JP4714328B2 - Method for controlling the diameter of graphite nanofibers - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling the diameter of graphite nanofibers, and in particular, when a graphite nanofiber thin film is formed by a thermal CVD method, a graphite nanofiber is used by using a substrate having a metal thin film having a specific thickness as an underlayer. The present invention relates to a method for controlling the diameter. This method can be used to fabricate an electroluminescent device used in place of a flat display (field emission display) or a CRT electron tube.
[0002]
[Prior art]
Conventionally, a cold cathode source, which is an electron emission source that emits electrons without heating, has been proposed in which a conical cathode tip (a tip made of W, Mo, Si, etc.) is formed on an electrode substrate. Yes. In the case of this cathode chip, for example, an emitter manufactured using a Mo chip and used for a display can only be driven by an electric field of 100 V / μm at present.
[0003]
As described above, Si, Mo, and the like have been studied as cathode materials, but in recent years, the use of carbon nanotubes as cathode materials has been studied. The carbon nanotube is a graphite fiber having a multi-structured structure in which the inside of a spiral structure having a carbon 6-membered ring as a main structure has a hollow cylindrical shape and the cylinders are arranged in an extremely fine concentric shape. The performance of the carbon nanotube is superior to other metal materials in performance such as electron emission characteristics, heat resistance, and chemical stability. Carbon nanotubes are usually produced by an arc discharge method, a laser evaporation method, a plasma CVD method, or the like.
[0004]
The inventors of the present invention have made extensive research and development on cathode materials having high electron emission density and low field electron emission performance. The process of forming a film by a thermal CVD method using a carbon-containing gas and hydrogen gas. Thus, a graphite nanofiber having a structure that has not been reported so far has been found, and since this graphite nanofiber has excellent electron emission characteristics, on February 4, 2000 and March 28, 2000, respectively, Patent applications were filed as Application Nos. 2000-28001 and 2000-89468. Unlike the carbon nanotube, the graphite nanofiber is a solid in which graphene sheets are cut into small pieces and laminated, for example, has a cylindrical structure in which crystals having a frustoconical shape are laminated, There is a through gap in the center, which is hollow or filled with amorphous carbon. The obtained graphite nanofiber has a diameter of 10 nm to 600 nm. Those having a diameter of less than 10 nm have not been synthesized so far, and those having a diameter of more than 600 nm have poor electron emission performance. Such graphite nanofibers are useful as cathode materials having excellent electron emission characteristics such as high electron emission characteristics and low field electron emission performance.
[0005]
[Problems to be solved by the invention]
However, when the conventional carbon nanotubes as described above are to be used as a cold cathode source (electron emission source), the electron emission from the carbon nanotubes occurs from the tip or the defect portion, so that it is like a CRT electron source. As an electron emission source that requires a high current density, there is a problem that it cannot be applied so far.
[0006]
The inventors of the present invention have a technique related to the formation of a graphite nanofiber thin film by a thermal CVD method as described above, because it is difficult to efficiently form a graphite nanofiber thin film at a predetermined location on a substrate to be processed. Although a method for selectively forming a graphite nanofiber thin film at a predetermined position has been found, there is a problem that it is difficult to control the diameter of the formed graphite nanofiber when this forming method is performed. .
[0007]
The present invention solves the above-mentioned problems, and as a cathode material capable of achieving high electron emission density and low field electron emission performance, when a graphite nanofiber thin film that can be a carbon-based electron emission source is neglected. Another object of the present invention is to provide a method for controlling the diameter of the obtained graphite nanofiber.
[0008]
[Means for Solving the Problems]
The method for controlling the diameter of the graphite nanofiber according to the present invention is a method in which a catalytic metal thin film of Fe, Co or an alloy containing at least one of these metals is formed on a glass substrate or Si substrate as an underlayer to a thickness of 10 to 50 nm. The substrate formed into a predetermined pattern in step 1 is used as a substrate to be processed, the substrate to be processed is heat-treated under vacuum, and then only a pattern portion on the substrate to be processed is formed by a thermal CVD method using a carbon-containing gas and hydrogen gas. Graphite nanofibers with a desired diameter can be produced by changing the thickness of the catalytic metal thin film within the above range by controlling the diameter of the grown graphite nanofibers by uniformly growing graphite nanofibers can do. The catalytic metal means a metal capable of forming a graphite nanofiber thin film on the metal. When the thickness of the catalytic metal thin film is less than 10 nm, the diameter of the graphite nanofiber to be produced is thin, but the growth rate is too slow, so it is not practical, and when the film thickness exceeds 50 nm, it is produced. Among graphite nanofibers, those with a diameter of about 100 nm or thicker are observed, and the catalyst metal thin film tends to be peeled off, which is not preferable.
