JPH05174703A - Electric field emitting type element and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture an electric field emitting element which is low in electron emitting voltage and stable in electric property excellently in reproducibility and uniformity. CONSTITUTION:A cold cathode 10, which constitutes an electric field emitting type element, has a sharply pointed projection on at its top, and it has such a shape that the projection and the barrel part are connected to each other in the shape of a continuous curve. In this manufacture, a cavity is formed on a silicon board 1, and a cold cathode is formed by using a mold being formed by oxidizing the cavity. For the manufacture of the electron emitting type element, the interval between the cold cathode 10 and a gate electrode 11 is decided by the thickness, etc., of a silicon oxide film 9, and the positioning is performed by using the etchstop technics by the buried silicon oxide film inside the silicon substrate 1 or electrochemical etching. The electron emission voltage of the cold cathode is low, and the stability and the life of electric properties can be improved. A plurality of electric field emitting type elements, each of which has a pointed cold cathode and a gate electrode installed accurately in the position very near to the cold cathode, can be manufactured equally and excellently in reproducibility.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission device suitable for use in various electronic signal processing circuits, electronic signal amplifiers, etc., for example, used in scanning electron microscopes and cathode ray tubes, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A micron-sized field emission device formed on a silicon substrate or a glass substrate by using an integrated circuit manufacturing process technique has been actively researched in recent years, and a vacuum composed of a cold cathode, a control electrode and an anode. New applications are expected, such as application to a vacuum tube integrated circuit forming a triode structure, and application to a flat panel display in which a large number of cold cathodes are arranged on a plane and phosphors are provided on opposite surfaces.

As a conventional field emission device and its manufacturing method, for example, the method of Gray in US Patent 4,307,507 (Dec.29, 1981), SMZimmerman, DB Colavito and W.
DEVELOPMENT PROGRESS TOWARD THE FABR by T.Babie
ICATION OF VACUUM MICROELECTRONIC DEVICES USING CO
NVENTIONAL SEMICONDUCTOR PROCESSING (PROCEEDINGSOF
IEDM90, P.163-P.166 (1990)), WILLIAM J. ORVIS, CHARLES F. McCONAGHY, DINO R.
"Modeling by CIARLO, JICK H. YEE and ED W. HEE
and Fabricating Micro-Cavity Integrated VacuumTub
es "(IEEE TRANSACTIONS ON ELECTRON DEVICES VOL.36 N
The one proposed in O.11 NOVEMBER 1989) is known. The outline of these is as follows.

First, the cold cathode invented by Gray et al. And its manufacturing method will be described. In this method, a single or a plurality of minute openings are provided in an etching mask formed on a single crystal silicon substrate, and when etching the single crystal silicon substrate, the etching rate is different depending on the crystal orientation. By using an etching solution, it is possible to reproducibly obtain an etching hole having a sharp bottom.

For example, if a (100) substrate is used and the above-mentioned etching is performed with an aqueous potassium hydroxide solution,
Square-pyramidal etching holes are formed. Then, a cold cathode material is formed as a thin film on the single crystal silicon substrate having the etching holes. At this time, the cold cathode material may be formed after forming some kind of protective film on the single crystal silicon substrate. Finally, the cold cathode is manufactured by etching away the single crystal silicon substrate used as the template. As a result, a cold cathode in the shape of a quadrangular pyramid is obtained.

Next, a method for manufacturing a micro triode by SMZimmerman et al. Will be described. 27 to 31 show SMZimmer.
It is an element sectional view of a manufacturing process of a micro triode carried out by man et al. First, as shown in FIG. 27, the single crystal silicon substrate 23 is oxidized to form a silicon oxide film 19 on the substrate 23, and a silicon nitride film 20 is further formed thereon.
Then, a polysilicon film 21 to be a gate electrode is sequentially deposited.

Next, as shown in FIG. 28, a square opening 22 having a side of, for example, about 2 μm is formed in the polysilicon film 21, and the silicon nitride film 20 and the silicon oxide film 19 are etched through the opening 22.

Next, as shown in FIG. 29, when the silicon oxide film 27 is deposited on the entire surface of the substrate by the low pressure chemical vapor deposition method (LPCVD method), the silicon oxide film 27 is formed in the opening 22 in an inverted conical shape. It Then, as shown in FIG. 30, when the polysilicon film 24 is formed on the entire surface of the substrate by the LPCVD method, the polysilicon film 24 is formed in the reverse conical shape using the silicon oxide film 27 having the reverse conical shape as a template to form an electron emission gun. The cold cathode 26 is formed.

Thereafter, as shown in FIG. 31, an opening 25 is formed in the polysilicon film 24 in the vicinity of the cold cathode 26 made of polysilicon, and the silicon oxide deposited through the opening 25 into the opening 22 formed first. A space is formed by etching away the film 27, and the anode 23,
A micro triode consisting of the gate 21 and the cold cathode 26 is formed.

In the conventional method for manufacturing a micro triode described above, the substrate 23 is used as a method for forming the cold cathode 26.
By forming a silicon oxide film 27 in the minute opening 22 formed above by the LPCVD method, a reverse conical mold of the silicon oxide film 27 is formed, and a polysilicon film is formed on this mold. Is going.

Next, a method for manufacturing a micro triode by WILLIAM J. ORVIS and others will be described.

First, after forming an etching protection film such as a silicon oxide film on the entire surface of a single crystal silicon substrate, this etching protection film is patterned by etching to form a square pattern having a side length of about 5 μm, for example. ..

Next, using this etching protection film as an etching mask, an anisotropic etching solution, such as an ethylenediaminepyrocatechol aqueous solution, whose etching rate is dependent on the crystal orientation (anisotropic) of single crystal silicon is used. By etching the single crystal silicon substrate,
Pyramid type single crystal silicon is formed under the etching protection film, and this is used as a cold cathode which is an electron emission gun.

Next, a phosphorus glass layer is formed so as to fill the cold cathode, a polysilicon film is formed on the phosphorus glass layer, and then the polysilicon layer is patterned in a stripe shape to form a gate electrode. At the same time, an opening is formed in the polysilicon layer at the tip of the cold cathode by etching.

Next, a second phosphorous glass layer is formed on the polysilicon layer and inside the opening formed in the polysilicon layer, and a polysilicon layer serving as an anode electrode is further formed thereon. Finally, the phosphorous glass layer between the tip of the cold cathode and the gate electrode and between the gate electrode and the anode electrode is removed by etching. As a result, a closed cavity type micro triode is formed.

[0016]

However, the conventional techniques described above have the following problems.

In the method of Gray et al., Since a template formed by anisotropically etching a silicon single crystal is used,
Although the reproducibility and uniformity of the shape of the cold cathode are good, it is difficult to sharpen and miniaturize the tip of the cold cathode, and it is difficult to form the control electrode close to the cold cathode.

Further, since the angle of the cold cathode tip formed by this method is determined by the angle formed by the crystal plane exposed by anisotropic etching, it is difficult to reduce the angle of the cold cathode tip and sharpen it. It was difficult to lower the electron emission voltage.

