JP2001261316A - Method of crowing carbon nanotube and method of producing electron gun and probe using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of growing a carbon nanotube, by which the carbon nanotube can locally be grown only at the tip of a projection in a controlled length and by which the by-production of wastes as impurities can be suppressed. SOLUTION: This method of growing a carbon nanotude, comprising forming a mask layer 120 comprising a silicon oxide film obtained by thermally oxidizing a conical shape 104 and a surface layer 102 on the conical shape 104 and the surface layer 102 except the tip portion 104A, bringing the tip portion 104A into contact with a catalyst 140 in a state having the formed mask layer, decomposing a carbon-containing gas under a heated state to grow the carbon nanotube 110 in the tip portion 104A in the gas phase, thus projecting the tip 110A of the carbon nanotube from the tip portion 104A, and then peeling the mask layer 120 to remove the carbon mass 150 formed on the mask layer 120.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for growing carbon nanotubes and a method for manufacturing an electron gun and a probe using the same.

[0002]

2. Description of the Related Art For example, as a device using a cold cathode as an electron emission source (electron gun),
FED (Field Emission Display) is known. F
An ED is a display that emits electrons by emitting electrons emitted into a vacuum by field emission into a phosphor. The light emission principle of FED is CRT (Cathode Ray
Tube), but the CRT scans the two-dimensional phosphor with the electron beam from the point electron source, while F
Since the ED has a planar electron source in which a number of field emission electron sources (Field Emitters) are arranged, it is possible to make an extremely thin panel with low power consumption. The FED is a self-luminous display that does not require external light (backlight in the case of a transmissive type, external light in the case of a reflective type) unlike a liquid crystal display device. It can be provided, and has high luminous efficiency and does not require a light source, so that power consumption is small.

In the FED, electrons are extracted from an emitter by a gate electrode (also called a grid),
The electrons are incident on the anode on which the phosphor is formed. By controlling the voltage applied to this gate electrode,
The amount of electrons emitted from the emitter is controlled, and gray scale display becomes possible.

[0004] In the FED, electron emission is generated from an emitter according to the Fowler-Nordheim rule. According to the Fowler-Nordheim equation, the operating voltage can be reduced by reducing the tip radius of the emitter electrode, bringing the emitter-gate closer, and using a low work function material for the emitter. I have.

[0005] A practically used FED uses a Spindt-type conical emitter cone made of Mo as a field emission electron source. The voltage is concentrated on the sharp portion of the emitter cone to make it easier to extract electrons.

A Spindt-type emitter is disclosed in
48083, JP-A-8-202286, JP-A-8-30
6327, JP-A-9-245618, JP-A-10-50
240, and Japanese Patent Application Laid-Open No. 10-208649.

The ability of a Spindt-type emitter to emit electrons into a vacuum depends on the shape of the three-dimensional structure, and in particular, on the apex angle or tip diameter of the emitter cone.

However, in the current fine processing technology, the diameter of the tip of the emitter cone is about 10 nm, and there is room for further improvement. In addition, it is difficult to form an emitter cone with fine processing of about 10 nm, and the size of the exposure apparatus naturally limits the increase in area. Particularly, it is difficult to produce a panel of several tens of inches or more using the current photolithography technology. Met.

Since molybdenum (Mo) and the like have a large work function, a technique of forming a diamond-like carbon having a low work function on the cathode surface has also been provided (Japanese Patent Application Laid-Open Nos. 10-112736 and 10-112736). 502
06, JP-A-10-134701, JP-A-10-199
398).

However, even if the surface of the emitter edge from which atoms are emitted is covered with a material having a low work function, the tip diameter of the emitter cone is still around 10 nm, and the problem of sharpening still remains.

In Applied Physics Vol. 67, No. 12 (1998), pp. 1390-1394, anisotropic chemical etching (ODE) or reactive ion etching (RIE) is used to form a Si emitter cone. An experiment has been reported in which low-temperature thermal oxidation is performed after etching to sharpen the Si emitter cone.

