JP4033238B2 - Ballistic electron field emission electron source and manufacturing method thereof - Google Patents

Description

  In the present invention, a drift layer in which semiconductor layers and insulator layers are alternately stacked between a pair of electrodes is formed on a supporting substrate, and a voltage is applied between the pair of electrodes to substantially The present invention relates to a field emission electron source which emits an electron beam in a plane in parallel and a method for manufacturing the same.

  As an electron source that emits an electron beam, a device in which a cathode is heated to emit thermoelectrons has been used for a long time.

  However, in the case of an electron source that emits thermoelectrons as described above, there are problems that the apparatus becomes large and the electron emission density and efficiency are not sufficient.

  Therefore, a cold cathode type electron source that emits electrons by concentrating the electric field on a fine surface called Spindt type has been developed, and an electron source that concentrates the electric field on the tip of carbon nanotube (CNT) has also been developed. Has been.

  However, in the case of the electron source of the type in which the electric field is concentrated on the minute tip as described above, there are problems that the manufacturing process becomes complicated and the emission ability of the electron beam changes due to the change of the tip shape.

  In recent years, as a planar electron source using thin film lamination technology, an MIM type planar electron source in which a metal layer, an insulator layer, and a metal layer are laminated (see, for example, Patent Document 1), An MIS type planar electron source (for example, see Patent Document 2) in which a metal layer, an insulator layer, and a semiconductor layer are stacked has been proposed.

  Here, such a planar electron source normally emits tunnel electrons by applying a high electric field to an ultra-thin insulating layer of about 20 to 30 nm. Therefore, sufficient durability can be obtained. In order to do so, a material with high thinning technology and excellent insulation resistance is required, and there are problems in terms of manufacturing processes and materials.

  As another planar electron source, a planar electron source based on the principle of a ballistic electron emission phenomenon has been proposed (see, for example, Patent Document 3).

  Here, in the above-mentioned planar electron source, nano-sized silicon particles are arranged so as to be connected with an ultra-thin silicon oxide coating, and this is sandwiched between a pair of electrodes. By applying a voltage to the pair of electrodes, electrons drifting in silicon are converted into ballistic electrons, and these electrons are emitted from the electrodes on the surface.

  However, it is very difficult to manufacture the above-mentioned nano-sized silicon particles with high precision and to arrange them appropriately so as to connect them, and it is also difficult to sufficiently improve the electron emission efficiency. There was a problem.

  Recently, a planar field emission electron source has been proposed, in which a large number of conductive silicon films and insulating silicon oxide films are alternately stacked on a support substrate made of n-type silicon. (For example, refer to Patent Document 4).

  Here, in the above field emission electron source, in order to improve the electron emission capability, it is necessary to form a silicon film with a high crystallinity having a large mean free path of electrons as the silicon film. .

  However, when a highly crystalline silicon film is formed by a normal film formation method, it is generally necessary to raise the temperature of the support substrate to about 1000 ° C., and the support substrate to be formed is required to have very high heat resistance. There was a problem.

  In addition, when obtaining a silicon film with high crystallinity as described above, the temperature of the support substrate is greatly different between the formation of this silicon film and the formation of the silicon oxide film. When a large number of silicon films and insulating silicon oxide films are alternately stacked, the interface between the silicon film and the silicon oxide film may be distorted due to the difference in thermal expansion coefficient between the silicon film and the silicon oxide film. There is a problem that the electron emission efficiency is greatly reduced due to the destruction of the interface.

On the other hand, when a silicon film is formed at a lower temperature of the support substrate, the silicon film becomes amorphous, and the mean free path of electrons, which is an important physical property value required in the above-described ballistic electron emission phenomenon, is obtained. There is a problem that the electron emission capability is remarkably lowered, the heat conduction efficiency is lowered, the temperature of the field emission electron source is increased, and the durability is deteriorated.
JP-A-7-65710 JP-A-8-250766 Japanese Patent Laid-Open No. 2000-100360 JP 2002-352698 A

  In the present invention, a drift layer in which semiconductor layers and insulator layers are alternately stacked between a pair of electrodes is formed on a supporting substrate, and a voltage is applied between the pair of electrodes to substantially An object of the present invention is to solve the above-described problems in a field emission electron source that emits electron beams in a plane in parallel.

  That is, in the present invention, in the field emission electron source as described above, the electron emission capability is improved so that high electron emission efficiency can be obtained, and excellent durability can be obtained. It is an object of the present invention to make it possible to easily manufacture such a field emission electron source.

In the ballistic electron field emission electron source according to the present invention, in order to solve the above-described problem, a drift layer in which a semiconductor layer and an insulator layer are alternately stacked between a pair of electrodes is provided on a support substrate. In the formed ballistic electron field emission electron source, the semiconductor layer is made of a metal oxide and the insulator layer has a thickness of 0.5 to 10 nm .