In the method of manufacturing a micro triode by SM Zimmerman et al., LP is provided in the opening 22 on the silicon substrate 23.
The inverted conical mold formed by depositing the silicon oxide film 27 by the CVD method changes its shape depending on the size and shape of the opening 22, the forming conditions of the silicon oxide film 27, and the film thickness, and therefore has extremely high reproducibility. As a result, the radius of curvature of the tip of the cold cathode 26 is also poor in reproducibility. Also cold cathode 2
It is also extremely difficult to control the position of the tip of 6 due to the above-described change in the shape of the mold, and therefore the distance between the single crystal silicon substrate 23 serving as the anode electrode and the cold cathode 26, and the gate electrode. Polysilicon film 21 and cold cathode 26
The positional relationship of can not be controlled. Therefore, the electron emission voltage becomes non-uniform and the electron transit time varies depending on the element, which causes a problem in terms of stability of electrical characteristics.

Further, the cold cathode formed by this method has a problem that the inclination angle of the body becomes small, so that the resistance becomes high and the cold cathode is heated by the generation of Joule heat, and the cold cathode is destroyed.

In the method of manufacturing a micro-triode of WILLIAM J. ORVIS et al., Single crystal silicon is used as a material for the cold cathode, and the single crystal silicon is etched to form the cold cathode. The closed cavity type micro triode manufactured by the conventional method has not obtained the characteristics as a practical triode because the electron emission efficiency of the cold cathode made of single crystal silicon is not sufficiently good. Therefore, it has been desired to improve the characteristics of the cold cathode.

On the other hand, the characteristics of the cold cathode are mainly determined by the material of the cold cathode and the radius of curvature of the tip of the cold cathode. As a material for this cold cathode, metals and metal carbides are superior to silicon in terms of electron emission efficiency, but materials such as these metals and metal carbides can be used for electron emission by the same etching method as that for silicon. It is difficult to make the radius of curvature of the tip of the gun extremely small.

According to the present invention, a cold cathode having a small radius of curvature at the tip and a projection having a small inclination angle at the tip is formed, and the positional relationship between the cold cathode, the anode and the gate is precisely controlled, and further, Since a material with a high electron emission efficiency can be used as a material for the cold cathode, a field emission device having a low electron emission voltage, a high electron emission efficiency, and stable electrical characteristics, and a method for manufacturing the device uniformly and with good reproducibility are provided. provide.

[0024]

In order to solve the above problems, a field emission device according to the present invention comprises a sharply pointed projection at the tip and a body portion having a shape having a continuous curved connection with the projection. It has a cold cathode.

The method for manufacturing a cold cathode according to the present invention is
A recess is formed by etching on a silicon substrate or on a silicon substrate having a sandwich structure of an insulating film and a silicon thin film on the surface of the substrate, and the recess is oxidized to produce a first
Forming a silicon oxide film, forming a conductive film on the first silicon oxide film, and removing the first silicon oxide film to expose the conductive film.

Further, the method for manufacturing a micro-diode according to the present invention includes an insulating film on a silicon substrate or on the surface of the substrate.
Forming a recess on a silicon substrate having a sandwich structure of a silicon thin film by etching, locally oxidizing only the recess to form a first silicon oxide film, and surrounding the recess on the silicon substrate Etching the substrate surface, oxidizing the surface of the etched substrate to form a second silicon oxide film, and
Forming a first conductive film on the silicon oxide film, forming a second conductive film on the second silicon oxide film, and removing the first silicon oxide film.

Further, the method for manufacturing a micro-triode according to the present invention comprises an insulating film on a silicon substrate or on the surface of the substrate,
Forming a recess on a silicon substrate having a sandwich structure of a silicon thin film by etching, locally oxidizing only the recess to form a first silicon oxide film, and surrounding the recess on the silicon substrate Etching the substrate surface, oxidizing the surface of the etched substrate to form a second silicon oxide film, and
Forming a first conductive film on the silicon oxide film, and forming a second conductive film on the second silicon oxide film;
Forming a first insulating film and a second insulating film on the second conductive film and opening the first and second insulating films to expose the first and second conductive films; and the opening. And removing the first silicon oxide film, and depositing an insulating film in vacuum to seal the opening.

Further, in the method for manufacturing a micro-diode according to the present invention, a recess is formed by etching on a silicon substrate having a sandwich structure of an insulating film and a conductive silicon thin film on the surface, and the recess is oxidized to form a first recess. Forming a silicon oxide film, forming a conductive film on the first silicon oxide film, removing the silicon substrate, removing the first silicon oxide film, and removing the conductive film. And exposing.

Further, the method for manufacturing a micro-diode according to the present invention comprises a step of forming a second conductive layer on the surface of a silicon substrate made of a first conductive layer, and a step of forming a recess in the silicon substrate by etching to form the recess. To form a first silicon oxide film by forming a first conductive film on the first silicon oxide film, and a step of forming a conductive film on the first silicon oxide film. Removal step,
And removing the first silicon oxide film to expose the conductive film.

The cold cathode manufacturing method according to the present invention is
A step of etching a substrate or depositing a thin film on the substrate and forming a recess by opening the thin film, a step of forming an insulating film on the substrate, and a silicon thin film on the insulating film. A step of depositing, a step of oxidizing the silicon thin film to form a first silicon oxide film, a step of forming a conductive film on the first silicon oxide film, the first silicon oxide film and the And removing the insulating film to expose the conductive film.

Further, the method for manufacturing a micro-diode according to the present invention includes a first insulating film, a first insulating film and a first insulating film on the surface of the substrate.
Forming a sandwich structure of the conductive film and the second insulating film, and forming a recess by opening the sandwich structure of the first insulating film, the first conductive film and the second insulating film, Forming a third insulating film on the second insulating film; depositing a silicon thin film on the third insulating film; oxidizing the silicon thin film to form a first silicon oxide film. Step, forming a second conductive film on the first silicon oxide film, removing the first silicon oxide film and the third insulating film, and exposing the second conductive film And a process.

Further, in the method for manufacturing a micro-triode according to the present invention, a step of forming a first silicon nitride film on a conductive substrate and a step of forming a first opening in the first silicon nitride film. A step of etching the substrate through the first opening, a step of oxidizing the etched substrate through the first opening to form a first silicon oxide film, and a step of etching the first nitride film. Etching the remaining portion of the silicon film, etching the substrate exposed by the removal of the first silicon nitride film to a desired depth, oxidizing the etched substrate surface, and Forming a silicon oxide film, forming a first metal film on the first silicon oxide film and the second silicon oxide film, and forming a third silicon oxide film on the entire surface of the substrate. Forming a second silicon nitride film on the third silicon oxide film, forming a second opening in the second silicon nitride film, and forming a second opening in the second silicon nitride film. Through, the step of etching the third silicon oxide film, the second silicon oxide film, and the first silicon oxide film, and the step of forming a protective film on the entire surface of the substrate in vacuum.

Further, the method for manufacturing the closed cavity type micro triode according to the present invention is characterized in that the first method is carried out on a conductive substrate.
A step of forming an insulating film of
And forming a second conductive film on the first conductive film.
Forming an insulating film, forming a first opening in the first insulating film, the first conductive film, and the second insulating film; on the second insulating film and the second insulating film; A step of forming a silicon film inside the first opening; a step of thermally oxidizing the silicon film to form a silicon oxide film; a step of patterning the silicon oxide film into a predetermined shape; and a step of forming a silicon oxide film on the silicon oxide film. Second conductive film forming step, and the second step
Forming a second opening in the conductive film, removing the silicon oxide film through the second opening by etching, and forming a protective film over the entire surface of the substrate in vacuum.

