JP2008041272A - Manufacturing method for cold cathode element, and cold cathode element using the manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a cold cathode element that is simpler and more controllable to offer improved reliability and electron emission characteristics, compared to a conventional cold cathode element, and to provide the cold cathode element using the method. <P>SOLUTION: The cold cathode element 10 includes a board 11, a cathode electrode 12 formed on the board 11, an insulating layer 13 formed on the cathode electrode 12, an electron extraction electrode 14 formed on the insulating layer 13, and a carbonic microfiber 15 that emits electrons. The carbonic microfiber 15 is subjected to a trimming treatment with an oxygen radical, and is further subjected to an activation treatment in a hydrogen gas. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a cold cathode device and a cold cathode device using the same.

  In recent years, carbon-based fine fibers such as carbon nanotubes (hereinafter “CNT”) and graphite nanofibers (hereinafter “GNF”) are expected to be applied as electron source materials for cold cathode devices. A conventional cold cathode device has a structure as shown in FIG. 12, for example.

  As shown in FIG. 12, a conventional cold cathode device 1 includes a cathode electrode 3 formed on a glass substrate 2, an insulating layer 4 formed on the cathode electrode 3, and electrons formed on the insulating layer 4. An extraction electrode 5 and carbon-based fine fibers 6 made of CNT, GNF, or the like are provided, and electrons are emitted from the carbon-based fine fibers 6 as an electron source when a voltage is applied to the electron extraction electrode 5. It has become. Although a plurality of cold cathode devices 1 are usually formed on the glass substrate 2, in order to make the configuration easy to understand, FIG. 12 shows a configuration for one cold cathode device.

  As a device using a cold cathode element, for example, a field emission display that can cause a phosphor to emit light by colliding emitted electrons on an anode electrode on which the phosphor is formed and display a desired image ( Hereinafter, “FED”) is known (see, for example, Non-Patent Documents 1 and 2).

  However, in order to apply a cold cathode device using carbon-based fine fibers to FED and put it to practical use, there are problems to be improved in the reliability and electron emission characteristics of the cold cathode device using carbon-based fine fibers. Various proposals have been made to solve the problems.

  First, the problem in reliability will be described. In the cold cathode device 1 shown in FIG. 12, one of the causes for reducing the reliability is an electrical short circuit between the cathode electrode 3 and the electron extraction electrode 5. The thickness of the insulating layer 4 provided between the cathode electrode 3 and the electron extraction electrode 5 is usually about several μm, and the length of the carbon-based fine fiber 6 formed on the cathode electrode 3 is also usually about several μm. Therefore, the carbon-based fine fiber 6 may come into contact with the electron extraction electrode 5, and as a result, the cathode electrode 3 and the electron extraction electrode 5 are electrically short-circuited, causing the cold cathode device 1 to malfunction. There are challenges.

  As a solution to this problem, a trimming method for shortening the length of the carbon-based fine fiber 6 using ozone or hydride plasma has been proposed (for example, see Patent Document 1 and Non-Patent Document 1). Trimming refers to a process in which the length of the carbon-based fine fiber 6 is made shorter than that after formation. The carbon-based fine fiber 6 is separated from the electron extraction electrode 5, and the cathode electrode 3 and the electron extraction electrode 5 are separated. It is the process for preventing the electrical short circuit between.

Next, problems in the electron emission characteristics will be described. FEDs have characteristics of faster response and lower power consumption than liquid crystal displays, plasma displays, etc., but there is a need for improved electron emission characteristics to further improve brightness and uniformity. . In order to improve the electron emission characteristics, a method has been proposed in which the surface of the carbon-based fine fiber is activated by irradiating the carbon-based fine fiber with laser light (see, for example, Non-Patent Document 3).
S. Kang, et al. , SID'03 Digest, pp. 802-805 (2003) M.M. Levis, et al. , Proc. IDW / AD'05, pp. 1635-1638 (2005) W. Rochanachirapar, et al. J. et al. Vac. Sci. Technol. B23, pp. 765-768 (2005) JP 2005-317415 A

  However, since the trimming process for improving reliability and the process for improving the electron emission characteristics as described above are conventionally performed in separate containers, the manufacturing process of the cold cathode device becomes complicated and the manufacturing cost increases. There was a problem to do.

  In addition, if an activation process of carbon-based fine fibers by laser light is applied to, for example, a relatively large screen FED, it is difficult to uniformly irradiate the laser light over the entire screen on which the cold cathode elements are formed. Therefore, there has been a problem that the carbon-based fine fibers cannot be stably activated and the electron emission characteristics cannot be improved.

