JP5148124B2 - Method for manufacturing substrate for electron emitter and method for manufacturing electron emitter - Google Patents

Description

The present invention relates to a manufacturing method and manufacturing method of the electron emitter electron emitter substrate.

  Conventionally, a carbon-containing gas introduced into a vacuum film-forming chamber is decomposed by DC plasma, and a carbon film of size nm order having a field electron emission performance of emitting electrons by field emission is formed on the surface of the substrate to form an electron emitter. Manufacturing processes for manufacturing are known. In this electron emitter manufacturing process, before the carbon film is formed, it is necessary to prepare a buffer layer on the surface of the substrate disposed in the vacuum film forming chamber and to adjust the film forming conditions. However, since this buffer layer manufacturing process takes a long time of several tens of minutes, it has heretofore been difficult to mass-produce electron emitters.

JP 2002-509339 A proposes a method for producing an electron emitter in which a composite layer containing graphite particles and glass is formed on a wire and the graphite particles are formed into whiskers.
Special Table 2002-509339

  The problem to be solved by the present invention is to make it possible to omit the process of generating the buffer layer on the surface of the substrate in advance before the film formation, which is included in the above-mentioned electron emitter manufacturing process.

The method of manufacturing a substrate for an electron emitter according to the present invention includes a step of simultaneously immersing a large number of conductive bases in a graphite-containing paste solution and attaching the graphite-containing paste to the conductive surface of the base. And firing a graphite-containing paste to form a graphite-containing film as a buffer layer that conforms to the conditions for forming a carbon film by direct current plasma on the conductive surface of the substrate. It is preferable that the graphite-containing paste contains a catalyst that promotes carbon film formation by contacting the carbon component in the direct current plasma. The deposition includes various coatings and printing, such as spin, spraying, dipping, web, die or evaporation coating, electroless deposition, inkjet printing, screen printing, microcontact printing, stamping or soft lithography, etc. Is included. The paste includes a paste and can also include a slurry.

  The substrate may be a conductive wire extending in a wire shape or a flat panel substrate having a rectangular shape in plan view. This substrate may be entirely conductive, or may be internally insulating and have a conductive surface. This substrate may be solid inside or hollow inside. In the case of an internal insulating member, the conductive material on the surface may be attached by, for example, spraying, dipping, web or spin coating, or liquid coating, or vacuum deposition or vapor deposition. The graphite-containing paste may be prepared from a mixture of graphite, which is a powdered active material, a metal surface, and an adhesive polymer binder.

  In the method for producing a substrate for an electron emitter according to the present invention, for example, by immersing a large number of substrates such as conductive wires in a solution containing a graphite-containing paste at a time, the graphite-containing paste is adhered to the surface at a time, For example, by firing in a firing furnace, other components in the paste are vaporized on the surface, and a large amount of electron emitter base materials having a graphite-containing film having a high graphite-containing purity can be produced.

In the present invention, when the electron emitter base material manufactured by the method for manufacturing an electron emitter base material is used, it is not necessary to prepare a buffer layer on the surface of the base material in the vacuum film forming chamber. Process time can be greatly reduced.
An electron emitter manufacturing method according to the present invention comprises a vacuum film forming chamber, a cylindrical electrode formed by connecting a plurality of opposing semi-cylindrical electrodes provided in the vacuum film forming chamber, and a vacuum film forming chamber. Electrons manufactured by the above-described electron emitter substrate manufacturing method using a DC plasma film forming apparatus having a gas introduction system for introducing a film gas and a DC power source for applying a DC negative voltage to the cylindrical electrode. An emitter base material is disposed between the semi-cylindrical electrodes of the cylindrical electrode, a film forming gas is introduced from the gas introducing system into the vacuum film forming chamber, and a DC negative voltage is applied to the cylindrical electrode. This film forming gas is converted into plasma, and a carbon film having field electron emission performance is formed on the surface of each electron emitter substrate.

  In this electron emitter manufacturing method, since the buffer layer is already provided on the surface of the electron emitter substrate, the buffer layer manufacturing process by direct current plasma in the vacuum film forming chamber can be omitted, and the manufacturing time is greatly reduced. Can be shortened.

