the first conductive material and the second conductive material are made of a metal or a semiconductor having different Fermi levels from each other. Wherein the Fermi level of the first conductive material is higher than the Fermi level of the second conductive material;
When a predetermined voltage is applied between the upper electrode layer and the lower electrode layer, the particles are filled with a density sufficient to allow a current to flow between them.
[0007]
(2) According to a second aspect of the present invention, in the MIM / MIS electron source according to the first aspect,
Aluminum is used as the first conductive material, gold is used as the second conductive material, and aluminum oxide is used as the insulating layer.
[0008]
(3) A third aspect of the present invention provides the MIM / MIS electron source according to the first aspect, wherein:
Silicon is used as the first conductive material, gold is used as the second conductive material, and silicon oxide is used as the insulating layer.
[0009]
(4) According to a fourth aspect of the present invention, in the MIM / MIS electron source according to the first to third aspects,
Ultrafine particles having a diameter of 100 nm or less are used as the fine particles constituting the fine particle layer.
[0010]
(5) A fifth aspect of the present invention is a method for manufacturing the MIM / MIS electron source according to the first to fourth aspects,
Forming a lower electrode layer on a predetermined support substrate,
Preparing a first chamber containing a first conductive material, and a second chamber for forming a fine particle layer;
In the first chamber, the first conductive material is evaporated while introducing the inert gas and the material gas for the insulating layer to generate fine particles, and the supporting substrate is accommodated in the second chamber, and the generated fine particles are contained. Is introduced into the second chamber and discharged from the nozzle toward the lower electrode layer on the support substrate, thereby forming a fine particle layer on the lower electrode layer.
An upper electrode layer made of a second conductive material is formed on the fine particle layer.
[0011]
(6) According to a sixth aspect of the present invention, in the method for manufacturing an MIM / MIS electron source according to the fifth aspect,
A moving stage for moving the supporting substrate is provided in the second chamber, and the fine particle layer is grown while moving the supporting substrate by the moving stage, thereby forming a fine particle layer having a pattern corresponding to the movement locus. Things.
[0012]
[Operation]
The basic concept of the present invention is that a part of basic components of a metal-insulator-metal MIM electron source or a metal-insulator-semiconductor MIS electron source is realized using fine particles. For example, an insulating film made of aluminum oxide is formed on the surface of fine particles of aluminum. If these fine particles are deposited on a predetermined substrate at a certain density to form a fine particle layer, the fine particle layer becomes a metal-insulator layer containing many of the basic components of the MIM electron source. Become. If, for example, a gold thin film is formed on the upper surface of the fine particle layer, a junction of "aluminum-aluminum oxide-gold", that is, a MIM junction of "metal-insulator-metal" is obtained. Here, if the thickness of the aluminum oxide is set to be sufficiently small so as to cause a tunnel effect, and the individual fine particles are filled at a sufficient density, the MIM called “aluminum-aluminum oxide-gold” can be obtained. Junctions can be seen everywhere, and each such junction will function as an individual MIM electron source element. Therefore, if a lower electrode layer is formed on the lower surface of the fine particle layer and a predetermined voltage is applied between the lower electrode layer and the upper electrode layer, a current flows between the two electrode layers. Here, if the thickness of the upper electrode layer is set to a thickness suitable for electron emission, electron emission occurs from the surface of the upper electrode layer. In particular, if ultrafine particles having a diameter of 100 nm or less are used as fine particles to be used, very fine and uniform electron emission can be obtained from the surface of the upper electrode layer.
[0013]
The element of the MIM electron source having such a structure can be manufactured by a very simple manufacturing process. For example, by maintaining the inside of the first chamber at a predetermined degree of vacuum and evaporating aluminum while introducing oxygen gas, the inside of the chamber can be filled with aluminum fine particles covered with an oxide film. In general, aluminum is a metal that is very easily oxidized. Therefore, even if aluminum particles are created in a chamber filled with an inert gas, the surface of the aluminum particles is oxidized when the aluminum particles are removed in the atmosphere. And the surface tends to be oxidized by impurity oxygen and water in the inert gas even in the chamber. Therefore, although it is not always necessary to positively introduce oxygen gas into the chamber, it becomes possible to control the oxide film thickness by introducing oxygen gas.