  For example, when the activation process of the carbon-based fine fiber 6 by laser light is to be performed on the cold cathode element 1 having the structure shown in FIG. 12, only the surface of the carbon-based fine fiber 6 is activated. It is difficult to control the laser beam so that the electron extraction electrode 5 and the carbon fine fiber 6 as a whole are thermally damaged and the characteristics of the cold cathode device 1 are deteriorated, so that the electron emission characteristics can be improved. There was no problem.

  The present invention has been made to solve the conventional problems, and a method for manufacturing a cold cathode device capable of improving the reliability and the electron emission characteristics more easily and with controllability than the conventional ones and the use thereof. An object of the present invention is to provide a cold cathode device.

  As a result of repeated experiments and examinations related to the production of carbon-based fine fibers, the inventor of the present invention (1) trimming carbon-based fine fibers by generating oxygen active species by irradiation with light having a wavelength of 185 nm or less, (2) It has been found that the above-described problems can be solved by activating the carbon-based fine fibers by irradiating light having a wavelength of 172 nm or less in an atmosphere containing hydrogen after trimming.

  That is, the manufacturing method of the cold cathode device of the present invention includes a carbon-based fine fiber forming step for forming carbon-based fine fibers, a trimming step for trimming the formed carbon-based fine fibers, and the trimmed carbon-based fine fibers. And an activation treatment step for activating the fiber.

  With this configuration, the manufacturing method of the cold cathode device of the present invention can perform the trimming step and the activation treatment step chemically in the same container, so that it is easier and more controllable than the conventional one. The trimming process of the carbon-based fine fiber can be performed to improve the reliability, and the electron emission characteristics can be improved.

  Moreover, the manufacturing method of the cold cathode element of this invention has the structure which activates the said carbon-type fine fiber by irradiating light to the gas containing hydrogen in the said activation process process.

  With this configuration, the cold cathode device manufacturing method of the present invention activates carbon-based fine fibers by irradiating light to a gas containing hydrogen, so that the electron emission characteristics can be improved as compared with the conventional one. .

  Also, with this configuration, the cold cathode device manufacturing method of the present invention activates only the carbon-based fine fibers in the light irradiation region and does not activate the carbon-based fine fibers outside the light irradiation region. The current due to the electrons emitted from the carbon-based fine fibers outside the light irradiation region is relatively lower than the current due to the electrons emitted from the carbon-based fine fibers within the light irradiation region. The extraction efficiency can be improved.

  Furthermore, the manufacturing method of the cold cathode device of the present invention has a configuration in which the wavelength of the light is 172 nm or less.

  With this configuration, the manufacturing method of the cold cathode device of the present invention can improve the electron emission characteristics over the conventional one by activating the carbon-based fine fiber with light having a wavelength of 172 nm or less.

  Furthermore, the manufacturing method of the cold cathode device of the present invention has a configuration in which the trimming step and the activation processing step are performed in the same container.

  With this configuration, the manufacturing method of the cold cathode device of the present invention is simpler than the conventional method in which these steps are performed in separate containers by performing the trimming process and the activation process in the same container. In addition, the trimming process of the carbon-based fine fiber can be performed with good controllability to improve the reliability, the electron emission characteristics can be improved, and the manufacturing cost can be reduced as compared with the conventional one.

  The cold cathode device of the present invention is a cold cathode device manufactured by the method for manufacturing a cold cathode device according to any one of claims 1 to 4, wherein the carbon-based fine fibers that emit electrons are used. A cathode electrode to be formed; and an electron extraction electrode that is provided opposite to the cathode electrode and has a through-hole through which the electrons pass, and draws the electrons from the carbon-based fine fiber, The density of the current due to the electrons emitted from the carbon-based fine fibers in the projection region in which the through hole is projected in the vertical direction is larger than the density of the current due to the electrons emitted from the carbon-based fine fibers outside the projection region. have.

  With this configuration, in the cold cathode device of the present invention, the current density due to the emitted electrons from the carbon-based fine fibers in the projection region is higher than the current density due to the electrons emitted from the carbon-based fine fibers outside the projection region. Since it is large, it is possible to improve the current extraction efficiency by the electrons emitted from the through hole.

  INDUSTRIAL APPLICABILITY The present invention can provide a method for manufacturing a cold cathode device having an effect that the reliability and electron emission characteristics can be improved more easily and more easily than conventional devices, and a cold cathode device using the same. Is.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, the configuration of the first embodiment of the cold cathode device according to the present invention will be described.