In this ballistic electron field emission electron source, the film thickness of the semiconductor layer is in the range of 1/1000 to 5/4 of the mean free path of electrons in the semiconductor layer, and the ratio of the semiconductor layer The dielectric constant is preferably in the range of 1.5 to 100 times the relative dielectric constant of the insulator layer.

Further, in this ballistic electron field emission electron source, it is preferable that the thermal conductivity of the semiconductor layer is in the range of 0.05 W / cm · K to 100 W / cm · K.

In this ballistic electron field emission electron source, it is preferable to use zinc oxide as the metal oxide constituting the semiconductor layer.

In this ballistic electron field emission electron source, the insulator layer may be at least one selected from insulating oxides, nitrides, and oxynitrides, in particular, silicon oxide, It is preferable to use at least one selected from silicon nitride and silicon oxynitride.

In the method of manufacturing the ballistic electron field emission electron source in the present invention, in producing a ballistic electron field emission electron source as described above, the plasma treatment under atmospheric pressure above the semiconductor layer and the insulator layer It was made to form by.

  Here, it is preferable to use chemical vapor deposition as the plasma treatment under atmospheric pressure.

  In addition, when plasma treatment is performed under atmospheric pressure as described above, it is preferable to use nitrogen or argon as the atmospheric gas.

  Further, when performing the plasma treatment under atmospheric pressure as described above, the temperature of the support substrate is preferably set to 300 ° C. or lower.

  Further, as the plasma treatment under the atmospheric pressure, it is preferable to perform treatment using capacitively coupled plasma.

As in the ballistic electron field emission electron source (hereinafter simply referred to as a field emission electron source) in the present invention, a semiconductor layer and an insulator layer are alternately stacked between a pair of electrodes on a support substrate . In forming the drift layer, when a metal oxide is used as the main component of the semiconductor layer, the crystallization temperature is lower than that of silicon.

  For this reason, it is not necessary to increase the temperature of the support substrate to form a semiconductor layer made of a crystalline metal oxide, and a field emission electron source having a good electron emission capability can be easily obtained. When the semiconductor layer and the insulator layer are formed, the temperature difference of the support substrate is also reduced, and when the drift layer in which the semiconductor layer and the insulator layer are alternately stacked is formed, the semiconductor layer and the insulator layer are It is also possible to prevent the interface from being distorted and the interface from being destroyed, thereby preventing the electron emission efficiency from being lowered.

  In addition, the metal oxide used for the semiconductor layer has ionic bonds in the crystal lattice, and thus is more flexible than covalently bonded silicon, and is advantageous when it is curved.

  Further, the film thickness of the semiconductor layer is set to a range of 1/1000 to 5/4 of the mean free path of electrons under atmospheric pressure in the semiconductor layer, and the relative dielectric constant of the semiconductor layer is When the dielectric constant of the insulator layer is in the range of 1.5 to 100 times, by applying a voltage to the pair of electrodes, electrons injected from one electrode are not scattered by the semiconductor layer. In addition, the insulator layer is accelerated by a sufficient electric field, and the electrons are trajected to improve the electron emission efficiency.

  In addition, when the thermal conductivity of the semiconductor layer is in the range of 0.05 W / cm · K to 100 W / cm · K, sufficient heat is applied even when a voltage is applied to the pair of electrodes to emit electrons. Emission is performed, and the temperature rise of the field emission electron source is suppressed, and the durability is improved.

  In addition, when zinc oxide is used for the metal oxide used in the semiconductor layer, it is crystallized at a lower temperature, and the orientation in the c-axis direction is increased on various supporting substrates, so that an electric field with good electron emission capability The emission electron source can be more easily and stably manufactured.

  Further, when at least one selected from insulating oxides, nitrides, and oxynitrides is used as the main component of the insulator layer, the durability of the insulator layer is improved, and a field emission type The durability of the electron source is also improved. In particular, when at least one selected from silicon oxide, silicon nitride, and silicon oxynitride is used, it can be easily manufactured using a conventional semiconductor manufacturing process.

  In manufacturing the field emission electron source, if the semiconductor layer and the insulator layer are formed by plasma treatment under atmospheric pressure, no vacuum equipment is required, and the field emission electron source is manufactured at low cost. become able to.

  Further, when the semiconductor layer and the insulator layer are formed by chemical vapor deposition for the above-described plasma treatment under atmospheric pressure, the internal stress in each of these layers is reduced, and continuous film formation is easy. Will be able to do.