[0034]

In the cold cathode of the present invention, the inclination angle of the body (Fig.
By increasing ₁ ) and decreasing the resistance, the heating of the cold cathode due to Joule heat is suppressed and the destruction of the cold cathode, the change in shape and the deterioration of the vacuum degree due to the desorption of adsorbed molecules from the cold cathode surface are prevented. You can The tip of the cold cathode is
The projection shape having a small inclination angle (θ _{2 in} FIG. 8) can be formed to increase the electric field concentration on the tip portion and reduce the electron emission voltage. By lowering the electron emission voltage, the energy of emitted electrons can be reduced, and problems such as destruction of the cold cathode due to discharge of gas molecules in vacuum can be prevented. further,
The protrusion and the body portion are connected to each other in a continuous curved line, and a sharp increase in resistance at the protrusion portion at the tip can be reduced.

Next, a method of manufacturing the micro triode will be described. An insulating film having a plurality of openings is formed on a Si substrate having a (100) crystal plane, and single crystal silicon is etched through the openings with an anisotropic etching solution such as an aqueous solution of potassium hydroxide or an aqueous solution of hydrazine. Since the etching rate of the crystal plane is very slow, a quadrangular pyramid cavity surrounded by the crystal plane is reproducibly formed. The width and height of the quadrangular pyramid are adjusted by the size of the opening of the insulating film.
Further, this cavity is oxidized to form a cold cathode mold. When silicon is heated and oxidized in an oxidizing atmosphere such as oxygen or water vapor, stress is generated in the concave portion in the oxide film formed by oxidation and at the interface between silicon and the oxide film.
This stress causes a decrease in the oxidation rate and viscous flow of the oxide film near the tip of the recess, and the thickness of the oxide film becomes thinner closer to the tip of the recess, resulting in the formation of deep depressions (reference document H.UMIMOTO, S.ODANAKA, I.NAKAO NUERICAL SIMULATI
ON OF STRESS-DEPENDENT OXIDE GROWTH AT CONVEX AND
CONCAVE CORNERS OF TRENCH STRUCTURES IEEE, ELECTRO
N DEVICE LETTERS, VOL.10, NO.7,1989 pp.330〜332
).

FIG. 8 shows the result of computer simulation of the above-mentioned shape. The dotted line in the figure represents the position of the surface of single crystal silicon before oxidation. The angle θ _{2 of the} groove tip formed by the silicon oxide film 28 formed by thermally oxidizing the single crystal silicon having the V-shaped groove is smaller than the original angle θ ₁ of the V groove, and the groove is sharper. Is formed. By using the groove as a mold for forming a cold cathode and then removing the silicon oxide film 28 with an aqueous solution of hydrofluoric acid, a cold cathode with a sharp tip and an extremely small radius of curvature can be formed.

After locally oxidizing only the above-mentioned cavity, the insulating film is removed and the single crystal silicon substrate around the cavity is treated with a silicon etching solution such as an aqueous potassium hydroxide solution, an ethylenediaminepyrocatechol aqueous solution, or a hydrazine aqueous solution. Etching a few μm from the surface. A pn junction was formed by introducing an impurity of a conductivity type opposite to that of the silicon substrate to form a pn junction on the surface of the silicon substrate up to the etching depth, or by forming a layer into which a high concentration of impurities was introduced and using this pn junction. The accuracy and reproducibility of the etching depth are improved by utilizing an electrochemical etch stop technique or an etch stop technique utilizing the impurity concentration dependence of the etching rate. A step is formed around the cavity by this silicon etching. Therefore, when a material for the cold cathode and the gate electrode is deposited by a vacuum deposition method or a sputtering method, the electrode material is electrically charged on the cavity and around the cavity due to the above step. Are insulated, and at the same time, a cold cathode and a gate electrode are formed.
Further, the gate electrode is automatically arranged at a position separated from the tip of the cold cathode by the thickness of the oxide film on the cavity.

Next, a silicon oxide film and a silicon nitride film are sequentially deposited on the above electrode material by a vacuum evaporation method, a sputtering method or the like. An opening is provided in the silicon oxide film and the silicon nitride film on the gate electrode near the cold cathode, and the silicon oxide film is etched with an aqueous solution of hydrofluoric acid through the opening to remove the silicon oxide film under the cold cathode to remove the cold cathode. Expose. Finally, after making the void opened through the above-mentioned opening into a vacuum state, a silicon oxide film is deposited by a vacuum evaporation method to close the opening. As described above, a micro triode having a silicon substrate as an anode electrode and having a space held in a vacuum in the silicon substrate is manufactured.

According to the present invention, a field emission device having a low electron emission voltage and stable electric characteristics can be manufactured with good reproducibility and uniformity.

[0040]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding parts are designated by the same reference numerals.

First, the micro 3 according to the embodiment of the present invention.
The outline of the manufacturing process of the polar tube will be described.

In the process of manufacturing the micro-triode according to the present invention, the mold for forming the cold cathode which is the electron emission gun is formed by etching in the Si substrate 1 as shown in FIG. Forming the cavity 3 of FIG.
As shown in FIG. 3, the mold is formed by oxidizing the cavity 3 to form the silicon oxide film 5. It is preferable that the cavity 3 has a concave portion at the tip of the electron emission gun and the solid angle thereof is as small as possible. When a substrate having a plane orientation of (100) is used as the Si substrate 1 and a potassium hydroxide aqueous solution, a hydrazine aqueous solution, or the like is used for etching the cavity 3, the shape reverse to the shape determined by the size of the etching window opened in the etching mask. Pyramid-shaped cavities can be formed very reproducibly.

Further, in the oxidation of the cavity 3, stress is generally generated in the silicon oxide film 5 which grows in the concave and convex portions of silicon in the silicon oxidizing step, and the growth rate of that portion is higher than that of other flat portions. It takes advantage of the slowness. As a result, as shown in FIG. 26, the silicon oxide film 28 formed by the oxidation is performed by oxidizing the inverted pyramid type silicon cavity.
The angle θ ₂ of the concave portion of is smaller than the tip angle θ ₁ of the original inverted pyramid structure, and a sharper concave portion structure is formed. Such a recess is shown in FIG.
As shown in FIG. 3, by depositing the material 10 to be the cold cathode and then removing the mold of the silicon oxide film, a cold cathode having a sharp tip and a very small radius of curvature can be formed. The present embodiment makes effective use of such characteristics.

Next, in order to form a gate electrode, the single crystal silicon substrate 1 on which the above template is formed is etched and removed from its surface by several μm as shown in FIG. The etching depth determines the positional relationship between the gate electrode 11 and the cold cathode 10 in FIG. In the etching of the single crystal silicon substrate 1 in this step, an etching solution that etches only the single crystal silicon substrate 4 without etching the silicon oxide film 5 that is the template of the cold cathode 10 is used.

As such an etching solution, a potassium hydroxide aqueous solution, an ethylenediaminepyrocatechol aqueous solution,
Examples include hydrazine aqueous solution. In this step, it is preferable to use an electrochemical etch stop using a pn junction, an etch stop using a dopant concentration difference, or the like in order to perform etching to a preset depth.

After the above-described etching of the single crystal silicon substrate, as shown in FIG. 7, oxidation is performed to form an insulating layer between the gate electrode and the single crystal silicon substrate to be the anode electrode, and the silicon oxide film 9 is formed. To form. Oxidation of the single crystal silicon substrate is a well-established technique in IC manufacturing, and precise film thickness control is possible, so the positional relationship between the gate and the anode is accurately determined by the oxidation process performed here.