[0009]
Moreover, the method for controlling the diameter of the graphite nanofiber according to the present invention comprises forming a catalytic metal thin film of Fe, Co or an alloy containing at least one of these metals as a base layer on a glass substrate or Si substrate to a thickness of 10 to 50 nm. A substrate formed in a predetermined pattern with a thickness is used as a substrate to be processed, and the substrate to be processed placed in a vacuum chamber evacuated is heated with an infrared lamp to heat-treat the substrate to be processed under vacuum. Next, a carbon-containing gas and a hydrogen gas are introduced into the vacuum chamber, and the pressure in the vacuum chamber is maintained at approximately 1 atm, and graphite nanofibers are uniformly applied only to the pattern portion on the substrate to be processed by the thermal CVD method. It consists of growing and controlling the diameter of the grown graphite nanofibers.
[0010]
A non-catalytic metal thin film was formed in a predetermined pattern on a glass substrate or Si substrate as the substrate to be processed, and then Fe, Co, or at least one of these metals was included on the non-catalytic metal pattern. A substrate having a base layer of a two-layer structure in which a catalytic metal thin film of an alloy is formed in a predetermined pattern with a thickness of 10 to 50 nm may be used. A non-catalytic metal means a metal that cannot form a graphite nanofiber thin film on the metal.
[0011]
The temperature at which the heat treatment is performed is preferably 400 ° C. or higher and lower than the heat resistant temperature of the substrate. If the heat treatment temperature is less than 400 ° C., the diameter of the graphite nanofibers can be controlled, but the adhesion of the underlayer to the substrate is poor, so it is not practical. Since no alloying occurs at the interface between the catalyst and the non-catalytic metal, the adhesion between the two layers is poor and impractical. Further, there is a problem that the substrate is deformed when the heat resistance temperature of the substrate is exceeded.
[0012]
The mixing ratio of the carbon-containing gas and the hydrogen gas is preferably carbon-containing gas / hydrogen gas = 0.1 to 10 on a volume basis. When the mixing ratio is less than 0.1, it is difficult to efficiently grow graphite nanofibers. When the mixing ratio exceeds 10, the concentration of carbon-containing gas is too high to control the formation process of the graphite nanofiber thin film. There is a problem that it is practically difficult. Hydrogen gas is used for dilution and catalysis in a gas phase reaction.
[0013]
The temperature at which the thermal CVD method is performed is preferably 450 to 650 ° C. If it is lower than 450 ° C., the carbon-containing gas as the raw material gas is hardly decomposed, so that there is a problem that the growth rate of the graphite nanofiber becomes extremely slow and is not economical. Also, the higher the temperature, the faster the growth rate. However, when the temperature exceeds 650 ° C., there is a problem that it is substantially difficult to control the formation process of the graphite nanofiber thin film.
[0014]
As the carbon-containing gas, for example, a carbon-containing gas such as carbon monoxide, carbon dioxide, or a lower hydrocarbon such as methane can be used, and carbon monoxide or carbon dioxide is preferable.
[0015]
Further, after forming the underlayer metal thin film in a predetermined pattern and performing heat treatment under vacuum, the surface of the catalyst metal thin film of the underlayer is etched by a wet etching method or the like to roughen the surface state, Preferably, a thermal CVD method is performed, which makes the growth of graphite nanofibers extremely good.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
According to the control method of the present invention, as described above, a catalytic metal thin film of Fe, Co, or an alloy containing at least one of these metals is formed into a predetermined pattern with a thickness of 10 to 50 nm as the underlayer. A formed glass substrate or Si substrate is used, or a non-catalytic metal thin film such as Ni, Cu or the like is preferably formed as a base layer in a predetermined pattern, and then Fe film is formed on the non-catalytic metal pattern. A glass substrate or Si substrate on which a catalytic metal thin film of an alloy containing at least one of these metals, Co, or an alloy containing these metals is formed in a predetermined pattern with a thickness of 10 to 50 nm is used under vacuum at a predetermined temperature. Heat treatment is then performed on the catalytic metal thin film pattern of the underlayer using, for example, a carbon-containing gas such as carbon monoxide or carbon dioxide and hydrogen gas by a thermal CVD method. By allowed to grow only graphite nanofibers, it is possible to produce a controlled graphite nanofiber diameter. By setting the catalyst metal thin film of the underlayer to a specific thickness, the diameter of the graphite nanofiber can be controlled, and adhesion between the underlayer and the substrate, or between the catalytic metal thin film and the non-catalytic metal thin film Also improves.