  In addition, when forming the semiconductor layer and the insulator layer by the plasma treatment under atmospheric pressure as described above, if nitrogen or argon is used as the atmosphere gas, it is manufactured at a lower cost than when other atmosphere gases are used. become able to.

  Further, when performing the plasma treatment under the atmospheric pressure as described above, if the temperature of the support substrate is set to 300 ° C. or lower to form the semiconductor layer and the insulator layer, the internal stress in each of these layers is reduced, and the above-mentioned A material having low heat resistance can also be used for the support substrate.

  Furthermore, as a plasma treatment under the above atmospheric pressure, when a capacitively coupled plasma treatment is performed, it is possible to stably maintain a high density plasma under the atmospheric pressure and to control the voltage waveform to be applied. High semiconductor layers and insulator layers can be formed.

It is a schematic explanatory drawing of the field emission type electron source which concerns on embodiment of this invention. In manufacturing the field emission electron source according to the above embodiment, a schematic explanation of a capacitively coupled plasma processing apparatus used to form a drift layer in which a semiconductor layer and an insulator layer are alternately and repeatedly stacked. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Support substrate 12 Lower surface electrode 13 Drift layer 13a Semiconductor layer 13b Insulator layer 14 Surface electrode 15 Collector electrode 20 Plasma processing apparatus 21 Lower electrode 22 Upper electrode 23 Base material 24 Gas supply apparatus 25 Gas flow path 26 1st power supply 27 2nd Power supply

  Next, a field emission electron source and a manufacturing method thereof according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. In addition, the field emission electron source and the manufacturing method thereof according to the present invention are not limited to those shown in the following embodiments, and can be appropriately modified and implemented without changing the gist thereof.

  In the field emission electron source according to this embodiment, as shown in FIG. 1, a lower electrode 12 is provided on a support substrate 11, and a semiconductor layer 13a and an insulator layer 13b are alternately arranged on the lower electrode 12. The drift layer 13 is formed by repeatedly stacking the layers so as to have a predetermined number of layers, and the surface electrode 14 is provided on the drift layer 13.

  In emitting electrons from the field emission electron source, the voltage Ve is applied between the lower surface electrode 12 and the surface electrode 14 so that the surface electrode 14 is positive.

  Further, in order to detect electrons emitted from the field emission electron source, a collector electrode 15 is disposed at a predetermined distance from the surface electrode 14, and the collector electrode 15 is the surface electrode 14. The voltage Vc is applied so as to have a higher potential.

  Then, the voltage Ve and the voltage Vc are appropriately set, electrons are injected from the lower surface electrode 12 into the drift layer 13, and the strong force acting on the semiconductor layer 13a and the insulator layer 13b constituting the drift layer 13 is applied. Electrons are drifted by an electric field and emitted through the surface electrode 14, and the electrons thus emitted are guided to the collector electrode 15.

  Here, as said support substrate 11, what was comprised with the hard material conventionally used for the electronic device, such as soda-lime glass, an alkali free glass, quartz, a silicon wafer, can be used, for example. It is also possible to use a material made of flexible plastic. Examples of the plastic material include polyethylene terephthalate (PET), triacetyl cellulose (TAC), cellulose acetate propionate (CAP), polycarbonate (PC), polyethersulfone (PES), and polyethylene naphthalate (PEN). ), Polyimide (PI) or the like can be used, and in order to improve the characteristics of the substrate made of these plastic materials, it is preferable to use a substrate whose surface is subjected to a known surface coating or surface treatment.

Moreover, as a material of said lower surface electrode 12, it is preferable to use low resistance metals, such as Al, Cr, Ta, Au, Ag, Cu, Pt, and a silicon wafer is used for said support substrate 11, for example. In some cases, silicon having a low resistance by performing a high concentration doping treatment can be used. Further, in the case where an optically transparent base material is used for the support substrate 11 and the support substrate 11 side has an optically transparent characteristic, a tin-doped material is used as the material for the lower surface electrode 12. A transparent electrode material such as indium oxide (ITO) or SnO _2, or a conductive polymer material such as polyethylene dioxythiophene polystyrene sulfonate (PEDOT: PSS) can be used. The thickness of the lower surface electrode 12 is not particularly limited, and when transparency is not required, it can be appropriately set in consideration of electrode resistance, film strength, and workability, and transparency is required. In this case, the light transmittance can be set as appropriate in addition to the above.

  In forming the lower electrode 12 on the support substrate 11, a coating method such as a spin coating method or a roll coating method is used in addition to a physical vapor deposition method such as a vacuum deposition method or a sputtering method. be able to.

