JP2003197088A - Field emission type electron source and method of manufacturing the electron source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable field emission type electron source and a method of manufacturing the electron source. <P>SOLUTION: A plurality of electron source elements 10a are formed on one surface of an insulation substrate 11. The electron source element 10a comprises a drift part 6a having a lower electrode 12 and an oxidized porous polycrystalline silicon layer and a surface electrode 7. The drift part 6a is formed on a strong field drift layer 6 formed on one surface side of the insulation substrate 11 at a portion overlapped with the surface electrode 7. The drift parts 6a adjacent to each other are electrically insulated from each other through a separation part 6b formed of a non-doped polycrystalline silicon layer. A plurality of surface electrodes 7 arranged along the longitudinal direction of the lower electrode 12 are connected to each other through a bus electrode 15. A protective film 14 covering the surface side of the portion of the strong field drift layer 6 excluding a connection wiring 16 between the electron source element 10 and surface electrode 7 and the bus electrode 15 is installed on the strong field drift layer 6. Thus the separation part 6b is covered with the protective film 14. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission electron source adapted to emit an electron beam by field emission and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a strong electric field drift composed of a lower electrode, a surface electrode made of a conductive thin film facing the lower electrode, and an oxidized porous polycrystalline silicon layer interposed between the lower electrode and the surface electrode. Field-emission electron sources of this kind, for which field-emission electron sources with layers have been proposed,
As shown in FIG. 5, a strong electric field drift layer 6 made of an oxidized porous polycrystalline silicon layer is formed on the main surface (one surface) side of an n-type silicon substrate 1 as a conductive substrate, and on the strong electric field drift layer 6. A surface electrode 7 made of a metal thin film (for example, a gold thin film) is formed on. In addition, the n-type silicon substrate 1
An ohmic electrode 2 is formed on the back surface of the n-type silicon substrate 1 and the ohmic electrode 2 to form a lower electrode 12. Although the non-doped polycrystalline silicon layer 3 is interposed between the n-type silicon substrate 1 and the strong electric field drift layer 6 in the example shown in FIG. 5, the polycrystalline silicon layer 3
There is also proposed a structure in which the strong electric field drift layer 6 is formed on the main surface of the n-type silicon substrate 1 without the interposition of.

A field emission type electron source 10 'having a structure shown in FIG.
In order to emit electrons from the surface electrode 7, a collector electrode 21 arranged opposite to the surface electrode 7 is provided, and the surface electrode 7 is higher than the lower electrode 12 in a vacuum state between the surface electrode 7 and the collector electrode 21. A DC voltage Vps is applied between the surface electrode 7 and the lower electrode 12 so as to be on the potential side, and the collector electrode 21 and the surface electrode 7 are arranged so that the collector electrode 21 is on the high potential side with respect to the surface electrode 7. DC voltage Vc between
Is applied. If the DC voltages Vps and Vc are set appropriately, the electrons injected from the lower electrode 12 drift in the strong electric field drift layer 6 and are emitted through the surface electrode 7 (FIG. 5).
An alternate long and short dash line indicates an electron e ⁻ emitted through the surface electrode 7.
Shows the flow of). The thickness of the surface electrode 7 is 10 to 15
It is set to about nm.

The above-mentioned strong electric field drift layer 6 is composed of the lower electrode 1.
After forming a non-doped polycrystalline silicon layer on 2
By making this polycrystalline silicon layer porous by anodizing treatment, a porous polycrystalline silicon layer is formed, and the porous polycrystalline silicon layer is rapidly thermally oxidized at a temperature of, for example, 900 ° C. by a rapid heating method. As shown in FIG. 6, at least a column-shaped polycrystalline silicon grain 51 arranged in a row on the main surface side of the n-type silicon substrate 1 (that is, the surface electrode 7 side of the lower electrode 12), A thin silicon oxide film 52 formed on the surface of the grain 51;
A large number of nanometer-order silicon microcrystals 63 interposed between the grains 51, and a large number of silicon oxides which are insulating films formed on the surface of each silicon microcrystal 63 and having a film thickness smaller than the crystal grain size of the silicon microcrystal 63. And the membrane 64. In short, the strong electric field drift layer 6
The surface of each grain of the polycrystalline silicon layer is made porous, and the crystalline state is maintained in the central portion of each grain.
Note that each grain 51 extends in the thickness direction of the lower electrode 12.

In the field emission type electron source 10 'described above, it is considered that electron emission occurs in the following model. That is, the DC voltage Vps is applied between the surface electrode 7 and the lower electrode 12 with the surface electrode 7 on the high potential side, and the DC voltage Vps is applied between the collector electrode 21 and the surface electrode 7 with the collector electrode 21 on the high potential side. When the DC voltage Vps reaches a predetermined value (critical value) by applying Vc, the lower electrode 12
The electrons e ⁻ are injected into the strong electric field drift layer 6 by thermal excitation. On the other hand, most of the electric field applied to the strong electric field drift layer 6 is applied to the silicon oxide film 64, so the injected electrons e ⁻ are accelerated by the strong electric field applied to the silicon oxide film 64, and the strong electric field drift layer 6 6 drifts toward the surface in the direction of the arrow in FIG. 6 (upward in FIG. 6), tunnels through the surface electrode 7, and is discharged into a vacuum.

However, in the strong electric field drift layer 6, the electrons injected from the lower electrode 12 are accelerated by the electric field applied to the silicon oxide film 64 without being scattered by the silicon microcrystals 63 and drift, and the surface electrode 7 (ballistic electron emission phenomenon), and the strong electric field drift layer 6
Since the heat generated in 1 is radiated through the grain 51,
Popping phenomenon does not occur during electron emission, and electrons can be emitted stably. The electrons that have reached the surface of the strong electric field drift layer 6 are considered to be hot electrons, and easily tunnel through the surface electrode 7 and are emitted into a vacuum.