After the steps described above, as shown in FIG. 8, materials for the cold cathode and the gate electrode are formed by using the vacuum evaporation method or the sputtering method. In this case, the material deposited on the mold portion of the cold cathode becomes the cold cathode 10, and the material deposited on the other substrate becomes the gate electrode 11. Here, the gate electrode 11 is formed in a self-aligned manner with respect to the cold cathode 10 using the mold 5 of the cold cathode 10 as a mask. Therefore, if the vapor deposition atoms are obliquely incident on the substrate by using, for example, a planetary type vacuum vapor deposition method or sputtering method, the thickness of the mold of the cold cathode 10 to the cold cathode 10 can theoretically be increased. It is possible to form the end portion of the gate electrode 11 at about a position.

A silicon oxide film is formed as shown in FIG. 9, and finally, as shown in FIG. 13, the silicon oxide films 12, 5 and 9 between the electrodes are removed by etching with a hydrofluoric acid aqueous solution to form a vacuum space. To form.

As described above, the micro 3 according to this embodiment is used.
In the method of manufacturing a cathode, the positional relationship of each electrode and the shape of the cold cathode can be manufactured with extremely high accuracy and reproducibility. The present embodiment will be described in more detail below.

FIG. 1 is a sectional view of an element of a micro triode according to an embodiment of the present invention. The surface orientation of the Si substrate 1 is (10
0) substrate, and n is used when an electrochemical etching stop is used when etching a silicon substrate described later.
Use a mold substrate. When etching is stopped by another method, an n-type substrate or a p-type substrate may be used as necessary. In this example, an n-type substrate having a specific resistance of 0.8 to 1.2 Ωcm was used. Reference numeral 9 denotes a silicon oxide film, which is an interlayer insulating film between a gate electrode 11 and the Si substrate 1 described later. The film thickness is, for example, 500 nm
And

Reference numeral 10 denotes a cold cathode, which is formed simultaneously with the formation of the gate film 11, as described later. The material should be one that is not attacked by the hydrofluoric acid aqueous solution used for under-etching of the silicon oxide film, which will be described later, and is determined in consideration of the electron emission efficiency and stability. Specifically, for example, the molybdenum film has a thickness of 500 nm. A gate film 11 has the same material and film thickness as those of the cold cathode 10 as described above. Specifically, the molybdenum film has a thickness of 500 nm.

Reference numeral 12 is a silicon oxide film, which is a gate film 1.
1 is an interlayer insulating film between 1 and a cold cathode 10 described later. The film thickness is, for example, 700 nm. A silicon nitride film 13 is used as a protective film when etching the silicon oxide film. The film thickness is, eg, 300 nm. Reference numeral 15 is an electrode film for the cold cathode, which is preferably made of a material which is not attacked by an aqueous solution of hydrofluoric acid, and its film thickness is set so as to obtain a sufficient contract with the cold cathode 10. Specifically, molybdenum was set to 1 μm.

Numeral 16 is an etching hole for under-etching the silicon oxide film 9, the silicon oxide film 12 and a silicon oxide film used as a template for a cold cathode described later, the size of which is hydrofluoric acid which is an etching solution. Set it so that the exchange of the aqueous solution occurs sufficiently. Cold cathode 1
The distance from 0 is preferably as close as possible, but it is determined in consideration of mask alignment accuracy at the time of lithography patterning. Further, the number of the cold cathodes is usually always one or more for one cold cathode, but one etching hole may be provided for a plurality of cold cathodes depending on the layout method. Specifically, a 2 μm square etching hole was formed 2 μm away from the cold cathode 10.

Reference numeral 17 is a metal film for the anode electrode, which is made of Si.
It must be a material that forms an ohmic contact with the substrate 1. Specifically, for example, In was formed to a thickness of 200 nm and Au was formed to a thickness of 300 nm.

Next, a method of manufacturing the micro-triode according to the embodiment configured as described above will be described.

First, as shown in FIG. 2, n-type Si (10
0) Specifically, on the surface of the substrate 1, for example, an opening 3 of 2 μm square is used.
On the other hand, a p-type layer 4 having a thickness of 1 μm is formed by an epitaxial growth method. Next, the silicon nitride film 2 is applied to, for example, LP.
It is formed by a CVD method, a sputtering method, a plasma CVD method, or the like. The film thickness of the silicon nitride film 2 is set to be a film thickness sufficient as a mask at the time of LOCOS oxidation described later. Specifically, the film thickness of the silicon nitride film 2 is 300 nm.

After that, the opening 3 is formed in the silicon nitride film 2 by photolithography. Reactive ion etching is preferable for etching the silicon nitride film 2, but hot phosphoric acid or the like may be used. The size of the opening 3 determines the size of the inverted pyramid type cavity formed in the opening 3 as shown in FIG.
The depth of the cavity is preferably such that the film thicknesses of the silicon oxide film 9, the gate film 11 and the silicon oxide film 12 are added from the viewpoint of easy formation of contacts between the cold cathode 10 and the cold cathode electrode film 15 which will be described later. Therefore, considering the above matters, the opening 3
Determine the size of. Specifically, for example, the size of the opening 3 is 2 μm square.

Next, as shown in FIG. 3, the silicon substrate 1 is anisotropically etched with a KOH aqueous solution through the opening 3 described above. This etching ends when the side surfaces of the etched silicon substrate are all (111) planes. Thereafter, as shown in FIG. 4, the silicon substrate surface exposed by the above KOH etching is thermally oxidized to form a silicon oxide film 5. At this time, the above-mentioned silicon nitride film 2 functions as a mask for other portions, and only the surface of the silicon substrate exposed in the opening 3 is oxidized. Specifically, for example, the thickness of the silicon oxide film 5 is set to 500 nm.

After that, the above-mentioned silicon nitride film 2 is removed by etching with hot phosphoric acid. As a result, the silicon oxide film is formed only in the cavity portion of the opening 3 as shown in FIG. 4, and the silicon substrate 4 is exposed in other portions.

Next, as shown in FIG. 5, an electrode film 6 is formed on the back surface of the silicon substrate 1 by, for example, a vacuum evaporation method. The material should just be able to form ohmic contact with the silicon substrate 1. Specifically, for example, In is 200 nm and A
u was formed to a thickness of 300 nm. Next, a lead wire 8 coated with a material that is not attacked by an alkaline aqueous solution such as vinyl is attached to the above-mentioned metal film 6 with, for example, a silver paste, and then a protective film 7 that is also a material that is not attacked by an alkaline aqueous solution is replaced by the metal film 6 And the silicon substrate 1 so as to completely cover the n-type portion.

Next, in the KOH aqueous solution, a positive voltage of about 1 V is applied to the lead wire 8 with respect to the electrode provided in the KOH aqueous solution to etch the silicon substrate 1. In this etching, the n-type silicon substrate part 1 is not etched due to the positively applied voltage, while the p-type silicon substrate part 4 is easily etched. Therefore, as shown in FIG. 6, after only the p-type layer is etched, the etching automatically ends. K for the silicon oxide film 5
Since the etching rate of the OH aqueous solution is much slower than the etching rate for the silicon substrate 4, the silicon oxide film 5 remains almost unetched in the above-described etching of the silicon substrate 4.

After etching the p-type layer 4, the protective film 7, the lead wire 8 and the electrode film 6 are removed. These are removed with an organic solvent such as acetone and aqua regia. As a result, the structure as shown in FIG. 6 is formed.

Next, as shown in FIG. 7, a silicon oxide film 9 is formed by a thermal oxidation method, and thereafter, as shown in FIG. 8, a gate film 11 and a cold cathode 10 are formed by, for example, a vacuum evaporation method. As the gate film 11 and the cold cathode 10, metals, metal chemicals and various semiconductors can be used. Further, a sputtering method can be used as a forming method.