On the other hand, as the material of the surface electrode 14, for example, metals such as Au, Pt, W, Ru, and Ir are effective, but Al, Ti, Cr, Mn, Ni, Cu, Ag, Mo, Zr, Ta, Zn, In, Sn, etc. can also be used, and alloys thereof may be used. Furthermore, as long as it exhibits conductivity, oxides of the above metal materials, for example, highly transparent conductive materials such as SnO ₂ , In ₂ O ₃ and ZnO, composite oxides thereof, A conductive polymer material such as polystyrene sulfonate polyethylene dioxythiophene (PEDOT: PSS) can also be used. When an optically transparent material is used for the lower surface electrode 12 and the front surface electrode 14, a field emission electron source having a high light transmittance can be obtained.

  In order to efficiently emit electrons from the surface electrode 14, it is preferable to use a material having a small work function as the material of the surface electrode 14, and the thinner the better, the Au is preferable from the viewpoint of stability. Pt, Ag, Cu, or an alloy of these metals is preferably used, and the thickness of the surface electrode 14 is preferably in the range of 1 to 50 nm.

  In forming the surface electrode 14 on the drift layer 13, a conventionally used thin film forming method can be used, but the drift electrode 13 is formed so as not to be damaged. It is preferable to use a facing target sputtering method, a spray coating method, or a plasma CVD method, which is a sputtering method with little damage.

The material of the semiconductor layer 13a in the drift layer 13, a zinc oxide ZnO which is an oxide semiconductor, titanium oxide TiO _2, indium oxide _{an In} 2 _{O 3,} tin oxide SnO _2, cadmium oxide CdO, tungsten oxide _{W 2} O ₅ , niobium oxide Nb ₂ O ₅ , nickel oxide NiO, strontium titanate SrTiO _3, etc. can be used, and in particular, c-axis oriented crystals can be easily obtained near room temperature, and by plasma treatment under atmospheric pressure It is preferable to use zinc oxide ZnO on which a high-quality thin film with few defects is formed.

  As for the thickness of the semiconductor layer 13a, if the thickness is too thick, electrons injected into the semiconductor layer 13a collide and scatter in the semiconductor layer 13a, and the electron emission efficiency is reduced. If the thickness is too thin, it becomes difficult to form the semiconductor layer 13a having a uniform thickness without defects, and thus the thickness of the semiconductor layer 13a is set to the mean free path of electrons in the semiconductor layer 13a as described above. It is preferable to make it the range of 1/1000 to 5/4.

  Further, as the material of the insulator layer 13b in the drift layer 13, various insulators can be used, and in particular, an inorganic oxide, nitride, or oxynitride having a low relative dielectric constant is preferably used. . Here, as the oxide, for example, silicon oxide, aluminum oxide, tantalum oxide, vanadium oxide, or the like can be used. In particular, it is preferable to use silicon oxide, fluorinated silicon oxide, or carbon-containing silicon oxide SiOC, which has a low dielectric constant and can be manufactured by a generally widely used semiconductor manufacturing technique. For the same reason, nitride is nitrided. It is preferable to use silicon and silicon oxynitride as the oxynitride.

  The thickness of the insulator layer 13b is set so thin that electrons passing through the semiconductor layer 13a can be tunneled, and generally within a range of 0.5 to 10 nm.

  Further, when the drift layer 13 is formed by alternately and repeatedly laminating the semiconductor layer 13a and the insulator layer 13b by plasma treatment under atmospheric pressure, the discharge is performed under atmospheric pressure or pressure near atmospheric pressure. After starting, the reactive gas introduced into the plasma is excited (dissociated, recombined or ionized), and then this is chemically reacted on the substrate to form a film. The atmospheric pressure or the pressure in the vicinity thereof is about 20 kPa to 110 kPa, and preferably about 93 kPa to 104 kPa.

  Here, as a device for forming the drift layer 13 by plasma processing under atmospheric pressure as described above, a capacitively coupled plasma processing device 20 as shown in FIG. 2 can be used.

  In this plasma processing apparatus 20, a plurality of upper electrodes 22 are juxtaposed at appropriate intervals in the arrangement direction above a flat plate-like lower electrode 21 with a predetermined interval therebetween, and the lower portion The electrode 21 and the upper electrode 22 can be moved relatively in parallel. In the plasma processing apparatus 20 shown in the figure, the base material 23 is set on the lower electrode 21, and the base material 23 is thus attached. The set lower electrode 21 is reciprocated in parallel.

  In addition, the gas is supplied from the gas supply device 24 between the lower electrode 21 and the upper electrode 22 through the gas flow path 25 between the upper electrodes 22.

  Then, the first high frequency voltage is applied to the lower electrode 21 from the first power source 26 and the second high frequency voltage is applied to the upper electrodes 22 from the second power source 27 so that the lower electrode 21 and the upper electrode The gas between the electrodes 22 is excited, the excited gas is brought into contact with the surface of the base material 23, and a thin film derived from the gas is formed on the surface of the base material 23. Yes.