By the way, the above-mentioned field emission type electron source 10 '
In FIG. 7, the n-type silicon substrate 1 and the ohmic electrode 2 form the lower electrode 12, but as shown in FIG. 7, the lower electrode made of a metal material is formed on one surface of the insulating substrate 11 made of, for example, a glass substrate. Field emission electron source 1 having 12 formed therein
0 "is also proposed. Here, the same components as those of the field emission electron source 10 'shown in FIG.

A field emission electron source 10 "having the structure shown in FIG.
In order to emit electrons from the surface electrode 7, a collector electrode 21 arranged opposite to the surface electrode 7 is provided, and the surface electrode 7 is higher than the lower electrode 12 in a vacuum state between the surface electrode 7 and the collector electrode 21. A DC voltage Vps is applied between the surface electrode 7 and the lower electrode 12 so as to be on the potential side, and the collector electrode 21 and the surface electrode 7 are arranged so that the collector electrode 21 is on the high potential side with respect to the surface electrode 7. DC voltage Vc between
Is applied. If the DC voltages Vps and Vc are set appropriately, the electrons injected from the lower electrode 12 drift in the strong electric field drift layer 6 and are emitted through the surface electrode 7 (FIG. 7).
An alternate long and short dash line indicates an electron e ⁻ emitted through the surface electrode 7.
Shows the flow of). The electrons that have reached the surface of the strong electric field drift layer 6 are considered to be hot electrons, and easily tunnel through the surface electrode 7 and are emitted into a vacuum.

Each of the above-mentioned field emission type electron sources 10 ', 10 "
Then, the current flowing between the surface electrode 7 and the lower electrode 12 is called a diode current Ips, and the current flowing between the collector electrode 21 and the surface electrode 7 is called an emission current (emission electron current) Ie. (See FIGS. 5 and 7), the emission current I with respect to the diode current Ips
The larger the ratio of e (= Ie / Ips), the higher the electron emission efficiency (= (Ie / Ips) × 100 [%]). In the field emission electron sources 10 ′ and 10 ″ described above, electrons can be emitted even when the DC voltage Vps applied between the surface electrode 7 and the lower electrode 12 is a low voltage of about 10 to 20V. The emission current Ie increases as the DC voltage Vps increases.

The field emission type electron source 1 shown in FIG.
When 0 "is applied as the electron source of the display, for example, the configuration shown in FIG. 8 may be adopted.

In the display shown in FIG. 8, a face plate 30 made of a flat glass substrate is arranged so as to face the field emission type electron source 10, and the face plate 30 has a face facing the field emission type electron source 10. A collector electrode (hereinafter, referred to as an anode electrode) 21 made of a transparent conductive film (for example, an ITO film) is formed. Although not shown, a fluorescent material formed for each pixel and a black stripe made of a black material formed between the fluorescent materials are provided on the surface of the anode electrode 21 facing the field emission electron source 10. Has been. The fluorescent substance is applied to the surface of the anode electrode 21 facing the field emission electron source 10, and emits visible light by the electron beam emitted from the field emission electron source 10. The fluorescent substance is emitted from the field emission electron source 10 and is emitted from the anode electrode 2
The high-energy electrons accelerated by the voltage applied to 1 collide with each other.
(Red), G (green), and B (blue) emitted light colors are used. Further, the face plate 30 is separated from the field emission electron source 10 by a rectangular frame-shaped frame (not shown), and the airtight space formed between the face plate 30 and the field emission electron source 10 is evacuated. .

The field emission electron source 10 shown in FIG. 8 is an insulating substrate 11 made of a glass substrate, a plurality of lower electrodes 12 arranged in a row on one surface of the insulating substrate 11, and a lower electrode 12. Electric field drift having a drift portion 6a formed of a plurality of oxidized porous polycrystalline silicon layers formed in a shape overlapping with each other and a separation portion 6b formed of a polycrystalline silicon layer formed so as to fill a space between the drift portions 6a. The layer 6 and a plurality of surface electrodes 7 formed on the strong electric field drift layer 6 in a direction intersecting (orthogonal to) the lower electrode 12 are provided.

In this field emission electron source 10, a plurality of lower electrodes 12 arranged in a row on one surface of an insulating substrate 11.
, And the plurality of surface electrodes 7 formed on the strong electric field drift layer 6, the drift portion 6a of the strong electric field drift layer 6 is sandwiched between the surface electrode 7 and the lower electrode 12. By applying a voltage between the selected and selected pairs,
The strong electric field acts only on the drift portion 6a at the portion corresponding to the intersection of the selected surface electrode 7 and the lower electrode 12, and electrons are emitted. That is, the electron source element 10a including the surface electrode 7, the lower electrode 12, and the drift portion 6a is provided at the lattice point of the matrix (lattice) including the group of the plurality of surface electrodes 7 and the group of the plurality of lower electrodes 12. Corresponding to the arrangement, electrons can be emitted from a desired electron source element 10a by selecting a set of the surface electrode 7 and the lower electrode 12 to which a voltage is applied. Here, the drift unit 6
It is considered that a has the same configuration as that of FIG. 6 described above. That is, the drift portion 6 a includes at least a columnar polycrystalline silicon grain (semiconductor crystal) 51 and a thin silicon oxide film 52 formed on the surface of the grain 51.
And a nanometer-order silicon microcrystal 63 interposed between the grains 51, and a silicon oxide film 64 which is an oxide film formed on the surface of the silicon microcrystal 63 and having a film thickness smaller than the crystal grain size of the silicon microcrystal 63. It is considered to be composed of

[0014]

In the field emission electron source 10 shown in FIG. 8, electrons are emitted even if the DC voltage applied between the surface electrode 7 and the lower electrode 12 is as low as about 10 to 20V. Can be released.

However, the above-mentioned field emission type electron source 1 is used.
At 0, the surfaces of the drift portion 6a and the separation portion 6b in the strong electric field drift layer 6 that do not intersect with the surface electrode 7 are exposed, so that impurities (for example, sodium ions), moisture, etc. may enter from the outside. However, there was a problem that it was easily scratched and unreliable.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a highly reliable field emission electron source and a method for manufacturing the same.