However, it is extremely difficult to carry out the ultrafine processing uniformly on a large number of Si emitter cones on the substrate.

As a solution to both the sharpening of the emitter edge and the use of a material having a low work function, it has been proposed to use a carbon nanotube as an emitter. Utilization of carbon nanotubes as an emitter is disclosed in JP-A-10-208677 and JP-A-10-19.
9398 and the aforementioned Applied Physics Vol. 67, No. 12, (199)
8).

JP-A-10-208677 and Applied Physics Vol. 67, No. 12 describe that carbon nanotubes are arranged vertically. Although this arrangement method is not directly disclosed in each of the above documents, it was necessary to collect carbon nanotubes formed by using an arc discharge with a solution or the like, and to paste them on a substrate in a uniform direction.

However, it is difficult to handle carbon nanotubes of nano-order size, and quality (length,
It is practically impossible to mass-produce carbon nanotubes with uniform diameter, chirality, electric resistance, etc. and to attach them to a substrate. When the carbon nanotube is made longer in consideration of handling (Japanese Patent Laid-Open No. 10-20867)
7 has a vertical diameter of 10 nm and a length of 1 μm), increases the electrical resistance, and requires a large amount of carbon nanotubes to secure a sufficient current as an emitter.

Japanese Patent Application Laid-Open No. 10-199398 states that carbon nanotubes can be deposited on a cathode by a method such as arc plasma discharge of a carbon material, laser ablation, or the like.

However, there is no disclosure of a method of depositing carbon nanotubes with the axial direction directed toward the anode.

The present inventor has proposed, as a prior application, a method of manufacturing an electron gun which solves the above-mentioned problems of the prior art (Japanese Patent Application No. 11-245033).

An object of the present invention is to further improve the invention of the prior application, and to grow carbon nanotubes locally and at a controlled growth length only on the tops of projections, and to generate dust as impurities. It is an object of the present invention to provide a method for growing carbon nanotubes capable of suppressing the occurrence of an electron gun and a method for producing an electron gun and a probe using the method.

[0020]

According to one aspect of the present invention, there is provided a method for growing a carbon nanotube, comprising: forming a projection having a top on a surface layer; Forming a mask layer different from the material for forming the surface layer and the protrusions, contacting the top not covered with the mask layer with a catalyst, and containing carbon under heating Decomposing a gas, vapor-growing carbon nanotubes on the tops, and projecting the tips of the carbon nanotubes from the tops.

According to one aspect of the invention, the area other than the top that is to be brought into contact with the catalyst is covered by a mask layer. In the region where the catalyst has come into contact, carbon nanotubes can be surely grown. The reason for this is that the nucleus is easily formed on the top by the catalyst, or it literally functions as a catalyst during the vapor phase growth of carbon nanotubes. As described above, since the region in contact with the catalyst is limited to the top of the protrusion, the growth length of the carbon nanotube can be controlled by controlling the growth time of the carbon nanotube formed on the top. If other area (proximal end and surface layer)
If the growth of other carbon nanotubes or unnecessary carbon lump progresses in parallel with the top in other regions without being masked, it will cause the growth length of the top carbon nanotube to vary, and the top carbon nanotube This is because the growth length cannot be accurately controlled.

The process gas in the vapor phase growth step is preferably a hydrocarbon-based gas, and more preferably contains at least one selected from methane, ethane and propane. After the carbon nanotube vapor phase growth step, a step of removing the mask layer can be performed.

Unnecessary carbon lumps are formed on the mask layer during the vapor phase growth step. This unnecessary carbon lump is easily peeled off and has an adverse effect as an impurity, but the carbon lump can be removed together with the mask layer.

