ES2370507T3 - PROCEDURE FOR MANUFACTURE OF ELECTRONIC SOURCE OF THE FIELD ISSUANCE TYPE. - Google Patents

Abstract

A process for manufacturing an electron source of the field emission type (10) comprising an electrically conductive substrate (1), a strong field driving layer (6) formed on the surface of the electrically conductive substrate (1), driving layer ( 6) comprising column-shaped polycrystalline silicon grains (61), thin films of silicon oxide (62) formed on the surfaces of polycrystalline silicon grains (61), layers of fine crystalline silicon (63) of nanometric order which are placed between the polycrystalline silicon grains (61) and silicon oxide films (64) formed on the surfaces of the thin crystalline silicon layers (63), each of the films (64) being an insulating film having a thickness smaller than the diameter of a crystal particle of the thin crystalline silicon layer (63), and an electrically conductive thin film (7) formed on the driving layer of the strong field (6), and n that the electrons, which are injected into the electrically conductive substrate (1), propel in the driving layer of the strong field (6) so that they are emitted outward through the electrically conductive thin film (7) by applying a voltage between the electrically conductive thin film (7) and the electrically conductive substrate (1), the process comprising a major oxidation stage of the strong field driving layer formation (6) by the oxidation of a porous semiconductor layer by means of the minus one of a treatment that applies ultraviolet radiation to the porous semiconductor layer in a gas atmosphere that contains at least one of oxygen and ozone, a treatment that heats the porous semiconductor layer in an ozone-containing gas atmosphere, a treatment that applies ultraviolet radiation to the porous semiconductor layer and heats the porous semiconductor layer in a gas atmosphere containing at least one of o Oxygen and ozone and heats the porous semiconductor layer.

Description

Manufacturing procedure of electron source of field emission type

Background of the invention

1. Field of the invention

The present invention relates to a method of manufacturing a source of electrons of the field emission type.

2. Description of the prior art

Conventionally, as an electronic source of field emission type, a so-called Spindt type electrode is well known which is disclosed, for example, in US Patent No. 3,665,241, and other equivalents. The Spindt type electrode is provided on a substrate on which many small (thin) emitting chips in the shape of a triangular pyramid are arranged, outlet holes for exposing the apexes of the emitting chips to the outside, and gate layers arranged in such a way that They can isolate from the emitting chip. In this way, the Spindt type electrode can emit electron beams from the apexes of the emitting chips to the outside through the exit holes by applying a high voltage between the emitting chips and the gate layers under vacuum atmosphere such that the emitting chips become negative electrodes in front of the gate layers.

However, in the Spindt type electrode, there is such a problem that when it is applied, for example, to a flat light emitter or to a screen, it is difficult to increase its area (electron emission area), because it complicates the electrode manufacturing process, and, additionally, it is difficult to produce many triangular shaped emitting chips with greater efficiency. Meanwhile, in the Spindt type electrode, the electric field converges at the apex of the emitting chips. Therefore, when the degree of vacuum around the apexes of the emitting chips is lower than that of the residual gas that exists around, the residual gas is ionized by the electrons emitted to make the ions positive so that the positive ions clash with the apex of the emitting chips. Accordingly, the apexes of the emitting chips are damaged (for example, damage due to the impacts of the ions) such that a problem can occur such that the density or efficiency of the current of the emitted electrons becomes unstable, or the lives of the emitting chips are shortened. Therefore, the Spindt type electrode should be used under a higher vacuum atmosphere (approximately 10-5 Pa to approximately 10-6 Pa) in order to avoid the occurrence of the aforementioned problem. Accordingly, a disadvantage may occur such that the cost of manufacturing the electrode is increased and additionally, the electrode treatment process is difficult.

In order to improve the aforementioned disadvantage, an electron source of the field emission type of MIM (Metal Insulating Metal) or MOS (Metal Oxide Semiconductor) style has been proposed. The first is a source of electrons of the flat-field emission type having a laminated structure of (metal) - (insulating film) - (metal), while the latter is a source of electrons of the flat-field emission type that has a laminated structure of (semiconductor) - (oxide film) - (metal). In order to increase the electron emission efficiency of the electron source of the field emission type of the mentioned type (that is, in order to emit more electrons) it is necessary to reduce the thickness of the insulating film or oxide film. However, if the thickness of the insulating film or oxide film becomes thinner in excess, it is feared that dielectric interruption will occur when the voltage between the upper and lower electrodes of the laminated structure is applied. Therefore, there may be a certain restriction on reducing the thickness of the insulating film or oxide film. In this way, there is a disadvantage that its electron emitting efficiency (electron extraction efficiency) cannot be increased too much, because the aforementioned dielectric interruption must be avoided.

In addition, in recent years, as described in Japanese Patent Publication Open for Consultation by the Public No. 8-250766, another source of electrons of the field emission type (semiconductor element for emitting cold electrons) has been proposed in the that a porous semiconductor layer (porous silicon layer) is formed by carrying out anodic oxidation on a surface of a monocrystalline semiconductor substrate such as a silicon substrate in order to increase its electronic emission efficiency, forming a thin metal film over the porous layer of the semiconductor. That said, the electronic source can emit electrons when the voltage between the semiconductor substrate and the thin metal film is applied,

However, in the source of electrons of the field emission type described in Japanese Patent Publication Open for Consultation by Public No. 8-250766, there is a disadvantage such that it is difficult to increase its area and decrease its manufacturing cost, due to that the substrate material can be restricted to the semiconductor. Meanwhile, in the electron source of the field emission type, because a so-called snapping phenomenon easily occurs when electrons are emitted, the amount of emitted electrons tends to become unstable. Accordingly, when the electronic source is applied to a flat light emitter or a screen, a disadvantage may occur such that the light emission becomes unstable.

Thus, in Japanese Patent Applications No. 10-272340, No. 10-272342 and No. 10-271876, etc., the authors of the present application have proposed another source of field emission type electrodes that includes a driving layer of strong field that can drive the injected electrons from an electrically conductive substrate, the layer being disposed between the electrically conductive substrate and a thin metal film, and the layer being formed by oxidation of a porous layer of polycrystalline silicon, by medium of the Rapid Thermal Oxidation procedure (RTO procedure).

That said, the polycrystalline porous silicon layer is formed by manufacturing a polycrystalline silicon layer on an electrically conductive porous substrate by means of an anodic oxidation treatment. Meanwhile, oxidation of the polycrystalline silicon porous layer is carried out by the RTO process in a dry oxygen atmosphere using a lamp tempering equipment. In this case, the oxidation temperature may be 800-900 ° C, and the oxidation time may be 30-120 minutes (Japanese Patent Application No. 10-271876. Additionally, the thin metal film is formed using a thin gold film approximately 10 nm thick, because electrons (electrons are considered hot electrons), which have reached the surface of the strong field's driving layer, must be emitted in the vacuum atmosphere of such so that they pass through the thin metal film without dispersing in it. In the electron source of the field emission type, electrons can be emitted stably, because their electron emission property has a minor dependence on the degree of vacuum, and additionally there is no clicking phenomenon when electrons are emitted, additionally, in addition to a semiconductor substrate such as a monocrystalline silicon substrate , a substrate may be used in which an electrically conductive film (eg, ITO film) is provided on a surface of a glass substrate or the like, such as the electrically conductive substrate mentioned above. Therefore, in the electron source of the field emission type, its area can be increased and its manufacturing cost can be reduced, compared to the conventional electronic source that uses the porous semiconductor layer produced by manufacturing the porous semiconductor substrate , or the Spindt electrode. That said, when a screen is produced using this type of electronic field emission source, the thin metal film should be designed with a predetermined shape.

However, in the electron source of the field emission type described in Japanese Patent Applications No. 10-272340, No. 10-272342 or No. 10-271876, the oxidation temperature cannot be increased by the RTO method above The thermal resistance temperature of the electrically conductive substrate. Therefore, there is a disadvantage such that the substrate materials or the electrically conductive film are restricted so that the increase in the diameter (area) of the substrate is also restricted.

Meanwhile, in the electron source of the field emission type described in Japanese Patent Applications No. 10-272340, No. 10-272342 or No. 10-271876, the porous layer of polycrystalline silicon, which has been formed by oxidation of The polycrystalline silicon layer by means of anodic oxidation treatment is oxidized by means of the RTO process. That said, since an electrolyte solution is used in the anodic oxidation treatment, a solution can be used in which an aqueous solution of hydrogen fluoride and ethanol is mixed together in the ratio of 1: 1.

That said, in the porous semiconductor layer (porous layer of polycrystalline silicon or porous layer of monocrystalline silicon) formed by anodic oxidation treatment, silicon atoms are terminated by hydrogen atoms. Therefore, as disclosed in Japanese Patent Applications No. 10-272340, No. 10272342 or No. 10-271876, if an oxidized film is grown by the RTO process in the porous layer of the semiconductor by anodic oxidation treatment , hydrogen atoms can remain in the oxidized film, or Si-OH bonds can be produced. Consequently, there is a disadvantage such that it is difficult to form an instant oxidized film having a SiO2 structure, such that its interruption voltage is decreased. Additionally, because the strong field driving layer contains relatively much hydrogen, the distribution of hydrogen in the strong field driving layer may change over time (for example, hydrogen atoms that come off the surface of the the driving layer of the strong field.). Therefore, it is feared that the stability of electron emission efficiency will deteriorate as time passes.

EP-A-0913849 discloses a method of developing an electron source of the field emission type that includes an electrically conductive substrate, a strong field driving layer formed on the surface of the electrically conductive substrate and a thin electrically conductive thin film formed in the strong field driving layer, in which the process comprises a major oxidation step of forming the strong field driving layer by oxidizing a porous layer of the semiconductor by means of a treatment that applies the porous layer of the semiconductor to plasma in an atmosphere of oxygen-containing gas

EP-A-0874384 discloses a source of electrons, in which the porous semiconductor layer is oxidized by treatment in an oxygen plasma before a thin film metal electrode is placed forming a layer on it.

JP-B2-2966842 discloses a method of forming an electron source of the emission type comprising a major oxidation stage of forming a strong field driving layer by a rapid thermal oxidation process of a porous semiconductor layer, in which Oxidation can also be carried out using oxygen plasma oxidation.

Thus, in the source of electrons of the field emission type described in Japanese Patent Applications No. 10-272340, No. 10-272342 or No. 10-271876, although their cost can be reduced and the batteries can be emitted stably electrons with high efficiency compared to the electron source of the field emission type described in Japanese Patent Publication opened for consultation by Public No. 8-250766, it is hoped to improve the efficiency of electron emission further.

Summary of the Invention

The present invention, which has been carried out to solve the problems described above, has the objective of providing an electron source of the field emission type that can easily increase its area (electron emission area) and decrease its cost and procedure of elaboration of the same.

Additionally, the present invention has another objective of providing an electron source of the field emission type in which the change in electron emission efficiency is smaller as time passes and its interruption voltage is higher, and a manufacturing process thereof.

In addition, the present invention has a further objective of providing a source of electrons of the lower cost field emission type that can stably emit electrons with high efficiency, and a process thereof.

In accordance with one aspect of the present invention, there is provided a method of developing an electron source of the field emission type that includes an electrically conductive substrate, a strong field driving layer formed on the surface of the electrically conductive substrate, driving layer that it includes polycrystalline column-shaped silicon grains, fine silicon oxide films on the surfaces of polycrystalline silicon grains, thin crystalline silicon layers of the order of nanometers that exist between polycrystalline silicon grains and silicon oxide films formed on the surfaces of the thin crystalline silicon layers, each of the films being an insulation film having a thickness less than the diameter of the crystal particle of the thin crystalline silicon layer and a thin electrically conductive thin film formed on the strong field driving layer, in which the electron that is, they are injected into the electrically conductive substrate, they are propelled into the driving layer of the strong field to be emitted outwardly by the electrically conductive thin film by applying voltage between the electrically conductive thin layer and the electrically conductive substrate such that the Electrically conductive thin film acts as a positive electrode against the electrically conductive substrate, the process including a major oxidation step of forming a strong field driving layer by oxidizing a porous layer of the semiconductor at relatively low temperature.

Additionally, a supplementary oxidation step can be carried out by means of a thermal process (preferably a rapid thermal process, which consequently is hereinafter referred to as a rapid thermal process although it includes a process simple thermal) before and / or after the main oxidation stage.