[0014]
The fine particles thus generated are introduced into the second chamber, and are discharged toward the lower electrode layer on the supporting substrate, whereby a fine particle layer can be formed on the lower electrode layer. The size of the fine particles and the thickness of the oxide film can be controlled by the degree of vacuum in the chamber and the evaporation temperature of the material. In the fine particle layer formed on the lower electrode layer, an enormous number of fine particles are deposited, and a “metal-insulator” junction is formed on the surface of each fine particle. Therefore, if an upper electrode layer is formed on the upper surface of the fine particle layer, an MIM junction of "metal-insulator-metal" can be finally obtained, and the area of the MIM junction obtained as a whole is very large. It will be big. Therefore, very efficient electron emission becomes possible. In addition, since the density and distribution of the fine particles are uniform on the lower electrode layer as a whole, uniform and stable electron emission in the plane can be obtained.
[0015]
Note that a moving stage for moving the supporting substrate is provided in the second chamber, and the fine particle layer is grown while moving the supporting substrate by the moving stage. Deposition can be performed at an arbitrary position, and an arbitrary pattern according to the movement locus can be formed very easily.
[0016]
【Example】
Hereinafter, the present invention will be described with reference to the illustrated embodiments. First, the structure and operation of a conventionally proposed general MIM electron source will be briefly described for reference.
[0017]
FIG. 1 is a cross-sectional view showing a general MIM electron source conventionally proposed and a configuration of an electronic device using the MIM electron source. In this example, the MIM electron source is composed of three layers, a metal layer 1, an insulating layer 2, and a metal layer 3. Here, the metal layer 1 is made of aluminum (Al), and the insulating layer 2 is made of aluminum oxide (Al). ₂ O ₃ ), And the metal layer 3 is made of gold (Au). In the MIM electron source having such a three-layer structure, a voltage V1 (for example, V1 = 10 V) is applied between the metal layer 1 and the metal layer 3 as shown in FIG. When the anode voltage V2 (for example, V2 = 500 V) is applied to the counter electrode 4 at an inclined position, the electrons e from the MIM electron source toward the counter electrode 4 are generated. ⁻ Is released (between them, for example, 10 ^-5 The pressure is maintained at about Pa).
[0018]
Such a phenomenon is explained by the energy level diagram shown in FIG. Aluminum and gold are metals having different Fermi levels from each other, but when a voltage V1 is applied in a direction in which both Fermi levels match, an energy level as shown is obtained with the intermediate aluminum oxide layer 2 interposed therebetween. Will be. Here, assuming that the applied voltage V1 is about 10 V and the thickness of the aluminum oxide layer 2 is about 10 nm where a tunnel effect can occur, the electric field in the aluminum oxide layer 2 becomes 10 ⁹ In order to reach about V / m, electrons tunnel from the aluminum layer 1 to the conduction band of the aluminum oxide layer 2, and the tunnel electrons e ⁻ Move to the gold layer 3 and lose energy due to scattering. Such a tunnel electron e ⁻ Moves, a diode current I1 flowing through the three layers having the MIM structure is generated. On the other hand, the tunnel electron e with a small energy loss ⁻ Is released into the vacuum beyond the barrier of the work function φ and travels to the counter electrode 4. The emission current I2 flowing through the counter electrode 4 is equal to the tunnel electrons e thus emitted. ⁻ Is due to the movement of Here, the current ratio I2 / I1 indicates a ratio (emission ratio) of electrons emitted to the counter electrode side of all tunnel electrons. In the case of a general MIM electron source reported so far, I2 / I1 = 10 ^-3 -10 ^-5 It is about.
[0019]
An MIM electron source that operates based on such a principle becomes a device that is extremely resistant to surface contamination. This is because the tunnel current governs not the surface barrier but the interface barrier between the aluminum layer 1 and the aluminum oxide layer 2.
[0020]
However, as described above, it is difficult for such a conventional MIM electron source to uniformly and stably emit electrons from the emission surface, and the manufacturing process is difficult. For example, in the case of the example shown in FIG. 1, in order to uniformly and stably emit electrons from the surface of the gold layer 3, the thickness of each thin film is made uniform, and a high-quality thin film without partial defects is formed. There is a need to. With current technology, it is very difficult to uniformly form such a high-quality thin film.
[0021]
Although the MIM electron source according to the present invention is an element that operates based on the principle of operation described by the energy level diagram shown in FIG. 2, its physical structure is completely different. FIG. 3 is a cross-sectional view for explaining a basic configuration of the MIM electron source according to one embodiment of the present invention. The MIM electron source includes a lower electrode layer 5, a fine particle layer 6, and an upper electrode layer 7. Here, the lower electrode layer 5 is a layer used simply as an electrode for supplying electrons to the fine particle layer 6, and may be made of any material that functions as an electrode. For example, the lower electrode layer 5 may be configured using a metal such as gold, silver, copper, aluminum, zinc, nickel, and chromium, or any other conductive material.