In one embodiment of the present invention, a step of removing the mask layer may be provided before the step of vapor-phase growing carbon nanotubes. In this case, the base end of the protrusion and the surface layer are exposed during the vapor phase growth, but since the mask layer formed in these regions does not come into contact with the catalyst, unnecessary carbon is exposed. No lump is produced.
Although there is a possibility that the unnecessary carbon lump is formed on a part of the top portion, the generation region thereof is extremely narrow, so that the risk of causing a variation in the growth length of the carbon nanotube on the top portion is considerably reduced.

The carbon nanotubes used in the present invention may be either single-walled or multi-walled, but more preferably single-walled nanotubes whose tip can be made smaller in diameter.

The surface layer and the projection are preferably made of any of amorphous silicon, polycrystalline silicon, single crystal silicon and conductive silicon doped with impurities. With these materials, carbon nanotubes can be directly grown. Further, by heat-treating the surface layer and the projection, the mask layer can be formed using a silicon compound such as a silicon oxide film or a silicon nitride film. The materials of the surface layer and the protrusion are not limited to those described above, and may be, for example, a metal thin film, a semiconductor, or the like.
Further, if the surface layer and the protruding portions are the above-mentioned materials, the substrate itself as a base material for forming these may be an insulator such as a glass substrate.

As the material of the mask layer, in addition to the above-described silicon compound, a semiconductor, polycrystalline silicon, amorphous silicon, metal, or an organic molecular film can be used. The mask layer may be made of any material that can prevent the lower layer of the mask layer from coming into contact with the catalyst and that can be peeled off from the lower layer later. In addition, when the mask layer is removed after the vapor phase growth step, the mask layer is required to be made of a material that can withstand high temperatures during the vapor phase growth step. When the mask layer is formed of a photoresist, it can be removed by ashing or the like, and when formed of an organic molecular film, it can be removed by etching or ashing. When the mask layer is formed of a metal such as tungsten, platinum, titanium, germane, or the like, it can be removed by dry etching or dissolving with acid.

In one embodiment of the present invention, the step of forming the mask layer so as to cover the surface layer and the protrusions, and the step of forming a coating layer, which is different from a material for forming the mask layer, on the mask layer, Forming the projections except for the top portion by forming a top portion, removing the mask layer on the top portion that is not covered with the coating layer, and then removing the coating layer. The mask layer covering the portion and the surface layer can be formed.

In this case, the coating layer can be formed of any of a photoresist, an organic molecular film, a semiconductor, polysilicon, amorphous silicon, and a metal.

The catalyst may be a solution containing chloride. The solution preferably contains at least one chloride selected from ferrous chloride, ferric chloride, molybdenum oxide chloride, and silicon chloride. In this case, an alcohol solution is used as a solvent for the solution. be able to. Also,
This solution can include a surfactant.

According to another aspect of the present invention, there is provided an electron having a sharp emitter formed on a surface layer of a substrate, a grid for controlling electron emission from the emitter, and an anode opposed to a tip of the emitter. In a method for manufacturing a gun, the emitter is formed by using the above-described method for growing a carbon nanotube according to one embodiment of the present invention.

In the electron gun manufactured in this manner, the tip of the carbon nanotube directly grown on the projection projects from the tip of the projection, and the tip of the carbon nanotube is used as an emitter edge. Electrons can be emitted from the tip. Since the carbon nanotubes are formed along the protrusions, the carbon nanotubes can be arranged with the axial direction facing the anode. At this time, even if the axial direction of the carbon nanotube is not necessarily perpendicular to the anode surface, the emitted electrons can reach the anode by the electric field. Since the diameter of the carbon nanotube is as thin as 1 to 10 nm, the tip is sharpened and the emitter edge can be formed by carbon having a low work function. Also, since the carbon nanotubes are grown directly on the protrusions, there is no need for operations such as sticking,
The length of the carbon nanotube can be set optimally.