  Here, when the drift layer 13 is formed by alternately stacking the semiconductor layers 13a and the insulator layers 13b using the plasma processing apparatus 20, the first power source 26 applies the drift layer 13 to the lower electrode 21. The first and second high-frequency electric fields are controlled independently by making the frequency and voltage of the first high-frequency voltage different from the second high-frequency voltage applied to each upper electrode 22 from the second power source 27. Is preferred. In this way, stable discharge can be performed under atmospheric pressure or a pressure condition in the vicinity thereof, and the semiconductor layer 13a made of a thin film with few defects and high crystallinity, and a thin film with high density and high insulation properties. The insulator layers 13b can be formed alternately and continuously.

  The distance between the lower electrode 21 and the upper electrode 22 is the thickness of the support substrate 11, the magnitude of the high-frequency voltage applied to the lower electrode 21 and the upper electrode 22, the semiconductor layer 13a, It is determined in consideration of the type of the insulator layer 13b and the like, and from the viewpoint of maintaining a uniform discharge, it is preferably in the range of 0.5 to 20 mm, more preferably 1 mm ± 0.5 mm. To.

Further, as the high frequency voltage applied to the lower electrode 21 and the upper electrode 22 described above, a gas is generated by exciting a gas between the lower electrode 21 and the upper electrode 22 under atmospheric pressure or a pressure condition in the vicinity thereof, thereby generating a dense plasma. In order to form a layer having a uniform thickness, it is preferable to supply a power of 1 W / cm ² or more at a high frequency voltage of 100 kHz or more.

  Further, when the drift layer 13 is formed by alternately laminating the semiconductor layers 13a and the insulator layers 13b on the lower surface electrode 12 formed on the support substrate 11, the support at the time of plasma processing is provided. When the temperature of the substrate 11 becomes high, thermal stress due to the difference in thermal expansion coefficient between the semiconductor layer 13a or the insulator layer 13b and the support substrate 11 remains, and these characteristics such as adhesion deteriorate, and the electron emission efficiency is reduced. In order to decrease, it is preferable that the temperature of the support substrate 11 at the time of plasma treatment is in the range of room temperature to 300 ° C.

  Further, the type of gas introduced between the lower electrode 21 and the upper electrode 22 is different depending on the semiconductor layer 13a and the insulator layer 13b to be formed, but basically, an atmospheric gas for performing discharge, A gas in which a thin film forming gas used as a raw material for forming the semiconductor layer 13a and the insulator layer 13b is mixed is used, and the volume ratio of the thin film forming gas in the entire gas is 0.01 to 10% by volume. The range is preferable from the viewpoint of maintaining good discharge.

  Here, as the atmospheric gas, for example, a rare gas such as helium, neon, argon, or xenon can be used. In particular, argon is preferably used from the viewpoint of reducing the production cost, and the rare gas described above is used. For example, oxygen, nitrogen, carbon dioxide, hydrogen, or the like can be used instead of the gas, but nitrogen is preferably used from the viewpoint of cost and environment.

  Moreover, as a gas for forming a thin film used for forming the semiconductor layer 13a and the insulator layer 13b, for example, an organic metal compound, a halogen metal compound, a metal hydrogen compound, or the like can be used. It is preferable to use an organometallic compound with a low risk of explosion, and in particular, an organometallic compound having at least one oxygen in the molecule is preferable.

  The organometallic compound used to form the semiconductor layer 13a includes a general formula R1xM · R2yR3z (wherein M is a metal, R1 is an alkyl group, R2 is an alkoxy group, R3 is a β-diketone complex group, β A group selected from a ketocarboxylic acid ester complex group, a β-ketocarboxylic acid complex group, a ketooxy group and a ketooxy complex group, where x + y + z = m, where x is the valence of the metal M, x, y , Z are both 0 or a positive integer). Examples of the alkyl group for R1 include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkoxy group of R2 include methoxy group, ethoxy group, propoxy group, butoxy group, 3,3,3-trifluoropropoxy group, and the like. May be substituted. Examples of the β-diketone complex group of R3 include 2,4-pentanedione (also referred to as acetylacetone or acetoacetone), 1,1,1,5,5,5-hexamethyl-2,4- Pentanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 1,1,1-trifluoro-2,4-pentanedione, and the like, and β-ketocarboxylic acid ester complex group As, for example, acetoacetic acid methyl ester, acetoacetic acid ethyl ester, acetoacetic acid propyl ester, trimethylacetoacetic acid ethyl, trifluoroacetoacetic acid methyl etc. can be mentioned, and β-ketocarboxylic acid includes, for example, acetoacetic acid, Examples of the ketooxy group include an acetooxy group and a propyloxy group. Pioniruokishi group, Buchirirokishi group, acryloyloxy group and a methacryloyloxy group. The number of carbon atoms of the ketoxy group is preferably 18 or less including the organometallic compound. These groups may be linear or branched, and may be those in which a hydrogen atom is substituted with a fluorine atom.