  According to the present invention, the process of generating a buffer layer on the substrate surface in advance of film formation, which is included in the electron emitter preparation process, can be omitted, so that the electron emitter preparation time can be greatly reduced, and mass production of electron emitters can be achieved. Can be easily realized.

  Hereinafter, an electron emitter substrate, an electron emitter substrate manufacturing method, and an electron emitter manufacturing method according to embodiments of the present invention will be described with reference to the accompanying drawings.

  An electron emitter substrate will be described with reference to FIGS. 1A is a side sectional view of the electron emitter substrate, and FIG. 1B is a sectional view taken along line AA of FIG. The electron emitter base material 10 is configured by adhering a graphite-containing film 12 as a buffer layer that conforms to the conditions for forming a carbon film by direct current plasma on the surface of a conductive wire 11 forming the base. Although the said base | substrate was the electroconductive wire 11 as an example, the base material of planar view rectangular shapes, such as a flat panel shape, may be sufficient.

  The graphite-containing film 12 may include a catalyst that promotes carbon film formation by contacting the carbon component of the direct current plasma. Examples of the catalyst include iron, nickel, cobalt, and alloys thereof.

  The graphite-containing film 12 is preferably a film made of high-purity and high-density graphite. The graphite may be artificial (artificial) graphite, but highly crystalline graphite such as natural graphite is preferred. There is no restriction | limiting in particular as natural graphite, Commercial products, such as F48C (brand name made from Nippon Graphite Co., Ltd.) and H-50 (brand name of Chuetsu Graphite Co., Ltd.), can be used. The shape of graphite in the graphite-containing film 12 includes a spherical shape and the like, but it is preferable that the shape is ultrafine particles such as a scale shape or a scale shape having a relatively sharp end. This ultrafine particle formation is preferable because the formation of the carbon film in the DC plasma film forming apparatus can be promoted.

  A method for manufacturing the electron emitter substrate 10 will be described with reference to FIGS. The substrate may have any shape as long as the surface has conductivity, but in the embodiment, the conductive wire 11 is used as an example of the description. The conductive wire 11 may be a metal having conductivity as shown in FIG. 2A in its side cross section and in FIG. 2B in its BB line cross section, but is not limited to this. As shown in the sectional side view in FIG. 3 (a) and in the sectional view taken along the line CC in FIG. 3 (b), the substrate having the structure in which the conductive film 11b is provided on the surface of the insulator 11a having a solid inside, or FIG. The substrate may be a structure having an inner hollow insulator 11c and a conductive film 11d on the surface thereof as shown by a side cross section in a) and a DD cross section in FIG. 4B. In the embodiment, the entire base is composed of a metal wire, particularly an iron-based conductive wire 11.

  A number of the conductive wires 11 are immersed in the graphite-containing paste solution 18 as shown in FIG. As the graphite-containing paste 20, Hitachi GA-263 manufactured by Hitachi Powdered Metallurgy Co., Ltd., marketed as “graphite paste for fluorescent display tube” was used. In addition to graphite, potassium silicate, glycerin, and alumina are mixed in the graphite-containing paste. Since this graphite-containing paste 20 dissolves in all proportions with respect to water, it is possible to arbitrarily adjust the viscosity by adding water. The viscosity of the graphite-containing paste 20 may be adjustable with a volatile solvent. Therefore, the graphite-containing paste 20 can be attached to the surface of the conductive wire 11 with a desired film thickness. When the conductive wire 11 is pulled up from the graphite-containing paste solution 18, the graphite-containing paste 20 adheres to the surface of the conductive wire 11. The graphite-containing paste 20 can be attached to the surface of the conductive wire 11 with a desired film thickness by adjusting the immersion time in the graphite-containing paste solution 18, the lifting time from the solution, and adjusting the ratio of water.

  Catalyst 22 may be mixed in the graphite-containing paste solution 18 as shown in FIG. This is because the catalyst 22 can be used as a carbon film growth nucleus on the surface of the conductive wire 11 in a DC plasma film forming apparatus. However, this catalyst is not indispensable by using a direct-current plasma film forming apparatus described later.