As an electronic device using this electron gun, a field emission display can be mentioned. This display has an anode in which a phosphor is formed for each pixel, and an electron gun array configured by arranging one or a plurality of electron guns formed as described above so as to face each pixel. The emitter of the field emission display uses the tip of the carbon nanotube as an emitter edge, thereby sharpening the emitter edge, thereby eliminating the need for fine processing. Accordingly, this field emission display can be adapted to a large screen.

As other electronic equipment using this electron gun,
Examples thereof include a scanning electron microscope, an electron beam exposure device, an exposure device, and a repair device.

According to still another aspect of the present invention, in a method of manufacturing a probe having a cantilever, a projection formed at the tip of the cantilever, and a contact projecting from the projection, the contact is described above. It is formed using the method for growing a carbon nanotube according to one embodiment of the present invention.

Electronic devices using this kind of probe include an atomic force microscope, a scanning tunnel microscope, a scanning probe microscope, and the like.

In these methods for manufacturing an electron gun or a probe, a vapor phase growth step is performed until the tip of the carbon nanotube protrudes from the tip of the projection, so that the carbon nanotube having a desired projection length is placed on the projection. Can be grown directly. Therefore, this carbon nanotube can be suitably used as an emitter edge of an electron gun and a contact of a probe.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electron gun to which the method of the present invention is applied will be described below with reference to the drawings.

(Explanation of Principle of Electron Gun of the Present Invention) FIG. 1 is a schematic explanatory view showing the principle of an electron gun to which the method of the present invention is applied. In FIG. 1, a large number of projections, for example, Si cones 12 are formed on the surface of, for example, a conductive silicon layer 10 serving as a cathode. On the conical surface of the Si cone 12, a carbon nanotube 20 serving as an emitter (also called a microcathode) is formed by directly growing,
The tip 20A protrudes further than the top 12A of the Si cone 12. A grid (gate) 30 for controlling the amount of electrons emitted from the carbon nanotube 20 is disposed at a position that does not interfere with the flight path of the electrons emitted from the carbon nanotube 20. Further, an anode (fluorescent plate) 40 is arranged at a position facing the conductive silicon layer 10 with the grid 30 interposed therebetween.

A constant voltage from a constant power supply Va is applied to the conductive silicon layer 10 and the anode 40, and a variable voltage from a variable gate voltage source Vg is applied to the conductive silicon layer 10 and the grid (gate) 30. Applied.

FIG. 1 shows an electron gun which is a cathode device for displaying one pixel of the EFD. A large number of electron guns having the structure shown in FIG. 1 are provided on the same substrate or a divided substrate in correspondence with the phosphor of each pixel. A two-dimensional image forming apparatus as an FED can be configured by forming a multi-electron beam source in a matrix. Note that, as shown in FIG. 1, a plurality of carbon nanotubes 20 may be arranged facing one pixel, or one carbon nanotube 20 may be arranged.

The driving principle of the panel constituting the FED is as follows. Carbon nanotube (emitter) 20
Assuming that the voltage required for the operation of Ve is Ve, a voltage of, for example, -Ve / 2 is applied to the conductive silicon layer (cathode line) 10 and, for example, + Ve is applied to the grid (gate line) 30.
/ 2 voltage is applied. Only the pixel line in which the potential of the conductive silicon layer (cathode line) 10 became −Ve / 2 was selected, and the grid (gate line) 3 was selected.
Due to the luminance signal of + Ve / 2 applied to 0, the voltage Ve acts only on the selected field emitter, and the plurality of carbon nanotubes 20 corresponding to one pixel
More electrons are emitted. Since only the voltage of Ve / 2 is applied to the emitters of the other pixel lines, no electrons are emitted. Further, by controlling the voltage applied to the grid (gate line) 30, the amount of electrons emitted from the carbon nanotube (emitter) 20 is controlled,
On the anode 40, gradation display for each pixel becomes possible.