  As shown in FIG. 1, the cold cathode device 10 in this embodiment includes a substrate 11, a cathode electrode 12 formed on the substrate 11, an insulating layer 13 formed on the cathode electrode 12, and an insulating layer 13. An electron extraction electrode 14 formed thereon and carbon-based fine fibers 15 that emit electrons are provided. Although a plurality of cold cathode elements 10 are usually formed on the substrate 11, in order to make the configuration easy to understand, FIG. 1 shows the structure for one cold cathode element.

  The substrate 11 is made of, for example, an insulating material such as glass, ceramics, or silicon, or a conductive material whose surface is covered with an insulating film, such as a silicon substrate whose surface is oxidized.

  The cathode electrode 12 is made of a conductive material such as Cr, Al, Au, Ag, Ti, Ta, Mo, Zr, W, Pt, Ir, Ni, and is electrically connected to the carbon-based fine fiber 15. Has been.

The insulating layer 13 is made of, for example, SiO ₂ , TEOS, Si ₃ N ₄ , Ta ₂ O ₅ , MgO, Al ₂ O ₃ or the like.

  The electron extraction electrode 14 is made of a conductive material such as Cr, Al, Au, Ag, Ti, Ta, Mo, Zr, W, Pt, Ir, or Ni.

  The carbon-based fine fiber 15 is composed of CNT, GNF, or the like, and emits electrons by a voltage applied between the cathode electrode 12 and the electron extraction electrode 14.

  The cold cathode device 10 in the present embodiment is configured as described above, and when a voltage is applied between the cathode electrode 12 and the electron extraction electrode 14, electrons are emitted by the carbon-based fine fibers 15. . When this cold cathode device 10 is applied to an FED, for example, an anode substrate in which an anode electrode and a phosphor layer are sequentially laminated on a glass substrate is prepared, and the electron extraction electrode 14 and the phosphor layer of the cold cathode device 10 are provided. They are placed facing each other and vacuum sealed. In this configuration, when a voltage is applied between the cathode electrode 12 and the electron extraction electrode 14, electrons are emitted by the carbon-based fine fiber 15, and the emitted electrons are interposed between the cathode electrode 12 and the anode electrode. A predetermined image is displayed by accelerating by the applied anode voltage and proceeding in the direction of the anode electrode, passing through the phosphor layer, causing the phosphor layer to emit light, and then performing an operation reaching the anode electrode.

  Next, a method for manufacturing the cold cathode device 10 in the present embodiment will be described. In the present embodiment, a method for manufacturing the cold cathode device 10 by a so-called lift-off method will be described as an example. However, the manufacturing method, dimensions, temperature, and the like described below are examples, and the present invention is not limited to these.

  First, the cathode electrode 12 is formed on the substrate 11 made of, for example, glass (FIG. 2A). Specifically, the cathode electrode 12 is formed, for example, by depositing, for example, a Cr thin film to a thickness of about 10 nm to 5 μm by sputtering or vapor deposition, and then patterning, for example, in a belt shape by photolithography.

Next, an insulating layer 13, an electron extraction electrode 14, and a resist 16 are sequentially formed on the cathode electrode 12 (FIG. 2B). Specifically, for example, SiO ₂ is deposited on the cathode electrode 12 to a thickness of about 100 nm to 5 μm by sputtering or vapor deposition to form an insulating layer 13, and Cr is deposited on the insulating layer 13 by sputtering or vapor deposition, for example. The electron extraction electrode 14 is formed by deposition with a thickness of about 10 nm to 1000 nm by a method, and a resist 16 is applied on the electron extraction electrode 14.

  Subsequently, the insulating layer 13, the electron extraction electrode 14, and the resist 16 are patterned by photolithography and etching to form the electron extraction electrode 14 and the hole 14a (FIG. 2C). Etching of the hole 14a is performed so that the cathode electrode 12 is exposed.

  Further, for example, a catalyst 17 made of a metal containing at least one of Fe, Ni, and Co is deposited on the cathode electrode 12 and the resist 16 to a thickness of about 1 nm to 50 nm by sputtering or vapor deposition (FIG. 3 ( d)).

  Next, the catalyst 16 is left only on the cathode electrode 12 by removing the resist 16 deposited on the electron extraction electrode 14 with a stripping solution by a lift-off method (FIG. 3E).