Meanwhile, before the main oxidation stage or before the main oxidation stage and the supplementary oxidation stage, a pre-oxidation stage can be carried out to oxidize the porous layer of the semiconductor using an oxidizing solution. In this case, the hydrogen atoms, which terminate the group of atoms on the surface of the porous layer of the semiconductor, formed, for example, by anodic oxidation, are replaced with oxygen atoms by the oxidizing solution. Accordingly, the amount of hydrogen contained in the driving layer of the strong field becomes less. Consequently, the time-dependent change of hydrogen distribution becomes smaller so that the time-dependent stability of the electron source of the field emission type can be improved.

In addition, in the main oxidation stage, the porous layer of the semiconductor is oxidized by means of at least one of a treatment that applies ultraviolet rays to the porous layer of the semiconductor in an atmosphere of gas containing at least one of oxygen and ozone, a treatment that heats the porous layer of the semiconductor in an ozone-containing gas atmosphere, a treatment that applies ultraviolet rays to the porous layer of the semiconductor and heats the porous layer of the semiconductor, and a treatment that applies ultraviolet rays to the porous layer of the semiconductor in a gas atmosphere that contains at least one of oxygen and ozone and heats the porous layer of the semiconductor. In this case, the electron emission efficiency of the electron source can be increased compared to that of the electron source manufactured by the conventional manufacturing process, in which the strong field driving layer is formed by oxidation of the Porous semiconductor layer using the RTO procedure. Additionally, because the process temperature is lower, the restriction for the materials usable by the electrically conductive substrate becomes smaller so that a source of electrons of the field emission type can be manufactured at a lower cost with a larger area of electron emission.

Additionally, if the main oxidation stage is carried out after the electrically conductive thin film has formed, contamination due to the organic materials produced in the processes can be eliminated before the present oxidation. Consequently, an effect can be obtained such that the electron emission property is improved.

That said, before and / or after the main oxidation stage, a supplementary oxidation stage can be carried out to oxidize the porous layer of the semiconductor by means of a rapid thermal process, a supplementary oxidation stage to oxidize the porous layer of the semiconductor using an acid solution, or both supplementary oxidation steps described above. In this case, the efficiency of electron emission can be greatly increased.

Additionally, before the main oxidation stage (in the case of not including supplementary oxidation), or before the main oxidation stage and the supplementary oxidation stage (s), it can be carried out Perform a pre-oxidation step of oxidizing the porous layer of the semiconductor using an oxidizing solution. In this case, as described above, because the hydrogen atoms, which terminate the group of atoms on the surface of the porous layer of the semiconductor are replaced with oxygen atoms by the oxidizing solution, the amount of hydrogen contained in the strong field driving layer such that the time-dependent stability of the electron source of the field emission type can be improved.

Meanwhile, the pre-oxidation stage can be carried out before the oxidation stage by means of a rapid thermal process.

In each of the above-mentioned manufacturing processes, the porous layer of the semiconductor may be a porous layer of monocrystalline silicon or a porous layer of polycrystalline silicon. The electrically conductive substrate can be a n-type silicon substrate. Additionally, the electrically conductive substrate may be a substrate in which an electrically conductive film is formed on a surface of an insulating plate, such as, for example, a glass plate, a ceramic plate or the like. The porous layer of the semiconductor can be formed by performing an anodic oxidation in a layer of the semiconductor.

In each of the above-mentioned manufacturing processes, it is preferable that the acid solution, which is used in the supplementary oxidation stage, is diluted in nitric acid, diluted in sulfuric acid or in royal water. Additionally, it is preferable that the oxidizing solution, which is used in the pre-oxidation stage, is any one or several mixtures of concentrated nitric acid, concentrated sulfuric acid, hydrochloric acid and hydrogen peroxide. That said, it is preferable that the oxidized solution is used in a heated state in order to shorten the processing time of the pre-oxidation stage such that its performance is improved.

Brief description of the drawings

The present invention will become more fully understood from the detailed description given below and the accompanying drawings, in which:

Fig. 1A is an elevation view of a section of an electron source of the field emission type, in which the electrically conductive substrate is composed of a n-type silicon substrate;

Fig. 1B is an elevation view of a section of an electron source of the field emission type, in which the electrically conductive substrate is composed of a substrate in which an electrically conductive film is formed on a glass plate;

Figs. 2A to 2D are elevational views of a section of the intermediate products or an end product in the main stages of the manufacturing process of the electron source of the field emission type shown in Fig. 1A;

Fig. 3 is a schematic view showing an outline of an electrochemical oxidation process in a porous silicon;

Fig. 4 is a view showing a principle of an electron emission mechanism in the electron source of the field emission type shown in Fig. 1A;

Fig. 5 is a view showing an electron emission action of the electron source of the field emission type shown in Fig. 1A;

Fig. 6A is an elevational view of a section of another electron source of the field emission type, in which the electrically conductive substrate is composed of a n-type silicon substrate;

Fig. 6B is an elevation view of a section of another electron source of the field emission type, in which the electrically conductive substrate is composed of a substrate in which an electrically conductive film is formed on a glass plate;

Figs. 7A to 7D are elevational views of a section of the intermediate products or an end product in the main stages of the manufacturing process of the electron source of the field emission type shown in Fig. 6A;

Fig. 8 is a view showing a principle for measuring the active properties of the electron source of the field emission type shown in Fig. 6A;

Fig. 9 is a graph showing the relationships between voltage and current density (current-voltage property) in the electron source of the field emission type made in accordance with a method of the present invention and the source of electrons of the field emission type of a comparative example;

Figs. 10A and 10B are views showing the oxidized states of a nanocrystalline silicon layer;

Fig. 11 is an inaccurate perspective view of a screen using an electron source of the field emission type using a n-type silicon substrate;

Fig. 12 is an elevational view of a section of a screen using an electron source of the field emission type using a glass substrate;

Fig. 13 is a graph showing an operating characteristic of an electron source of the field emission type according to Example 5 in the embodiment 14;

Fig. 14 is a graph showing an operating characteristic of an electron source of the field emission type according to Example 2; Y

Fig. 15 is a graph showing an operating characteristic of an electron source of the field emission type according to Example 3.

Detailed description of the preferred embodiments

From now on in this document, the embodiments of the present invention will be specifically described.

In the following only embodiments 6 to 14 are in accordance with the invention. Embodiments 1 to 5 serve merely for illustrative purposes.

(Embodiment 1) (not according to the invention)

Fig. 1A shows an elevational section of one of an electron source of the field emission type in which the electrically conductive substrate is composed of a n-type silicon substrate. That said, the n-type silicon substrate is composed of a substrate (100) whose electrical resistivity is approximately 0.1 0 cm. As shown in Fig. 1A, the source of electrons of the field emission type 10 is provided with a silicon substrate of type n 1, a layer of non-doped polycrystalline silicon 3 formed on a surface of the silicon substrate of type 1, a strong field driving layer 6 formed on the polycrystalline silicon layer 3, and an electrically conductive thin film 7 formed on the strong field driving layer 6, the thin film 7 being composed of a thin gold film. Additionally, an ohmic electrode 2 is provided on the back surface of the silicon substrate type n 1.

Thus, in the electron source of the field emission type 10, silicon substrate 1 of type n is used as an electrically conductive substrate. That said, the electrically conductive substrate is desired to construct a negative electrode of the electron source of the field emission type 10, to support the driving layer of the strong field 6 in an empty space and additionally to inject electrons into the driving layer of the strong field 6. Therefore, the electrically conductive substrate does not need to be restricted to the n-type silicon substrate, if it is only capable of constructing the negative electrode of the electron source of the field emission type 10 and supporting the driving layer of the strong field 6. For example, the electrically conductive substrate may be composed of metal such as chromium.

In addition, as shown in Fig. 1B, the electrically conductive substrate may be composed of a substrate in which an electrically conductive film 12 (eg, ITO film) is formed on a surface of an insulating plate 11 such as a glass plate (or a ceramic plate). In this case, it would be possible to increase the electron emission area of the electron source of the field emission type and decrease the manufacturing cost of the source, compared to the case using the semiconductor substrate.

The driving layer of the strong field 6, which is formed by oxidizing a polycrystalline porous silicon using an acid solution, is a layer in which electrons are injected when voltage is applied between the electrically conductive substrate and the electrically conductive thin film (thin film of metal). The driving layer of the strong field 6 is composed of a polycrystalline body that includes many grains. On the surface of each of the grains, there is a nanometric structure that has an oxide film (hereinafter referred to as "nanostructure"). The size of the nanostructure is required to be smaller than the average free path of the electron in the monocrystalline silicon, which is approximately 50 nm, in order for the injected electrons produced in the driving layer of the strong field 6 to reach the surface of the driving layer of the strong field 6 without colliding the electrons with the nanostructure (that is, without producing the dispersion of the electrons). Specifically, it is preferable that the dimension of the structure is

smaller than 10 nm, and, additionally, it is more preferable that the dimension be smaller than 5 nm.

In one embodiment 1, the electrically conductive thin film 7 (thin metal film) is composed of a thin gold film. The electrically conductive thin film 7 is desired to construct a positive electrode of the electron source of the field emission type 10 and to apply an electric field to the driving layer of the strong field 6. The electrons, which have reached the surface of the layer driving the strong field 6 by applying the electric field, they are emitted outward from the surface of the electrically conductive thin film 7 by means of the tunnel effect. That said, an ideal energy of the emitted electrons is the difference in energy obtained by subtracting the energy of the work function of the electrically conductive thin film 7 from the energy of the electrons obtained by applying the DC voltage between the substrate

10 electrically conductive and electrically conductive thin film 7. Therefore, the minimum of the working function of electrically conductive thin film 7 is more desirable.

In Embodiment 1, although gold is used as the electrically conductive thin film material 7, the material is not necessarily restricted to gold. Any metal can be used as material, if only its work function is small. For example, aluminum, chromium, tungsten, nickel, platinum or the like can be used.

15 The work function of each of the metals described above is as follows.

Gold: 5.10 eV Aluminum: 4.28 eV

Chrome: 4.50 eV Tungsten: 4.55 e V

Nickel: 5.15 eV Platinum: 5.65 eV

From now on in this document, a process for preparing an electron source of the field emission type 10 will be described, while referring to Figs. 2A to 2D.

In the manufacturing process, after an ohmic electrode 2 has been formed on the back surface of the silicon substrate of type n 1 first, a layer of non-doped polycrystalline silicon 3 of

approximately 1.5 µm thick on the tipon silicon layer so that the structure that

is shown in Fig. 2A. The process of manufacturing the film of the polycrystalline silicon layer 3 is carried out by means of the LPCVD process. In the film manufacturing process, the degree of vacuum is adjusted to 20 Pa, the substrate temperature is adjusted to 640 ° C, and the monosilane gas flow rate is adjusted to

25 600 scm3 / m. That said, if the electrically conductive substrate is a semiconductor, the process of manufacturing the film of the polycrystalline silicon layer 3 can be carried out by means of the LPCVD process or the sizzling process. Alternatively, the film manufacturing process can be carried out by tempering in an amorphous silicon film in such a way that it crystallizes, the amorphous silicon film having been formed by the plasma CVD process.

30 If the electrically conductive substrate is a substrate in which an electrically conductive film is formed on a glass plate, the polycrystalline silicon layer can be formed by tempering an amorphous silicon film using an excimer laser, the film having formed amorphous silicon on the electrically conductive film by the CVD procedure. Because the process for forming the polycrystalline silicon layer 3 on the electrically conductive film does not need to be restricted to the CVD procedure,

35 you can use, for example, the CGS (Continuous Grain Silicone) procedure or the catalytic CVD procedure.

After the non-doped polycrystalline silicon layer 3 has formed, a porous layer of polycrystalline silicon 4 is formed by performing an anodic oxidation treatment of the polycrystalline silicon layer 3 using an anodic oxidation processing tank containing an electrolyte composed of a mixture in which an aqueous solution of hydrogen fluoride of 55% by weight and ethanol are mixed together in the ratio of almost 1: 1. The anodic oxidation treatment is carried out with constant current while applying light to the layer 3 in such a way that a platinum electrode (not shown) acts as a negative electrode and the silicon substrate of type n 1 (ohmic electrode 2) , acts as a positive electrode. In this way, the structure shown in Fig. 2B is obtained. That said, in the anodic oxidation treatment, the density of the current is adjusted to the constant value of 10 mA / cm2, and the time of the anodic oxidation stage is adjusted to 30 seconds. By way of

In addition, during the anodic oxidation treatment, light is applied to the surface of the polycrystalline silicon layer 3 using a 500 W tungsten lamp. Accordingly, the porous layer of polycrystalline silicon 4 of almost 1 µm is formed. thickness. Although only a part of the polycrystalline silicon layer 3 crystallizes in this case, the entire polycrystalline silicon layer 3 can be crystallized.