[0017]

In order to achieve the above object, the invention of claim 1 emits an electron beam along a substrate and one surface side of the substrate and along a normal direction of the one surface. An electron source element, wherein the electron source element has a lower electrode formed on the one surface side of the substrate, a surface electrode facing the lower electrode on the one surface side of the substrate, and between the lower electrode and the surface electrode. And a drift portion in which electrons injected from the lower electrode drift toward the surface electrode due to an electric field that acts when a voltage is applied between the lower electrode and the surface electrode. A protective film which is provided in a partial region of the one surface and covers the surface side of the substrate except the electron source element on the one surface side of the substrate. One surface side excluding the electron source element Since a protective film covering the front surface side is provided, impurities or moisture enter from the outside through the surface of the part where the electron source element is not formed on the one surface side of the substrate, or the electron source element is not formed Since it is possible to prevent the surface of the part from being scratched, reliability can be improved.

According to a second aspect of the present invention, the substrate, a plurality of lower electrodes arranged in a row on one surface side of the substrate and parallel to each other, and intersecting the lower electrode in a plane parallel to the one surface of the substrate. A plurality of surface electrodes formed via a drift part where electrons drift on the surface side of the lower electrode at a portion corresponding to an intersection of a plurality of virtual straight lines parallel to each other and the lower electrode, and one for each virtual straight line A plurality of electron source elements including a plurality of bus electrodes that commonly connect surface electrodes arranged on a virtual straight line, and a lower electrode, a drift portion, and a surface electrode respectively on the one surface side of the substrate, a surface electrode, and a bus. It is characterized in that a protective film is provided to cover the surface side of the portion excluding the connection wiring with the electrode, and the connection wiring between the electron source element and the surface electrode and the bus electrode is provided on one surface side of the substrate. Surface of the removed part Since a protective film is provided to cover the surface of the substrate, impurities and moisture will invade from the outside through the surface of the one surface side of the substrate excluding the electron source element and the connection wiring between the surface electrode and the bus electrode, and scratches will be scratched. Since it can be prevented from attaching, the reliability can be improved, and the connection wiring connecting the surface electrode and the bus electrode is exposed, so that the bus electrode and the surface electrode can be easily connected. become.

According to a third aspect of the present invention, in the second aspect of the present invention, the protective film is formed with an inclined surface whose distance from the substrate gradually increases as the distance from the surface electrode approaches the bus electrode. Since the connection wiring extends from the side edge of the front surface electrode to the bus electrode along the inclined surface, it is possible to prevent disconnection between the front surface electrode and the bus electrode.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the drift portion is formed of an oxidized porous polycrystalline semiconductor layer formed for each electron source element, and fills a space between the drift portions. Since the isolation portion made of the formed polycrystalline semiconductor layer is provided, crosstalk can be prevented.

According to a fifth aspect of the invention, in the first to fourth aspects of the invention, the protective film is formed of SiO ₂ , SiN _x ,
Since it is formed of a material selected from the group of SiON, AlO _x , and AlN, the protective film can be formed by using a material and a film forming method used in a general semiconductor manufacturing process.

According to a sixth aspect of the invention, in the invention of the first to third or fifth aspects, the drift portion is
Oxidized or nitrided or oxynitrided porous polycrystalline silicon layer, at least, a plurality of columnar grains extending in the thickness direction of the lower electrode, and a large number of nanometer-order silicon microcrystals interposed between the grains, Since the insulating film has a film thickness smaller than the crystal grain size of the silicon body microcrystals formed on the surface of each silicon microcrystal, most of the electric field applied to the drift portion is concentrated on the insulating film. Thus, the electrons injected from the lower electrode into the drift portion are accelerated by the strong electric field applied to the insulating film and drift toward the surface electrode, so that the electron emission efficiency can be improved and the electron Since the heat generated by the source element is radiated through the grains,
The popping phenomenon does not occur during electron emission, and electrons can be emitted stably. In addition, since the emission direction of the electron beam emitted from the electron source element is easily aligned with the normal direction of the surface electrode, it is necessary to provide a complicated shadow mask or electron converging lens when applied as an electron source of a display, for example. It is possible to make the display thinner.

The invention of claim 7 is the method for manufacturing a field emission type electron source according to claim 4, wherein a polycrystalline semiconductor layer is formed on the entire surface on the one surface side of the substrate on which the lower electrode is formed. A first film forming step, a first electrode forming step of forming the bus electrode on the front surface side of the polycrystalline semiconductor layer after the first film forming step, and a substrate after the first electrode forming step. A second film forming step of forming a protective film on the entire surface on the one surface side of
After the second film forming step, a patterning step of removing a portion of the protective film corresponding to the site where the electron source element is to be formed, and after the patterning step, forming the electron source element of the polycrystalline semiconductor layer An anodizing step of forming a porous polycrystalline semiconductor layer by making a portion corresponding to the site porous by anodizing treatment, an oxidizing step of oxidizing the porous polycrystalline semiconductor layer to form the drift portion, Characterized by comprising a processing step of forming the inclined surface on the surface side of the protective film after the oxidation step, and a second electrode forming step of forming the surface electrode and the connection wiring after the processing step, After patterning the protective film in the patterning process, the anodizing process and the oxidizing process are sequentially performed to form a drift portion composed of the oxidized porous polycrystalline semiconductor layer, and then the surface electrode is formed. Since the electron source element is not formed during the formation of the protective film, the reliability of the electron source element is not affected by the formation of the protective film, and the connection wiring is formed. A high field emission electron source can be provided. Further, since each process is similar to the process of a general semiconductor manufacturing process, capital investment can be reduced and cost can be reduced by sharing or diverting an existing semiconductor manufacturing device.