  Here, as the gas for forming a thin film used for forming the semiconductor layer 13a made of zinc oxide, for example, bis (2,4-pentanedionate) zinc, zinc acetylacetonate, diethylzinc, dimethylzinc and the like are used. Can be used.

  Examples of the gas for forming a thin film used to form the semiconductor layer 13a made of tin oxide include dibutyltin diacetate, etraethyltin, etramethyltin, di-n-butyltin diacetate, tetrabutyltin, and tetraoctyl. Tin can be used.

  In addition, as a thin film forming gas used to form the semiconductor layer 13a made of titanium oxide, for example, metal alkoxides such as tetraethoxy titanium, tetraisopropoxy titanium, and tetrabutoxy titanium can be used.

  On the other hand, examples of the organometallic compound of the thin film forming gas used to form the insulator layer 13b include tetraethylsilane, tetramethylsilane, tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), and trimethoxysilane. (TMS), trimethylsilane (4MS), hexamethyldisilane, and the like can be used.

  Further, in addition to the above atmospheric gas and thin film forming gas, it is also possible to add a reaction promoting gas that promotes the reaction of thin film formation. Examples of such reaction promoting gas include oxygen, ozone, Examples include hydrogen peroxide, carbon dioxide, carbon monoxide, hydrogen, ammonia, etc. Among them, use of oxygen, carbon monoxide and hydrogen widens the power range in which stable discharge can be obtained and promotes the reaction. It is preferable because it is advantageous for improving the denseness of the film. Further, the addition amount of such a reaction promoting gas is preferably in the range of 0.01 to 5% by volume with respect to the total amount of the gas, thereby promoting the reaction for forming a thin film and a dense and high-quality thin film. Can be formed.

  Next, specific examples of the present invention will be given, and it will be clarified that high electron emission efficiency can be obtained in the field emission electron source according to the examples of the present invention.

Example 1
In Example 1, non-alkali glass # 1737 manufactured by Corning Inc. was used for the support substrate 11, and the lower electrode 12 made of aluminum having a thickness of 300 nm formed by RF magnetron sputtering on the support substrate 11. Formed.

  In forming the drift layer 13 in which the semiconductor layer 13a and the insulator layer 13b are alternately and repeatedly stacked on the lower surface electrode 12, the plasma processing apparatus 20 shown in FIG. 60 layers of the semiconductor layer 13a made of zinc oxide having a thickness of 3 nm and the insulator layer 13b made of silicon oxide having a thickness of 2 nm were alternately stacked, resulting in a total of 120 layers. A drift layer 13 was formed.

Here, in forming the semiconductor layer 13a made of zinc oxide, the substrate temperature is set to room temperature, the pressure of the atmosphere is set to 103 kPa, and argon as the gas is 98.25% by volume, Using zinc acetylacetonate at 1.25 vol% and oxygen in the reaction promoting gas at 0.5 vol%, a high frequency voltage with a frequency of 100 kHz is applied from the first power source 26 to the lower electrode 21 at 1 W. both supplies the output power density / cm ^2, and so the frequency in the upper electrode 22 from the second power supply 27 described above is supplied to 13.56MHz RF voltage at the output power density of 5W / cm ^2. In the semiconductor layer 13a made of zinc oxide thus formed, the mean free path of electrons near room temperature is about 8 nm, the relative dielectric constant is about 7.9, and the thermal conductivity is about 0.55 W / cm · K. there were.

Further, in forming the insulator layer 13b made of silicon oxide, the substrate temperature is set to room temperature, the atmospheric pressure is set to 103 kPa, and the atmosphere gas nitrogen is 98.9% by volume. A solution in which tetraethoxysilane is 0.1% by volume and oxygen of the reaction promoting gas is 1.0% by volume is used, and a high frequency voltage of 100 kHz is applied to the lower electrode 21 from the first power source 26 described above. While supplying an output power density of cm ² , a high-frequency voltage having a frequency of 13.56 MHz was supplied from the second power source 27 to each upper electrode 22 at an output power density of 3 W / cm ² . The dielectric layer 13b made of silicon oxide thus formed had a relative dielectric constant of about 3.9.

  And after forming the drift layer 13 which laminated | stacked the semiconductor layer 13a and the insulator layer 13b alternately on the lower surface electrode 12 as mentioned above, film thickness is 15 nm by the vacuum evaporation method on it. A surface electrode 14 made of gold was formed.