After the anodic oxidation treatment is completed, the electrolyte is removed from the

Anodic oxidation processing and then the diluted nitric acid of concentration close to 10% is introduced back into the anodic oxidation processing tank. Then, using the anodic oxidation processing tank containing dilute nitric acid, the porous layer of polycrystalline silicon 4 is oxidized leaving the constant current flow between the platinum electrode (not shown) and the n 1 type silicon substrate (ohmic electrode 2) such that the platinum electrode acts as a negative electrode and the silicon substrate 1 acts as a positive electrode. In this way, the structure shown in Fig. 2C is obtained. In Fig. 2C, the number 6 denotes a strong field driving layer formed by oxidation of the porous layer of polycrystalline silicon 4 using acid (nitric acid diluted in this case).

That said, it can be considered that when the porous layer of polycrystalline silicon 4 is oxidized by dilute nitric acid, such reactions occur as shown by the following reaction formulas 1 and

2. In the reaction formulas, h + denotes a hole, and e-denotes an electron.

(Negative electrode)

HNO3 + 3H + - NO + 2H2O + 3h + …………… reaction formula 1

(Positive electrode)

3h ++ Si + 2H2O - SiO2 + 4H + + e- …………. Reaction formula 2

As shown schematically in Fig. 3, silicon oxide (SiO2) is formed on the surface of the pores of the porous layer of polycrystalline silicon 4 due to the aforementioned reactions. Additionally, the concentration of the diluted nitric acid or the current density (constant value) in correspondence with any desired thickness or quality, etc., of the porous layer of polycrystalline silicon 4 to be oxidized can be conveniently changed. .

Additionally, the potential voltage at the end point can be adjusted to a preferable (optimal) value, for example, in the range of several V to several tens of V. Moreover, the applied light can be conveniently adjusted

or the temperature at a preferable value.

That said, as regards the driving layer of the strong field 6, it can be considered that the surface of the fine silicon crystal, composed of the nanostructure, which is formed by means of anodic oxidation treatment, is oxidized by dilute nitric acid.

As shown in Fig. 4, it can be considered that the driving layer of the strong field 6 includes at least column-shaped polycrystalline silicon grains 61, the thin silicon oxide film 62 formed on the grain surfaces of polycrystalline silicon 61, the thin layers of crystalline silicon 63 that exist between the polycrystalline silicon grains 61 and the silicon oxide films 64 formed on the surfaces of the thin layers of crystalline silicon 63.

In Embodiment 1, because the porous layer of polycrystalline silicon 4 is oxidized using acid (dilute nitric acid), the process temperature is lower than that of the conventional manufacturing process (disclosed in Japanese Patent Applications No. 10-272340, No. 10-272342 or No. 10-271876 by the authors of the present application), in which the driving layer of the strong field is formed by oxidizing the porous layer of the semiconductor by means of the RTO procedure. Accordingly, the restriction of materials usable by the electrically conductive substrate becomes smaller so that the electron source of the field emission type can have a larger area of electron emission and can be manufactured at a lower cost . Additionally, because the porous layer of polycrystalline silicon 4 is oxidized by means of the wet process after the anodic oxidation treatment, the manufacturing process can be simplified compared to the case of oxidizing layer 4 by means of the RTO process after anodic oxidation treatment.

After the driving layer of the strong field 6 has been formed, an electrically conductive thin film 7 is formed, which is composed of a thin gold film, on the driving layer of the strong field 6, for example, by means of the deposition process with steam In this way, such an electron source of the field emission type 10 is obtained which has the structure shown in Fig. 2D (Fig. 1A). Although the thickness of the electrically conductive thin film 7 is adjusted to almost 10 nm in Embodiment 1, the thickness need not be restricted to this. That said, in the electron source of the field emission type 10, a diode is formed in which the electrically conductive thin film acts as a positive electrode (anode) while the ohmic electrode 2 acts as a negative electrode (cathode). In the meantime, although the electrically conductive thin film 7 (thin gold film) is formed in the Embodiment Form 1 by means of the steam deposition process, the process of forming the electrically conductive thin film 7 need not be restricted to the process of steam tank. For example, the sizzle procedure can be used.

It can be considered that in the electron source of the field emission type 10 of Embodiment 1, the electrons are emitted according to the following model.

That is, as shown in Fig. 5, it makes us assume that a collector electrode 21 is arranged in such a way that it faces the electrically conductive thin film 7, DC voltage Vps is applied between the electrically conductive thin film 7 and the ohmic electrode 2 and the DC voltage Vc is applied between the collector electrode 21 and the electrically conductive thin film 7. In this condition, when the DC voltage, which is applied to the electrically conductive thin film 7 such that the thin film 7 becomes a positive electrode against the silicon substrate of type n 1, reaches a predetermined value (critical value), the electrons e-are injected from the silicon substrate of type n 1 next to the driving layer of the strong field 6 by means of thermal excitation. On the other hand, because the electric field, which is applied to the driving layer of the strong field 6, is mostly applied to silicon oxide films 64, the injected electrons are accelerated by the strong electric field applied to the silicon oxide films 64. In this way, inside the driving layer of the strong field 6, electrons are driven in the direction indicated by an arrow A in Fig. 4 in the space between the polycrystalline silicon grains 61 towards the surface of the layer 6. Next, the electrons pass through the electrically conductive thin film 7 to emit in a vacuum after passing through the oxide layer on the outermost surface of the strong field driving layer 6.

In the source of electrons of the field emission type 10 elaborated in accordance with the aforementioned procedure, in the same case of the source of electrons of the field emission type proposed in Japanese Patent Applications No. 10-272340, No. 10- 272342 or No. 10-271876 by the authors of the present application, electrons can be emitted stably, because their electron emission property has a smaller dependence on the degree of vacuum, and additionally, it cannot be It produces a clicking phenomenon when electrons are emitted. Additionally, in addition to a semiconductor substrate such as a monocrystalline silicon substrate, a substrate can be used in which an electrically conductive thin film (for example, ITO film) is provided on a surface of a glass plate or the like , as the electrically conductive substrate. Therefore, in the electron source of the field emission type, its electron emission area can be increased and its manufacturing cost can be reduced, compared to the Spindt type electrode.

Although both the anodic oxidation treatment and the acid-used oxidation treatment are carried out after the anodic oxidation treatment using the same anodic oxidation processing tank in Embodiment 1, it is of course assumed that they can be carried out. Perform each of the treatments using your individual anodic oxidation processing tank.

(Embodiment 2) not according to the invention

From now on in this document, the Form of Embodiment 2 will be described. That said, the fundamental construction of the source of electrons of the field emission type and the manufacturing process thereof according to the Embodiment Form 2 are almost the same as those of Form 1, except the following topics.

Particularly, in Embodiment 2, after the anodic oxidation treatment has been completed, the electrolyte from the anodic oxidation processing tank is removed and then sulfuric acid of almost 10% concentration is introduced again into the tank of anodic oxidation processing. Then, using the processing tank containing dilute sulfuric acid, the porous layer of polycrystalline silicon 4 is oxidized leaving constant the flow of current between the platinum electrode (not shown) and the n 1 type silicon substrate (ohmic electrode 2) such that the platinum electrode acts as a negative electrode and the silicon substrate 1 acts as a positive electrode. That is, in Embodiment 2, the surface of the thin silicon crystal composed of the nanostructure is oxidized, which is formed by means of anodic oxidation treatment, by dilute sulfuric acid.

That said, it can be considered that when the porous layer of polycrystalline silicon 4 is oxidized by dilute sulfuric acid, such reactions occur as shown by the following reaction formulas 3 and 4. In the reaction formulas, h + denotes a hollow, and e-denotes an electron.

(Negative electrode)

H2SO4 + 2H + - SO2 + 2H2O + 2h + reaction formula 3

(Positive electrode)

2h ++ Si + 2H2O - SiO2 + 4H + 2e-reaction formula 4

That said, the concentration of the diluted sulfuric acid or the current density corresponding to any desired thickness or quality, etc., of the porous layer of polycrystalline silicon 4 to be oxidized can be conveniently changed.

Additionally, the potential voltage at the end point can be adjusted to a preferable (optimal) value, for example, in the range of several V to several tens of V. Moreover, the applied light can be conveniently adjusted

or the temperature at a preferable value.

(Embodiment Form 3) (not according to the invention)

From now on in this document, the Form of Embodiment 3 will be described. That said, the fundamental construction of the electron source of the field emission type and the manufacturing process thereof according to the Embodiment Form 3 are almost the same as those of Form 1, except the following topics.

Particularly, in the Embodiment Form 3, after the anodic oxidation treatment has been completed, the electrolyte from the anodic oxidation processing tank is removed, and then royal water is introduced again ((concentrated hydrochloric acid): (nitric acid concentrate) = 3: 1) in the anodic oxidation processing tank. In this way, the porous layer of polycrystalline silicon 4 is oxidized by royal water. Because the silicon oxidizes gradually in the royal water, the surface of the thin silicon crystal is oxidized by the royal water that has permeated the pores of the porous layer of polycrystalline silicon 4 in Embodiment 3.

Thus, in Embodiments 1 to 3, the porosity of the porous layer of polycrystalline silicon 4 is almost uniform in the direction of the thickness of the layer producing the constant current density during the anodic oxidation stage. However, by changing the current density during the anodic oxidation stage, a structure can be produced such that the porous layers of polycrystalline silicon with larger porosity and the porous layer of polycrystalline silicon with smaller porosity, or a porous layer, or a Such structure successively changes the porosity in the direction of the thickness of the layer.

Meanwhile, in Embodiments 1 to 3, the driving layer of the strong field 6 is formed by oxidation of the porous layer of polycrystalline silicon using acid. However, the strong field driving layer can be formed using acid by oxidizing polycrystalline porous silicon that is formed by manufacturing monocrystalline porous silicon by means of anodic oxidation treatment.

(Embodiment Form 4) (not according to the invention)

From now on in this document, Embodiment Form 4 will be described. In the source of electrons of the field emission type 10 according to any one of Embodiment Forms 1 to 3, the driving layer of the strong field 6 is formed. oxidizing the porous layer of the semiconductor (porous layer of polycrystalline silicon 4 or porous layer of monocrystalline silicon), which has been formed by means of anodic oxidation treatment, using acid. Additionally, because the solution of the mixture, in which aqueous solution of hydrogen fluoride and ethanol is mixed together, is used as an electrolyte in the treatment of anodic oxidation, the silicon atoms in the porous layer of the semiconductor They are terminated by hydrogen atoms. Accordingly, because the hydrogen content in the driving layer of the strong field 6 becomes comparatively higher, the distribution of the hydrogen atoms changes over time so that the stability of The efficiency of electron emission over time. For example, when the electrically conductive thin film 7 (thin gold film) is modeled on the driving layer of the strong field 6, the hydrogen atoms can be released from the driving layer of the strong field 6 such that stability can deteriorate with Over time. Additionally, because the silicon atoms in the porous layer of the semiconductor are terminated by hydrogen atoms, it can be difficult to form an instant oxide film such as SiO2.

On the other hand, in Embodiment 4, before the porous layer of the semiconductor is oxidized (porous layer of polycrystalline silicon 4 or porous layer of monocrystalline silicon) that has been formed by means of anodic oxidation treatment, using acid ( for example, dilute nitric acid, dilute sulfuric acid or royal water), particularly before the silicon oxide film is electrochemically formed, the hydrogen atoms that terminate the silicon atoms are replaced with oxygen atoms by submerging the porous layer of the semiconductor in an oxidizing solution for a time capable of oxidizing its very superficial layer. That said, as the above-mentioned oxidant solution, it is preferable to use any one or a mixture of several selected in a group of oxidants composed of nitric acid (HNO3), sulfuric acid (H2SO4), hydrochloric acid (HCl) and hydrogen peroxide ( H2O2).