  And the cold cathode element 31 is obtained by forming the carbon-type fine fiber 15 comprised by CNT, GNF, etc. on the catalyst 17 by chemical vapor deposition methods, such as a thermal CVD method and a plasma CVD method (FIG. 3). (F)). At this time, as shown in FIG. 3 (f), the electron extraction electrode 14 and the carbon-based fine fiber 15 may contact each other. In this case, the electron extraction electrode 14 and the carbon-based fine fiber 15 are electrically short-circuited. As a result, a malfunction occurs.

  Subsequently, a container 41 having a light source 42 that emits light having a wavelength of 185 nm or less, preferably a wavelength of 172 nm or less (hereinafter referred to as this wavelength) in consideration of an activation process described later is prepared. After introducing 31, a gas containing oxygen is injected, and the carbon-based fine fibers 15 are irradiated with light having a wavelength of 172 nm or less. As a result, chemically active species such as ozone and excited oxygen atoms (hereinafter referred to as “oxygen active species”) are generated from oxygen molecules by light having a wavelength of 172 nm or less, and the carbon-based fine fiber 15 is generated by the oxygen active species. Is trimmed (FIG. 4G: trimming step). As a result of the trimming process, the cold cathode element 32 in which the electrical short circuit between the cathode electrode 12 and the electron extraction electrode 14 is eliminated is obtained (FIG. 4 (h)).

  Here, trimming refers to a process of shortening the length of the carbon-based fine fiber 15. By the trimming process, the carbon-based fine fibers 15 are separated from the electron extraction electrode 14 and the electrical short circuit between the cathode electrode 12 and the electron extraction electrode 14 is eliminated. This trimming is performed when ozone or excited oxygen atoms generated by irradiating oxygen-containing gas with light having a wavelength of 185 nm or less cause a chemical reaction such as an oxidative decomposition reaction with the surface of the carbon-based fine fiber 15. It is considered a thing. Note that the wavelength of the light source 42 is set to 172 nm because it is assumed that the same light source 42 performs the activation process described later, and according to an experiment, the wavelength of light used in the trimming process may be 185 nm or less. I know.

Although the trimming step can be performed in the atmosphere, it is preferable that the trimming speed can be arbitrarily controlled by performing it in the container 41 as shown in FIG. For example, by introducing a gas containing oxygen such as O ₂ , CO ₂ , CO or the like into the container 41 or a gas not containing oxygen such as N ₂ or Ar, the amount of oxygen in the container 41 is reduced. The trimming speed can be controlled arbitrarily.

  The trimming speed can be increased or decreased by changing the illuminance of light by changing the distance from the light source 42 to the cold cathode element 31 in the range of 1 mm to 30 cm, for example, in FIG. The temperature can be increased or decreased by changing the temperature of the substrate 11 to 20 to 300 ° C., for example. The above-described distance between the light source 42 and the cold cathode element 31 and the temperature of the substrate 11 are merely examples, and the present invention is not limited to these, and the energy that can generate oxygen active species. Any condition may be used as long as the carbon-based fine fibers 15 are trimmed by light having a wavelength having the above.

  Subsequently, after introducing the cold cathode element 32 into the container 41, a gas containing hydrogen is injected, and the light source 42 irradiates the carbon-based fine fiber 15 with light having a wavelength of 172 nm or less (FIG. 5 (i): activation. Treatment step), the cold cathode device 10 (see FIG. 1) in which the electron emission characteristics from the carbon-based fine fibers 15 are activated and stabilized is obtained. The light source 42 does not necessarily have to be the same as that used in the trimming step (see FIG. 4G), and may have any energy that can activate the carbon-based fine fibers 15. .

  In this activation treatment, the carbon bond on the surface of the carbon-based fine fiber 15 is terminated with hydrogen by a photochemical reaction, so that the electron emission characteristics from the carbon-based fine fiber 15 are activated and stabilized. Conceivable. Similarly to the above-described trimming step (see FIG. 4G), the speed of the activation process is arbitrarily controlled by changing the distance from the light source 42 to the cold cathode element 32 and the temperature of the substrate 11. be able to.

  Next, an experiment for confirming the effects of the trimming process and the activation process in the present embodiment will be described.

First, a substrate on which cold cathode elements as shown in FIG. 6A were integrated was manufactured by a lift-off method. That is, the cold cathode element used in the experiment includes a cold cathode substrate, and the cold cathode substrate is a glass substrate, a cathode electrode using Cr having a thickness of about 200 nm formed on the glass substrate by a sputtering method, and a cathode An electron extraction electrode using SiO ₂ having a thickness of about 2.5 μm formed on the electrode by sputtering, Cr having a thickness of about 200 nm formed on SiO ₂ by sputtering, and a hole formed by etching. On the exposed cathode electrode, an alloy catalyst having a thickness of about 5 nm formed by vapor deposition of Fe, Cr, and Ni and GNF are provided.