[0022]
On the other hand, the fine particle layer 6 and the upper electrode layer 7 are parts that perform essential functions as an MIM electron source. That is, the fine particle layer 6 is a layer formed by filling a large number of fine particles made of the first conductive material whose surface is covered with the insulating layer, and the upper electrode layer 7 is formed of the first conductive material. Is a layer made of a second conductive material different from the above. Here, the first conductive material and the second conductive material are made of metals having different Fermi levels from each other, and the Fermi level of the first conductive material is higher than the Fermi level of the second conductive material. Has become. Moreover, the insulating layer formed on the surface of each of the fine particles constituting the fine particle layer 6 has a thickness that allows electrons to pass through due to the tunnel effect. Further, when a predetermined voltage is applied between the lower electrode layer 5 and the upper electrode layer 7, the fine particles are filled with a density sufficient to allow a current I1 to flow therebetween, thereby forming the fine particle layer 6. ing. In the case of the present embodiment, aluminum oxide (Al) ₂ O ₃ The fine particle layer 6 is formed by filling a large number of ultrafine particles having the above-mentioned layer, and the upper electrode layer 7 is a gold (Au) thin film layer.
[0023]
Generally, the term “ultrafine particles” is used for fine particles having a diameter of 100 nm or less. In the present embodiment, ultrafine particles constituting the fine particle layer 6 have a diameter of about 10 to 30 nm, and the total thickness of the fine particle layer 6 is set to about 20 μm (FIG. 3). Although the illustration of the fine particles in the middle portion of the fine particle layer 6 is omitted, the diameter of the fine particles is on the order of nm, whereas the thickness of the fine particle layer 6 is on the order of μm. 10 in the vertical direction ³ This is because particles of the order are filled.) On the other hand, the insulating film of aluminum oxide formed on the surface of the ultrafine particles has a thickness of about 5 nm, and has a thickness through which electrons can pass through by a tunnel effect. The upper electrode layer 7 made of gold needs to have a thickness such that the tunnel electrons supplied from the fine particle layer 6 are emitted from the upper surface thereof. Specifically, the thickness is preferably set to 100 nm or less. It is extremely preferable that the thickness can be set to about 10 nm.
[0024]
The inventor of the present application fills and forms such ultrafine particles as a fine particle layer 6 on the lower electrode layer 5 and forms the upper electrode layer 7 on the upper surface thereof. Such a structure functions as an MIM electron source. It was found out. For example, in FIG. 3, when a predetermined applied voltage V1 is supplied between a point P in the lower electrode layer 5 and a point Q in the upper electrode layer 7, the space between the two electrode layers 5, 7 is filled. Electric current will flow through some ultrafine particles. If the packing density of the ultrafine particles is maintained at a certain level, most of the ultrafine particles will come into surface contact with other ultrafine particles in the three-dimensional space, and the aluminum oxide layer will have a thickness that allows tunnel electrons to pass through. Therefore, a moving path of electrons from the lower electrode layer 5 to the upper electrode layer 7 through the fine particle layer 6 is eventually formed. In a structure having such an electron movement path, a phenomenon equivalent to the three-layer structure of the MIM electron source shown in FIG. 1 occurs. That is, when the voltage V1 is supplied, a part of the tunnel electrons in the fine particle layer 6 is released into the vacuum over the work function φ barrier based on the difference in Fermi level between aluminum and gold. In other words, electrons moving from the fine particle layer 6 to the upper electrode layer 7 are emitted from the surface. Therefore, as shown in FIG. 3, a counter electrode 8 (any material may be used as long as it functions as an electrode) is disposed above the upper electrode layer 7 with a predetermined space therebetween. If a predetermined anode voltage V2 is applied between a point Q in the electrode layer 7 and a point R in the counter electrode 8, electrons emitted from the surface of the upper electrode layer 7 are transferred to the counter electrode 8. I will head.