Thus, in Embodiment 4, as shown in Fig. 6A, the driving layer of the strong field 6 is formed by oxidizing the porous layer of the semiconductor, whose very superficial layer has been oxidized by the oxidizing solution, using acid. Accordingly, when the porous layer of the semiconductor is formed, by means of anodic oxidation treatment, the hydrogen atoms, which terminate the surface atoms of the porous layer of the semiconductor, are replaced with oxygen atoms by the solution oxidizing Consequently, the hydrogen content in the driving layer of the strong field 6 becomes smaller, therefore the time-dependent change of the hydrogen distribution in the driving layer of the strong field 6 becomes smaller in such a way that The stability of the layer can be improved. Additionally, in Embodiment 4, because the oxide film produced by oxidizing the porous layer of the semiconductor using acid tends to form a SiO2 structure or a structure similar to the SiO2 structure, smallness can be improved and quality of the oxide film in such a way that the efficiency of electron emission is improved and additionally the voltage interruption is increased. That said, the function of the driving layer of the strong field 6 is the same as that of the driving layer of the strong field 6 in Embodiment 1.

That said, if the oxidant solution is heated, the oxidation treatment process time can be shortened by means of the oxidant solution so that its performance can be improved.

In addition, as shown in Fig. 6B, as the electrically conductive substrate, a substrate can be used in which the electrically conductive film 12 (for example, ITO film) is formed on an insulating plate 11 such as a glass plate (or ceramic plate). In this case, it is more easily possible to increase the area of electron emission of the electron source of the field emission type and decrease the cost of processing the source compared to the case using a semiconductor substrate.

In the following, a process for preparing an electron source of the field emission type according to Embodiment 4 will be described as an example, while referring to Figs. 7A to 7D. However, because the manufacturing process is almost the same as the manufacturing procedure described in Embodiment 1 (Figs 2A-2D), the members corresponding to the members of Embodiment 1 are given with the same number as those of Embodiment 1 so that the detailed description about them will be omitted. Additionally, since the stages are the same as those described in Embodiment 1, the description about them will be simplified or omitted.

In the manufacturing process according to Embodiment Form 4, as in the case of Embodiment Form 1, after an ohmic electrode 2 has been formed on the back surface of a silicon substrate of type 1, a layer of non-doped polycrystalline silicon 3 of approximately 1.5 µm thick is formed on the front surface of the n 1 type silicon layer by means of the LPCVD process such that the structure shown in the Fig. 7A. In Embodiment 4, the silicon substrate of type n 1 (substrate type (100)), which is used as an electrically conductive substrate, has an electrical resistivity of 0.01

at 0.02 0 cm and a thickness of 525 µm.

Next, a porous layer of polycrystalline silicon 4 is formed by carrying out an anodic oxidation treatment in the polycrystalline silicon layer 3 using an electrolyte-containing anodic oxidation processing tank composed of a mixture in which a solution is mixed together Hydrogen fluoride aqueous 55% by weight and ethanol in the ratio of almost 1: 1. The anodic oxidation treatment is carried out with constant current while applying light to layer 3 in such a way that the platinum electrode (not shown) acts as a negative electrode and the silicon substrate of type 1 (electrode Ohmic 2) acts as a positive electrode. In this way, the structure shown in Fig. 7B is obtained. In the anodic oxidation treatment, the density of the current is adjusted to the constant value of 30 mA / cm2, and the time of the anodic oxidation stage is adjusted to 10 seconds. Additionally, during the anodic oxidation treatment, light is applied to the surface of the polycrystalline silicon layer 3 using a 500 W tungsten lamp. That said, in Embodiment Form 4, the treatment of anodic oxidation such that only an area whose diameter is 10 mm on the surface of the polycrystalline silicon layer 3 contacts the electrolyte, while the other area is sealed in such a way that contact with the electrolyte is avoided. Additionally, in Embodiment 4, the polycrystalline silicon layer 3 is made completely porous.

Next, the very superficial layer of the porous silicon layer 3 is oxidized by an oxidizing solution. In Embodiment 4, as an oxidizing solution, nitric acid (concentrated nitric acid) heated to 115 ° C is used, the concentration of which is almost 70%. The oxidation time is 10 minutes.

Then, the diluted nitric acid of almost 10% concentration is introduced back into the anodic oxidation processing tank. In this way, using the anodic oxidation processing tank containing diluted nitric acid, the porous layer of polycrystalline silicon 4 is oxidized, leaving constant the flow of the current between the platinum electrode and the silicon substrate of type 1 of such so that the platinum electrode acts as a negative electrode and the silicon substrate 1 acts as a positive electrode. In this way, the structure shown in Fig. 7C is obtained. In Fig. 7C the number 6 denotes a driving layer of the strong field formed by oxidizing the porous layer of polycrystalline silicon 4, whose true surface layer has been oxidized by the oxidizing solution, using acid (although in Embodiment Form 4 acid is used diluted nitric, sulfuric acid or royal water can be used).

After the driving layer of the strong field 6 has been formed, an electrically conductive thin film 7 is formed, which is composed of a thin gold film, on the driving layer of the strong field 6. In this way, a source of such electrons of the field emission type 10 having the structure shown in Fig. 7D. Although the thickness of the electrically conductive thin film 7 is adjusted to almost 15 nm in Embodiment 4, the thickness need not be restricted to this.

(Embodiment Form 5) (not according to the invention)

From now on in this document, the Form of Embodiment 5 will be described. However, because the fundamental construction and manufacturing procedure of the electron source of the field emission type according to Embodiment Form 5 are almost the same as those of the Form of Embodiment 4 (additionally the Embodiment Form 1), as well as the construction elements and the elaboration stage, which correspond to those of the Embodiment Form 4, a description will be simplified or omitted Detailed about them. In this way, the differences with the Form of Embodiment 4 will be described mainly. The Embodiment Form 5 will be described, referring to Figs. 6A-6B, Figs. 7A-7D, Fig. 8 and Fig. 9. In Embodiment 5, as the electrically conductive substrate, a monocrystalline n-type silicon substrate 1 is used whose electrical resistivity is comparatively close to that of an electrical conductor (by example the type of substrate (100) whose electrical resistivity is approximately 0.1 0 cm).

In the electron source of the field emission type 10 shown in Fig. 6A according to Embodiment 5, also, as in the case of Embodiment 4, electrons injected from the silicon substrate of Type n 1 to the driving layer of the strong field 6 is driven to the layer 6 and then pass through the electrically conductive thin film 7 (surface electrode) to be emitted outward. The electron source of the field emission type 10 is characterized in that the driving layer of the strong field 6 has an instantaneous oxide film in which the hydrogen content (input) is lower compared to the conventional case. That said, the oxide film is a very tiny film that has a SiO2 structure

or a structure closer to the structure of SiO2. In the electron source of the field emission type 10, because the hydrogen content (input) in the driving layer of the strong field 6 is less, the deterioration of the electron emission efficiency due to the time-dependent change is less of hydrogen distribution compared to the conventional case. Additionally, because the oxide film is very instantaneous compared to the conventional case, the interruption of the voltage by source isolation is higher.

In addition, in Embodiment 5, although the driving layer of the strong field 6 is composed of the porous layer of polycrystalline silicon, the layer 6 may be composed of oxidized monocrystalline porous silicon.

Next, a manufacturing method of an electron source of the field emission type according to Embodiment 5 will be described as an example, referring to Figs. 7A to 7D. However, because the manufacturing process is almost the same as the manufacturing process is almost the same as the manufacturing procedure described in Embodiment 4 (Figs. 7A-7D), the members corresponding to the members in the Embodiment 4 with the same numbers as those in the Embodiment Form 4 such that the detailed description about them will be simplified or omitted. Additionally, since the stages are the same as those of Embodiment Form 4, the description about them will be simplified or omitted.

In the manufacturing process according to Embodiment Form 5, as in the case of Embodiment Form 4, after an ohmic electrode 2 has been formed on the back surface of a silicon substrate of type 1, a layer of non-doped polycrystalline silicon 3 with a predetermined thickness is formed (by

example 1.5 µm), which is one of the semiconductor layers, on the front surface of the n-type silicon layer

1 such that the structure shown in Fig. 7A is obtained. That said, as in the case of Embodiment Form 4 (Embodiment Form 1), when the electrically conductive substrate is a semiconductor substrate, the polycrystalline silicon layer 3 can be formed by means of the LPCVD procedure, the process of crackling or similar. Meanwhile, when the electrically conductive substrate is a substrate in which an electrically conductive film is formed on a glass plate, a layer of polycrystalline silicon 3 can be formed by the procedure similar to that of Embodiment 4.

After the non-doped polycrystalline silicon layer 3 has been formed, as in the case of Embodiment 4, a porous layer of polycrystalline silicon 4 is formed by carrying out the anodic oxidation treatment such that it is obtained the structure shown in Fig. 7B. Although the intensity of the light applied to the polycrystalline silicon layer 3 and the current density are constant during the anodic oxidation process in the anodic oxidation treatment in Embodiment 5, those conveniently can be changed during the procedure (for example, the density of the current can be changed).

After the anodic oxidation is complete, the very superficial layer of the porous layer of polycrystalline silicon 4 is oxidized using an oxidizing solution. Additionally, the layer 4 is oxidized by means of an RTO process such that a strong field driving layer 6 is formed. In this way, the structure shown in Fig. 7C is obtained. In short, in Embodiment 5, the hydrogen atoms, which terminate the silicon atoms in the porous layer of polycrystalline silicon 4 formed by means of the anodic oxidation treatment, are replaced with oxygen atoms by the oxidizing solution. That said, as the oxidizing solution, any one or a mixture of several selected in a group of oxidants composed of nitric acid (HNO3), sulfuric acid (H2SO4), hydrochloric acid (HCl) and hydrogen peroxide (H2O2) can be used .

After the driving layer of the strong field 6 has been formed, an electrically conductive thin film 7, which is composed of a thin gold film, is formed on the driving layer of the strong field 6, for example, by means of the deposition process with steam In this way, an electron source of the field emission type 10 is obtained such that it has the structure shown in Fig. 7D. That said, the thickness of the electrically conductive thin film 7 does not need to be restricted to a specific value, it can be any desirable value if only the electrons, which have passed through the driving layer of the strong field 6, can pass through the film 7. Additionally, even if the electrically conductive thin film 7 is formed by means of the steam deposition process in Embodiment 5, the process of forming the electrically conductive thin film 7 for the deposition process is not restricted. steam. It can be used, for example the sizzle procedure.

Thus, in the above-mentioned manufacturing process, the RTO process is carried out on a very superficial layer of the porous layer of polycrystalline silicon 4 formed by means of the anodic oxidation treatment after the oxidation process using the oxidizing solution, therefore the hydrogen content in the driving layer of the strong field 6 becomes smaller in such a way that a small oxide film having a SiO2 structure or a structure closer to the SiO2 structure is formed. Consequently, the source of electrons of the field emission type can be obtained, in which the time-dependent change of the electron emission efficiency is smaller and additionally the voltage interruption is higher.

In addition, in the source of electrons of the field emission type 10 elaborated in accordance with the aforementioned processing procedure, as in the source of electrons of the field emission type 10 in accordance with Embodiment 4, they can be emitted electrons stably, because their electron emission property has a smaller dependence on the degree of vacuum, and additionally, there is no clicking phenomenon when electrons are emitted. Additionally, in addition to a semiconductor substrate such as a monocrystalline silicon substrate, a substrate can be used in which an electrically conductive film (eg, ITO film) is provided on a surface of a glass plate or the like, such as electrically conductive substrate. Therefore, in the electron source of the field emission type, its electron emission area can be increased and its processing cost can be reduced, compared to the Spindt type electrode.

Example 1

From now on, as Example 1, an electron source of the field emission type 10 manufactured under the following conditions will be described, by means of the manufacturing process according to the Embodiment Form

5.

In Example 1, as in the n-type silicon substrate 1, a silicon-type substrate (100) was used, in which the electrical resistivity was 0.01-0.02 0 cm and the thickness was 525 m. It formed

or the polycrystalline silicon layer 3 (see Fig. 7A), by means of the LPCVD procedure. In the film formation process, the vacuum degree was 20 Pa, the substrate temperature was 640 ° C, and the monosilane gas flow rate was 600 scm3 / m.

In the anodic oxidation treatment, an electrolyte was used in which the 55% by weight aqueous solution of hydrogen fluoride and ethanol were mixed together in the ratio close to 1: 1. In the anodic oxidation treatment, only a region of 10 mm in diameter on the surface of the polycrystalline silicon layer 3 made contact with the electrolyte, while the other region of the surface was sealed, so that it did not make contact with The electrolyte Additionally, a platinum electrode was immersed in the electrolyte, and then a predetermined current was flowed between the platinum electrode and the n 1-type silicon substrate (ohmic electrode 2) such that the platinum electrode is a negative electrode turned and the substrate 1 became a positive electrode, while applying light with a constant light energy (intensity) to the polycrystalline silicon layer 3 using a 500 W tungsten lamp. That said, the density of the current had a constant value of 30 mA / cm2, and the time of the anodic oxidation procedure was 10 seconds.