  GNF is formed by an infrared lamp installed in a container in which hydrogen alloy and carbon monoxide are introduced at a ratio of about 1: 1 until a pressure corresponding to atmospheric pressure (101 kPa) is reached after forming an alloy catalyst. By heating to about 600 ° C., GNF is grown as carbon-based fine fibers on the alloy catalyst. Further, the cathode electrode and the electron extraction electrode are patterned in a strip shape so as to be orthogonal to each other when the substrate is viewed from above, and the number of electrodes is 192 for the cathode electrode and 64 for the electron extraction electrode. . When the substrate is viewed from above, holes and GNF are formed at the intersections of the cathode electrode and the electron extraction electrode, and a desired position is obtained by applying a voltage to the desired cathode electrode and the electron extraction electrode. Electrons can be emitted from the cold cathode device. In addition, 55 cold cathode elements are integrated at each portion where the cathode electrode and the electron extraction electrode intersect.

  Next, GNF trimming was performed by irradiating with vacuum ultraviolet light for about 30 minutes in a container having a vacuum ultraviolet light source having a dominant wavelength of 160.8 nm. At this time, the input power of the vacuum ultraviolet light source was 150 W, and air was introduced into the container at a pressure of 101 kPa. The distance from the vacuum ultraviolet light source to the cold cathode substrate was about 10 cm, and the temperature of the cold cathode substrate was 23 ° C. After irradiation with vacuum ultraviolet light, the container was evacuated until the pressure in the container was less than 1 Pa, and hydrogen gas was introduced into the container. Hydrogen gas was introduced until the pressure in the container reached a pressure equivalent to atmospheric pressure, and then an activation treatment was performed by irradiation with vacuum ultraviolet light for about 6 hours. At this time, the input power of the vacuum ultraviolet light source was 150 W, and the pressure in the container was atmospheric pressure. The distance between the vacuum ultraviolet light source and the cold cathode substrate was about 10 cm, and the temperature of the cold cathode substrate was 23 ° C.

Furthermore, in order to confirm the effects of the trimming process and the activation process in the present embodiment, an anode substrate as shown in FIG. 6A is disposed opposite to the cold cathode substrate. Here, the anode substrate includes a glass substrate, a transparent electrode as an anode, and a phosphor. In addition, the distance from the cold cathode substrate to the anode substrate is 7 mm, and under a vacuum of 5 × 10 ⁻⁵ Pa, an electron extraction voltage is applied between the cathode electrode and the electron extraction electrode, and between the transparent electrode and the electron extraction electrode. By applying an anode voltage of 300 V to each, electrons emitted from 3520 cold cathode devices were measured as an anode current. As a result, an experimental result as shown in FIG. 6B was obtained as an effect of the trimming process in the present embodiment.

  FIG. 6B shows that by performing the trimming process in the present embodiment, the current flowing through the electron extraction electrode is reduced in the case of the same electron extraction voltage. This is probably because the trimming process of the present embodiment shortens the length of the GNF and reduces the short circuit between the cathode electrode and the electron extraction electrode. In addition, the experimental result shown in FIG. 6B shows that the GNF is actually trimmed by the trimming process in the present embodiment.

On the other hand, the result shown in FIG. 7 was obtained as an effect of the activation process in the present embodiment. The distance from the cold cathode substrate to the anode substrate is about 7 mm, and under a vacuum of 5 × 10 ⁻⁵ Pa, an electron extraction voltage is applied between the cathode electrode and the electron extraction electrode, and between the transparent electrode and the electron extraction electrode. By applying an anode voltage of 300 V, electrons emitted from 3520 cold cathode devices were measured as an anode current. It is shown that the anode current increases in the case of the same electron extraction electrode by applying the activation treatment. This indicates that GNF was actually activated by the activation process of the present embodiment.

  As described above, according to the cold cathode device 10 of the present embodiment, the structure includes the carbon-based fine fibers 15 that have been subjected to the trimming process by the oxygen active species and then subjected to the activation process in hydrogen gas. Therefore, reliability and electron emission characteristics can be improved as compared with the conventional one.

  Therefore, when the cold cathode device 10 in the present embodiment is applied to, for example, an FED, all pixels can be operated, and a display having uniform display characteristics over the entire light emitting surface can be obtained. Significant effect can be obtained in high image quality.