The gate film 11 is formed up to the bottom of the inverted pyramid-type cold cathode mold formed of the silicon oxide film 5 by vacuum vapor deposition such that atoms obliquely enter the silicon substrate 1 by a planetary system or the like. It is preferable for the triode operation to be formed. In this embodiment, the gate film 11 and the cold cathode 10 are formed by using a planetary type vacuum deposition apparatus. In addition, if necessary, the gate film 1
Patterning 1 may be performed.

After that, as shown in FIG. 9, the silicon oxide film 12 and the silicon nitride film 13 are subjected to, for example, LPCVD.
Method, plasma CVD method, sputtering method, or the like. In this embodiment, both the silicon oxide film 12 and the silicon nitride film 13 are formed by the sputtering method.

Next, as shown in FIG. 10, the opening 14 is formed. As a method of forming the photoresist, the flattening effect of the photoresist is used, and the photoresist is spin-coated on the entire surface and baked, and then the entire surface is subjected to reactive ion etching with CF ₄ gas plasma. The opening 14 can be formed only in the portion where the 10 is formed. That is, in spin coating of the resist, the convex portion has a smaller resist film thickness than the other regions. Therefore, in the reactive ion etching, the resist is gradually etched first, but the cold cathode 10 is formed. Since the resist in the exposed portion is thinner than the other regions, it is directly etched, so that the silicon nitride film 13 on the cold cathode 10 is exposed and etching is started. As a result, the opening 14 is formed.
It is also possible to pattern the resist by photolithography to form the opening 14.

Next, as shown in FIG. 11, a cold cathode electrode film 15 is formed, and if necessary, patterned. Next, as shown in FIG. 12, the cold cathode electrode film 15 is formed by photolithography, reactive ion etching, or the like.
And an opening 16 is formed in the silicon nitride film 13, and thereafter,
A part of the silicon oxide film 12, the silicon oxide film 5 and the silicon oxide film 9 is etched with an aqueous solution of hydrofluoric acid. In this etching, at least the silicon oxide film 5 and the silicon oxide film 9 at the tip of the cold cathode 10 are etched. Next, as shown in FIG. 13, the anode electrode film 17 is formed on the back surface of the silicon substrate.

Finally, as shown in FIG. 14, an insulating film 18, specifically, a silicon oxide film is deposited by a vacuum evaporation method, the opening 16 is filled with the silicon oxide film, and the micro triode is sealed in a vacuum. To form the operating region of. As a result, even if the silicon substrate 1 is exposed to the atmosphere, the operating region of the micro triode is kept in vacuum, so that the micro triode can be used without using a special vacuum device.

In this way, in this embodiment, it is possible to manufacture a micro-triode having a cold cathode having a small radius of curvature at the tip and having a high positional relationship between the electrodes.

A method of manufacturing a micro-diode according to another embodiment of the present invention will be described.

FIGS. 15A to 15E are cross-sectional views of elements showing a method for manufacturing the micro-diode of this embodiment.

First, as shown in FIG. 15A, a first silicon oxide film 29 having a thickness of 200 nm is formed at a depth of 1 μm from the surface of silicon, and a (100) n-type SIMOX film is formed.
Apply a phosphorus coating diffusing agent to the silicon substrate 30 and heat it to 150 ° C.
Bake in nitrogen atmosphere for 30 minutes, then diffuse for 2 hours in 900 ° C. nitrogen atmosphere. As a result, an n-type conductive layer is formed on the silicon on the first silicon oxide film 29 to form the gate electrode 31.

Next, the film thickness is set to 300 n by the LPCVD method.
m silicon nitride film 32 is formed. After that, a 2 μm square opening 33 is formed in the silicon nitride film 32 by using a photolithography technique. Through this opening 33, the silicon substrate 30 is etched with a potassium hydroxide aqueous solution. The etching is stopped when the crystal plane 34 is exposed because the etching rate of the (111) crystal plane 34 is very slow.

Next, as shown in FIG. 15b), after the etching, the silicon nitride film 32 is completely removed with a phosphoric acid solution heated to about 150.degree. Then, the silicon substrate 30 is oxidized in a water vapor atmosphere at 1000 ° C.
A silicon oxide film 35 is formed. Next, a 1 μm tungsten film 36 is deposited by a vacuum evaporation method, and a cold cathode 37 is formed.
To form.

Then, as shown in FIG. 15c), a transparent conductive film (ITO) of 1 μm is formed on the glass substrate 38 by a vacuum deposition method.
Film) 39 is deposited. After that, the transparent conductive film 39 on the glass substrate and the tungsten film 36 on the silicon substrate 30 are bonded with a silver epoxy resin 40.

Next, as shown in FIG. 15d), the silicon is etched from the back side of the silicon substrate 30 with an aqueous solution of potassium oxide to completely remove it. At this time, the first silicon oxide film 29 is hardly etched by the potassium hydroxide aqueous solution.

Finally, as shown in FIG. 15e), a second silicon oxide film 29 and a second cold cathode 37 are formed on the first silicon oxide film 29 and the cold cathode 37 with an aqueous solution of hydrofluoric acid.
By removing the silicon oxide film 35 and exposing the gate electrode 31 and the cold cathode 37, a micro diode is manufactured.

In the present embodiment, the distance between the gate electrode 31 and the cold cathode 37 can be controlled by the thickness of the second silicon oxide film 35, and the positional relationship between the gate electrode 31 and the tip of the cold cathode 37 is nitrided. The width of the opening 33 of the silicon film 32 and the second
Since it can be controlled by the film thickness of the silicon oxide film 35, the gate electrode 31 can be accurately arranged at a position very close to the cold cathode 37, and the micro-diode having a low electron emission voltage is reproducible.
It can be manufactured with good uniformity.

A method for manufacturing a micro-diode according to still another embodiment of the present invention will be described.

16 (a) to 16 (e) are cross-sectional views of elements showing a method for manufacturing a micro-diode.

First, as shown in FIG.
0) Apply a phosphorus coating diffusing agent to the p-type silicon substrate 41, and
After baking for 30 minutes in a nitrogen atmosphere at 50 ℃, 900 ℃
Diffuse in a nitrogen atmosphere for 1 hour to form an n-type conductive layer 42 of 0.5 μm.

Next, a silicon nitride film 32 is formed by the LPCVD method, and a 2 μm square first opening 43 is formed in the silicon nitride film 32 by using the photolithography technique.
Through this first opening 43, the silicon substrate 41 is etched with an aqueous potassium hydroxide solution. Etching is (1
11) Since the etching rate of the crystal plane 34 is extremely slow, the etching stops when the crystal plane 34 is exposed.

Next, as shown in FIG. 16B, after etching, the silicon nitride film 32 is completely removed with a phosphoric acid solution heated to about 150.degree. After that, the silicon substrate 41 is oxidized in a water vapor atmosphere at 1000 ° C. to 0.5 μm.
The silicon oxide film 44 is formed, and a 1 cm square second opening 45 is formed in the silicon oxide film 44 by using the photolithography technique.

Next, a 1 μm tungsten film 36 is deposited by a vacuum evaporation method to form a cold cathode 37, the tungsten film 36 is patterned by using a photolithography technique, and tungsten on the n-type conductive layer 42 is formed. The film 36 and the tungsten film 36 of the cold cathode 37 are separated and electrically insulated.