As an oxidizing solution, nitric acid (with its 70% concentration) being heated to 115 ° C was used. It should be mentioned that, if the oxidizing solution is heated, the oxidation rate is increased in such a way that the process time can be shortened. oxidation using the oxidizing solution.

In the RTO process to oxidize the porous layer of polycrystalline silicon 4, the flow rate of the oxygen gas was 300 scm3 / m, the oxidation temperature was 900 ° C, and the oxidation time was 1 hour. The electrically conductive thin film 7 (thin gold film 7) was formed by the steam deposition process, the thickness of the film being 15 nm.

The electron source of the field emission type 10 was introduced into a vacuum chamber (not shown), and then a collecting electrode 21 (electrode for collecting the emitted electrons) was placed in a position facing the electrically conductive thin film 7 as shown in Fig. 8. Next, the degree of vacuum in the vacuum chamber was adjusted to 5 x 10-5 Pa, Vps voltage with DC was applied between the electrically conductive thin film 7 (anode) and the Ohmic electrode 2 (cathode), and additionally, Vc voltage with 100 V DC was applied between the collecting electrode 21 and the electrically conductive thin film 7. In this way, the Ips current of the diode flowing between the film was measured electrically conductive thin 7 and the ohmic electrode 2, and the current Ie of emitted electrons flowing between the collecting electrode 21 and the electrically conductive thin film 7 because the electrons ee measured from the source of electrons of the field emission type 10 pass through the electrically conductive thin film 7 (The dashed line in Fig. 8 shows the current of the emitted electrons.).

Fig. 9 shows the measurement result. In Fig. 9, the horizontal axis shows the voltage Vps with DC, and the vertical axis shows the density of the current. Additionally, in Fig 9, the marks 0 (�) and • (�) show the current Ips of the diode and the current Ie of the electrons emitted in Example 1, respectively.

In addition, in Fig. 9, as an example for comparison, the result obtained by carrying out a measurement similar to that of the aforementioned measurement as well as an electron source of the field emission type, which was manufactured under them, is also shown. conditions than those of Example 1 except that oxidation was omitted using the oxidizing solution before the RTO procedure. In Fig. 9, the • (�) and • (�) marks show the current Ips of the diode and the current Ie of the electrons emitted in the example for comparison, respectively.

As is evident from Fig. 9, when Example 1 is compared with the example for comparison, the current Ips of the diode of Example 1 is less than that of the example for comparison although the current Ie of emitted electrons of both is almost equal. . Because the electron emission efficiency is expressed by the ratio of the current Ie of electrons emitted to the current Ips of the diode, that is Ie / Ips, it can be understandable that the electron emission efficiency of the electron source of the field emission type 10 according to Example 1 is higher than that of the example for comparison. Additionally, a dielectric interruption occurs at a point where the Vps voltage with DC is 22 in the example for comparison, while said dielectric interruption does not occur in Example 1 even if the Vps voltage with DC is increased up to 28 V. That is, the interrupt voltage of Example 1 is higher than that of the example for comparison.

Example 2

Hereinafter, as Example 2, a source of electrons of the field emission type 10 manufactured under the following conditions will be described.

In Example 2, as in the silicon substrate of type n 1, a silicon substrate type (100) was used, in which the electrical resistivity was 0.01-0.02 0 cm and the thickness was 525 m. It formed

or the polycrystalline silicon layer 3 (see Fig. 7A) by means of the LPCVD procedure. In the film formation process, the vacuum degree was 20 Pa, the substrate temperature was 640 ° C, and the monosilane gas flow rate was 600 scm3 / m.

In the anodic oxidation treatment, an electrolyte was used in which the 55% by weight aqueous solution of hydrogen fluoride and ethanol were mixed together in the ratio close to 1: 1. In the anodic oxidation treatment only a region of 10 mm in diameter made contact on the surface of the polycrystalline silicon layer 3 with the electrolyte, while the other region of the surface was sealed in such a way that it did not make contact with the electrolyte . Additionally, a platinum electrode was immersed in the electrolyte, and then a predetermined current was flowed between the platinum electrode and the n 1-type silicon substrate (ohmic electrode 2) such that the platinum electrode is a negative electrode turned and the substrate 1 became a positive electrode, while applying light with a constant light energy (intensity) to the polycrystalline silicon layer 3 using a 500 W tungsten lamp. That said, the density of the current had a constant value of 30 mA / cm2, and the time of the anodic oxidation procedure was 10 seconds.

After the polycrystalline silicon layer 4 had formed, layer 4 was electrochemically oxidized with the constant current of 1 mA / cm 2 in a 1 molar solution in% by weight sulfuric acid at 70 ° C such that the platinum electrode it became a negative electrode and the n 1 type silicon substrate (electrically conductive substrate) became a positive electrode. The porous layer of polycrystalline silicon 4 was then washed using water and dried further. In addition, on the porous layer of polycrystalline silicon 4, an electrically conductive thin film 7 (surface electrode) composed of gold (Au) having a thickness of 10 nm was formed.

In this way, the electron emission efficiency of the electron source of the field emission type 10 obtained as described above was measured such that the electrically conductive thin film 7 became a positive electrode and the silicon substrate of type n 1 (ohmic electrode 2) became a negative electrode. According to the measurement, when the Vps voltage was 20 V, the emitted electron current was 1 µm / cm2. The result is shown in Fig. 14.

Thus, although the only oxidation treatment was carried out at a lower temperature, the emission of electrons from the emitted electron current was observed. Therefore, if a substrate such as a glass plate was used, which requires it to be treated in a lower temperature process, any source of electrons of the desired field emission type can be manufactured.

That said, processing conditions such as a type of acid, current density or similar to the aforementioned condition need not be restricted.

Example 3

Hereinafter, as Example 3, a source of electrons of the field emission type 10 manufactured under the following conditions will be described.

In Example 3, as in the n 1 type silicon substrate, a silicon type substrate (100) was used, in which the electrical resistivity was 0.01-0.02 0 cm and the thickness was 525 ! m. 3 was formed

or the polycrystalline silicon layer (see Fig. 7A) by means of the LPCVD procedure. In the film formation process, the vacuum degree was 20 Pa, the substrate temperature was 640 ° C, and the monosilane gas flow rate was 600 scm3 / m.

In the anodic oxidation treatment, an electrolyte was used in which the 55% by weight aqueous solution of hydrogen fluoride and ethanol were mixed together in the ratio close to 1: 1. In the oxidation treatment, only a region of 10 mm in diameter was contacted on the surface of the polycrystalline silicon layer 3 with the electrolyte, while the other region of the surface was sealed in such a way that it did not make contact with the electrolyte. Additionally, a platinum electrode was immersed in the electrolyte, and then a predetermined current was flowed between the platinum electrode and the n 1-type silicon substrate (ohmic electrode 2) such that the platinum electrode is a negative electrode turned and the substrate 1 became a positive electrode, while applying light with a constant light energy (intensity) to the polycrystalline silicon layer 3 using a 500 W tungsten lamp. That said, the density of the current had a constant value of 30 mA / cm2, and the time of the anodic oxidation procedure was 10 seconds.

After the polycrystalline silicon layer 4 had formed, layer 4 was electrochemically oxidized with the constant current of 20 mA / cm 2 in a 1 molar solution in% by weight sulfuric acid at 25 ° C such that the platinum electrode it became a negative electrode and the n 1 type silicon substrate (electrically conductive substrate) became a positive electrode. The porous layer of polycrystalline silicon 4 was then washed using water and dried further. Additionally, a supplementary oxidation treatment was carried out in layer 4 by means of the rapid thermal oxidation process. In the rapid thermal oxidation process, the oxygen gas flow rate was 300 scm3 / m, the oxidation temperature was 750 ° C and the oxidation time was 1 hour.

Next, on the porous layer of polycrystalline silicon 4, an electrically conductive thin film 7 (surface electrode) composed of gold (Au) having a thickness of 10 nm was formed.

In this way, the electron emission efficiency of the electron source of the field emission type 10 obtained as described above was measured such that the electrically conductive thin film 7 became a positive electrode and the silicon substrate of type n 1 (ohmic electrode 2) became a negative electrode. According to the measurement, when the Vps voltage was 20 V, the emitted electron current was 10 µm / cm2. The result is shown in Fig. 15.

Thus, although the only comparatively lower temperature oxidation treatment was carried out compared to the procedure using only the rapid thermal oxidation process, much electron emission from the emitted electron current was observed. Therefore, if a substrate is used, which requires it to be treated in a lower temperature process, any source of electrons of the desired field emission type can be manufactured.

That said, processing conditions such as the type of acid, the temperature of the acid, the density of the current, the type of rapid thermal oxidation need not be restricted to the aforementioned condition

or similar.

Embodiment 6

From now on in this document, Embodiment 6 of the present invention will be described. However, because the fundamental construction and manufacturing process of the electron source of the field emission type in accordance with Embodiment 6 are almost the same as those described for Embodiment 5, and also the elements constructive and the manufacturing stage corresponding to those of Form 5, the detailed description about them will be simplified or omitted. In this way, the differences with the Form of Embodiment 5 will be described mainly. The Embodiment Form 6 will be described, referring to Figs. 6A-6B, Figs. 7A-7D, Fig. 8 and Figs. 10A-10B.

As described above, in the electron source 10 of the field emission type shown in Fig. 4, the driving layer of the strong field 6 includes at least the polycrystalline silicon grains formed as column 61. the thin films 62 of silicon oxide formed on the surfaces of polycrystalline silicon grains 61, the thin layers of polycrystalline silicon 63 of nanometric order that exist between polycrystalline silicon grains 61, and silicon oxide films 64 formed on the surfaces of the thin layers of crystalline silicon 63, each of the films 64 being an insulating film having a thickness smaller than the diameter of a crystal particle of the thin layer of polycrystalline silicon 63.

In the driving layer of the strong field 6 of the electron source of the field emission type 10 described above, it can be considered that the surface of each of the grains is made porous, while maintaining the state of the crystal in the central portion of Each of the beans. Therefore, the electric field, which is applied to the driving layer of the strong field 6, is mostly applied to silicon oxide films 64. In this way, the electrons injected into the layer 6 are accelerated by the strong field applied to silicon oxide films 64 so electrons are derived between polycrystalline silicon grains 61 in the direction of arrow A in Fig. 4 towards the surface of layer 6. Consequently, efficiency is improved of electron emission from the source.

Thus, the inventors of the present application have carried out the following inventions in accordance with Embodiment Forms 6 to 14 in view of silicon oxide films 64. That is, the inventors of the present application consider that the entire surfaces of the thin layers of crystalline silicon 63 could be coated by oxygen atoms 65 as shown in Fig. 10A when the surfaces of the thin layers of crystalline silicon 63 have been completely oxidized, while the surfaces of the thin layers of crystalline silicon 63 may not be completely coated by the oxygen atoms 65 as shown in Fig. 10B when the oxidation has been carried out by the RTO process (i.e., the thin layers of crystalline silicon 63 would be insufficiently covered by oxygen atoms 65). Thus, the inventors have carried out the invention in accordance with Embodiment Forms 6 to 14 depending on the aforementioned consideration. In Embodiment 6, as an electrically conductive substrate, a silicon substrate of type 1 is used whose electrical resistivity is comparatively close to that of an electrical conductor (for example, of the silicon substrate type 8100) whose electrical resistivity is approximately 0,1 0 cm).

In the electron source of the field emission type 10 shown in Fig. 6A according to Embodiment 6, also, the electrons injected from the silicon substrate of type 1, which is an electrically conductive substrate, they drive the driving layer of the strong field 6, and then they are emitted outwardly through the electrically conductive thin film 7, by a procedure similar to that of Embodiment 5. Having said that, the materials of gold need not be restricted to gold. the electrically conductive thin film 7. Any material (for example, aluminum, chrome, tungsten, nickel, platinum or the like) can be used if only its working function is small.

Additionally, although the electrically conductive thin film 7 is formed as a single layer in Embodiment 6, it can be formed as a thin electrode laminated film composed of at least two laminated layers in the direction of the thickness of the layers. When the electrically conductive thin film 7 is composed of a thin electrode laminated film having two layers, for example, gold or the like can be used as the material for the upper layer of the thin electrode laminated film. On the other hand, they can be used as the material of the lower layer of the thin electrode laminated film (the thin layer facing the driving layer of the strong field 6), for example, chromium, nickel, platinum, titanium, iridium or the like.