  After the graphite-containing paste 20 is attached to the surface of the conductive wire 11, the conductive wire 11 is put into a firing furnace 24 as shown in FIG. The mixture is evaporated to dryness. After the drying, when the conductive wire 11 is taken out from the firing furnace 24, as shown in FIG. 8 (similar to FIG. 1 but again), the graphite-containing film 12 made of high-purity graphite is formed on the surface of the conductive wire 11. Can be produced. The firing temperature, firing time, and the like of the firing furnace 24 can be set as appropriate through experiments and the like. The firing furnace 24 can be a batch type, but a continuous type is preferable for improving the mass productivity of the electron emitter substrate 10. The continuous type includes a continuous firing furnace represented by a roller kiln and a kiln car type tunnel kiln. This can be fired by transporting the conductive wire 11 through the furnace from the entrance to the exit of the firing furnace.

  In the above manufacturing method, a large amount of the conductive wire 11 can be immersed in the graphite-containing paste solution 18 at a time, and a large amount of the conductive wire 11 can be put into the firing furnace 24 at a time and fired. The emitter base material 10 can be quickly and inexpensively mass-produced and prepared for the production of the electron emitter described below.

  The mass production of the wire-shaped electron emitter substrate 10 is not limited to the form of immersing in the graphite-containing paste solution 18, and similarly, the form of firing in the firing furnace 24 and drying. It is not limited.

  Moreover, although the graphite containing paste was used in the above, a surface coating paste was applied to the surface of the conductive wire 11, and a heat treatment was performed in a curing furnace with a graphite containing sheet containing graphite placed on the paste. The graphite-containing film 12 may be attached to the surface of the conductive wire 11 by cooling (a concept including coating).

  An electron emitter manufacturing method using the electron emitter substrate 10 will be described with reference to FIG. FIG. 9 is a diagram showing a schematic configuration of a DC plasma film forming apparatus 30 used for carrying out the manufacturing method of the electron emitter. A cylindrical electrode 34 is disposed in the vacuum film forming chamber 32. In the cylindrical electrode 34, the members constituting the peripheral wall have a mesh shape. An electron emitter base material 10 which is a film formation target is arranged in the space inside the cylindrical electrode 34. The cylindrical electrode 34 has a substantially circular cross section and extends in one direction, and its internal space forms a cylindrical plasma generation / confinement space extending in one direction. The electron emitter substrate 10 is arranged in the shape of an elongated wire that is arranged at substantially the center of the space inside the cylindrical electrode 34. The inner peripheral surface of the cylindrical electrode 34 and the outer peripheral surface of the electron emitter substrate 10 are opposed to each other with a required space in the extending direction. One end of the cylindrical electrode 34 is connected to the negative electrode of a voltage variable type DC power supply 36, and a DC negative voltage is applied thereto.

  In the DC plasma film forming apparatus 30 having the above-described configuration, the vacuum film forming chamber 32 is depressurized by the vacuum exhaust system 38 and a mixed gas of hydrocarbon gas and hydrogen gas is introduced as a processing gas from the gas introduction system 39. When a negative voltage of the DC power supply 36 is applied to the cylindrical electrode 34, DC plasma 40 is generated in the space inside the cylindrical electrode 34. In this case, the temperature of the electron emitter substrate 10 is, for example, 700 ° C. or higher. The temperature of the electron emitter substrate 10 may be achieved by electric heating.

  As described above, the carbon film 42 is formed on the surface of the electron emitter substrate 10 as shown in FIG. In this case, the cylindrical electrode 34 is preferably an electrode containing a catalyst metal, and examples thereof include Fe (iron), Ni (nickel), Co (cobalt), and alloys thereof. When the cylindrical electrode 34 is made of the above-described catalytic metal, the carbon film 42 on the surface of the electron emitter substrate 10 does not need to contain the catalytic metal, but the cylindrical electrode 34 is made of the catalytic metal. If not configured, the carbon film 42 on the surface of the electron emitter substrate 10 needs to contain a catalytic metal. In this case, fine particles of catalyst metal may be mixed in the graphite-containing paste solution 18 shown in FIG.