According to the invention of claim 8, in the invention of claim 7, since the protective film patterned in the patterning step is used as a mask material in the anodizing step, the anodizing step is separately performed. Since the step of forming the mask material and the step of removing the mask material are unnecessary, the manufacturing process can be simplified and the manufacturing cost can be reduced.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) As shown in FIGS. 1 and 2, a field emission electron source 10 of the present embodiment has an insulating substrate (for example, an insulating glass substrate, an insulating substrate). (For example, a ceramic substrate) 11 and an insulating substrate 11
A plurality of lower electrodes 1 arranged in parallel on one surface
2 and a plurality of virtual straight lines (not shown) that intersect (orthogonal to) the lower electrode 12 in a plane parallel to the one surface of the insulating substrate 11 and the intersection point of the lower electrode 12 A plurality of surface electrodes 7 are formed on the surface side of the lower electrode 12 via the drift portion 6a made of oxidized porous polycrystalline silicon in which electrons drift, and one virtual straight line for each virtual straight line. It is provided with a plurality of bus electrodes 15 that commonly connect the front surface electrodes 7 arranged side by side. Here, each lower electrode 12 is formed in a strip shape, and pads 28 are formed on both ends in the longitudinal direction. Further, both ends of the bus electrode 15 in the longitudinal direction are connected to the pads 27.

In short, in the field emission electron source 10 of the present embodiment, the strong electric field drift layer 6 laminated on the above-mentioned one surface side of the insulating substrate 11 in which the lower electrodes 12 are arranged in rows is shown in FIG. A portion (each electron source element 10) where the lower electrode 12 and the surface electrode 7 described in the conventional configuration intersect (orthogonal).
The drift portion 6a is formed only in a portion corresponding to a),
The surface electrode 7 is formed on each of the drift portions 6a.

More specifically, a plurality of drift portions 6a are formed on each lower electrode 12 so as to be separated from each other in the longitudinal direction of the lower electrode 12, and a surface electrode 7 is formed on each drift portion 6a. Here, the plurality of surface electrodes 7 arranged in the longitudinal direction of the lower electrode 12 are commonly connected to a bus electrode 15 parallel to the lower electrode 12. Here, each surface electrode 7 is connected to the bus electrodes 15 on both sides via a connection wiring 16. The strong electric field drift layer 6 includes the drift portion 6
It is electrically insulated by a separating portion 6b made of non-doped polycrystalline silicon formed so as to fill the space between a. That is, the strong electric field drift layer 6 is composed of the plurality of drift portions 6a and the separation portion 6b formed so as to fill the spaces between the drift portions 6a. Also in the present embodiment, the lower electrode 12, the drift portion 6a, and the surface electrode 7 constitute the electron source element 10a. The same components as those of the conventional configuration shown in FIG. 8 are designated by the same reference numerals.

In the field emission type electron source 10 of this embodiment,
The drift portion of the strong electric field drift layer 6 is provided at a portion where the plurality of lower electrodes 12 arranged in line on one surface of the insulating substrate 11 and the surface electrodes 7 arranged on a virtual straight line orthogonal to the lower electrodes 12 overlap each other. Since 6a is sandwiched, a bus electrode 15 and a lower electrode 12 are appropriately connected to each other, and a voltage is applied between the selected pairs to commonly connect to the bus electrode 15 selected in the strong electric field drift layer 6. The strong electric field acts only on the drift portion 6a in the portion where the surface electrode 7 and the lower electrode 12 overlap with each other, and electrons are emitted. That is, the electron source element 10a including the lower electrode 12, the drift portion 6a, and the surface electrode 7 is located at the lattice point of the matrix (lattice) including the group of the plurality of lower electrodes 12 and the group of the plurality of virtual straight lines described above. It is possible to emit electrons from a desired electron source element 10a by selecting a set of the bus electrode 15 and the lower electrode 12 to which a voltage is applied, which corresponds to the arrangement of the. As can be seen from the above description, the electron source element 10a is provided for each pixel.

The lower electrode 2 is made of, for example, Cr, W, Ti,
It may be formed of a metal such as Al, Cu, Au, Pt, Mo or an alloy thereof, or polycrystalline silicon doped with impurities.

The surface electrode 7 is made of, for example, Au, Pt, Cr.
It may be formed by a metal film made of a metal having a low work function such as, for example, a high oxidation resistance and being chemically stable, or a laminated film of these metal films. The thickness of the surface electrode 7 is 10
It may be set within a range of about 15 nm.

The above-mentioned connection wiring 16 is connected to the surface electrode 7
It extends from the side edge of the above to above the bus electrode 15 and electrically connects the surface electrode 7 and the bus electrode 15, and is made of the same material as the surface electrode 7.

The strong electric field drift layer 6 is formed by depositing a non-doped polycrystalline silicon layer on the entire surface on the one surface side of the insulating substrate 11 on which a plurality of lower electrodes 12 are formed. A portion of the layer in which the drift portion 6a of the strong electric field drift layer 6 is to be formed is made porous by anodization (hereinafter, this porous portion is referred to as a porous polycrystalline silicon layer), and a porous polycrystalline It is formed by oxidizing the silicon layer by, for example, a rapid heating method or an electrochemical method.

The operation of the field emission type electron source 10 of this embodiment is almost the same as the operation of the conventional structure shown in FIG. 8, and the surface electrode 7 is placed in a vacuum and the face plate 30 placed opposite to the surface electrode 7 is placed. An anode electrode 21 is provided, and a DC voltage Vps (see FIG. 7) is applied with the selected surface electrode 7 being the high potential side with respect to the lower electrode 12, and the anode electrode 21 is being DC with the high potential side being with respect to the surface electrode 7. Voltage V
By applying c (see FIG. 7), electrons injected from the lower electrode 12 into the drift portion 6a of the strong electric field drift layer 6 due to the electric field acting on the drift portion 6a of the strong electric field drift layer 6 drift in the drift portion 6a. Then, it is emitted through the surface electrode 7. Here, it is considered that the drift portion 6a of the strong electric field drift layer 6 has the same configuration as that of FIG. 6 described above. That is, the drift portion 6a is at least on the one surface side of the insulating substrate 11 (that is, the lower electrode 1).
No. 2 columnar polycrystalline silicon grains 51 arranged on the surface electrode 7 side), a thin silicon oxide film 52 formed on the surface of the grains 51, and a large number of nanometer-order silicon fine particles interposed between the grains 51. Crystal 63,
It is considered to be composed of a large number of silicon oxide films 64 which are insulating films formed on the surface of each silicon microcrystal 63 and having a film thickness smaller than the crystal grain size of the silicon microcrystal 63. In short, the drift portion 6a of the strong electric field drift layer 6
The surface of each grain of the polycrystalline silicon layer is made porous, and the crystalline state is maintained in the central portion of each grain.
Note that each grain 51 extends in the thickness direction of the lower electrode 12.