An example of a method of manufacturing a source of electrons of the field emission type according to Embodiment 6 will be described below, with reference to Figs. 7A to 7D. However, because the manufacturing process is almost the same as the manufacturing procedure described in Embodiments 4 or 5 (Figs. 7A-7D), the same numbers of the corresponding members are provided to the members in the Forms of Embodiment 4 or 5 as well as those in Forms of Embodiment 4 or 5 such that detailed description about them will be simplified or omitted. Additionally, since the stages are the same as those of Embodiment Forms 4 or 5, the description about them will be simplified or omitted.

In the manufacturing process according to Embodiment Form 6, as in the case of Embodiment Forms 4 or 5, after an ohmic electrode 2 has been formed on the back surface of a n-type silicon substrate 1, a layer of non-doped polycrystalline silicon 3 with a predetermined thickness is formed (by

example, 1.5 µm), which is one of the semiconductor layers, on the front surface of the n-type silicon layer

1 such that the structure shown in Fig. 7A is obtained. Immediately after this, the polycrystalline silicon layer 3 is formed by a procedure similar to that of Embodiment Forms 4 or 5.

After the non-doped polycrystalline silicon layer has been formed, as in the case of Embodiment Forms 4 or 5, a porous layer of polycrystalline silicon 4 is formed by carrying out the anodic oxidation treatment such that Obtain the structure shown in Fig. 7B. In the anodic oxidation treatment of Embodiment 6, the density of the current is constant. Additionally, during the anodic oxidation process, light is applied to the surface of the polycrystalline silicon layer 3 using a 500 W tungsten lamp such that the polycrystalline silicon layer 3 is completely porous. However, Only a portion of the layer 3 of polycrystalline silicon can be made porous.

Next, a strong field 6 driving layer is formed by oxidation of the polycrystalline silicon porous layer 4 such that the construction shown in Fig. 7C is obtained. That said, during the oxidation stage of the polycrystalline silicon porous layer 4, the polycrystalline silicon porous substrate is oxidized by applying ultraviolet rays to the former in a gas atmosphere containing at least one of oxygen (O2) and ozone (O3) . That said, as an ultraviolet light source, for example, an ultraviolet lamp (for example, a low pressure mercury lamp whose main wavelength component is 185 nm or 256 nm) or an excimer laser can be used whose main wavelength component is 172 nm. You can conveniently adjust the time to apply ultraviolet rays to a value in a range of a few minutes to a few hours.

After the driving layer of the strong field 6 has been formed, an electrically conductive thin film 7 is formed on the driving layer of the strong field 6, for example, by means of the steam deposition process. In this way, said source of electrons of the field emission type 10 having the structure shown in Fig. 7D is obtained. That said, although the electrically conductive thin film 7 is formed by means of the steam deposition process of Embodiment 6, the process of forming the electrically conductive thin film 7 does not need to be restricted to the steam deposition process. For example, the sizzle procedure can be used.

Thus, in the manufacturing process described in Japanese Patent Application No. 10-272340 or No. 10-272342, the driving layer 6 of the strong field is formed by oxidation of the porous layer of polycrystalline silicon 4 by means of the RTO procedure. In this case, because the oxidation temperature is comparatively higher (800-900 ° C), it is possible to use a substrate in which an electrically conductive film is provided on an expensive quartz glass, or a monocrystalline silicon substrate , as an electrically conductive substrate. Accordingly, because the increase in the area of the electrically conductive substrate is restricted, there can be, for example, a disadvantage such that it is difficult to achieve a screen having a larger area.

On the contrary, in the process of manufacturing the source of electrons of the field emission type according to Embodiment 6, because the porous layer of polycrystalline silicon 4 is oxidized in the gas atmosphere containing at least one of oxygen and ozone while applying ultraviolet rays to the previous one during the oxidation stage of the silicon layer 4, the electron emission efficiency (electron emission efficiency) is increased compared to the layer formation procedure booster of the strong field by oxidation of the porous layer of polycrystalline silicon 4 by means of the RTO process. That said, the efficiency of electron emission is the value obtained by the formula of (Ie / Ips) x 100 depending on the current Ips of the diode and the current Ie of emitted electrons. It can be considered that the reason why the electron emission efficiency is high as described above, is such an issue that when ultraviolet rays are applied in the ozone atmosphere, for example, silicon bonds are cut on the uppermost surface of the thin layer of crystalline silicon 63 shown in Fig. 10B by ultraviolet rays and Si-O bonds are produced by active ozone such that the surface ratio of the layer is improved Crystalline silicon thin 63, which is coated by oxygen atoms 65 (that is, it approaches an ideal state shown in Fig. 10A). In this way, the decomposition of the gas is promoted with the application of ultraviolet rays.

Thus, according to the manufacturing method of Embodiment Form 6, because the porous layer of polycrystalline silicon 4 is oxidized in the gas atmosphere containing at least one of oxygen and ozone, while applying rays ultraviolet to the previous one during the oxidation stage of the silicon layer 4, the efficiency of electron emission is increased. Additionally, because the driving layer of the strong field 6 is formed by oxidation of the porous layer of polycrystalline silicon without heating the layer 4, the driving layer of the strong field can be formed at a lower temperature compared to the case of formation of the driving layer of the strong field by oxidation of the porous layer of polycrystalline silicon by means of the RTO procedure (in this case, it must be heated to 800 to 900 ° C). Therefore, because the process temperature is lower, the restriction for electrically conductive substrate materials becomes less such that increasing the area and decreasing manufacturing cost can be easily achieved.

Embodiment 7

From now on in this document, Embodiment 7 of the present invention will be described. However, because the fundamental construction and manufacturing process of the electron source of the field emission type according to Embodiment 7 are almost the same as those of Embodiment 6 except that its oxidation stage of the porous layer of polycrystalline silicon 4 is different from that of the embodiment 6. Therefore, as regards the construction elements and the manufacturing stage corresponding to that of the Embodiment 6, the design will be simplified or omitted Detailed description about them. In this way, the differences with the Form of Embodiment 6 will be described mainly.

In Embodiment 7, in the oxidation stage of the polycrystalline silicon porous layer 4, the polycrystalline silicon porous layer 4 is oxidized by exposing the layer 4 to the plasma in a gas atmosphere containing at least one of oxygen or ozone (main oxidation stage). That said, plasma can be produced, for example, using a high frequency of 13.56 MHz. When the high frequency of 13.56 MHz is used, the RF energy can be adjusted to, for example, a few tens of W to a few hundred W. In addition, the exposure time of the polycrystalline silicon porous layer 4 to the plasma can be conveniently adjusted to a value in the range of a few minutes to a few hours. That said, plasma can be produced by producing an electric discharge in the gas atmosphere mentioned above (for example, inert gas).

In this way, according to the manufacturing process of the Embodiment Form 7, as in the case of the Embodiment Form 6, the efficiency of electron emission can be increased compared to the conventional case of formation of the driving layer of the strong field by means of the RTO procedure. Additionally, as in the case of Embodiment 6, the area of the electron source 10 of the field emission type can be easily increased and additionally, the manufacturing cost of the source can be easily reduced .

Embodiment 8

From now on in this document, Embodiment 8 of the present invention will be described. However, because the fundamental construction and manufacturing procedure of the electron source of the field emission type according to Embodiment 8 are almost the same as those of Embodiment Form 6 except, that its stage of Oxidation of the polycrystalline silicon porous layer 4 is different from that of Embodiment 6. Therefore, as regards the construction elements and the manufacturing stage corresponding to those in Embodiment 6, it will be simplified or omitted The description about them. In this way, the differences with the Form of Embodiment 6 will be described mainly.

In Embodiment 8, in the oxidation stage of the polycrystalline silicon porous layer 4, the polycrystalline silicon porous layer 4 is oxidized by heating the layer 4 in a gas atmosphere containing at least ozone (main oxidation stage) . That said, the temperature and time of the heating process can be conveniently adjusted to a value in the range of 100 to 600 ° C and a value in the range of a few minutes to a few hours, respectively. That said, the temperature of the heating process may be higher than 600 ° C. However, it is preferable to adjust the temperature to a convenient value in the range of 100 to 600 ° C with a view to decreasing the restriction of the electrically conductive substrate materials. (For example, in order to use a substrate in which an electrically conductive film is provided on a glass plate whose price is less expensive than that of the quartz glass plate, as an electrically conductive substrate).

In this way, according to the manufacturing process of the Embodiment Form 8, as in the case of the Embodiment Form 6, the efficiency of electron emission can be increased compared to the conventional case of formation of the driving layer of the strong field by means of the RTO procedure. Additionally, as in the case of Embodiment 6, the area of the electron source of the field emission type 10 can be easily increased and additionally, the manufacturing cost of the source can be easily reduced.

Embodiment 9

From now on in this document, Embodiment 9 of the present invention will be described. However, because the fundamental construction and manufacturing process of the electron source of the field emission type according to Embodiment 9 are almost the same as those of Embodiment Form 6 except that its oxidation stage of the porous layer of polycrystalline silicon 4 is different from that of the Form of Embodiment 6. Therefore, as regards the construction elements and the manufacturing stage corresponding to those of the Embodiment Form 6, it will simplify or omit the Detailed description about them. In this way, the differences with the Form of Embodiment 6 will be described mainly.

In Embodiment 9, in the oxidation stage of the porous layer of polycrystalline silicon 4, the porous layer 4 of polycrystalline silicon is oxidized by applying ultraviolet rays to layer 4 and heating layer 4 (main oxidation stage). That said, the temperature and time of the heating process can be conveniently adjusted to a value in the range of 100 to 600 ° C and a value in the range of a few minutes to a few hours, respectively. That said, although the temperature of the heating process may be higher than 600 ° C, it is preferable to adjust the temperature to a convenient value in the range of 100 to 600 ° C due to the same reason as that of Embodiment 8.

In this way, according to the manufacturing process of the Embodiment Form 9, as in the case of the Embodiment Form 6, the efficiency of electron emission can be increased compared to the conventional case of formation of the driving layer of the strong field by means of the RTO procedure. Additionally, as in the case of Embodiment 6, the area of the electron source 10 of the field emission type can be easily increased and, additionally, easily decrease the manufacturing cost of the source.

Embodiment 10

From now on in this document, Embodiment 10 of the present invention will be described. However, because the fundamental construction and manufacturing process of the electron source of the field emission type according to Embodiment Form 10 are almost the same as those of Embodiment Form 6 except that its oxidation stage of the porous layer of polycrystalline silicon 4 is different from that of the Form of Embodiment 6. Therefore, as regards the construction elements and the manufacturing stage corresponding to those of the Embodiment Form 6, it will simplify or omit the Detailed description about them. In this way, the differences with the Form of Embodiment 6 will be described mainly.

In Embodiment 10, in the oxidation stage of the polycrystalline silicon porous layer 4, the polycrystalline silicon porous layer is oxidized by applying ultraviolet rays to layer 4 in an inert gas atmosphere containing at least one of oxygen and ozone and heating layer 4 (main oxidation stage). That said, the temperature and time of the heating process can be conveniently adjusted to a value in the range of 100 to 600 ° C and a value in the range of a few minutes to a few hours, respectively. That said, although the temperature of the heating process may be higher than 600 ° C, it is preferable to adjust the temperature to a convenient value in the range of 100 to 600 ° C due to the same reason as that of Embodiment 8.

In this way, in accordance with the manufacturing process of the Embodiment Form 10, as in the case of the Embodiment Form 6, the efficiency of electron emission can be increased compared to the conventional case of formation of the driving layer of the strong field by means of the RTO procedure. Additionally, as in the case of Embodiment 6, the area of the electron source 10 of the field emission type can be easily increased and, additionally, easily decrease the manufacturing cost of the source.