[0017]
When the method of the present invention is carried out using a substrate made of a catalytic metal such as Fe without providing a base layer instead of the glass substrate or Si substrate having the base layer, the diameter of the obtained graphite nanofiber is about 100 nm. Even if the thickness of the substrate is changed, only a substrate having the same diameter can be obtained.
[0018]
The method for forming the metal thin film pattern underlayer on the substrate to be processed is not particularly limited. For example, the sputtering method, the CVD method, the vapor deposition method (for example, the EB vapor deposition method) or the like is used. This can be done by forming and adhering a pattern to a predetermined location. Alternatively, a substrate in which the metal thin film pattern is applied to a predetermined portion of the substrate surface by a photolithography process performed by applying a known photosensitive resin liquid on the substrate surface, by a printing process, or by a plating process or the like. As a result, graphite nanofibers may be uniformly grown by thermal CVD as described above at locations where this metal thin film has been applied. The shape of the pattern is not particularly limited, and may be a straight line, a curve, a dotted line, or any other arbitrary shape.
[0019]
In the method for controlling the diameter of graphite nanofibers according to the present invention, first, a substrate holder equipped with a substrate to be processed having an underlayer pattern as described above is disposed in a vacuum chamber of a thermal CVD apparatus equipped with an infrared lamp. The vacuum chamber is evacuated until it reaches 0.1 to 0.01 Torr. In this state, an infrared lamp provided opposite to the substrate to be processed is energized in the upper part of the vacuum chamber, and heat treatment is performed at a temperature of 400 ° C. or higher and lower than the heat resistant temperature of the substrate for 1 to 30 minutes. Thereafter, a mixed gas of carbon-containing gas and hydrogen gas is introduced into the chamber at a predetermined volume ratio, preferably carbon-containing gas / hydrogen gas = 0.1 to 10, and gas replacement is performed. In this case, the substrate is heated using the infrared lamp, and a graphite nanofiber thin film is formed by uniformly growing graphite nanofibers only on the catalytic metal pattern on the substrate, preferably at a temperature of 450 ° C. to 650 ° C. Form. In this way, the diameter of the graphite nanofiber can be controlled to, for example, about 25 nm or less according to the thickness of the catalyst metal thin film of the underlayer. If the mixed gas is preheated before being introduced into the vacuum chamber, the temperature can be raised to the film forming temperature in a short time, and the film forming speed is adjusted by providing such a heating means. You can also.
[0020]
In the case of the graphite nanofibers with controlled diameters obtained as described above, it is possible to improve the field electron emission characteristics from the carbon-based electron emission source. In other words, it is possible to emit electrons with a sufficiently high current density to the extent that it can be used for a CRT electron source with a low applied voltage similar to that of conventional carbon nanotubes.
[0021]
The thermal CVD apparatus for carrying out the method for controlling the diameter of the graphite nanofiber of the present invention is not particularly limited, but for example, an apparatus having a configuration as shown in FIGS. 1 and 2 of the attached drawings is used. can do.
[0022]
One example of a thermal CVD apparatus used for carrying out the method of the present invention is an apparatus described in Japanese Patent Application No. 2000-89468. As shown in FIG. 1, this apparatus introduces a raw material gas together with hydrogen gas into a stainless steel vacuum chamber 1 constituting a film forming chamber, and forms graphite nanofibers on a substrate to be processed 3 mounted on a substrate holder 2. An apparatus for forming a thin film, wherein an infrared transmission window 4 made of heat-resistant glass such as quartz is provided on the upper wall surface of the vacuum chamber 1 facing the substrate holder 2, and a substrate is provided outside the infrared transmission window 4. An infrared heater 5 for heating is provided, and the graphite nanofiber thin film can be formed on the substrate while the substrate 3 is heated by the infrared heater 5. The pressure in the vacuum chamber during thin film formation is maintained at approximately 1 atmosphere. Further, the heat treatment of the substrate to be processed 3 on which the metal thin film pattern of the underlayer is formed can be performed in the vacuum chamber 1 under vacuum.