In the field emission type electron source 10 of this embodiment,
It is considered that electron emission occurs in the following model. That is, between the surface electrode 7 and the lower electrode 12, the surface electrode 7
The DC voltage Vps is applied between the anode electrode 21 (see FIG. 8) and the surface electrode 7 while the anode electrode 21 is on the high potential side. When reaching a predetermined value (critical value), electrons e ⁻ are injected from the lower electrode 12 into the drift portion 6a of the strong electric field drift layer 6 by thermal excitation. On the other hand, most of the electric field applied to the drift portion 6a of the strong electric field drift layer 6 is applied to the silicon oxide film 64, so the injected electrons e ⁻ are accelerated by the strong electric field applied to the silicon oxide film 64, and drift. The region between the grains 51 in the portion 6a drifts toward the surface in the direction of the arrow in FIG. 6 (upward in FIG. 6), tunnels through the surface electrode 7, and is discharged into a vacuum.

Therefore, in the drift portion 6a of the strong electric field drift layer 6, the electrons injected from the lower electrode 12 are accelerated by the electric field applied to the silicon oxide film 64 without being scattered by the silicon microcrystal 63 and drift. ,
Is emitted through the surface electrode 7 (ballistic electron emission phenomenon),
Since the heat generated in the strong electric field drift layer 6 is radiated through the grains 51, the popping phenomenon does not occur at the time of electron emission, and the electrons can be emitted stably. The electrons that have reached the surface of the strong electric field drift layer 6 are considered to be hot electrons, and easily tunnel through the surface electrode 7 and are emitted into a vacuum. In the electron source element 10a described above,
Since the emission direction of the electron beam emitted through the surface electrode 7 is easily aligned with the normal direction of the surface electrode 7 (which coincides with the normal direction of the above-mentioned one surface of the insulating substrate 11), a complicated shadow mask or electron converging lens is used. It is not necessary to provide the display, and the display can be made thin. In addition, the surface electrode 7 and the lower electrode 12
Since the electrons can be emitted even when the voltage applied between and is as low as about 10 to 20 V, low power consumption can be achieved.

By the way, in the field emission electron source 10 of the present embodiment, in the strong electric field drift layer 6 on the one surface side of the insulating substrate 11, the electron source element 10a and the connection wiring 1 are provided.
A protective film 14 is provided to cover the surface side of the portion excluding 6. Therefore, the portion of the strong electric field drift layer 6 excluding the electron source element 10 a (separation portion 6 b) and the portion of the bus electrode 15 excluding the connection portion with the connection wiring 16 are covered with the protective film 14. Here, the protective film 14 is formed of SiO ₂ , SiN _x (SiN, Si ₂ N ₃ , S).
i ₃ N ₄ etc., but Si ₃ N ₄ is preferable), SiON,
It may be formed of a material selected from the group of AlO _x (Al ₂ O ₃ etc.) and AlN. If these materials are selected, a material used in a so-called silicon process that is typical in a general semiconductor manufacturing process. The protective film 14 can be formed by the film forming method. In addition, in this embodiment, the insulating substrate 11 constitutes a substrate.

In this embodiment, however, the insulating substrate 1
Since the protective film 14 that covers the surface side of the portion excluding the electron source element 10a and the connection wiring 16 on the one surface side of 1 is provided on the one surface side of the insulating substrate 11, the strong electric field drift layer 6 is formed. It is possible to prevent impurities and moisture from entering from the outside through the surface of the separating portion 6b and to prevent the surface of the separating portion 6b and the bus electrode 15 from being scratched, so that reliability can be improved. In short, in the present embodiment, the moisture resistance can be improved as compared with the conventional configuration shown in FIG.
It is possible to prevent the separation portion 6b around the a from being scratched. Moreover, since the portion of the bus electrode 15 connected to the front surface electrode 7 is exposed, there is an advantage that the connection between the bus electrode 15 and the front surface electrode 7 becomes easy.

Further, the field emission type electron source 10 of the present embodiment.
Since the drift portion 6a is formed only in the portion corresponding to the electron source element 10a, the drift portion 6a is spread over the plurality of electron source elements 10a as in the conventional configuration shown in FIG.
Crosstalk is less likely to occur as compared with the case where the gap is formed.

In the present embodiment, the drift portion 6a of the strong electric field drift layer 6 is made of an oxidized porous polycrystalline silicon layer, but the drift portion 6a of the strong electric field drift layer 6 is nitrided or oxynitrided. It may be composed of a porous polycrystalline silicon layer, or may be composed of another oxidized or nitrided or oxynitrided porous polycrystalline semiconductor layer. Here, when the drift portion 6a of the strong electric field drift layer 6 is formed by nitriding a porous polycrystalline silicon layer, each of the silicon oxide films 52 and 64 described in FIG. 6 becomes a silicon nitride film, resulting in a strong electric field drift. When the drift portion 6a of the layer 6 is a porous polycrystalline silicon layer obtained by oxynitriding, each of the silicon oxide films 52 and 64 becomes a silicon oxynitride film.