[0025]
The basic principle of the present invention has been described above with reference to the cross-sectional view of FIG. 3. The actual structure of the MIM electron source according to the specific embodiment of the present invention is shown in the perspective view of FIG. In the MIM electron source of this embodiment, a support substrate 9 is used to support the entire device. The support substrate 9 may be made of any material, but is made of a glass substrate in this embodiment. A lower electrode layer 5 made of aluminum is formed on the support substrate 9, and a so-called Kamaboko-shaped fine particle layer 6 is formed thereon. As shown in FIG. 3, the fine particle layer 6 is a layer in which ultrafine particles of aluminum whose surface is covered with a layer of aluminum oxide are filled to a predetermined density, and has a thickness of about 20 μm. Further, on the upper surface of the fine particle layer 6, an upper electrode layer 7 is further formed. The upper electrode layer 7 is a gold thin film layer, and has a thickness of about 10 nm as described above. As shown in the drawing, the lower electrode layer 5 and the upper electrode layer 7 are structured so as not to be short-circuited to each other.
[0026]
Here, when a predetermined applied voltage V1 is supplied between the lower electrode layer 5 and the upper electrode layer 7, as described above, a predetermined diode V1 The current I1 flows. At this time, some of the tunnel electrons are released into the vacuum beyond the work function φ barrier. Therefore, the counter electrode 8 as shown by a broken line in the figure is prepared, the anode voltage V2 is applied to the counter electrode 8, and the space between the support substrate 9 and the counter electrode 8 is maintained at a predetermined degree of vacuum. For example, electrons that have crossed the barrier of the work function φ are emitted from the surface of the fine particle layer 6 toward the counter electrode 8, and an emission current I2 is generated. Thus, the lower electrode layer 5, the fine particle layer 6, and the upper electrode layer 7 formed on the support substrate 9 function as an MIM electron source.
[0027]
Here, very stable electron emission is obtained from the surface of the upper electrode layer 7, and the electron emission distribution on the surface becomes uniform. This is because the fine particle layer 6 is a layer in which ultrafine particles are uniformly dispersed as shown in FIG. This is because an electron emission phenomenon occurs. Of course, when each ultrafine particle is viewed microscopically, the diameter and shape are different, and the contact state with adjacent ultrafine particles is also different. However, when viewed as a macroscopic view of the entire fine particle layer 6, both the distribution of the ultrafine particles and the state of mutual contact are uniform. In addition, in the case of the present embodiment, the fine particle layer 6 is filled with a large number of very fine particles having a diameter of about 20 nm, so that the area of the interface between aluminum and aluminum oxide, that is, the interface barrier at which a tunnel phenomenon occurs. The area becomes very large, and the tunnel phenomenon occurs effectively. In other words, since the insulating layer is formed as a surface layer of ultrafine particles, a stable insulating layer can be formed, a leakage current can be suppressed, and stable electron emission can be performed. .
[0028]
The MIM electron source according to the present invention has such a feature that a uniform and stable electron emission can be obtained and also that the manufacturing process is easy. Hereinafter, an example of a manufacturing process of the MIM electron source according to the present embodiment will be described. This manufacturing process utilizes a reactive ultrafine particle deposition technique using a so-called gas deposition apparatus.
[0029]
First, as shown in FIG. 5, two chambers are prepared. The first chamber 10 is a chamber for evaporating the contained aluminum material 11 and introducing oxygen gas to generate aluminum ultrafine particles whose surface is covered with an oxide film. The second chamber 20 is a chamber for forming the fine particle layer 6 by discharging the ultrafine particles generated in the first chamber to the lower electrode layer 5 on the support substrate 9.
[0030]
A heater 12 for heating the aluminum material 11 is provided in the first chamber 10. When a current is supplied from the power supply 13 to the heater 12, aluminum evaporates from the surface of the aluminum material 11, and a predetermined amount of aluminum is evaporated. The inside of the chamber kept at a vacuum degree will be filled. Helium as an inert gas and oxygen gas for forming an oxide film are introduced into the chamber through a gas introduction pipe 14. In such an environment, in the helium / oxygen atmosphere in the chamber, scattered aluminum atoms are bonded to each other to form aluminum fine particles, and the surface thereof is oxidized by oxygen gas. As a result, an oxide film is formed (gas evaporation method). The distribution ratio between the helium gas and the oxygen gas to be introduced can be appropriately selected. However, in order to reduce the thickness of the oxide film of the ultrafine particles to be generated, the distribution ratio of oxygen needs to be reduced. In this embodiment, the distribution ratio of oxygen is set to about 10%. The size of the generated fine particles can be controlled by the degree of vacuum in the chamber and the temperature of the heater 12. If the pressure in the chamber is maintained at about several tens mtorr to several thousand torr, it is possible to generate ultrafine particles of aluminum. It is preferable to maintain the above.