[0023]
The vacuum chamber 1 is connected to a vacuum pump 7 via a valve 6 so that the inside of the vacuum chamber 1 can be evacuated. A vacuum gauge 8 is attached to the vacuum chamber 1 so that the pressure in the chamber can be monitored. It is like that.
[0024]
A gas supply system 9 is also connected to the vacuum chamber 1. The gas supply system 9 includes a source gas supply system that is connected in series to a source gas cylinder 10d such as carbon monoxide gas through a gas pipe from a valve 10a via a gas flow rate regulator 10b and a pressure regulator 10c. 11a through a gas flow rate regulator 11b and a pressure regulator 11c are provided in parallel with a hydrogen gas supply system connected in series to the hydrogen gas cylinder 11d through a gas pipe, and the raw material gas supply system and the hydrogen gas supply system are The valves 10a and 11a and the vacuum chamber 1 are joined together, and a mixed gas of carbon-containing gas and hydrogen gas is supplied into the vacuum chamber. The mixed gas is allowed to reach the substrate 3 without being heated by the infrared heater 5.
[0025]
Cooling means 12 for cooling the vacuum chamber is provided outside the vacuum chamber 1, the inner wall of the vacuum chamber 1 is covered with an insulator 13, the infrared transmission window 4 is made of heat-resistant glass, and the substrate holder 2 is attached to the substrate holder 2. A resistance heater 14 may be provided.
[0026]
Further, another thermal CVD apparatus used for carrying out the method of the present invention includes a vacuum chamber 21 made of metal such as stainless steel and a load lock chamber 22 constituting a film forming chamber, as shown in FIG. It is a thing. In this vacuum chamber 21, an arbitrary number of support columns 25 for mounting a substrate holder 24 on which a substrate 23 to be processed is placed are provided, and in the load lock chamber 22, a transfer robot 26 is provided. . Further, a vacuum pump 27 is connected to the load lock chamber 22, and a vacuum gauge 29 is attached to measure and monitor the degree of vacuum in the room. The substrate holder 24 on which the substrate 23 to be processed is mounted is transferred from the substrate storage chamber to the load lock chamber 22 by the transfer robot 26. Next, the load lock chamber 22 is evacuated to a predetermined degree of vacuum (about 0.01 Torr), the gate valve 30 is opened, and the substrate to be processed is placed in the vacuum chamber 21 evacuated to a predetermined degree of vacuum. The substrate holder 24 to which the 23 is mounted is transported and placed on the column 25. When the transfer robot 26 is returned to the load lock chamber 22, the gate valve 30 is closed. In the above description, the substrate holder is transported to transport the substrate holder 24 on which the substrate 23 to be processed is mounted. However, the substrate is transported and fixed on the support 25 in the vacuum chamber 21. The substrate may be transported by placing the substrate on the holder 24.
[0027]
On the upper wall surface of the vacuum chamber 21, an infrared transmission window 31 made of heat-resistant glass such as quartz is provided so as to face the substrate to be processed 23, and a plurality of infrared rays having a predetermined arrangement outside the window. A lamp 32 is attached so that the substrate to be processed 23 can be heated uniformly.
[0028]
A vacuum pump 34 is connected to the vacuum chamber 21 via a valve 33 so that the inside of the vacuum chamber can be evacuated. A pipe 28 that bypasses the vacuum pump 34 is provided with a valve 39 interposed. Further, a vacuum gauge 35 is attached to the vacuum chamber 21 at an arbitrary location so that the degree of vacuum in the vacuum chamber can be measured and monitored. The vacuum gauge 35 may be connected to any location of such an exhaust system. Note that the heat treatment under vacuum on the substrate to be processed 23 on which the pattern of the metal thin film of the underlayer is formed can be performed in the vacuum chamber 21.