Next, as shown in FIG. 16C, a transparent conductive film (IT) having a thickness of 1 μm is formed on the glass substrate 38 by a vacuum deposition method.
O film) 39 is deposited. Then, this glass substrate 38
The upper transparent conductive film 39, the tungsten film 36 on the silicon substrate 30, and the silver epoxy resin 40 are bonded together.

Next, as shown in FIG. 16D, a lead wire 46 coated with a material that is not attacked by an alkaline aqueous solution such as vinyl is attached to the tungsten film 36 on the n-type conductive layer 42 with a silver paste, and an alkali is used. The surface and outer periphery of the glass substrate 38, the silicon substrate 41 are completely covered with the protective film 7 made of a material that is not attacked by the aqueous solution.

Thereafter, the silicon substrate 41 with the lead wire 46 and the platinum electrode were placed in a 40% aqueous potassium hydroxide solution at 85 ° C., and a positive voltage of about 1 V was applied to the lead wire 46 with respect to the platinum electrode. The silicon substrate 41 is electrochemically etched. When the etching of the silicon substrate 41 progresses and the n-type conductive layer 42 is exposed, the n-type conductive layer 42 is anodized and the silicon etching is automatically stopped, so that the p-type silicon is completely removed and the n-type conductive layer 42 is removed. Only remains. After etching the silicon, it is put in heated trichlene to remove the protective film 7 and the lead wire 46.

Finally, as shown in FIG. 16 (e), the silicon oxide film 44 on the cold cathode 37 is removed and the cold cathode 37 is exposed to manufacture a micro diode.

In this embodiment, the positional relationship between the gate electrode and the tip of the cold cathode 37 is the thickness of the n-type conductive layer 42 formed by using an impurity introduction technique such as diffusion or ion implantation.
Since it can be controlled by the width of the first opening 43 of the silicon nitride film 32 and the film thickness of the silicon oxide film 44, a micro diode having a low electron emission voltage can be manufactured with good reproducibility and uniformity.

Micro 3 of still another embodiment of the present invention
A method of manufacturing a polar tube will be described.

17 to 25 show the micro 3 of the present invention.
Figure 3 shows a cross section of a polar tube. In FIG. 17, 47 indicates a substrate as an anode electrode. This substrate 47 needs to have conductivity, but since it only needs to work as an anode electrode, it is not a substrate entirely made of a conductive material, but a substrate having a metal film formed on the entire surface of a glass substrate or a ceramic substrate, for example. It may be used, and further, the patterned metal film may be used. In this embodiment, this substrate 4
As No. 7, for example, an n-type single crystal silicon substrate having a crystal plane orientation (001) and a specific resistance of 0.8 to 1.2 Ωcm was used.

Reference numeral 48 is a silicon oxide film, and the film thickness of the silicon oxide film 48 is sufficient for dielectric breakdown with respect to an operating voltage applied between a gate film 49 described later and a substrate 47 as an anode electrode. Set the film thickness to withstand. Specifically, the film thickness of the silicon oxide film 48 is, eg, 500 nm. An insulating film such as a silicon nitride film may be used instead of the silicon oxide film 48.

Reference numeral 49 is a gate film, and this gate film 49
Is a silicon oxide film 56, 58 described later (see FIG. 24).
Is required not to be easily attacked by the hydrofluoric acid aqueous solution used during the etching. Specifically, the gate film 4
For example, a polysilicon film having a film thickness of 300 nm is used as 9.

Reference numeral 50 is a silicon nitride film, and this silicon nitride film 50 serves as an interlayer insulating film between the gate film 49 and a cold cathode described later. The film thickness of the silicon nitride film 50 is
The dielectric strength between the gate film 49 and the cold cathode 52a is set to be sufficiently high. Specifically, the film thickness of the silicon nitride film 50 is, eg, 500 nm.

51 is a silicon oxide film 48 and a gate film 49.
And the openings formed in the silicon nitride film 50. The opening 51 is used when forming a cold cathode 52a, which will be described later, and the size thereof is the same as that of the gate electrode 49 and the cold cathode 52a.
The optimum setting is based on the positional relationship with and the overall process. The shape of the opening 51 is
Since it is one factor that also determines the shape of the cold cathode 52a, it is necessary to optimize it experimentally. In particular,
The opening 51 is formed in a square shape having a side of 2 μm, for example.

Reference numeral 52 is a cold cathode conductive film. Then, the cold cathode 5 is formed on the conductive film 52 above the opening 51.
2a is formed. The conductive film 52 other than the cold cathode 52a is an electrode of the cold cathode 52a. The conductive film 52 preferably has a work function as small as possible in order to increase the emission current of the cold cathode 52a, and further, one that is not corroded by the hydrofluoric acid aqueous solution used when etching the silicon oxide film described later is used. Of course, as the conductive film 52, metal carbide, metal boride, or the like can be used.

52b is a silicon oxide film 56 and a silicon oxide film 58 used as a template in forming a cold cathode described later.
Etching holes used when removing (see FIG. 24) by etching. The size and number of the etching holes 52b are set so that the etching liquid can be sufficiently exchanged. Specifically, this etching hole 52
b is, for example, at a position 5 μm away from the center of the opening 51,
Two openings each having a side of 3 μm are formed symmetrically.

Reference numeral 53 is a protective film for passivation and vacuum encapsulation. The protective film 53 can be formed in a vacuum atmosphere having a vacuum degree as high as possible, and the vacuum should not be broken due to cracks or the like. In order to avoid it, it is preferable to use one having a small stress. The film thickness of the protective film 53 is set to a film thickness that completely seals the opening 52b formed in the cold cathode conductive film 52. Specifically, as the protective film 53, for example, a silicon oxide film having a film thickness of 2 μm is used by a sputtering method.

Reference numeral 54 is a back contact electrode of the substrate 47 as an anode electrode. When an n-type single crystal silicon substrate is used as the substrate 47, for example, an indium film having a thickness of 150 nm and a thickness of 300 nm are used as the back contact electrode 54 so that an ohmic junction with the n-type single crystal silicon substrate can be obtained. A two-layer film with a gold film is used. When a metal film formed on an insulating substrate such as a glass substrate is used as the substrate 47, the back contact electrode 54 needs to be formed because contact can be made with respect to the substrate 47 from the front surface side. There is no.

Next, a method of manufacturing the closed cavity type micro triode according to this embodiment having the above-described structure will be described with reference to FIG.
It will be described with reference to FIGS.

First, as shown in FIG. 18, silicon oxide is formed on the entire surface of a substrate 47 such as an n-type single crystal silicon substrate by, for example, a thermal oxidation method, a sputtering method, a low pressure CVD method (LPCVD) method, a plasma CVD method or the like. The film 48 is formed.

Next, LP is formed on the entire surface of the silicon oxide film 48.
After the gate film 49 is formed by the CVD method, the sputtering method, or the like, the gate film 49 is formed by lithography and etching so that the gate film 49 can be contacted with an external electrode for later examination of electrical characteristics of the triode. Pattern into a shape. If it is not necessary to check the electrical characteristics of the triode, it is not necessary to pattern the gate film 49.

Next, as shown in FIG. 19, a silicon nitride film 50 is formed on the entire surface of the substrate by LPCVD, sputtering or the like.

Then, as shown in FIG. 20, a resist pattern 55 having an opening corresponding to the opening 51 for forming the cold cathode is formed on the silicon nitride film 50 by lithography.