[0031]
Since aluminum is a metal which is very easily oxidized, it is not necessary to perform an operation for positively introducing oxygen gas into the first chamber 10. This is because the surface of the ultrafine aluminum particles is oxidized by oxygen or water contained in the inert gas in the chamber without actively introducing oxygen gas. However, since the oxide film thickness can be controlled by positively introducing oxygen gas, it is preferable to positively introduce a predetermined amount of oxygen gas in practical use.
[0032]
The aluminum fine particles covered with the oxide film generated in the first chamber 10 are sent into the second chamber 20 via the transfer pipe 15 and are discharged from the nozzle 21. If the pressure in the second chamber 20 is set lower than the pressure in the first chamber 10, the fine particles are naturally transferred into the second chamber 20 based on the pressure difference between the chambers. In this embodiment, the pressure in the first chamber 20 is maintained at 500 torr, and the pressure in the second chamber 20 is maintained at about 5 torr.
[0033]
A moving stage 22 is provided in the second chamber 20, and the support substrate 9 is fixed on the moving stage 22. At this time, the lower electrode layer 5 is formed on the support substrate 9 in advance. In this embodiment, a lower electrode layer 5 made of aluminum is formed by vapor deposition on a support substrate 9 made of glass. The ultrafine particles emitted from the nozzle 21 are sprayed on the upper surface of the support substrate 9. The moving stage 22 can freely move the support substrate 9 in a plane perpendicular to the blowing direction of the nozzle 21. Therefore, for example, as shown in FIG. 6, while slowly moving the support substrate 9 in the direction of arrow A in the figure along the lower electrode layer 5 formed in advance, By blowing the particles on the layer 5, the fine particle layer 6 having a pattern corresponding to the movement locus indicated by the arrow A can be grown on the lower electrode layer 5. In this embodiment, a fine particle layer 6 having dimensions of about 200 μm in width, 20 μm in thickness (height), and about 10 mm in length is obtained.
[0034]
According to the above-described method, the fine particle layer 6 having an arbitrary pattern can be formed according to the movement locus of the movement stage 22. This is a great advantage in using the MIM electron source for various elements. If necessary, if an etchant for aluminum is used, after the fine particle layer 6 is formed, patterning can be performed by an etching process. Finally, by forming a gold thin film layer as the upper electrode layer 7 on the upper surface of the fine particle layer 6 by vapor deposition or sputtering, the MIM electron source is completed.
[0035]
As described above, the present invention has been described based on the illustrated embodiments. However, the present invention is not limited to these embodiments, and can be implemented in various other modes. For example, in the embodiment described above, the lower electrode layer 5 is formed on the upper surface of the insulating support substrate 9 and the fine particle layer 6 is formed thereon, but if a conductive substrate is used as the support substrate 9, The support substrate 9 itself can function as the lower electrode layer 5, and the lower electrode layer 5 as a separate layer becomes unnecessary. However, in this case, it is necessary to take a method such as providing an insulating layer between the upper electrode layer 7 and the support substrate 9 so that the upper electrode layer 7 and the support substrate 9 do not come into direct contact with each other.
[0036]
Further, in the above-described embodiment, the MIM junction is obtained by the three-layer structure of aluminum-aluminum oxide-gold. However, the constituent material of each layer is not limited to these, and instead of aluminum or gold, another material is used. A suitable metal may be used, or another conductive material other than the metal may be used. The “conductive material” in the present specification is a broad concept including a semiconductor. When a semiconductor is used as one conductive material, a MIS electron source can be formed. For example, if silicon is used instead of aluminum as the first conductive material and an insulating film made of silicon oxide is formed on the surface of the fine particles of silicon, an MIS electron source having a structure of gold-silicon oxide-silicon can be obtained. Can be configured. Note that when silicon is used as the first conductive material, it is preferable that oxygen be positively introduced into the first chamber 10 to form a silicon oxide film on the surface. Further, it is preferable to maintain the oxygen fraction in the chamber 10 at about 5 to 20%.