Embodiment 11

From now on, the Embodiment 11 of the present invention will be described. The fundamental construction and manufacturing process of the electron source of the field emission type in accordance with Embodiment 11 are almost the same as those of any one of the Forms 6 to 10. However, the The manufacturing process is characterized in that it includes a supplementary oxidation stage to oxidize the porous layer of polycrystalline silicon 4 by means of the rapid thermal process before and / or after the main oxidation stage in any one of the Embodiment Forms 6 to 10. That said, the supplementary oxidation stage is carried out by the rapid thermal process, in which for example an annealing lamp equipment is used, in a dry oxygen atmosphere by adjusting the temperature and time of the oxidation process at 600-900º C and 30-120 minutes, respectively. In this way, according to the manufacturing process of the Embodiment Form 11, the efficiency of electron emission can be greatly increased, because insufficient oxidation is supplemented in the oxidation process, which occurs in the process conventional oxidation

Embodiment 12

From now on in this document, Embodiment 12 of the present invention will be described. The fundamental construction and manufacturing process of the electron source of the field emission type according to Embodiment 12 are almost the same as those of any one of Embodiment Forms 6 to 11. However, the process of Manufacturing is characterized in that this includes another supplementary oxidation stage to oxidize the porous layer of polycrystalline silicon 4 using acid, carried out before and / or after the main oxidation stage (or the supplemental oxidation stage in the Embodiment Form 11) in any one of the Forms of Embodiment 6 to 11. That is, in the manufacturing process according to the Embodiment 12, the driving layer of the strong field 6 is formed, for example, by carrying out any one of the following treatments (1) to (10) towards the porous layer of polycrystalline silicon 4. In the following treatments [A] denotes the supplementary stage using acid, [M] denotes the main oxidation stage, and [H] denotes the supplementary oxidation stage by means of the rapid thermal process.

(one)

[A] - ���

(2)

[M] - �A�

(3)

[H] - ���

(4)

[M] - �H�

(5)

[A] [M] - �H�

(6)

[H] - ��� - �A�

(7)

[A] -�H� - ���

(8)

[H] - �A� - ���

(9)

[M] -�A� - �H�

(10)

[M] -�H� - �A�

That said, the supplementary oxidation step can be carried out using acid using a processing tank (the processing tank for the treatment of anodic oxidation in Embodiment Form 6) containing acid (for example HNO3 can be used for this purpose) , H2SO4, regal water or the like) maintaining the flow at a predetermined current between the platinum electrode (not shown) and the silicon substrate of type n 1 (ohmic electrode 2) such that the platinum electrode acts as an electrode negative and the substrate 1 acts as a positive electrode.

That said, it can be considered that when the porous layer of polycrystalline silicon 4 is oxidized using, for example, nitric acid diluted to 10%) before the main oxidation stage, such reactions occur as shown by the reaction formulas 1 and 2 described above (Embodiment Form 1). In the meantime, it can be considered that when the porous layer of polycrystalline silicon 4 is oxidized using dilute sulfuric acid (for example, 10% diluted sulfuric acid) before the main oxidation stage, such reactions occur as shown by the reaction formulas 3 and 4 described above (Embodiment Form 2).

Thus, according to the manufacturing process of Embodiment 12, insufficient oxidation in the oxidation process, which occurs in the conventional oxidation process, is supplemented in such a way that efficiency can be increased much more. of electron emission.

Embodiment 13

From now on, Embodiment 13 of the present invention will be described. The fundamental construction and manufacturing process of the electron source of the field emission type according to Embodiment Form 13 are almost the same as those of any one of Embodiment Forms 6 to 10. However, the process of Manufacturing is characterized in that this includes a stage of pre-oxidation to oxidize the porous layer of polycrystalline silicon 4 using an oxidizing solution before the main stage of oxidation in any one of Embodiments 6 to 10. That is, the layer is formed strong field impeller 6 carrying out the main oxidation stage after the true surface layer of the polycrystalline silicon porous layer 4 has been oxidized.

In the manufacturing process according to each of the Forms of Embodiment 6 to 10, because the solution of the mixture, in which aqueous solution of hydrogen fluoride and ethanol is mixed together, is used as an electrolyte in the treatment of anodic oxidation, silicon atoms are terminated by hydrogen atoms. Accordingly, the hydrogen content in the driving layer of the strong field 6 becomes comparatively higher such that the interruption voltage decreases or the distribution of the hydrogen atoms changes over time. Consequently, it is feared that the stability of electron emission efficiency may deteriorate over time.

On the contrary, in the manufacturing process according to Embodiment 13, the hydrogen atoms that terminate the silicon atoms in the porous layer of polycrystalline silicon 4, which have been formed by the anodic oxidation treatment, are replaced with oxygen atoms through the oxidizing solution. That said, as an oxidizing solution, any one or a mixture of several selected in an oxidant group consisting of nitric acid, sulfuric acid, hydrochloric acid and aqueous hydrogen peroxide solution can be used.

Thus, in the manufacturing process according to Embodiment 13, the main oxidation stage is carried out after the same surface layer of the porous layer of polycrystalline silicon 4 formed by the oxidation treatment has been oxidized anodic, using the oxidizing solution, consequently, the hydrogen content in the driving layer of the strong field can be decreased 6. Therefore, in the source of electrons of the field emission type, the time-dependent change of the efficiency of Electron emission may be smaller and the interruption voltage may be higher.

In the meantime, in the manufacturing process according to each of the Forms of Embodiment 11 and 12, a pre-oxidation step can be carried out to oxidize the porous layer of polycrystalline silicon 4 using an oxidizing solution before the main stage of oxidation and the supplementary oxidation stage (s).

In the oxidation stage using the oxidizing solution, if the oxidizing solution is heated, the oxidation rate becomes larger so that the processing time can be shortened.

Example 4

From now on in this document, as Example 4, a source of electrons of the field emission type 10 will be described under the following conditions, by means of the manufacturing process according to Embodiment Form 13.

In Example 4, as a type 1 silicon substrate, a type (100) silicon substrate was used, in which the electrical resistivity was 0.1 0 cm and the thickness was 525 µm. Polycrystalline silicon layer 3 was formed (see Fig. 7A), by means of the LPCVD procedure. In the film formation process, the vacuum degree was 20 Pa, the substrate temperature was 640 ° C, and the monosilane gas flow rate was 600 scm3 / m.

In the anodic oxidation treatment, an electrolyte was used in which a 55% by weight aqueous solution of hydrogen fluoride and ethanol were mixed together in the ratio of almost 1: 1. In the anodic oxidation treatment, the surface of the polycrystalline silicon layer 3 was contacted with the electrolyte. Additionally, the flow of a predetermined current between the platinum electrode immersed in the electrolyte and the silicon substrate of type 1 (ohmic electrode 2) was maintained such that the platinum electrode became a negative electrode and the substrate 1 became a positive electrode. That said, the current density had a constant value of 30 mA / cm2, and the time of the anodic oxidation procedure was 10 seconds.

In the pre-oxidation stage, as an oxidizing solution, a mixed solution was used in which sulfuric acid and an aqueous solution of hydrogen peroxide were mixed together. Next, a sample was immersed, in which a porous layer of polycrystalline silicon 4 was formed, in the oxidizing solution for 30 minutes.

After the pre-oxidation stage, a supplementary oxidation stage was carried out. In the supplementary oxidation stage, the sample was oxidized electrochemically in a 1 molar sulfuric acid solution in weight percent, maintaining the flow at a constant current of 20 mA / cm2 between the platinum electrode and the type silicon substrate n 1 (ohmic electrode 2) such that the platinum electrode became the negative electrode and the substrate 1 became positive electrode. Additionally, the sample was washed using water, and dried. Next, the main oxidation stage was carried out. In the main oxidation stage, ultraviolet rays, whose main wavelengths are 185 nm and 254 nm, were applied to the main surface of the sample (substrate) in a gas atmosphere containing oxygen and ozone, while heating the Sample up to 500º C. The time of the main oxidation procedure was 1 hour.

The electrically conductive thin film 7 was formed by modeling a thin gold film using a photolithography technique, a chemical attack technique or the like, the gold film being deposited on the entire surface of the driving layer of the strong field 6 by means of the Steam deposit procedure. That said, the thickness of the electrically conductive thin film 7 was 10 nm.

The electron source of the field emission type 10, which had been manufactured as described above, was introduced into a vacuum chamber (not shown), and then a collector electrode 21 (electrode to collect the emitted electrons was placed) ) in a position facing the electrically conductive thin film 7 as shown in Fig. 8. The degree of vacuum in the vacuum chamber was then adjusted to 5 X 10-5 Pa, and then Vc voltage was applied with 100 V DC between the collecting electrode 21 and the electrically conductive thin film 7. Additionally, the current Ips of the diode flowing between the electrically conductive thin film 7 and the ohmic electrode 2, and the current Ie of emitted electrons was measured flowing from the collector electrode 21 and the electrically conductive thin film 7 because the electrons e-emitted outward from the source of the emission type electrons of field 10 pass through the electrically conductive thin film 7, while simultaneously changing the voltage Vps with DC applied between the electrically conductive thin film 7 (anode) and the ohmic electrode 2 (cathode). Consequently, this good result was obtained that the current �e of emitted electrons was 10 µA / cm2.

Embodiment 14

From now on in the following document, Embodiment 14 of the present invention will be described. Fig. 11 shows an example of a screen using an electronic source of the field emission type 10 which has a construction almost equal to that of Embodiment 6. However, in the electron source of the field emission type 10 of the Embodiment Form 14, which is not very different from the electronic source of the emission field type 10 of the Embodiment Form 6, each of the electrically conductive thin films 7 is strip-shaped.

As shown in Fig. 11, the screen P1 is equipped with a glass substrate 33 that is arranged so that it faces the electrically conductive thin films 7 of the electron source of the field emission type

10. In this way, on the surface of the glass substrate 33, which faces the source of electrons of the field emission type 10, the electrodes of the strip-shaped collector 31 are formed. In addition, the screen P1 is equipped with a fluorescent layer 32 that emits visible light due to the beams of electrons emitted from the electrically conductive thin films 7, the layer 32 being formed so as to cover the electrodes of the collector 31. That said, a space formed between the source of electrons of the field emission type 10 and the glass substrate 33 remains in a vacuum state.

In the screen P1, each of the electrically conductive thin films 7 is strip-shaped, and in addition, each of the electrodes of the collector 31 is also strip-shaped so that it extends perpendicularly to each of the thin films 7 electrically conductive. Accordingly, when voltage (electric field) is applied to one of the electrodes of the collector 31 and one of the electrically conductive thin films 7, the electrode 31 and the film 7 being properly selected, the electrons are emitted only from the 7 electrically conductive thin film to which the voltage is applied. That said, only the electrons emitted from said region, which exists in the electrically conductive thin film 7 from which the electrons are emitted, corresponds to the electrode of the collector 31, to which the voltage is applied, are accelerated so that the electrons make the fluorescent layer 32 covering the electrode of the collector 31 emit light.

That is, in the screen P1 shown in Fig. 11, a portion of the fluorescent layer 32, which corresponds to the region where the electrically conductive thin film 7 and the collector electrode 31 intersect, applying voltage to each of them, it can emit light, applying voltage to a specific electrically conductive thin film 7 and to a specific collector electrode 31. In this way, images or letters can be displayed on the screen P1 by conveniently changing the electrically conductive thin film 7 and the collector electrode 31, applying voltage to each of them.

The manufacturing process of the electron source of the field emission type 10 in the Embodiment Form 14 is practically the same as in the Embodiment Form 6. However, the fabrication process is characterized in that, once they have been formed the electrically conductive thin films 7 modeled in the predetermined form (as strip in Embodiment 14), at least one treatment is applied that applies ultraviolet rays to the layer in an atmosphere of gas containing the minus one of oxygen and ozone described in Embodiment 6, a treatment that exposes the layer to plasma in a gas atmosphere containing at least one of oxygen and ozone described in Embodiment 7, a treatment that heats the layer in an atmosphere of gas that contains at least one of oxygen and ozone described in Embodiment 8, a treatment that applies ultraviolet rays to the c Apa and heats the layer as described in Embodiment 9 and a treatment that applies ultraviolet rays to the layer in an atmosphere of gas containing at least one of oxygen and ozone described in Embodiment 10. Thus In accordance with the treatments described above, contamination due to organic materials produced before the treatments can be eliminated, as well as the porous layer of polycrystalline silicon is oxidized so that the emission efficiency of electrons

That said, electrically conductive thin films 7 in strip form can be formed, for example, in accordance with the following procedure. That is, once an electrically conductive thin film 7 has been formed on the entire surface of the driving layer of the strong field 6, a photoresist layer is applied, and it is formed on the electrically conductive thin film 7. Next, the photoresist layer is modeled by photolithography techniques. Next, the electrically conductive thin film 7 is trimmed using the photoresist layer as a mask, and then the photoresist layer is removed.

That said, electrically conductive thin films 7 in strip form can be formed directly on the driving layer of the strong field 6 by a steam deposition process or the like using a metal mask having a strip-shaped opening model.