Here, the carbon nanotubes 20 functioning as emitters are those in which a six-membered ring is twisted helically to form a hollow tube, and a single-walled carbon nanotube having a single-layered twisted structure and a double-walled or more double-walled carbon nanotube. There is a multi-layer carbon nanotube having a multi-layer twisted structure. In the present invention, single-walled and multi-walled carbon nanotubes can be employed, but single-walled carbon nanotubes having a smaller diameter are preferred.

The diameter of the carbon nanotube 20 is 1
And a diameter of 1 to 3 nm in the case of a single-walled carbon nanotube. Further, the length of the carbon nanotube 20 can be grown up to about 100 nm, but when used as an emitter, a shorter one is superior in that the resistance value can be reduced. In particular, it is effective to shorten the length of the protrusion 20A protruding from the top 12A of the Si cone 12 to reduce the resistance value. The length of the protrusion 20A is 50 nm or less, preferably 20 nm or less, and more preferably. Is preferably 10 nm or less.

As described above, if the emitter is the carbon nanotube 20 and the axial tip protruding from the protrusion such as the Si cone 12 is used as the emitter edge, the emitter tip diameter becomes nano-order and the emitter current is increased by sharpening. Or a drive voltage for obtaining a desired emitter current can be reduced.

(Example of Structure of Electron Gun) FIG. 2 shows an example of the structure of the electron gun of FIG. 1 more specifically. In FIG. 2, a cathode electrode layer 1 is formed on a substrate such as a glass substrate 100.
02 is formed. When forming an FED, the cathode electrode layer 102 can be formed by depositing amorphous silicon or polycrystalline silicon in a line on the glass substrate 100. This cathode electrode layer 10
2 may be single crystal silicon or conductive silicon doped with impurities. When a multi-electron source used for an FED or the like is not formed, an insulating substrate is unnecessary. In this case, the substrate 100 itself can be a single-crystal silicon substrate or a silicon substrate doped with impurities.

Further, at least the surface layer of the substrate is not limited to the one formed of a silicon-based material, but may be another semiconductor, a conductor, such as a metal.

On the cathode electrode layer 102, a plurality of projections, for example, cones 104 are formed. On this cone shape 104, a carbon nanotube 110 protruding from the top 104A of the cone shape 104 is formed, thereby constituting an electron gun. Note that a resistance layer (for example, amorphous silicon) may be formed on the cathode electrode layer 102, and the resistance layer itself may be processed, or the cone shape 104 may be formed on the resistance layer. On the cathode electrode layer 102, an anode electrode can be formed around the cone 104 with an insulating layer interposed therebetween.
Is omitted.

(Method of Manufacturing Electron Gun) FIGS. 3 to 10 show steps of manufacturing the structure shown in FIG. Note that the glass substrate 100 is omitted in FIGS.

FIG. 3 shows a process in which the cathode electrode layer 102 and the cone shape 104 formed on the glass substrate 100 are thermally oxidized to form a silicon oxide film 120. As a method of forming the cone shape 104 on the cathode electrode 102, the CVD method described in FIGS. 3A and 3B of Japanese Patent Application No. 11-245033, or FIGS. 5A and 5B Can be used.

The silicon oxide film 120 functions as a mask layer later. The mask layer may be made of another silicon compound such as a silicon nitride film, or may be made of a semiconductor, a metal, an organic molecular film, or the like, which is different from a material for forming the protrusion.

FIGS. 4 to 7 show the top part 1 of the cone shape 104.
The step of leaving the silicon oxide film 120 only in the region other than the region 04A is shown.