[0029]
A gas supply system 36 is connected to the vacuum chamber 21. The gas supply system 36 includes a source gas supply system connected in series with a source gas cylinder 37e such as carbon monoxide through a gas pipe from a valve 37a through a gas flow rate regulator 37b, a pressure regulator 37c, and a valve 37d. A hydrogen gas supply system connected in series with a gas pipe from the valve 38a to the hydrogen gas cylinder 38e via a gas flow rate regulator 38b, a pressure regulator 38c and a valve 38d is provided in parallel. The source gas supply system and the hydrogen gas supply system are configured to join between the valves 37 a and 38 a and the vacuum chamber 21 and supply a mixed gas of carbon-containing gas and hydrogen gas into the vacuum chamber 21. . The introduction of the mixed gas is performed through gas injection nozzle means provided so as to be lower than the mounting position of the substrate to be processed 23 or the substrate holder 24 and to surround the substrate in the vicinity of the outside thereof. The gas injection nozzle means connected to the gas supply system 36 is provided with a gas flow passage inside, and a plurality of gas injection ports communicating with the internal gas flow passage are arranged in an upper surface thereof. Any shape can be used as long as the gas can be uniformly injected into the vacuum chamber. The gas injection nozzle means is preferably disposed in surface contact with the bottom wall and / or side wall surface in the vacuum chamber 21. This is for cooling the gas injection nozzle means. By providing such gas injection nozzle means, when the mixed gas is injected upward from the plurality of gas injection ports, the mixed gas is uniformly diffused over the entire upper portion of the substrate to be processed 23, and then downward. It descends evenly and reaches uniformly over the entire substrate to be processed. Thus, a uniform film thickness distribution can be achieved. The gas injection nozzle means disposed in the vacuum chamber 21 is preferably made of a metal having a high thermal conductivity such as Cu.
[0030]
Further, the inner wall of the vacuum chamber 21 may be mirror-polished and the inner wall may be coated with an insulator such as alumina by thermal spraying. This is to prevent the produced graphite nanofibers from adhering to the wall surface. Further, in order to prevent the graphite nanofibers from adhering to the wall surface of the vacuum chamber, as a means for cooling the wall surface, a cooling medium, for example, a cooling pipe for flowing cooling water may be provided on the outer periphery of the chamber. Furthermore, a heating mechanism for preheating the mixed gas introduced into the vacuum chamber 21 may be provided.
[0031]
【Example】
A method for controlling the diameter of graphite nanofibers performed using the apparatus shown in FIG. 2 among the thermal CVD apparatuses having the above-described configuration will be described below with reference to examples.
Example 1
By EB vapor deposition, Ni is vapor-deposited at a thickness of 100 nm only on a predetermined portion (pattern portion of a predetermined shape) on a glass substrate, and Fe is deposited on this Ni thin film pattern in four types of 10, 20, 50, and 100 nm. Vapor deposited with thickness. Next, the substrate 23 on which the two layers of Ni thin film and Fe thin film are deposited on the substrate holder 24 is mounted on the substrate holder 24 by the transfer robot 26 from the substrate storage chamber for the substrate holder in the vacuum chamber 21 of the thermal CVD apparatus. It was placed on the support column 25. While the vacuum pump 34 was operated, the valves 33a and 33b were opened, and the pressure in the vacuum chamber was measured with the vacuum gauge 35, and evacuation was performed to about 0.05 Torr. The infrared lamp 32 was energized to bring the substrate temperature to 500 ° C., and heat treatment was performed under this temperature for 5 minutes. Thereafter, the main plugs of the carbon monoxide gas cylinder 37e and the hydrogen gas cylinder 38e are opened, adjusted to about 1 atm (absolute pressure) by the pressure regulators 37c, 38c, and the valves 37a, 38a are opened to open the gas flow regulators 37b, 38b. Thus, a mixed gas of carbon monoxide gas and hydrogen gas (capacity ratio: CO: H ₂ = 30: 70) is adjusted to about 1000 sccm, and the vacuum chamber 21 is moved from below the substrate holder 24 to be processed. Then, the gas was replaced through gas injection nozzle means. At this time, the valves 33a and 33b were closed, the vacuum pump 34 was stopped, and the valve 39 of the bypass pipe 28 was opened, so that the inside of the vacuum chamber 21 became almost atmospheric pressure (760 Torr). In this case, the mixed gas was introduced in a state where the infrared lamp 32 was energized and the substrate to be processed 23 was heated to 500 ° C.