  In addition, according to the method for manufacturing the cold cathode device 10 in the present embodiment, the trimming step for shortening the length after the formation of the carbon-based fine fibers 15 with the oxygen active species, and the activity for activating the carbon-based fine fibers 15. Therefore, it is possible to improve the reliability by performing the trimming process of the carbon-based fine fiber 15 more easily and with better control than the conventional process, and to improve the electron emission characteristics.

  Moreover, according to the manufacturing method of the cold cathode device 10 in the present embodiment, since the trimming step and the activation processing step are performed in the same container, these steps are performed in separate containers. It is possible to improve the reliability by trimming the carbon-based fine fiber more easily and with better controllability than the conventional one, improve the electron emission characteristics, and reduce the manufacturing cost than the conventional one. be able to.

  In the above-described embodiment, the example in which the carbon-based fine fibers 15 are formed by the chemical vapor deposition method has been described. However, the present invention is not limited to this, and other manufacturing methods are used. The same effect can be obtained when the carbon-based fine fiber 15 is formed.

  In the above-described embodiment, the method for manufacturing the cold cathode device 10 by the lift-off method has been described as an example, but the present invention is not limited to this.

(Second Embodiment)
First, the structure of the second embodiment of the cold cathode device according to the present invention will be described.

  As shown in FIG. 8, the cold cathode device 20 in the present embodiment includes a substrate 21, a cathode electrode 22 formed on the substrate 21, a catalyst layer 23 formed on the cathode electrode 22, and a catalyst layer 23. An insulating layer 24 formed above, an electron extraction electrode 25 formed on the insulating layer 24, and carbon-based fine fibers 26 that emit electrons are provided.

  The cold cathode device 20 in the present embodiment is a so-called stacked type, and has a configuration in which a catalyst layer 23 is added to the cold cathode device 10 (see FIG. 1) in the first embodiment. Therefore, the description of the configuration other than the catalyst layer 23 is omitted. In addition, a plurality of cold cathode elements 20 are usually formed on the substrate 21. In order to make the configuration easy to understand, FIG. 8 shows a structure corresponding to one cold cathode element.

  The catalyst layer 23 is made of, for example, a metal containing at least one of Fe, Ni, and Co.

  The cold cathode device 20 in the present embodiment is configured as described above, and when a voltage is applied between the cathode electrode 22 and the electron extraction electrode 25, electrons are emitted by the carbon-based fine fibers 26. . When this cold cathode device 20 is applied to an FED, for example, an anode substrate in which an anode electrode and a phosphor layer are sequentially laminated on a glass substrate is prepared, and the electron extraction electrode 25 and the phosphor layer of the cold cathode device 20 are provided. They are placed facing each other and vacuum sealed. In this configuration, when a voltage is applied between the cathode electrode 22 and the electron extraction electrode 25, electrons are emitted by the carbon-based fine fibers 26, and the emitted electrons are interposed between the cathode electrode 22 and the anode electrode. A predetermined image is displayed by accelerating by the applied anode voltage and proceeding in the direction of the anode electrode, passing through the phosphor layer, causing the phosphor layer to emit light, and then performing an operation reaching the anode electrode.

  Next, a method for manufacturing the cold cathode device 20 in the present embodiment will be described. The manufacturing method, dimensions, temperature, and the like described below are examples, and the present invention is not limited to these.

  First, a cathode electrode 22 and a catalyst layer 23 are sequentially formed on a substrate 21 made of, for example, glass (FIG. 9A). Specifically, the cathode electrode 22 is formed by depositing, for example, a Cr thin film to a thickness of about 10 nm to 5 μm by sputtering or vapor deposition, and then patterning it into a strip shape, for example, by photolithography. Further, after forming the catalyst layer 23 made of a metal containing at least one of Fe, Ni, and Co on the cathode electrode 22 by sputtering or vapor deposition, the catalyst layer 23 is formed on the cathode electrode 22 by etching or lift-off method. To pattern.

Next, an insulating layer 24, an electron extraction electrode 25, and a resist 27 are sequentially formed on the catalyst layer 23 (FIG. 9B). Specifically, for example, SiO ₂ is deposited on the catalyst layer 23 to a thickness of about 100 nm to 5 μm by sputtering or vapor deposition to form an insulating layer 24, and Cr is deposited on the insulating layer 24 by sputtering or vapor deposition, for example. The electron extraction electrode 25 is formed by deposition with a thickness of about 10 nm to 1000 nm by a method, and a resist 27 is applied on the electron extraction electrode 25.