In FIG. 4, a photoresist film 130 is formed on the silicon oxide film 120 by, for example, a spin coating method.
Is applied. FIG. 5 shows a step of removing the upper layer of the photoresist film 130 by, for example, ashing. In this step, the height H of the portion exposed from the photoresist film 130 is controlled by controlling the ashing time, for example.
1 can be determined. FIG. 6 shows a process of removing a portion of the silicon oxide film 120 that is not covered with the photoresist 120 by etching using the photoresist film 130 as a mask. By this etching, the silicon oxide film 120 is locally removed only at the top 104A of the cone shape 104. FIG. 7 shows a step of removing the photoresist film 130 by, for example, ashing. By performing this step, all regions except the top portion 104A, that is, the cathode electrode layer 102 and the base end 104B of the cone shape 104 are covered with the silicon oxide film (mask layer) 120. The height H2 of the top 104A that is not covered by the mask layer 120 is uniquely determined by the relationship with the height H1 obtained in the step shown in FIG.

FIG. 8 shows a step of applying the catalyst. In this embodiment, the silicon oxide film (mask layer) 120 and the exposed top 104A are brought into contact with the catalyst 140.

A solution containing chloride is used as the catalyst 140, and the glass substrate 100 is immersed in the solution. The chloride may be one or two selected from ferrous chloride, ferric chloride, molybdenum oxide chloride, and silicon chloride.
It can be a mixture of more than one species. After this dipping step, a vapor phase growth step of the carbon nanotubes 110 is started. For this purpose, a substrate is placed in a CVD furnace, and one or a mixture of two or more gases selected from hydrocarbon-based gases such as methane, ethane, and propane is added to the substrate.
It is supplied at a flow rate of about 0 sccm. This hydrocarbon-based gas is decomposed at a temperature of, for example, 900 ° under heating in a CVD furnace, and the carbon nanotube
Grow directly on top. FIG. 9 shows a process in which the carbon nanotube 110 has grown on the top 104A.

Here, when the vapor phase growth step is performed after immersion in the above-mentioned chloride solution, the carbon nanotubes 11
0 has definitely grown. This is considered that chloride contributes to the formation of nuclei formed in the initial stage of carbon nanotube vapor phase growth. Alternatively, it is conceivable that chloride contributes as a catalyst for promoting the growth of carbon nanotubes 110.

As a solvent for converting a chloride into a solution,
For example, an alcohol solution such as ethanol can be used. It is preferable to use an alcohol solution as the solvent because the alcohol solution evaporates after chloride adheres to the cone shape 104.

This solution preferably contains a surfactant. By activating the interface of the top 104A,
This is because the growth of the carbon nanotubes 110 is promoted, and the adhesion strength is increased.

The carbon nanotubes 110 are
A nucleus is first formed on the conical surface of 4A, and is formed as it grows. Although carbon nanotubes are formed on the entire conical surface of the top 104A, one carbon nanotube 110 eventually grows protruding from the top 104A. By controlling the processing time and the like, the growth length of the carbon nanotube 110 can be adjusted. As a result, the protrusion length L (see FIG. 9) of the tip 110A of the carbon nanotube 110 projecting from the top 104A of the cone shape 104 can be appropriately adjusted.

Here, during the above-described vapor phase growth step, a carbon lump 150 is formed on the surface of the mask layer 120. However, the carbon lump 150 can be lifted off by peeling off the silicon oxide film 120 as shown in FIG. The silicon oxide film 120 can be removed, for example, by immersing the substrate 100 in hydrofluoric acid. In addition, the carbon lump 15
When 0 remains, the carbon lump 150 that has been peeled off later may become impurities or dust and impair the function of the electron gun, but in the present embodiment, such danger is eliminated.

Since the growth area of the carbon nanotube 110 is limited to the top 104A of the cone 104, the growth length of the carbon nanotube 110 is controlled by controlling the growth time of the carbon nanotube 110 formed on the top 104A. You can control the If the region other than the top 104A is not masked, the growth of other carbon nanotubes or unnecessary carbon lump proceeds in the other region simultaneously with the top 104A. This causes a large variation in the growth length of the carbon nanotubes 110 at the top 104A, and the growth length of the carbon nanotubes 110 at the top 104A cannot be accurately controlled.