[0037]
Of course, it is also possible to form a MIS electron source with metal fine particles having an insulating film formed on the surface and an upper electrode layer made of a semiconductor material. In short, two types of conductive materials having different Fermi levels are prepared, and an insulating film having a thickness through which electrons can pass through by the tunnel effect is provided on the surface of the fine particles made of the first conductive material having a high Fermi level. Is formed, and any element or compound may be used as each material as long as the upper electrode layer can be formed with the second conductive material having a low Fermi level. The larger the difference in Fermi level, the more stable electron emission can be obtained. However, from the viewpoint that a stable oxide film can be easily formed, it is practically preferable to use aluminum as one conductive material.
[0038]
In the above-described embodiment, the same fine particles using one kind of conductive material are used as the fine particles constituting the fine particle layer 6, but two or more kinds of fine particles are formed using two or more kinds of conductive materials. It is also possible to prepare and mix these fine particles to form a fine particle layer.
[0039]
【The invention's effect】
As described above, according to the present invention, since the MIM junction or the MIS junction is realized by the fine particle layer and the upper electrode layer, uniform and stable electron emission is possible within a predetermined plane, and the manufacturing process is simplified. A simple MIM / MIS electron source can be realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a general MIM electron source conventionally proposed and a configuration of an electronic device using the MIM electron source.
FIG. 2 is an energy level diagram for explaining a phenomenon occurring in the MIM electron source shown in FIG.
FIG. 3 is a cross-sectional view illustrating a basic configuration of an MIM electron source according to one embodiment of the present invention.
FIG. 4 is a perspective view showing an actual structure of an MIM electron source according to one embodiment of the present invention.
FIG. 5 is a block diagram showing an apparatus configuration for implementing a method of manufacturing an MIM electron source according to the present invention.
FIG. 6 is a detailed view of the inside of a second chamber 20 in the apparatus shown in FIG.
[Explanation of symbols]
1: Aluminum layer
2: Aluminum oxide layer
3… Gold layer
4: Counter electrode
5 Lower electrode layer
6 ... Particle layer
7 Upper electrode layer
8: Counter electrode
9 ... Support substrate
10: first chamber
11 ... Aluminum material
12 ... heater
13. Power supply
14 ... Gas inlet pipe
15 ... Transfer pipe
20: second chamber
21 ... Nozzle
22. Moving stage
I1: Diode current
I2: emission current I2
P, Q, R: Voltage supply point
V1 ... applied voltage
V2: Anode voltage
φ ... work function

Claims (6)

A fine particle layer formed by filling a large number of fine particles made of the first conductive material, the surface of which is covered with an insulating layer; a lower electrode layer formed on the lower surface of the fine particle layer; And an upper electrode layer formed,
The insulating layer has a thickness through which electrons can pass through by a tunnel effect, and the upper electrode layer is made of a second conductive material different from the first conductive material, and The second conductive material is made of a metal or a semiconductor having a different Fermi level from the second conductive material. The Fermi level of the first conductive material is higher than the Fermi level of the second conductive material,
MIM / MIS, wherein the fine particles are filled with a density sufficient to allow a current to flow between the upper electrode layer and the lower electrode layer when a predetermined voltage is applied. Electron source. The MIM / MIS electron source according to claim 1,
A MIM / MIS electron source, wherein aluminum is used as a first conductive material, gold is used as a second conductive material, and aluminum oxide is used as an insulating layer. The MIM / MIS electron source according to claim 1,
A MIM / MIS electron source, wherein silicon is used as a first conductive material, gold is used as a second conductive material, and silicon oxide is used as an insulating layer. The MIM / MIS electron source according to claim 1,
An MIM / MIS electron source characterized in that ultrafine particles having a diameter of 100 nm or less are used as fine particles constituting a fine particle layer. The method for manufacturing a MIM / MIS electron source according to claim 1,
Forming a lower electrode layer on a predetermined support substrate,
Preparing a first chamber containing a first conductive material, and a second chamber for forming a fine particle layer;
In the first chamber, the first conductive material is evaporated while introducing an inert gas and a material gas for the insulating layer to generate fine particles, and the support substrate is accommodated in the second chamber, By introducing the generated fine particles into the second chamber and discharging them from the nozzle toward the lower electrode layer on the support substrate, a fine particle layer is formed on the lower electrode layer,
A method for manufacturing an MIM / MIS electron source, comprising forming an upper electrode layer made of a second conductive material on the fine particle layer. The method for manufacturing a MIM / MIS electron source according to claim 5,
A moving stage for moving the support substrate is provided in the second chamber, and the fine particle layer is grown while moving the support substrate by the moving stage, thereby forming a fine particle layer having a pattern corresponding to the movement locus. A method for manufacturing an MIM / MIS electron source.

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