  Subsequently, the insulating layer 24, the electron extraction electrode 25, and the resist 27 are patterned by photolithography and etching to form the electron extraction electrode 25 and the hole 25a (FIG. 9C). The etching of the holes 25a is performed so that the catalyst layer 23 is exposed. In the following description, as shown in FIG. 9C, among the exposed areas of the catalyst layer 23, the area where the hole 25 a is projected is “inside the hole” and the area outside the hole is “outside the hole”. That's it. Here, the hole 25a, the region inside the hole, and the region outside the hole respectively correspond to the through hole, the projection region, and the projection region described in the claims.

  Next, after the resist 27 deposited on the electron extraction electrode 25 is removed with a stripping solution, the carbon-based fine fiber 26 composed of CNT, GNF, or the like is formed by a chemical vapor deposition method such as a thermal CVD method or a plasma CVD method. Is formed on the catalyst layer 23 to obtain the cold cathode element 33 (FIG. 10D). At this time, as shown in FIG. 10D, the electron extraction electrode 25 and the carbon-based fine fiber 26 may come into contact with each other. In this case, the electron extraction electrode 25 and the carbon-based fine fiber 26 are electrically short-circuited. As a result, a malfunction occurs. Note that an electrical short circuit is also generated outside the hole indicated by the broken line in FIG.

  Subsequently, a container (not shown) having a light source 43 that emits light having a wavelength of 185 nm or less, preferably a wavelength of 172 nm or less (hereinafter referred to as this wavelength) is prepared in consideration of the activation process described later. After introducing the cold cathode element 33, a gas containing oxygen is injected, and the carbon-based fine fiber 26 is irradiated with light having a wavelength of 172 nm or less. As a result, oxygen active species are generated by light having a wavelength of 172 nm or less, and the carbon-based fine fibers 26 are trimmed by the oxygen active species (FIG. 10E: trimming step). As a result of the trimming process, the cold cathode element 34 in which the electrical short circuit between the cathode electrode 22 and the electron extraction electrode 25 is eliminated is obtained.

  Here, since it is considered that trimming proceeds when the oxygen active species reacts on the surface of the carbon-based fine fibers 26, the formed carbon-based fine fibers 26 are trimmed isotropically. Due to this isotropic property of trimming, not only the carbon-based fine fibers 26 existing in the hole, but also the carbon-based fine fibers 26 existing outside the hole (in the broken line portion in FIG. 10D) are trimmed uniformly. Will be. As a result, the electrical short circuit between the cathode electrode 22 and the electron extraction electrode 25 can be eliminated not only inside the hole but also outside the hole, and the reliability can be improved.

  Note that the wavelength of the light source 43 is set to 172 nm because it is assumed that the same light source 43 performs the activation process described later, and according to the experiment, the wavelength of light used in the trimming process may be 185 nm or less. I know. In addition, the trimming process can be performed in the atmosphere.

  In the trimming step, the trimming speed can be arbitrarily controlled by changing the distance from the light source 43 to the cold cathode element 33.

  Subsequently, after introducing the cold cathode element 34 into a container (not shown), a gas containing hydrogen is injected, and the light source 43 irradiates the carbon-based fine fiber 26 with light having a wavelength of 172 nm or less (FIG. 11 (f ): Activation treatment step), the cold cathode device 20 (see FIG. 8) in which the electron emission characteristics from the carbon-based fine fibers 26 are activated and stabilized is obtained.

  The light source 43 does not necessarily have to be the same as that used in the trimming step (see FIG. 10E), and may have any energy that can activate the carbon-based fine fibers 26. . In addition, the speed of the activation process can be arbitrarily controlled by changing the distance from the light source 43 to the cold cathode element 34 and the temperature of the substrate 21.

  In the activation process in the present embodiment, as shown in FIG. 11 (f), no light is irradiated outside the hole, so that only the carbon-based fine fibers 26 existing in the hole can be activated. . As a result, the current density due to the emitted electrons from the carbon-based fine fibers 26 existing outside the holes is relatively lower than the current density due to the electrons emitted from the carbon-based fine fibers 26 existing inside the holes. Thus, the rate at which the current due to all the emitted electrons from the carbon-based fine fiber 26 flows into the electron extraction electrode 25, that is, the current extraction efficiency due to the emitted electrons from the hole 25a can be improved.