(Embodiment 2) The basic structure of the field emission electron source 10 of this embodiment is substantially the same as that of Embodiment 1 shown in FIGS. 1 and 2, and the electrons are not formed on the surface side of the strong electric field drift layer 6. Protective film 1 provided on a portion excluding the source element 10a
4 is formed in a shape as shown in FIG. That is, the protective film 14 in the present embodiment is formed with an inclined surface in which the distance from the insulating substrate 11 gradually increases as the distance from the surface electrode 7 approaches the bus electrode 15, and the surface electrode 7 and the bus electrode 15 are formed. A connection wiring 16 for connecting between and is formed along the inclined surface from the side edge of the surface electrode 7 to above the bus electrode 15 (connection wiring 16).
Is formed on the inclined surface). Here, an insulating layer 13 made of SiO ₂ is interposed between the protective film 14 and the separation portion 6b. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

By the way, in the field emission electron source 10 of the first embodiment, the connection wiring 16 for electrically connecting the surface electrode 7 and the bus electrode 15 is formed along the side surface and the upper surface of the bus electrode 15. The connection wiring 16 may be broken.

On the other hand, in the field emission electron source 10 of this embodiment, since the connection wiring 16 is formed along the inclined surface of the protective film 14, the surface electrode 7 and the bus electrode 1 are formed.
It is possible to prevent disconnection between the wiring and the wiring 5, and further improve the reliability.

Hereinafter, the field emission electron source 10 of this embodiment will be described.
The manufacturing method will be described with reference to FIG.

First, the lower electrode 12 is formed on the one surface of the insulating substrate 11 by, for example, a sputtering method or a vapor deposition method, and then a predetermined film thickness (here, a predetermined film thickness) is formed on the entire surface of the insulating substrate 11 on the one surface side. By performing a step (hereinafter, referred to as a first film forming step) of forming the non-doped polycrystalline silicon layer 3 having a thickness of 1.5 μm), as shown in FIG.
A structure as shown in (a) is obtained. As a method of forming the non-doped polycrystalline silicon layer, for example, CV
D method (LPCVD method, plasma CVD method, catalytic CVD method, etc.), sputtering method and CGS (Continuous Grain Sil)
icon) method, laser annealing after depositing amorphous silicon, etc. may be adopted.

After forming the non-doped polycrystalline silicon layer 3, SiO 2 is formed on the entire surface of the insulating substrate 11 on the one surface side.
4B by removing the portion of the insulating layer 13 corresponding to the site where the electron source element 10a is to be formed by using the photolithography technique and the etching technique. The structure shown is obtained. In addition, the insulating layer 13 is opened in a forward tapered shape at a portion corresponding to a site where the electron source element 10a is to be formed.

Next, a step of forming the bus electrode 15 on the insulating layer 13 by a sputtering method, a vapor deposition method or the like (hereinafter, this step is referred to as a first electrode forming step) is carried out, so that FIG. The structure shown in is obtained.

After forming the bus electrode 15, the insulating substrate 1 is formed.
1. A protective film 14 made of SiO ₂ is formed on the entire surface on the one surface side of FIG.
Is performed (hereinafter, this step is referred to as a second film forming step), and thereafter, the electron source element 1 of the protective film 14 is formed using the photolithography technique and the etching technique.
A step of removing the portion corresponding to the planned formation portion of 0a (hereinafter, this step is referred to as a patterning step) is performed, and then the polycrystalline silicon layer 3 is predetermined in the anodizing step using the protective film 14 as a mask material. A porous polycrystalline silicon layer is formed by making it porous to a depth, and a drift portion 6a made of the oxidized porous polycrystalline silicon layer is formed by oxidizing the porous polycrystalline silicon layer in the oxidation step. Then, the structure as shown in FIG. 4D is obtained. Here, in the anodizing process, a treatment tank containing an electrolytic solution composed of a mixed solution of 55 wt% hydrogen fluoride aqueous solution and ethanol at a ratio of about 1: 1 was used, and a platinum electrode (not shown) was used. Porous polycrystalline silicon is formed by applying a voltage between the lower electrode 12 and anodizing the polycrystalline silicon layer 3 with a constant current while irradiating the polycrystalline silicon layer 3 with light. The porous polycrystalline silicon layer thus formed contains grains of polycrystalline silicon and silicon microcrystals. In this embodiment, the portion of the polycrystalline silicon layer 3 around the drift portion 6a becomes the separation portion 6b.
Further, the polycrystalline silicon layer 3 may be made porous to a depth that does not reach the lower electrode 12. In the oxidation step, the drift portion 6a including the grains 51, the silicon microcrystals 63, and the silicon oxide films 52 and 64 is formed by oxidizing the porous polycrystalline silicon by the rapid heating method, for example. In the oxidation process by the rapid heating method, a lamp annealing apparatus is used and the inside of the furnace is set to an O ₂ gas atmosphere, and the substrate temperature is changed from room temperature to a predetermined oxidation temperature (for example, 9 ° C.).
Up to a specified temperature increase rate (eg, 80 ° C / se)
In step c), the substrate temperature is raised to a predetermined oxidation time (for example,
Rapid thermal oxidation (Rapid Therm)
al Oxidation (RTO) is performed, and then the substrate temperature is lowered to room temperature. The oxidation step is not limited to the rapid heating method, and for example, an electrolyte solution (for example, 1 mol / L H 2
₂ SO ₄ , 1 mol of HNO ₃ , aqua regia, etc. is used to apply a constant current between the platinum electrode (not shown) and the lower electrode 2 to form a porous polycrystalline silicon layer. An electrochemical method of forming the drift portion 6a including the grains 51, the silicon microcrystals 63, and the silicon oxide films 52 and 64 by electrochemical oxidation may be adopted.

After forming the strong electric field drift layer 6 including the plurality of drift portions 6a and the separation portion 6b, the protective film 14 is formed by using the photolithography technique and the etching technique.
The step of forming the above-mentioned inclined surface in the following (hereinafter referred to as a processing step)
The structure shown in FIG. 4E is obtained by carrying out. By forming this inclined surface, a part of the surface of bus electrode 15 is exposed.

After that, a step of forming the surface electrode 7 and the connection wiring 16 (hereinafter referred to as a second electrode forming step) is performed by, for example, a sputtering method or a vapor deposition method, so that the structure shown in FIG. The electron source element 10a is obtained (that is, the field emission electron source 10 is obtained).