[0032]
In this embodiment, after the pressure in the vacuum chamber 21 becomes atmospheric pressure, the infrared lamp 32 is energized to heat the substrate to be processed 23 to 500 ° C., and this temperature is applied by thermal CVD for 20 minutes. The growth reaction of graphite nanofibers was performed on the substrate. When the carbon monoxide gas reached the target substrate 23, the carbon monoxide was dissociated, and a graphite nanofiber thin film was formed only on the Fe thin film pattern deposited on the target substrate. The substrate after the growth reaction was taken out from the vacuum chamber 21 and the graphite nanofiber thin films obtained when the film thickness of the Fe thin film pattern was 10, 20, and 50 nm were measured with a scanning electron microscope (SEM, × 40000). ), A thin graphite nanofiber with a diameter of about 20 to 50 nm grows when the film thickness is 10 nm (FIG. 3), and a thin graphite nanofiber with a diameter of about 20 to 50 nm grows when the film thickness is 20 nm. However, in the case of a film thickness of 50 nm, thin graphite nanofibers with a diameter of about 20 to 50 nm are growing, but thick graphite nanofibers with a diameter of about 100 to 200 nm are also growing somewhat (FIG. 5). I understand. Further, when the film thickness is 100 nm, it is possible to grow a thick graphite nanofiber having a diameter of about 100 nm, but this Fe thin film pattern has been peeled off from the substrate. From the above, by setting the film thickness of the catalyst metal thin film pattern of the underlayer to 10 to 50 nm, the diameter of the formed graphite nanofiber can be controlled to about φ50 nm or less, and No peeling occurred.
[0033]
Further, instead of the substrate to be processed having the base layer, an Fe plate having a thickness of 125 μm was used as it was, and after heat treatment under vacuum in the same manner as described above, a thermal CVD method was performed. When the graphite nanofibers formed on this Fe plate were observed by SEM in the same manner as described above, only thick ones with a diameter of about 100 nm were obtained (FIG. 6). Similar results were obtained even when the thickness of the Fe substrate was changed.
[0034]
The characteristics of the electron emission source comprising the graphite nanofiber thin film thus obtained were measured. As a result, the start of electron emission was confirmed when the applied electric field reached 1 V / μm, and the amount of electron emission increased as the applied electric field was increased thereafter, reaching about 100 mA / cm ² at 5 V / μm.
(Example 2)
The underlayer was formed by changing the EB vapor deposition method of Example 1 to the sputtering method, and a graphite nanofiber thin film was formed according to the same procedure as in Example 1. When the obtained graphite nanofiber thin film was observed in the same manner as in Example 1 for the substrate on which the growth reaction had been completed, the same result was obtained.
(Example 3)
Instead of the substrate used in Example 1, a substrate having a single underlayer formed by pattern-depositing Fe in four types of thicknesses of 10, 20, 50, and 100 nm only at predetermined positions on a glass substrate. A graphite nanofiber thin film was formed using the same procedure as in Example 1. When the obtained graphite nanofiber thin film was observed in the same manner as in Example 1 for the substrate on which the growth reaction had been completed, the same result was obtained.
[0035]
In the above embodiment, an underlayer pattern having a two-layer structure made of an Ni thin film and an Fe thin film having a specific thickness on a glass substrate, or an underlayer pattern having a single layer structure made of an Fe thin film having a specific thickness. In this example, a graphite nanofiber thin film was formed only on the pattern portion, and the diameter was examined. A thin film pattern of a non-catalytic metal such as Cu other than Ni, a specific film of a catalytic metal other than Fe Similar results were obtained in the case of a thin film pattern having a thickness and also in the case of forming a metal thin film as a base layer on a Si substrate.
[0036]
【The invention's effect】
According to the present invention, a glass substrate or Si substrate having a base layer composed of a single layer structure of a catalytic metal thin film pattern having a thickness of 10 to 50 nm, or a non-catalytic metal thin film pattern and a catalytic metal having a thickness of 10 to 50 nm. Using a glass substrate or Si substrate having an underlayer composed of a two-layer structure with a thin film pattern, this is heat-treated under vacuum, and then the thermal CVD method is performed to appropriately adjust the diameter of the produced graphite nanofibers. It is possible to control. In that case, the adhesiveness between a base layer and a board | substrate and the adhesiveness between both by alloying in the interface of a catalyst metal and a non-catalyst metal also improve. Therefore, by utilizing this method, a carbon-based electron emission source (cold cathode source) that can achieve high electron emission density and low field electron emission performance can be produced and provided. It is also possible to provide a display element that has a system electron emission source and enables light emission of a desired portion of a light emitter.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a film forming apparatus for carrying out a method of the present invention.
FIG. 2 is a schematic configuration diagram showing another example of a film forming apparatus for carrying out the method of the present invention.