(Another Example of Method for Manufacturing Electron Gun) Each step of FIGS. 9 and 10 can be replaced with each step of FIGS. 11 and 12. That is, the steps shown in FIGS. 3 to 8 can be used as they are as the steps before the steps shown in FIGS.

FIG. 11 shows a step of removing the silicon oxide film 120 as a mask layer after the step of contacting with the catalyst shown in FIG. 8 and before the vapor phase growth step. Reference numeral 140 shown in FIG. 11 emphasizes the catalyst remaining on the cone shape 104. Thereafter, as shown in FIG. 12, the carbon nanotubes 110 are vapor-phase grown on the top 104A of the cone shape 104.

As shown in FIG. 11, if mask layer 120 is removed before the vapor phase growth step shown in FIG. 12, mask layer 120 is not exposed to the process temperature during vapor phase growth, and The layer 120 is not required to have heat resistance.

In the vapor phase growth step shown in FIG. 12, a carbon lump 150 is formed at a part of the top 104A of the cone 104 (the lower end of the top 104A). It cannot be removed together with 120 and remains. However, as compared with the case where the catalyst is brought into contact with the catalyst without forming the mask layer 120, the formation area of the carbon lump 150 is extremely narrow. For this reason, the risk of causing a variation in the growth length of the carbon nanotube is sufficiently reduced, and the risk of scattering as impurities or dust is also reduced.

(Exemplary Structure of Probe) FIG. 13 schematically shows a probe 200 which is another use of the carbon tube. The probe 200 is used, for example, in an atomic force microscope or the like, and includes a cantilever 210, a projection formed at the tip of the cantilever 200, for example, a cone 104, and a top 104 of the cone 104.
And a carbon nanotube 110 as a contact that protrudes from A and comes into contact with the measured object 220.

The probe 200 can be manufactured by using the method shown in FIGS. 3 to 10 or FIGS. 3 to 8, 11 and 12. At this time, the cantilever 210
Are formed on the surface layer 102 shown in FIGS.

As described above, the contact can be manufactured using the carbon nanotubes 110 on the order of several nanometers, so that the contact can be used as various measurement probes for measuring a fine object.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, the projection on which the carbon nanotubes are grown is not limited to a cone (cone), but may be a trapezoidal or columnar projection. In short, the tip of the carbon nanotube protrudes from the tip of the projection. Just do it. In this case, the tip of the carbon nanotube in the axial direction can be used as an emitter edge for emitting electrons or a contact of a probe. When the carbon nanotube is used as the emitter of the electron gun, the axial direction does not necessarily have to be perpendicular to the anode surface. This is because electrons emitted from the tip of the carbon nanotube by the electric field reach the anode surface. Further, the projections on which the carbon nanotubes are grown are not limited to those formed by processing the surface layer of the substrate, but may be those utilizing unevenness of the surface layer itself. At this time, the step of forming the protrusions on the surface layer is performed simultaneously by forming the surface layer on the substrate.

Further, the above-mentioned electron gun is not limited to the one applied to the image display device such as the above-mentioned FED, but emits electrons or electron beams, such as an image recording device, an exposure device, a circuit repair device, and an electron microscope. It can be used as an electron emission source for realizing various functions.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of an electron gun in which a carbon nanotube manufactured according to the present invention is used as an emitter.

FIG. 2 is a cross-sectional view showing a specific structure example of the electron gun of FIG.

FIG. 3 is a cross-sectional view showing a thermal oxidation step of a silicon surface.

FIG. 4 is a cross-sectional view showing a photoresist coating process.

FIG. 5 is a cross-sectional view showing a cueing step of a silicon oxide film from which an upper layer of a photoresist is removed.

FIG. 6 is a cross-sectional view showing a step of removing the silicon oxide film from the top of the cone shape.

FIG. 7 is a sectional view showing a photoresist film removing step.

FIG. 8 is a cross-sectional view showing a catalyst application step performed by masking a region excluding a cone-shaped top portion.