  When the DC plasma 40 is generated, the catalytic metal contained in the cylindrical electrode 34 is sputtered, and the sputtered metal particles 41 adhere to the surface of the electron emitter substrate 10. When the catalyst metal particles 41 adhere, a carbon film 42 having a field electron emission performance is formed on the surface of the electron emitter substrate 28 by the catalytic action of the catalyst metal particles 41, and the electron emitter 44 is manufactured.

  In the case where the cylindrical electrode 34 is not composed of a catalyst metal, the field electron emission performance on the surface of the electron emitter substrate 10 is caused by the catalytic action of the catalyst metal fine particles in the graphite-containing film 12 on the surface of the electron emitter substrate 10. The carbon film 42 having the above is formed, and the electron emitter 44 is manufactured.

  In the manufacturing method of the electron emitter 44 described above, it is not necessary to go through a film forming process for forming a buffer layer for forming the carbon film 42 on the surface of the electron emitter substrate 10, and the manufacturing time can be greatly shortened. . This is because the graphite-containing film 12 necessary for forming the carbon film 42 is formed on the surface of the electron emitter substrate 10.

 When the film forming operation is performed without the buffer layer, the carbon film 42 is difficult to form or is not formed. Therefore, conventionally, during the film formation process, a buffer layer is formed on the surface of the conductive wire 11 over several tens of minutes at a low temperature of 500 ° C. or lower, and then a carbon film is formed using the buffer layer at 700 ° C. or higher. Things were going on.

  In the electron emitter manufacturing method according to the above embodiment, the cathode and the anode are arranged in the vacuum film forming chamber in a state where the electrode surfaces of the cathode and the anode face each other in parallel with a predetermined interval without using the cylindrical electrode. This can also be carried out by a DC plasma film forming apparatus having a structure in which a DC power source negative electrode is connected to the cathode. In this direct current plasma film forming apparatus, a gas is introduced into a vacuum film forming chamber, a direct current negative voltage is applied to the cathode to generate plasma on the electrode surface of the anode, and the plasma is disposed on the electrode surface of the anode. An electron emitter can be manufactured by forming a carbon film on the surface of the electron emitter substrate 10 in the form.

  Moreover, as a DC plasma film-forming apparatus, what is shown in FIG. 11 may be used. In this apparatus, a plurality of cylindrical electrodes 50 are connected in series, and the supply ports 52 and the discharge ports 54 of each of the plurality of cylindrical electrodes 50 are arranged in a line in the transport direction indicated by the arrows in the figure of the electron emitter substrate 10. And communicate. The illustration of the transport mechanism is omitted. In FIG. 11, the electron emitter base material 10 at the inlet of the supply port 52 is discharged as an electron emitter 44 from the discharge port 54.

  The cylindrical electrode 50 includes two pairs of semi-cylindrical electrodes 50a and 50b whose opposite ends in the circumferential direction face each other with a predetermined gap therebetween. The facing gap on one end side in the direction is the supply port 52, and the facing gap on the other end side in the circumferential direction is the discharge port 54. A plurality of pairs of two semi-cylindrical electrodes 50a and 50b are connected in series, and opposing gaps 56 of the plurality of pairs of semi-cylindrical electrodes 50a and 50b communicate with each other in a line in the direction of transport of the electron emitter substrate 10. doing. The pair of semi-cylindrical electrodes 50a and 50b are configured such that the opposing gap 56 is closed during film formation and opened during conveyance.

  A film forming gas is introduced into the vacuum film forming chamber 58, and a voltage is applied to the semi-cylindrical electrodes 50a and 50b to turn the film forming gas into a plasma, which can be formed on the surface of the electron emitter substrate 10. It is like that.

  In the above apparatus, a plurality of electron emitter base materials 10 are sequentially supplied to the inside of the cylindrical electrode 50 through the opening of the cylindrical electrode 50 and discharged as electron emitters 44 sequentially from the opening of the cylindrical electrode 50. Since the electron emitter 44 can be manufactured by sequentially forming a film forming process inside the cylindrical electrode 50 on the plurality of electron emitter base materials 10, the mass production of the electron emitters 44 can be performed. The characteristics are greatly improved.