FIG. 3 is an SEM micrograph (× 40000) of graphite nanofibers obtained by the method of the present invention (Fe thin film thickness: 10 nm).
FIG. 4 is a SEM micrograph (× 40000) of graphite nanofibers (Fe thin film thickness: 20 nm) obtained by the method of the present invention.
FIG. 5 is a SEM micrograph (× 40000) of graphite nanofibers (Fe thin film thickness: 50 nm) obtained by the method of the present invention.
FIG. 6 is an SEM micrograph (× 40000) of graphite nanofibers formed using an Fe plate (thickness: 125 μm) as a substrate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Substrate holder 3 Substrate 4 Infrared transmission window 5 Infrared heater 6 Valve 7 Vacuum pump 8 Vacuum gauge 9 Gas supply system 10a, 11a Valve 10b, 11b Gas flow regulator 10c, 11c Pressure regulator 10d, 11d Gas cylinder DESCRIPTION OF SYMBOLS 12 Cooling means 13 Insulator 14 Resistance heating type heater 21 Vacuum chamber 22 Load lock chamber 23 Substrate 24 Substrate holder 25 Prop 26 Transport robot 27 Vacuum pump 29 Vacuum gauge 30 Gate valve 31 Infrared transmission window 32 Infrared lamp 33a, 33b Valve 34 Vacuum pump 35 Valve 36 Gas supply system 37a, 38a Valve 37b, 38b Gas flow regulator 37c, 38c Pressure regulator 37d, 38d Valve 37e, 38e Gas cylinder 39 Valve

Claims (8)

A glass substrate or a Si substrate, and as a base layer, Fe, and Co or the target substrate the substrate was allowed formed on the catalytic metal film to Jo Tokoro pattern of alloy containing at least one of these metals,該被process after the substrate was heat treated under vacuum, by a thermal CVD method, a carbon-containing gas and hydrogen gas, only the graphite nanofiber film forming method Ru allowed uniformly grow graphite nanofibers pattern portion on該被substrate, the method of the diameter of the graphite nanofibers and controlling the diameter of the graphite nanofibers grown by controlling the thickness of the catalytic metal film to a thickness of 10 to 50 nm. A glass substrate or a Si substrate, using as a base layer, Fe, Co or substrate was allowed formed catalytic metal film Jo Tokoro pattern of alloy containing at least one of these metals as a substrate to be processed, evacuation The substrate to be processed placed in the vacuum chamber is heated with an infrared lamp to heat-treat the substrate to be processed under vacuum, and then a carbon-containing gas and hydrogen gas are introduced into the vacuum chamber. while maintaining the pressure to approximately one atmosphere, the graphite nanofiber film forming method Ru allowed uniformly grow graphite nanofibers by a thermal CVD method only the pattern portion on該被substrate, the thickness of the catalytic metal film 10 graphite Na characterized by controlling the size of the graphite nanofibers grown by controlling the thickness of ~50nm Method of controlling the diameter of the fiber. A non-catalytic metal thin film was formed in a predetermined pattern on a glass substrate or Si substrate as the substrate to be processed, and then Fe, Co, or at least one of these metals was included on the non-catalytic metal pattern. 3. The method for controlling the diameter of graphite nanofiber according to claim 1, wherein a substrate having a base layer having a two-layer structure in which a catalytic metal thin film of an alloy is formed in a predetermined pattern is used.   The method for controlling the diameter of the graphite nanofiber according to any one of claims 1 to 3, wherein a temperature at which the heat treatment is performed is 400 ° C or more and a heat resistant temperature of the substrate or less.   The graphite nanofiber according to any one of claims 1 to 4, wherein a mixing ratio of the carbon-containing gas and the hydrogen gas is, on a volume basis, carbon-containing gas / hydrogen gas = 0.1 to 10. Diameter control method.   The method for controlling the diameter of the graphite nanofiber according to any one of claims 1 to 5, wherein a temperature at which the thermal CVD method is performed is 450 to 650 ° C.   The method for controlling the diameter of graphite nanofiber according to any one of claims 1 to 6, wherein the carbon-containing gas is carbon monoxide or carbon dioxide.   The base layer is formed, and after heat treatment, the surface of the catalytic metal thin film of the base layer is etched to roughen the surface state, and then a thermal CVD method is performed. The method for controlling the diameter of the graphite nanofiber according to any one of 7.

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