FIG. 9 is a cross-sectional view showing a carbon nanotube growth step performed while leaving a mask layer.

FIG. 10 is a sectional view showing a mask layer removing step performed after the step of FIG. 9;

FIG. 11 is a cross-sectional view showing a mask layer removing step performed in place of the step of FIG. 9;

FIG. 12 is a cross-sectional view showing a carbon nanotube growing step performed after the mask layer removing step of FIG. 11;

FIG. 13 is a schematic explanatory view schematically showing a probe provided with a carbon nanotube manufactured according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 cathode 12 Si cone 12A top 20 carbon nanotube 20A tip 30 grid 40 anode 100 glass substrate 102 cathode electrode layer (surface layer) 104 cone shape 104A top 104B base end 110 carbon nanotube 110A tip 120 silicon oxide film (mask layer) 130 photoresist film 140 carbon lump 150 catalyst 200 probe 210 cantilever

Claims (16)

[Claims] 1. A step of forming a projection having a top on a surface layer, and a mask different from a material for forming the surface layer and the projection on the projection except the top and the surface layer. Forming a layer; contacting the top not covered with the mask layer with a catalyst; decomposing a gas containing carbon under heating to vapor-grow carbon nanotubes on the top; And a step of projecting a tip of the carbon nanotube from the top portion. 2. The method according to claim 1, further comprising a step of removing the mask layer after the step of vapor-phase growing the carbon nanotubes. 3. The method according to claim 1, further comprising a step of removing the mask layer before the step of vapor-growing the carbon nanotubes. 4. The method for growing a carbon nanotube according to claim 1, wherein the carbon nanotube is a single-walled nanotube. 5. The method for growing a carbon nanotube according to claim 1, wherein the carbon nanotube is a multi-walled nanotube. 6. The semiconductor device according to claim 1, wherein the surface layer and the protrusion are any of amorphous silicon, polycrystalline silicon, single crystal silicon, or conductive silicon doped with an impurity. Characteristic method for growing carbon nanotubes. 7. The method according to claim 6, wherein the mask layer is a silicon compound formed by heat-treating the surface layer and the protrusion. 8. The method according to claim 1, wherein the mask layer is one of a semiconductor, polycrystalline silicon, amorphous silicon, a metal, and an organic molecular film. 9. The method according to claim 1, wherein a step of forming the mask layer so as to cover the surface layer and the protrusions is different from a material for forming the mask layer on the mask layer. Forming a coating layer while leaving the top portion, locally removing the mask layer on the top portion that is not covered with the coating layer, and thereafter removing the coating layer. A method for growing carbon nanotubes, comprising: forming the mask layer covering the protrusion except the top and the surface layer. 10. The method according to claim 9, wherein the coating layer comprises a photoresist, an organic molecular film, a semiconductor,
A method for producing carbon nanotubes, which is one of polysilicon, amorphous silicon, and metal. 11. The method according to claim 1, wherein the catalyst is a solution containing a chloride. 12. The method according to claim 11, wherein the solution contains at least one chloride selected from ferrous chloride, ferric chloride, molybdenum oxide chloride, and silicon chloride. A method for producing carbon nanotubes. 13. The method according to claim 12, wherein the solvent of the solution is an alcohol solution. 14. The method according to claim 11, wherein the solution contains a surfactant. 15. A method for manufacturing an electron gun, comprising: a sharp emitter formed on a surface layer of a substrate; a grid for controlling electron emission from the emitter; and an anode facing the tip of the emitter. A method for manufacturing an electron gun, wherein the emitter is formed by using the method for growing a carbon nanotube according to claim 1. 16. A method of manufacturing a probe having a cantilever, a projection formed at a tip of the cantilever, and a contact protruding from the projection, wherein the contact is any one of claims 1 to 14. A method for producing a probe, wherein the probe is formed by using the method for growing a carbon nanotube according to the above.