Next, using the resist pattern 55 as a mask, the silicon nitride film 50, the gate film 49 and the silicon oxide film 48 are subjected to, for example, reactive ion etching (R).
By sequentially etching by the IE) method, openings 51 are formed as shown in FIG.

Next, after removing the resist pattern 55, a silicon oxide film 56 is formed on the entire surface of the substrate by a sputtering method, an LPCVD method or the like, as shown in FIG. The silicon oxide film 56 is a silicon film 5 described later.
It is used as a protective film for the gate film 49 exposed on the side wall of the opening 51 at the time of oxidizing 7. Therefore, the film thickness of the silicon oxide film 56 is set to such a value that the oxidation reaction species do not reach the gate film 49 during the oxidation. Specifically, the film thickness of the silicon oxide film 56 is, for example, 50.
0 nm.

Next, a silicon film 57 such as a polysilicon film or an amorphous silicon film is formed on the entire surface of the substrate by, for example, the CVD method. The film thickness of the silicon film 57 needs to be optimally designed according to the diameter and the depth of the opening 51 described above, and when the silicon film 57 is oxidized as described later, the opening 51 has an inverted cone shape. Set the film thickness so that it can be filled. Specifically, the film thickness of the silicon film 57 is, eg, 500 nm.

Next, as shown in FIG. 23, the silicon film 5
All 7 are thermally oxidized to form a silicon oxide film 58. For this thermal oxidation, for example, burning oxidation at 1100 ° C. is performed for 20 minutes. In this case, in the place where the silicon oxide film 58 growing from the side surface of the opening 51 meets, the silicon oxide film 5 is formed.
8 causes a large stress and the silicon oxide film 5
Since the distance from the surface of No. 8 to the silicon film 57 becomes long, the supply of the oxidizing reaction species becomes small, so that the growth rate becomes slow. As a result, on the surface of the silicon oxide film 58 in the portion of the opening 51, an inverted cone-shaped concave portion having an extremely sharp tip is formed. The silicon oxide film 58 in the concave portion having the inverted pyramidal shape serves as a mold for forming the cold cathode.

Next, as shown in FIG. 24, the silicon oxide film 56 is left so that only the region which becomes the sacrifice layer including the opening 51 is left.
The silicon oxide film 58 is patterned by photolithography and etching. The size of the region serving as the sacrificial layer is set so that the etching hole 52b and the opening 51 described later are connected to each other when the sacrificial layer is removed.

Next, the cold cathode and the conductive film 5 which becomes the electrode thereof.
2 is formed on the entire surface of the substrate by, for example, an electron beam (EB) vapor deposition method or a sputtering method, and then the conductive film 52 is formed.
Patterning is performed. This patterning is performed so that the conductive film 52 completely covers the silicon oxide film 56 and the silicon oxide film 58 in the above-described sacrificial layer region. Next, the conductive film 5 is formed by lithography and etching.
Etching hole 52b is formed in 2.

Next, using the conductive film 52 as a mask, etching is performed with an aqueous solution of hydrofluoric acid through the etching hole 52b, so that the sacrificial layer (silicon oxide film 56 and silicon oxide film 58) is formed as shown in FIG. Are all removed by etching.

Next, as shown in FIG. 17, a protective film 53 such as a silicon oxide film is formed on the entire surface of the substrate by a sputtering method, an EB vapor deposition method or the like, and vacuum sealing and passivation are performed. Then, for example, indium and gold are formed on the back surface of the substrate 47 by a vapor deposition method to form the back contact electrode 54. As a result, the desired inverted closed cavity type micro triode is completed.

As described above, according to this embodiment, the silicon oxide film 58 formed by thermally oxidizing the silicon film 57 has an inverted cone shape with a very sharp tip on the surface inside the opening 51. Since a hole in the shape of is formed and the cold cathode 52a is formed by using this hole as a mold, it is possible to form the cold cathode 52a having an extremely small radius of curvature at the tip and to use a metal or a metal carbide as the material of the cold cathode 52a. It is possible to use those having a high electron emission efficiency such as. As a result, a cold cathode having an extremely high electron emission efficiency can be formed, and accordingly, the micro 3 having excellent characteristics can be formed.
A pole can be manufactured.

When the electrical characteristics of the closed cavity type micro triode manufactured as described above were measured, for example, the mutual conductance was 25 μS and the current amplification factor was 20.
A value of degree was obtained.

[0115]

As described above, in the cold cathode of the present invention, the electron emission voltage can be lowered and the electric resistance of the cold cathode main body can be reduced by providing the tip portion with the sharper protrusion than the body portion. , The energy of emitted electrons can be reduced, the degree of vacuum is deteriorated by the adsorption of adsorbed molecules and electrode materials from the anode electrode material due to the collision of high energy electrons, and the cold cathode is damaged by the discharge due to the collision of high energy electrons and gas molecules. It is possible to prevent desorption, desorption of adsorbed molecules caused by heating of the cold cathode by Joule heat, deformation and destruction of the shape of the tip of the cold cathode, and to improve the stability and life of the electric characteristics of the field emission device. it can.

Further, in the method for manufacturing a field emission device of the present invention, the cold cathode is formed by using the etch stop by anisotropic etching and the oxidation of silicon to improve the reproducibility and uniformity of the cold cathode shape. However, sharpening of the tip of the cold cathode can be realized. In addition, the distance between the gate electrode and the cold cathode is controlled by the thickness of the silicon oxide film, and the positional relationship between the gate electrode and the tip of the cold cathode is such that the embedded silicon oxide film in the silicon substrate or the etch stop technology by electrochemical etching, etc. Since it is controlled by using, the gate electrode can be accurately arranged at a position very close to the cold cathode, and a micro-diode having a low electron emission voltage can be manufactured with good reproducibility and uniformity. Furthermore, the cold cathode material most suitable for various field emission devices such as metals and metal carbides having excellent electron emission efficiency can be used.

[Brief description of drawings]

FIG. 1 is a micro 3 manufactured according to an embodiment of the present invention.
It is an element sectional view showing a polar tube.

FIG. 2 is an element cross-sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 3 is an element sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 4 is an element cross-sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 5 is an element cross-sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 6 is an element cross-sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 7 is an element sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 8 is an element cross-sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 9 is an element cross-sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 10 is an element cross-sectional view showing a step in a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 11 is an element cross-sectional view showing a step in a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 12 is an element cross-sectional view showing a step in a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 13 is an element cross-sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 14 is an element cross-sectional view showing steps of a method for manufacturing a micro-triode according to an embodiment of the present invention.

FIG. 15 is an element sectional view showing steps of a method for manufacturing a micro-diode according to another embodiment of the present invention.

FIG. 16 is an element sectional view showing steps of a method for manufacturing a micro-diode according to still another embodiment of the present invention.

FIG. 17 is a device cross-sectional view showing a micro-triode manufactured according to still another embodiment of the present invention.

FIG. 18 is a sectional view of an element showing steps of a method of manufacturing a micro-triode according to still another embodiment of the present invention.

FIG. 19 is an element sectional view showing steps of a method for manufacturing a micro-triode according to still another embodiment of the present invention.

FIG. 20 is an element cross-sectional view showing a step in a method for manufacturing a micro-triode according to still another embodiment of the present invention.

FIG. 21 is an element sectional view showing steps of a method for manufacturing a micro-triode according to still another embodiment of the present invention.

FIG. 22 is an element cross-sectional view showing a step in a method for manufacturing a micro-triode according to still another embodiment of the present invention.