An example of a screen using an electron source of the field emission type 10 'is shown in Fig. 12 which is equipped with a substrate in which an electrically conductive film 12 is formed on a glass plate 11, as shown in Fig. 6B.

As shown in Fig. 12, on screen P2, an anode electrode 42 is placed on the electron source of the field emission type 10 'while forming a space 41 therebetween, and in addition a fluorescent glass substrate 43 on the surface of the anode electrode 42 so that it is in close contact with the electrode. In addition, the space 41 is enclosed by a movable lid 44. That said, the space 41 is almost in a vacuum state. In addition, spacers 45 are placed in some desired positions between the source of electrons of the field emission type 10 'and the anode electrodes 42. The source of electrons of the field emission type 10' is equipped with a variety of electrically conductive thin films 7 . In addition, in the position facing each of the electrically conductive thin films 7, a fluorescent member 46 is provided on the lower surface of the anodic electrode 42.

Thus, when a predetermined voltage is applied between the specific (desired) of a variety of electrically conductive thin films 7 and the anodic electrodes 42 facing the specific films 7 the electrons emitted from the specific electrically conductive thin film 7 move the direction that shows the arrow X, and then collides with the fluorescent members 46 in front of the specific electrically conductive thin films 7. Accordingly, the fluorescent member 46 emits light as shown by the dashed line L.

In the screen P2, applying a voltage to the specific electrically conductive thin films 7, and to the specific anodic electrodes 42, and conductive electrical film 12, the specific members of a plurality of fluorescent members 46 facing the specific films 7 to which Apply voltage, can emit light. Accordingly, images or letters can be displayed on the screen P2 by conveniently changing the electrically conductive thin film 7 and the electrically conductive film 12, applying voltage to each of them.

Example 5

From now on in this document, as Example 5, a source of electrons of the field emission type 10 (see Fig. 11) manufactured under the following conditions will be described, by the manufacturing process according to the Embodiment Form 14.

In Example 5, as a type n silicon substrate, a type (100) silicon substrate was used, in which the electrical resistivity was 0.10, and the thickness was 525 µm. The polycrystalline silicon layer 3 (see Fig. 7A) was formed by the LPCVD procedure. In the film formation process the degree of vacuum was 20 Pa, the substrate temperature was 640 ° C, and the monosilane gas flow rate was 600 scm3 / m.

In the anodic oxidation process, an electrolyte was used in which 55% by weight aqueous hydrogen fluoride solution and ethanol were mixed in a ratio of almost 1: 1. In the anodic oxidation treatment, the surface of the polycrystalline silicon layer 3 was contacted with the electrolyte. In addition, a current was allowed to flow into the platinum electrode immersed in the electrolyte and the n-type silicon substrate (ohmic electrode 2) so that the platinum electrode becomes a negative electrode and the substrate 1 becomes an electrode positive. That said, the current density in the anodic oxidation process had the constant value of 30 mA / cm2, and the time of the anodic oxidation process was 10 seconds.

In the rapid thermal process to oxidize the porous layer of polycrystalline silicon 4, the flow rate of the oxygen gas was

5 of 300 scm3 / m, the oxidation temperature was 900 ° C, and the oxidation time was 1 hour. The electrically conductive thin film 7 was formed by modeling a thin gold film using the photolithography technique, a chemical attack technique or the like, the gold film being deposited on the outer surface of the driving layer of the strong field 6 by a process of steam tank That said, the thickness of the electrically conductive thin film 7 was 10 nm.

10 Once the electrically conductive thin film 7 is formed, an oxidation treatment (hereinafter referred to as "post-treatment") is carried out which applied ultraviolet rays to the layer in a mixed gas atmosphere (2000 ppm ) containing oxygen (O2) and ozone (O3). A 110 W low pressure mercury lamp was used as a source of ultraviolet radiation. The temperature and time of the heating procedure were 200 ° C and 30 minutes, respectively.

In addition, an electron source of the field emission type was manufactured to which the post-treatment had not been applied, as comparative example 1 (example for comparison). In addition, as a comparative example 2, an electron source of the field emission type was also manufactured, in which the electrically conductive thin film 7 had been formed using a metal mask and to which no post-treatment had been applied. The difference between Example 5 and comparative example 1 was only if post-treatment had been performed or not.

20 The difference between Example 5 and the comparative example was as follows. More specifically, in Embodiment 3, the electrically conductive thin film 7 had been modeled by a photolithography technique.

or similar, after which the post-treatment had been performed. On the other hand, in comparative example 2, the electrically conductive thin film 7 is modeled during the stage of film formation using a metal mask, and then post-treatment was not performed.

Each of the electron sources of the field emission type 10, which had been manufactured as described above, was introduced into a vacuum chamber (not shown), and then an electrode of the collector 21 (electrode was placed to collect the emitted electrons) in a position facing the electrically conductive thin film 7 as shown in Fig. 8. Thus, the degree of vacuum in the vacuum chamber is adjusted to 5 x 10-5, and then Apply 100 V DC voltage between collector electrode 21 and thin film 7

30 electrically conductive. In addition, the Ips diode current flowing between the electrically conductive thin film 7 and the ohmic electrode 2 was measured, and the emitted electrode current flowed between the collector electrode 21 and the electrically conductive thin film 7 due to the e-emitted electrons outward from the source of electrons of the field emission type 10 through the electrically conductive thin film 7, while varying the DC Vps voltage applied between the electrically conductive thin film 7 (anode) and the ohmic electrode 2 (cathode ). He

The result of that measurement is shown in Fig. 13.

In Fig. 13, the horizontal axis shows the DC Vps voltage. The left vertical axis shows the current density of the diode current IPs or the emitted electronic current Ie. The right vertical axis shows the efficiency of electron emission (Ie / Ips x 100). In addition, the graphs in Fig. 13 show the following physical properties, respectively:

Continuous line • (�) Ips in Example 5

Striped line • (�) Ie in Example 5

Broken line • (�) Eff in Example 5

Continuous line • (�) Ips in comparative example 1

Striped line • (�) Ie in comparative example 1

Broken line • (�) Eff in comparative example 1

Continuous line • (�) Ips in comparative example 2

Striped line • (�) Ie in comparative example 2

Broken line • (�) Eff in comparative example 2

Ips: diode current Ie: emitted electronic current Eff: electronic emission efficiency

In Fig. 13, when comparative example 1 is compared with comparative example 2, the current density of the emitted electronic current of comparative example 1 is smaller than that of comparative example 2 (see graphs �, �), although the current densities of the Ips diode currents of both are practically the same (see graphs �, �). Accordingly, the electronic emission efficiency of comparative example 1 is smaller than that of comparative example 2 (see graphs �, �). The reason can be considered as follows: Namely, in comparative example 1, contamination of the organic materials may remain due to the remaining resistance of the photoresist layer used to model the electrically conductive thin film 7. On the other hand, in comparative example 2, said contamination of organic materials can remain, since a metal mask is used to model the electrically conductive thin film 7.

Then, when Example 5 is compared with comparative example 1, the current density of the Ips diode current of Example 5 is smaller than that of comparative example 1 (see graphs �, �), although the density of current of the emitted electronic current Ie of Embodiment 3 is larger than that of comparative example 1 (see graphs �, �). Accordingly, the electronic emission efficiency of Example 5 is greater than that of comparative example 1 (see graphs �, �). For example, when the DC Vps voltage is 20 V, the current density of the emitted electronic current Ie of Example 5 is about 30 times that of comparative example 1, the current density of the Ips diode current of Example 5 is a fourth (1/4) of that of comparative example 1, and the electronic emission efficiency of Example 5 is about 120 times that of comparative example 1. More precisely, the electronic emission efficiency of Example 5 is much greater than that of comparative example 1.

Furthermore, when comparing Example 5 with comparative example 2, the current density of the emitted electronics current Ie of Example 5 is larger than that of comparative example 2, consequently, the electronic emission efficiency of Example 5 is larger than that of comparative example 2. That said, the reason why the current density of the electron current emitted in Example 5 is larger than that of comparative example 2 can be considered as follows. Namely, in Example 5 an effect can be obtained such that the surface of the electron source of the field emission type 10 is purified by post-treatment, and / or an effect such that the quality of the oxide film is improved. Silicon 64 is improved (see Fig. 10A) on the surface of the thin layer of silicon crystal 63 that builds the driving layer of the strong field 6 (the ratio of the surface covered with oxygen atoms increases).

Claims (11)

one.

 A process for manufacturing an electron source of the field emission type (10) comprising an electrically conductive substrate (1), a strong field driving layer (6) formed on the surface of the electrically conductive substrate (1), driving layer ( 6) comprising column-shaped polycrystalline silicon grains (61), thin films of silicon oxide (62) formed on the surfaces of polycrystalline silicon grains (61), layers of fine crystalline silicon (63) of nanometric order which are placed between the polycrystalline silicon grains (61) and silicon oxide films (64) formed on the surfaces of the thin crystalline silicon layers (63), each of the films (64) being an insulating film having a thickness smaller than the diameter of a crystal particle of the thin crystalline silicon layer (63), and an electrically conductive thin film (7) formed on the driving layer of the strong field (6), and n that the electrons, which are injected into the electrically conductive substrate (1), propel in the driving layer of the strong field (6) so that they are emitted outward through the electrically conductive thin film (7) by applying a voltage between the electrically conductive thin film (7) and the electrically conductive substrate (1), the process comprising a major oxidation stage of the strong field driving layer formation (6) by the oxidation of a porous semiconductor layer by means of the minus one of a treatment that applies ultraviolet radiation to the porous semiconductor layer in a gas atmosphere that contains at least one of oxygen and ozone, a treatment that heats the porous semiconductor layer in an ozone-containing gas atmosphere, a treatment that applies ultraviolet radiation to the porous semiconductor layer and heats the porous semiconductor layer in a gas atmosphere containing at least one of o Oxygen and ozone and heats the porous semiconductor layer.

2.

 The method of manufacturing the electron source of the field emission type (10) according to claim 1, wherein the main oxidation stage is carried out after the electrically conductive thin film (7) has been formed. .

3.

 The method of manufacturing the electron source of the field emission type (10) according to claim 1, further comprising a stage of supplementary oxidation to oxidize the porous semiconductor layer by a heating process, the step being carried out of supplementary oxidation before and / or after the main oxidation stage.

Four.

 The method of manufacturing the electron source of the field emission type (10) according to claim 2, further comprising a stage of supplementary oxidation to oxidize the porous semiconductor layer by a heating process, the step being carried out of supplementary oxidation before and / or after the main oxidation stage.

5.

 The method of manufacturing the electron source of the field emission type (10) according to claim 1 further comprising another stage of supplementary oxidation to oxidize the porous semiconductor layer by a heating process, the step of carrying out the supplementary oxidation before and / or after the main oxidation stage.

6.

 The process for manufacturing the electron source of the field emission type (10) according to claim 2, further comprising a stage of supplementary oxidation to oxidize the porous semiconductor layer using an acid solution, the step of carrying out supplementary oxidation before and / or after the main oxidation stage.

7.

 The method of manufacturing the electron source of the field emission type (10) according to claim 1, further comprising a pre-oxidation step to oxidize the porous semiconductor layer using an oxidizing solution, the pre-oxidation stage being carried out. before and / or after the main oxidation stage.

8.

 The method of manufacturing the electron source of the field emission type (10) according to claim 2, further comprising a step to oxidize the porous semiconductor layer using an oxidizing solution, the pre-oxidation stage being carried out before and / or after the main oxidation stage.

9.

 The method of manufacturing the electron source of the field emission type (10) according to claim 3, further comprising a stage of oxidation oxidation of the porous semiconductor layer using an oxidizing solution, the stage of pre-oxidation being carried out before and / or after the stage of supplementary oxidation.

10.

 The method of manufacturing the electron source of the field emission type (10) according to claim 4, further comprising a pre-oxidation step to oxidize the porous semiconductor layer using an oxidizing solution, the pre-oxidation stage being carried out. before and / or after the stage of supplementary oxidation.

The method of manufacturing the electron source of the field emission type (10) according to claim 5, further comprising a pre-oxidation step to oxidize the porous semiconductor layer using an oxidizing solution, the step of carrying out the pre-oxidation before the main oxidation stage and the supplementary oxidation stages. 12. The method of manufacturing the electron source of the field emission type (10) according to claim 6, further comprising a pre-oxidation step to oxidize the porous semiconductor layer using an oxidizing solution, the step being carried out of pre-oxidation before the main oxidation stage and the supplementary oxidation stages.