However, according to the above-described manufacturing method, the porous polycrystalline silicon layer (porous polycrystal) oxidized by sequentially performing the anodizing step and the oxidizing step after patterning the protective film 14 in the patterning step. Semiconductor layer)
Of the drift electrode 6a is formed, and then the front surface electrode 7
Since the electron source element 10a is not formed when the protective film 14 is formed, the reliability of the electron source element 10a is not affected by the formation of the protective film 14. , Highly reliable field emission electron source 10
Can be provided. Further, since each of the above-mentioned steps is the same as the step of a general semiconductor manufacturing process, the capital investment can be reduced and the cost can be reduced by sharing or diverting the existing semiconductor manufacturing apparatus. .

Further, in the anodizing process, the protective film 14 patterned in the patterning process is used as a mask material. Therefore, in the anodizing process, a step of separately forming a mask material and a step of removing the mask material. Is unnecessary, the manufacturing process can be simplified and the manufacturing cost can be reduced.

[0052]

According to the first aspect of the present invention, there is provided a substrate and an electron source element which is formed on one surface side of the substrate and emits an electron beam along a normal direction of the one surface. A lower electrode formed on the one surface side of the substrate, a surface electrode facing the lower electrode on the one surface side of the substrate, and interposed between the lower electrode and the surface electrode and between the lower electrode and the surface electrode. Electrons injected from the lower electrode due to the electric field that acts when a voltage is applied has a drift portion drifting toward the surface electrode, the electron source element is provided in a partial region of the one surface of the substrate, A protective film is provided on the one surface side of the substrate to cover the surface side of the portion excluding the electron source element, and the protection film covers the surface side of the portion of the substrate on the one surface side excluding the electron source element. Since the film is provided, one surface side of the substrate In this case, it is possible to prevent impurities and moisture from entering from the outside through the surface of the portion where the electron source element is not formed, and to prevent the surface of the portion where the electron source element is not formed from being scratched. Therefore, there is an effect that reliability can be improved.

According to a second aspect of the present invention, the substrate, a plurality of lower electrodes arranged in a row on one surface side of the substrate and parallel to each other, and intersecting the lower electrode in a plane parallel to the one surface of the substrate. A plurality of surface electrodes formed via a drift part where electrons drift on the surface side of the lower electrode at a portion corresponding to an intersection of a plurality of virtual straight lines parallel to each other and the lower electrode, and one for each virtual straight line A plurality of electron source elements including a plurality of bus electrodes that commonly connect surface electrodes arranged on a virtual straight line, and a lower electrode, a drift portion, and a surface electrode respectively on the one surface side of the substrate, a surface electrode, and a bus. A protective film is provided to cover the surface side of the portion excluding the connection wiring with the electrode, and the surface of the portion excluding the connection wiring between the electron source element and the surface electrode and the bus electrode on the one surface side of the substrate. The protective film that covers the side As a result, impurities, moisture, etc. may enter from the outside through the surface of the part other than the electron source element and the connection wiring between the surface electrode and the bus electrode on the one surface side of the substrate, or scratches may be caused. Therefore, there is an effect that reliability can be improved, and since the connection wiring that connects the surface electrode and the bus electrode is exposed, it is easy to connect the bus electrode and the surface electrode. There is an effect that.

According to a third aspect of the present invention, in the second aspect of the present invention, the protective film is formed with an inclined surface whose distance from the substrate gradually increases as the distance from the surface electrode approaches the bus electrode. Since the connection wiring extends from the side edge of the surface electrode to the bus electrode along the inclined surface, it is possible to prevent disconnection between the surface electrode and the bus electrode. There is.

According to a fourth aspect of the invention, in the invention of the third aspect, the drift portion is made of an oxidized porous polycrystalline semiconductor layer formed for each electron source element, and fills a space between the drift portions. Since the isolation portion formed of the polycrystalline semiconductor layer is provided, there is an effect that crosstalk can be prevented.

According to a fifth aspect of the invention, in the invention of the first to fourth aspects, the protective film is SiO ₂ , SiN _x ,
Since it is formed of a material selected from the group of SiON, AlO _x , and AlN, there is an effect that the protective film can be formed by a material and a film forming method used in a general semiconductor manufacturing process.

According to a sixth aspect of the present invention, in addition to the first to third or fifth aspects, the drift portion is
Oxidized or nitrided or oxynitrided porous polycrystalline silicon layer, at least, a plurality of columnar grains extending in the thickness direction of the lower electrode, and a large number of nanometer-order silicon microcrystals interposed between the grains, Since the insulating film has a film thickness smaller than the crystal grain size of the silicon body microcrystals formed on the surface of each silicon microcrystal, most of the electric field applied to the drift portion is concentrated on the insulating film. Thus, the electrons injected from the lower electrode into the drift portion are accelerated by the strong electric field applied to the insulating film and drift toward the surface electrode, so that the electron emission efficiency can be improved and the electron Since the heat generated by the source element is radiated through the grains,
There is an effect that the popping phenomenon does not occur at the time of electron emission and electrons can be emitted stably. In addition, since the emission direction of the electron beam emitted from the electron source element is easily aligned with the normal direction of the surface electrode, it is necessary to provide a complicated shadow mask or electron converging lens when applied as an electron source of a display, for example. The advantage is that the display can be made thinner.