FIG. 23 is an element sectional view showing steps of a method for manufacturing a micro-triode according to still another embodiment of the present invention.

FIG. 24 is an element sectional view showing steps of a method for manufacturing a micro-triode according to still another embodiment of the present invention.

FIG. 25 is an element sectional view showing steps of a method for manufacturing a micro-triode according to still another embodiment of the present invention.

FIG. 26 is an element cross-sectional view illustrating formation of a silicon oxide film in an inverted pyramid type recess.

FIG. 27 is an element cross-sectional view showing the steps of the conventional manufacturing method.

FIG. 28 is an element sectional view showing a step of the conventional manufacturing method.

FIG. 29 is an element cross-sectional view showing the steps of the conventional manufacturing method.

FIG. 30 is an element cross-sectional view showing a step in a conventional manufacturing method.

FIG. 31 is an element cross-sectional view showing steps of a conventional manufacturing method.

[Explanation of symbols]

 1 n-type Si (100) substrate 2 first silicon nitride film 3 first opening 4 p-type Si layer 5 first silicon oxide film 6 metal film 7 protective film 8 lead wire 9 second silicon oxide film 10 cold Cathode 11 Gate film 12 Third silicon oxide film 13 Silicon nitride film 14 Second opening 15 Cold cathode electrode film 16 Third opening 17 Metal film for anode electrode 18 Insulating film 19 Silicon oxide film 20 Silicon nitride film 21 Poly Silicon film 22 Opening for forming cold cathode 23 Silicon substrate 24 Polysilicon film 25 Opening for etching 26 Cold cathode 27 Silicon oxide film 28 Silicon oxide film 29 First silicon oxide film 30 (100) n-type SIMOX silicon substrate 31 Gate electrode 32 Nitriding Silicon film 33 Opening 34 (111) crystal face 35 Second silicon oxide film 36 Tungsten 37 cold cathode 38 glass substrate 39 transparent conductive film (ITO film) 40 silver epoxy resin 41 (100) p-type silicon substrate 42 n-type conductive layer 43 first opening 44 silicon oxide film 45 second opening 46 lead wire 47 substrate 48 oxidation Silicon film 49 Gate film 50 Silicon nitride film 51 Opening 52 Conductive film 52a Cold cathode 53 Protective film 56 Silicon oxide film 57 Silicon film 58 Silicon oxide film

Front page continuation (72) Inventor Kazuhiko Kawamura 1618 Ida, Nakahara-ku, Kawasaki City Nippon Steel Corp. Advanced Technology Research Laboratories

Claims (10)

[Claims] 1. A field emission device having a cold cathode having a sharply pointed projection at its tip and a body having a shape having a continuous curved connection with the projection. 2. A dent is formed by etching on a silicon substrate or a silicon substrate having a sandwich structure of an insulating film and a silicon thin film on the surface of the substrate, and the dent is oxidized to form a first silicon oxide film. A step of forming a conductive film on the first silicon oxide film; and a step of removing the first silicon oxide film and exposing the conductive film. Production method. 3. A step of forming a recess by etching on a silicon substrate or on a silicon substrate having a sandwich structure of an insulating film and a silicon thin film on the surface of the substrate, and locally oxidizing only the recess to form a first A step of forming a silicon oxide film, a step of etching the periphery of the recess of the silicon substrate, a step of oxidizing the etched substrate surface to form a second silicon oxide film, a first silicon oxide film And a step of forming a first conductive film on the film, a second conductive film on the second silicon oxide film, and a step of removing the first silicon oxide film. Method for manufacturing a dipole. 4. A step of forming a recess by etching on a silicon substrate or on a silicon substrate having a sandwich structure of an insulating film and a silicon thin film on the surface of the substrate, and locally oxidizing only the recess to form a first A step of forming a silicon oxide film, a step of etching the periphery of the recess of the silicon substrate, a step of oxidizing the etched substrate surface to form a second silicon oxide film, a first silicon oxide film Forming a first conductive film on the film, forming a second conductive film on the second silicon oxide film, and forming first and second insulating films on the first and second conductive films, respectively. Forming and opening the first and second insulating films to expose the first and second conductive films; removing the first silicon oxide film through the openings; insulating in a vacuum; Deposited film Micro triode manufacturing method characterized by comprising the step of sealing the said opening. 5. A step of forming a recess by etching on a silicon substrate having a sandwich structure of an insulating film and a conductive silicon thin film on the surface, and oxidizing the recess to form a first silicon oxide film; A step of forming a conductive film on the first silicon oxide film, a step of removing the silicon substrate, and a step of removing the first silicon oxide film and exposing the conductive film. A method of manufacturing a micro-diode. 6. A step of forming a second conductive layer on a surface of a silicon substrate composed of a first conductive layer, and forming a recess in the silicon substrate by etching, and oxidizing the recess to form a first silicon oxide film. A step of forming a conductive film on the first silicon oxide film, a step of removing the silicon substrate made of the first conductive layer while leaving the second conductive layer, and a step of forming the first silicon oxide film. And a step of exposing the conductive film to expose the conductive film. 7. A step of forming a recess by etching a substrate or depositing a thin film on the substrate and opening the thin film, a step of forming an insulating film on the substrate, and the insulating film. A step of depositing a silicon thin film thereon, a step of oxidizing the silicon thin film to form a first silicon oxide film, a step of forming a conductive film on the first silicon oxide film, And a step of removing the silicon oxide film and the insulating film to expose the conductive film. 8. A sandwich structure of a first insulating film, a first conductive film and a second insulating film is formed on the surface of the substrate or on the substrate, and the first insulating film, the first conductive film and the second conductive film are formed. Forming an indentation by opening the sandwich structure of the second insulating film; forming a third insulating film on the second insulating film; and depositing a silicon thin film on the third insulating film. A step of oxidizing the silicon thin film to form a first silicon oxide film, a step of forming a second conductive film on the first silicon oxide film, the first silicon oxide film And a step of removing the third insulating film and exposing the second conductive film, the method of manufacturing a micro-diode. 9. A step of forming a first silicon nitride film on a conductive substrate, a step of forming a first opening in the first silicon nitride film, and the substrate through the first opening. Etching the substrate after the etching through the first opening to form a first silicon oxide film, and removing the remaining portion of the first silicon nitride film by etching. Etching the substrate exposed by the removal of the first silicon nitride film to a desired depth; oxidizing the surface of the etched substrate to form a second silicon oxide film; Forming a first metal film on the second silicon oxide film and the second silicon oxide film; forming a third silicon oxide film on the entire surface of the substrate; Forming a second silicon nitride film on the first silicon film, forming a second opening in the second silicon nitride film, and through the second opening, the third silicon oxide film,
Manufacturing a micro triode, comprising: a step of etching the second silicon oxide film and the first silicon oxide film; and a step of forming a protective film on the entire surface of the substrate in vacuum. Method. 10. A step of forming a first insulating film on a conductive substrate, a step of forming a first conductive film on the first insulating film, and a step of forming a first conductive film on the first conductive film. Forming a second insulating film, forming a first opening in the first insulating film, the first conductive film, and the second insulating film; on the second insulating film; Forming a silicon film inside the first opening; thermally oxidizing the silicon film to form a silicon oxide film; patterning the silicon oxide film into a predetermined shape; Forming a second conductive film, forming a second opening in the second conductive film, etching the silicon oxide film through the second opening, and removing the silicon oxide film in a vacuum. And a step of forming a protective film on the entire surface of the substrate. Closed cavity micro triode manufacturing method.