Next, using the field emission electron source manufactured as described above, as shown in FIG. 1, a voltage of 20 V is applied so that the surface electrode 14 is positive between the lower electrode 12 and the surface electrode 14. As a result of applying Ve and applying a voltage Vc of 100 V so that the collector electrode 15 is at a higher potential than the surface electrode 14, a current of 1.0 × 10 ⁻⁵ A / cm is observed. An electron emission efficiency of 5% was obtained. Here, in the conventional field emission electron source, the electron emission efficiency is generally about 1%, and in the field emission electron source of this embodiment, the very high electron emission efficiency was obtained as described above. Further, in the field emission electron source of this example, there was no distortion or destruction of the interface, and the state was maintained even after voltage application.

Example 2
In Example 2, the same process as in Example 1 is performed until the lower surface electrode 12 is formed. Thereafter, the drift layer 13 in which the semiconductor layers 13a and the insulator layers 13b are alternately and repeatedly stacked on the lower surface electrode 12 is formed. In forming, using the plasma processing apparatus 20 shown in FIG. 2, a semiconductor layer 13a made of titanium oxide having a thickness of 5 nm and an insulator layer 13b made of silicon oxide having a thickness of 2 nm are respectively formed. 90 layers were alternately stacked to form the drift layer 13 having a total number of 180 layers.

Here, in forming the semiconductor layer 13a made of titanium oxide, the substrate temperature is set to room temperature, the atmospheric pressure is set to 103 kPa, and argon as the gas is 99.4% by volume. Tetraisopropoxytitanium is used in a volume of 0.1% by volume, and the reaction promoting gas hydrogen is used in a volume of 0.5% by volume. A high frequency voltage of 100 kHz is applied to the lower electrode 21 from the first power source 26 described above. both supplies the output power density / cm ^2, and so the frequency in the upper electrode 22 from the second power supply 27 described above is supplied to 13.56MHz RF voltage at the output power density of 3W / cm ^2. The semiconductor layer 13a made of titanium oxide formed in this manner has an electron mean free path around room temperature of about 7 nm, a relative dielectric constant of about 110, and a thermal conductivity of about 0.1, based on physical property measurements performed separately. It was 08 W / cm · K.

Further, in forming the insulator layer 13b made of silicon oxide, the substrate temperature is set to room temperature, the atmospheric pressure is set to 103 kPa, and the atmosphere gas nitrogen is 98.9% by volume. A solution in which tetraethoxysilane is 0.1% by volume and oxygen of the reaction promoting gas is 1.0% by volume is used, and a high frequency voltage of 100 kHz is applied to the lower electrode 21 from the first power source 26 described above. While supplying an output power density of cm ² , a high-frequency voltage having a frequency of 13.56 MHz was supplied from the second power source 27 to each upper electrode 22 at an output power density of 3 W / cm ² . The dielectric layer 13b made of silicon oxide thus formed had a relative dielectric constant of about 3.9.

  And after forming the drift layer 13 which laminated | stacked the semiconductor layer 13a and the insulator layer 13b alternately on the lower surface electrode 12 as mentioned above, film thickness is 15 nm by the vacuum evaporation method on it. A surface electrode 14 made of gold was formed.

Next, using the field emission electron source manufactured as described above, as shown in FIG. 1, a voltage Ve of 20 V is applied so that the surface electrode 14 is positive between the lower electrode 12 and the surface electrode 14. As a result of applying a voltage Vc of 100 V so that the collector electrode 15 has a higher potential than the surface electrode 14, a current of 7.0 × 10 ⁻⁶ A / cm is observed, and about 3. An electron emission efficiency of 5% was obtained. Here, in the conventional field emission electron source, the electron emission efficiency is generally about 1%, and in the field emission electron source of this embodiment, the very high electron emission efficiency was obtained as described above. Further, in the field emission electron source of this example, there was no distortion or destruction of the interface, and the state was maintained even after voltage application.

Example 3
In Example 3, the formation of the lower surface electrode 12 is the same as in Example 1, and then, the drift layer in which the semiconductor layer 13a and the insulator layer 13b are alternately and repeatedly stacked on the lower surface electrode 12. 2, the plasma processing apparatus 20 shown in FIG. 2 is used, and a semiconductor layer 13a made of tin oxide having a thickness of 2 nm and an insulator layer 13b made of silicon oxide having a thickness of 2 nm are formed. 60 layers were alternately laminated to form a drift layer 13 having a total of 120 layers.