The invention of claim 7 is the method for manufacturing a field emission type electron source according to claim 4, wherein a polycrystalline semiconductor layer is formed on the entire surface on the one surface side of the substrate on which the lower electrode is formed. A first film forming step, a first electrode forming step of forming the bus electrode on the front surface side of the polycrystalline semiconductor layer after the first film forming step, and a substrate after the first electrode forming step. A second film forming step of forming a protective film on the entire surface on the one surface side of
After the second film forming step, a patterning step of removing a portion of the protective film corresponding to the site where the electron source element is to be formed, and after the patterning step, forming the electron source element of the polycrystalline semiconductor layer An anodizing step of forming a porous polycrystalline semiconductor layer by making a portion corresponding to the site porous by anodizing treatment, an oxidizing step of oxidizing the porous polycrystalline semiconductor layer to form the drift portion, Characterized by comprising a processing step of forming the inclined surface on the surface side of the protective film after the oxidation step, and a second electrode forming step of forming the surface electrode and the connection wiring after the processing step, After patterning the protective film in the patterning process, the anodizing process and the oxidizing process are sequentially performed to form a drift portion composed of the oxidized porous polycrystalline semiconductor layer, and then the surface electrode is formed. Since the electron source element is not formed during the formation of the protective film, the reliability of the electron source element is not affected by the formation of the protective film, and the connection wiring is formed. There is an effect that a high field emission type electron source can be provided. Further, since each process is similar to the process of a general semiconductor manufacturing process, it is possible to reduce the capital investment by sharing or diverting the existing semiconductor manufacturing device, and it is possible to reduce the cost. There is.

According to an eighth aspect of the invention, in the seventh aspect of the invention, the protective film patterned in the patterning step is used as a mask material in the anodizing step, so that the anodizing step is performed separately. Since the step of forming the mask material and the step of removing the mask material are unnecessary, there is an effect that the manufacturing process can be simplified and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a field emission electron source showing a first embodiment.

FIG. 2 shows the same as above, and (a) and (b) are schematic cross-sectional views of a main part.

FIG. 3 is a schematic sectional view of a main part of a field emission electron source showing a second embodiment.

FIG. 4 is a cross-sectional view of main steps for explaining the above manufacturing method.

FIG. 5 is an operation explanatory view of a field emission electron source showing a conventional example.

FIG. 6 is an operation explanatory diagram of the above.

FIG. 7 is an operation explanatory view of a field emission electron source showing another conventional example.

FIG. 8 is a schematic configuration diagram of a display to which the above is applied.

[Explanation of symbols]

6 Strong electric field drift layer 6a Drift section 6b Separation part 7 Surface electrode 10 Field emission electron source 10a Electron source element 11 Insulating substrate 12 Lower electrode 14 Protective film 15 bath electrodes 16 connection wiring

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takuya Komoda             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Yoshishi Takekawa             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company

Claims (8)

[Claims] 1. A substrate, and an electron source element that is formed on one surface side of the substrate and emits an electron beam along a normal direction of the one surface. The electron source element is provided on the one surface side of the substrate. The formed lower electrode, the surface electrode facing the lower electrode on the one surface side of the substrate, and interposed between the lower electrode and the surface electrode and acting when a voltage is applied between the lower electrode and the surface electrode An electron source element is provided in a region of a part of the one surface of the substrate, and an electron source element is provided on a part of the one surface side of the substrate. A field emission type electron source, comprising a protective film covering a surface side of a portion excluding an electron source element. 2. A substrate, a plurality of lower electrodes arranged in parallel on one surface side of the substrate, and a plurality of parallel electrodes intersecting the lower electrode in a plane parallel to the one surface of the substrate and parallel to each other. Of a plurality of surface electrodes formed on the surface side of the lower electrode via the drift part where electrons drift at a portion corresponding to the intersection of the virtual straight line and the lower electrode and one virtual straight line for each virtual straight line. A plurality of electron source elements having a plurality of bus electrodes for commonly connecting the surface electrodes and a lower electrode, a drift portion, and a surface electrode on the one surface side of the substrate, and connection wiring between the surface electrodes and the bus electrodes. A field-emission electron source, characterized in that a protective film is provided to cover the surface side of the region except for. 3. The protective film is formed with an inclined surface that gradually increases in distance from the substrate as the distance from the surface electrode approaches the bus electrode, and the connection wiring is formed from the side edge of the surface electrode. 3. The field emission electron source according to claim 2, wherein the field emission electron source is extended to the bus electrode along the inclined surface. 4. The isolation part is formed of an oxidized porous polycrystalline semiconductor layer formed for each of the electron source elements, and the separation part is formed of a polycrystalline semiconductor layer formed so as to fill a space between the drift parts. The field emission electron source according to claim 3, further comprising: 5. The protective film is formed of SiO ₂ , SiN _x , Si.
ON, AlO _X, field emission electron source according to any one of claims 1 to 4, characterized in that is formed of a material selected from the group of AlN. 6. The drift portion is made of an oxidized, nitrided, or oxynitrided porous polycrystalline silicon layer, and is interposed between at least a plurality of columnar grains extending in the thickness direction of the lower electrode. 4. A plurality of nanometer-order silicon microcrystals and an insulating film having a film thickness smaller than the crystal grain size of the silicon body microcrystals formed on the surface of each silicon microcrystal. The field emission electron source according to claim 3 or 5. 7. The method for manufacturing a field emission type electron source according to claim 4, wherein a first semiconductor film forming method forms a polycrystalline semiconductor layer on the entire one surface side of the substrate on which the lower electrode is formed. And a first electrode forming step of forming the bus electrode on the surface side of the polycrystalline semiconductor layer after the first film forming step,
Second film forming step of forming a protective film on the entire surface of the one surface side of the substrate after the step of forming the electrode, and a plan of forming the electron source element in the protective film after the second film forming step. A patterning step of removing a portion corresponding to the portion, and a portion of the polycrystalline semiconductor layer corresponding to the portion where the electron source element is to be formed in the polycrystalline semiconductor layer after the patterning step is made porous by anodization to form a porous polycrystalline semiconductor. An anodizing step of forming a layer, an oxidizing step of oxidizing the porous polycrystalline semiconductor layer to form the drift portion, and a processing step of forming the inclined surface on the surface side of the protective film after the oxidizing step. And a second electrode forming step of forming the front surface electrode and the connection wiring after the processing step, the method for manufacturing a field emission electron source. 8. The method of manufacturing a field emission electron source according to claim 7, wherein in the anodizing step, the protective film patterned in the patterning step is used as a mask material.