  FIGS. 12A and 12B show a field emission lamp 60 incorporating the electron emitter 44 manufactured by the electron emitter manufacturing method. 12A is a cross-sectional view from the side, and FIG. 12B is a cross-sectional view taken along the line EE of FIG. In this field emission lamp 60, an anode 64 and a phosphor 66 are laminated in a film shape on the inner surface of a glass tube 62, and a wire-shaped electron emitter 44 is suspended in the glass tube 62 in the air.

  FIG. 13 shows a light emission photograph of the field emission lamp 60. As shown in the light emission photograph, the field emission lamp 60 in which the electron emitters 44 according to the embodiment are arranged in a wire shape emits light with a practical brightness in terms of light emission characteristics.

  The field emission lamp is not limited to the above tube type, and includes a pair of upper and lower flat panels. The electron emitter 44 of the embodiment is arranged in a wire shape on the inner surface of one flat panel, and the fluorescent light is disposed on the inner surface of the other flat panel. The present invention can also be applied to a flat type provided with a body-attached anode.

  The present invention is not limited to the above-described embodiment, and includes various changes or modifications within the scope described in the claims.

FIG. 1A is a diagram showing a cross-sectional configuration of an electron emitter substrate according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA of FIG. 2A is a cross-sectional view showing another example of the electron emitter substrate, and FIG. 2B is a cross-sectional view taken along the line BB of FIG. 2A. 3A is a side sectional view of the conductive wire, and FIG. 3B is a sectional view taken along the line CC of FIG. 3A. 4A is a side cross-sectional view of another example of the conductive wire, and FIG. 4B is a cross-sectional view taken along the line DD of FIG. 4A. FIG. 5 is a diagram showing a state in which a conductive wire is immersed in a graphite-containing paste solution in the method for manufacturing an electron emitter substrate. FIG. 6 is a view showing another example of a graphite-containing paste solution. FIG. 7 is a view showing a state in which the conductive wire after the graphite-containing paste is immersed in the firing furnace is fired in the electron emitter substrate manufacturing method. FIG. 8 is a side cross-sectional view of the electron emitter base material manufactured by the firing. FIG. 9 is a diagram showing a schematic configuration of a direct-current plasma film forming apparatus used for carrying out an electron emitter manufacturing method. FIG. 10 is an enlarged cross-sectional view of an electron emitter in which a carbon film is formed on the surface of an electron emitter substrate with a DC plasma film forming apparatus. FIG. 11 is a cross-sectional view showing another example of a DC plasma film forming apparatus. 12A is a cross-sectional view from the side of the electron emitter manufactured by the DC plasma film forming apparatus, and FIG. 12B is a cross-sectional view taken along the line EE of FIG. FIG. 13 is a view showing a light emission photograph of the field emission lamp.

Explanation of symbols

10 Electron Emitter Base Material 11 Conductive Wire 12 Graphite-Containing Film

Claims (3)

  Immersing a large number of electrically conductive substrates simultaneously in a graphite-containing paste solution, and attaching the graphite-containing paste to the conductive surface of the substrate;
  Firing the attached graphite-containing paste to produce a graphite-containing film as a buffer layer that conforms to the conditions of carbon film formation by direct current plasma on the conductive surface of the substrate;
  The manufacturing method of the base material for electron emitters characterized by including these. 2. The method for producing a base material for an electron emitter according to claim 1 , wherein the graphite-containing paste contains a catalyst that promotes the formation of a carbon film by contacting the carbon component in the direct current plasma.   A vacuum film forming chamber; a cylindrical electrode provided in the vacuum film forming chamber and provided with a plurality of opposed semi-cylindrical electrodes; and a gas introduction system for introducing a film forming gas into the vacuum film forming chamber; Using a DC plasma film forming apparatus provided with a DC power source for applying a DC negative voltage to the cylindrical electrode,
  An electron emitter base material manufactured by the method for manufacturing an electron emitter base material according to claim 1 or 2 is disposed between the semi-cylindrical electrodes of the cylindrical electrode, and the gas introduction system is disposed in the vacuum film forming chamber. And forming a carbon film having field electron emission performance on the surface of each electron emitter substrate by applying a negative DC voltage to the cylindrical electrode to convert the film forming gas into plasma. A method of manufacturing an electron emitter.