Here, in forming the semiconductor layer 13a made of tin oxide, the substrate temperature is set to room temperature, the atmosphere pressure is set to 103 kPa, and the atmosphere gas argon is 99.3% by volume. A dibutyltin diacetate of 0.2% by volume and a hydrogen of the reaction promoting gas of 0.5% by volume are used, and a high frequency voltage of 100 kHz is applied to the lower electrode 21 from the first power source 26. both supplies the output power density / cm ^2, and so the frequency in the upper electrode 22 from the second power supply 27 described above is supplied to 13.56MHz RF voltage at the output power density of 5W / cm ^2. The semiconductor layer 13a made of titanium oxide formed in this manner has an electron mean free path near room temperature of about 5 nm, a relative dielectric constant of about 3.7, and a thermal conductivity of about 3.7, according to physical property measurements performed separately. It was 0.83 W / cm · K.

In forming the insulator layer 13b made of silicon oxide, the substrate temperature is set to room temperature, the pressure of the atmosphere is set to 103 kPa, and argon as the gas is 98.9% by volume. A hexamethylenedisiloxane having a volume of 0.1 volume% and a reaction promoting gas having an oxygen volume of 1.0 volume% is used, and a high frequency voltage of 100 kHz is applied to the lower electrode 21 from the first power source 26 described above. both supplies the output power density / cm ^2, and so the frequency in the upper electrode 22 from the second power supply 27 described above is supplied to 13.56MHz RF voltage at the output power density of 3W / cm ^2. The dielectric layer 13b made of silicon oxide thus formed had a relative dielectric constant of about 3.9.

  And after forming the drift layer 13 which laminated | stacked the semiconductor layer 13a and the insulator layer 13b alternately on the lower surface electrode 12 as mentioned above, film thickness is 15 nm by the vacuum evaporation method on it. A surface electrode 14 made of gold was formed.

Next, using the field emission electron source manufactured as described above, as shown in FIG. 1, a voltage of 20 V is applied so that the surface electrode 14 is positive between the lower electrode 12 and the surface electrode 14. As a result of applying Ve and applying a voltage Vc of 100 V so that the collector electrode 15 has a higher potential than the surface electrode 14, a current of 6.0 × 10 ⁻⁶ A / cm was observed, and about An electron emission efficiency of 3.0% was obtained. Here, in the conventional field emission electron source, the electron emission efficiency is generally about 1%, and in the field emission electron source of this embodiment, the very high electron emission efficiency was obtained as described above. Further, in the field emission electron source of this example, there was no distortion or destruction of the interface, and the state was maintained even after voltage application.

Claims (11)

In a ballistic electron field emission electron source in which a drift layer in which a semiconductor layer and an insulator layer are alternately stacked between a pair of electrodes is formed on a support substrate, the semiconductor layer is made of a metal oxide. Ri, ballistic electron field emission electron source where the thickness of the insulator layer is characterized 0.5~10nm der Rukoto. The thickness of the semiconductor layer is in the range of 1/1000 to 5/4 of the mean free path of electrons in the semiconductor layer, and the relative dielectric constant of the semiconductor layer is 1 of the relative dielectric constant of the insulator layer. 2. The ballistic electron field emission electron source according to claim 1 , wherein the electron source is in the range of 5 times to 100 times. 3. The ballistic electron field emission electron source according to claim 1, wherein the semiconductor layer has a thermal conductivity in a range of 0.05 W / cm · K to 100 W / cm · K. The ballistic electron field emission electron source according to any one of claims 1 to 3 , wherein the semiconductor layer is made of zinc oxide. 5. The ballistic electron according to claim 1, wherein a main component of the insulator layer is at least one selected from insulating oxides, nitrides, and oxynitrides. Field emission electron source. 6. The ballistic electron field emission electron source according to claim 5 , wherein the main component of the insulator layer is at least one selected from silicon oxide, silicon nitride, and silicon oxynitride. A method of manufacturing a ballistic electron field emission electron source for producing ballistic electron field emission electron source according to any one of claims 1 to 6, the plasma in the atmospheric pressure and a semiconductor layer and an insulator layer A method of manufacturing a ballistic electron field emission electron source, characterized by forming by processing. 8. The method of manufacturing a ballistic electron field emission electron source according to claim 7 , wherein the plasma treatment under atmospheric pressure is a chemical vapor deposition method. The method for manufacturing a ballistic electron field emission electron source according to claim 7 or 8 , wherein the atmospheric gas during the plasma treatment under atmospheric pressure is nitrogen or argon. The method of manufacturing a ballistic electron field emission electron source according to any one of claims 7 to 9 , wherein the temperature of the support substrate when performing the plasma treatment under the atmospheric pressure is 300 ° C or lower. The method for manufacturing a ballistic electron field emission electron source according to any one of claims 7 to 10 , wherein the plasma treatment under atmospheric pressure is a treatment using capacitively coupled plasma.