  Therefore, by providing the trimming process and the activation process in the present embodiment, there is no electrical short circuit between the electron extraction electrode 25 and the carbon-based fine fiber 26 as shown in FIG. 8, that is, the reliability is improved. In addition, the cold cathode device 20 whose electron emission characteristics are improved by the activation process can be manufactured with good controllability by a simple process.

  As described above, according to the cold cathode element 20 in the present embodiment, the structure includes the carbon-based fine fiber 26 that has been subjected to the trimming process by the oxygen active species and then subjected to the activation process in the hydrogen gas. Therefore, reliability and electron emission characteristics can be improved as compared with the conventional one.

  Further, according to the method for manufacturing the cold cathode device 20 in the present embodiment, in the activation process of the carbon-based fine fibers 26, only the carbon-based fine fibers 26 in the light irradiation region are activated, and light irradiation is performed. Since the carbon-based fine fibers 26 outside the region are not activated, the current generated by the electrons emitted from the carbon-based fine fibers 26 outside the light irradiation region is emitted from the carbon-based fine fibers 26 within the light irradiation region. This is relatively lower than the current due to electrons, and the current extraction efficiency can be improved.

  In the above-described embodiment, the example in which the carbon-based fine fibers 26 are formed by the chemical vapor deposition method has been described. However, the present invention is not limited to this, and other manufacturing methods are used. The same effect can be obtained when the carbon-based fine fiber 26 is formed.

  As described above, the method for manufacturing a cold cathode device according to the present invention and the cold cathode device using the same can improve the reliability and electron emission characteristics more easily and with controllability than conventional devices. It is useful as a cold cathode device, a display, an imaging device, a lighting device, etc. having carbon-based fine fibers.

1 is a schematic sectional view showing a first embodiment of a cold cathode device according to the present invention. Schematic sectional view showing the manufacturing process of the first embodiment of the cold cathode device according to the present invention Schematic sectional view showing the manufacturing process of the first embodiment of the cold cathode device according to the present invention Schematic sectional view showing the manufacturing process of the first embodiment of the cold cathode device according to the present invention Schematic sectional view showing the manufacturing process of the first embodiment of the cold cathode device according to the present invention Explanatory drawing of the experimental result in 1st Embodiment of the cold cathode element which concerns on this invention (a) The block diagram of the cold cathode element used in experiment (b) The graph which shows the experimental result of a trimming process The graph showing the experimental result of the activation process in 1st Embodiment of the cold cathode element which concerns on this invention Schematic sectional view showing a second embodiment of a cold cathode device according to the present invention Schematic sectional drawing which shows the manufacturing process of 2nd Embodiment of the cold cathode element which concerns on this invention Schematic sectional drawing which shows the manufacturing process of 2nd Embodiment of the cold cathode element which concerns on this invention Schematic sectional drawing which shows the manufacturing process of 2nd Embodiment of the cold cathode element which concerns on this invention Schematic sectional view of a conventional cold cathode device

Explanation of symbols

10, 20 Cold cathode element 11, 21 Substrate 12, 22 Cathode electrode 13, 24 Insulating layer 14a, 25a Hole 14, 25 Electron extraction electrode 15, 26 Carbon-based fine fiber 16, 27 Resist 17 Catalyst 23 Catalyst layer 31-34 Cold Cathode element 41 Container 42, 43 Light source

Claims (5)

Including a carbon-based fine fiber forming step for forming the carbon-based fine fiber, a trimming step for trimming the formed carbon-based fine fiber, and an activation treatment step for activating the trimmed carbon-based fine fiber. A method for producing a cold cathode device, comprising: 2. The method of manufacturing a cold cathode device according to claim 1, wherein the activation treatment step activates the carbon-based fine fibers by irradiating light to a gas containing hydrogen. 3. The method for manufacturing a cold cathode device according to claim 2, wherein the wavelength of the light is 172 nm or less. The said trimming process and the said activation process process are performed in the same container, The manufacturing method of the cold cathode element of any one of Claim 1- Claim 3 characterized by the above-mentioned. A cold cathode device manufactured by the method for manufacturing a cold cathode device according to any one of claims 1 to 4, wherein a cathode electrode on which carbon-based fine fibers emitting electrons are formed, and An electron extraction electrode provided opposite to the cathode electrode, having a through-hole through which the electrons pass, and withdrawing the electrons from the carbon-based fine fiber;
The density of the current due to the emitted electrons from the carbon-based fine fibers in the projection region in which the through hole is projected in the direction perpendicular to the cathode electrode is the current density due to the electrons emitted from the carbon-based fine fibers outside the projection region. A cold cathode device characterized by having a density greater than the density.

Images