JP2011111380A - Apparatus and method for producing carbon nanotube - Google Patents

Abstract

A carbon nanotube manufacturing apparatus capable of growing carbon nanotubes while preventing plasma damage and deformation of an object to be processed (substrate).
A vacuum processing chamber (10) that includes a microwave introduction means (11) and maintains a predetermined pressure state while introducing a carbon-containing process gas into the internal space; and the microwave introduction means (11) in the internal space. A support 12 on which the plate-like object 2 is placed and a temperature control means 13 built in the support so as to be opposed to the plate-like microwave introduction window 16 attached thereto. A carbon nanotube manufacturing apparatus comprising at least a carbon nanotube visible from a plasma 20 generated by irradiating the process gas with a microwave introduced from the microwave introduction window 16 so as to cover the object to be processed. A plate material 18 having a transmittance of light having a wavelength longer than light of less than 5% and a porosity of greater than 70% and less than 95% is disposed.
[Selection] Figure 1

Description

  The present invention relates to a manufacturing apparatus and a manufacturing method capable of growing carbon nanotubes inexpensively and easily.

  Plasma CVD is used in low-temperature synthesis of carbon nanotubes. Since plasma CVD uses raw materials generated by plasma, in order to grow carbon nanotubes efficiently, the output of the plasma is increased as much as possible to generate a large amount of raw materials, and the generated raw materials grow the carbon nanotubes. It is desirable to shorten the distance between the plasma and the substrate so as not to lose reactivity before reaching.

  However, if plasma is generated in the vicinity of a substrate on which carbon nanotubes are grown, the substrate may be damaged by the effects of heat from the plasma, etching or sputtering with ions, and the growth of carbon nanotubes may be hindered. Therefore, various technologies have been developed to prevent growth inhibition by plasma.

For example, in Patent Document 1, a carbon nanotube is grown without being affected by the heat of plasma or etching by generating plasma at the tip of an antenna that is appropriately separated from the substrate.
However, there is a problem that the antenna that generates plasma evaporates due to the plasma, and the fine particles of the antenna material are mixed as impurities of the grown carbon nanotube.

In Patent Documents 2 and 3, a grid electrode or a mesh-like shielding means to which a bias voltage is applied is placed between the plasma and the substrate to prevent the growth inhibition by eliminating the influence of sputtering caused by ions generated from the plasma. .
However, since a separate power supply and device are required for electrical control, the manufacturing cost of the device increases, and the bias voltage condition is added to the growth conditions of the carbon nanotube, making the condition more complicated, so it is cheaper. And a simple method is demanded.

JP 2006-036593 A JP 2005-272284 A JP 2005-350342 A

The present invention was devised in view of such a conventional situation, and while preventing damage and deformation of the substrate due to the influence of plasma heat and sputtering, it suppresses mixing of impurities and growth inhibition of carbon nanotubes, A first object is to provide an apparatus for producing carbon nanotubes that can be grown inexpensively and easily.
In addition, the present invention prevents carbon from being damaged or deformed due to the effects of plasma heat or sputtering, and suppresses the incorporation of impurities and the growth inhibition of carbon nanotubes, allowing carbon to grow carbon nanotubes easily and inexpensively. A second object is to provide a method for producing a nanotube.

The apparatus for producing a carbon nanotube according to claim 1 of the present invention includes a vacuum processing chamber that includes a microwave introduction unit and maintains a predetermined pressure state while introducing a carbon-containing process gas into the internal space, and the internal space. A support body on which a flat plate-like object is placed so as to be opposed to a flat plate-like microwave introduction window attached to the microwave introduction means; and a temperature built in the support body. A carbon nanotube manufacturing apparatus comprising at least a control means, which covers the object to be processed as viewed from the plasma generated by irradiating the process gas with the microwave introduced from the microwave introduction window. Further, a plate material made of carbon and having air permeability is arranged.
The carbon nanotube manufacturing apparatus according to claim 2 of the present invention is characterized in that, in claim 1, the plate material is supported by a moving means and is movable relative to the object to be processed. To do.
According to a third aspect of the present invention, there is provided a carbon nanotube manufacturing method comprising: introducing a carbon-containing process gas into an internal space of a vacuum processing chamber; and irradiating the process gas with microwaves to generate a support from a plasma A method for producing carbon nanotubes, in which carbon nanotubes are vapor-grown on the surface of a target object placed on the substrate, wherein a breathable plate material made of carbon is disposed between the plasma and the target object. The carbon nanotubes are formed while maintaining the object to be processed in a predetermined temperature range using a temperature control means built in the support.

In the carbon nanotube manufacturing apparatus of the present invention, a temperature control means for keeping the object to be processed in a predetermined temperature range is built in the support, and a breathable plate material made of carbon is provided so as to cover the object to be processed. Since they are arranged, damage and deformation to the object to be processed due to the influence of plasma heat and sputtering can be prevented. Further, since the air-permeable plate material is disposed, it is possible to suppress the mixing of impurities and the inhibition of the growth of carbon nanotubes. Thereby, in this invention, the manufacturing apparatus of the carbon nanotube which can grow a carbon nanotube cheaply and simply can be provided.
In the method for producing carbon nanotubes of the present invention, the object to be treated is kept in a predetermined temperature range by the temperature control means built in the support, and the air-permeable plate material is made of carbon so as to cover the object to be treated. Therefore, it is possible to prevent damage or deformation to the object to be processed due to the influence of plasma heat or sputtering. Further, by arranging a gas-permeable plate material, it is possible to suppress the mixing of impurities and the growth inhibition of carbon nanotubes. Thereby, in this invention, the manufacturing method of the carbon nanotube which can grow a carbon nanotube cheaply and simply can be provided.

The typical sectional view showing the example of 1 composition of the manufacture device of the carbon nanotube of the present invention.

  Hereinafter, an embodiment of a carbon nanotube production apparatus and production method according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing a configuration example of the carbon nanotube production apparatus of the present invention.
The carbon nanotube manufacturing apparatus 1 includes a microwave introduction unit 11 including a microwave generation unit 11a and a guidance unit 11b for advancing microwaves, and introduces a predetermined process gas while introducing a carbon-containing process gas into an internal space. A vacuum processing chamber 10 that maintains a pressure state, and a planar object to be processed (in this internal space, so as to face the planar microwave introduction window 16 attached to the microwave introduction means 11 ( For example, at least a support 12 on which the substrate 2 is placed and a temperature control means 13 built in the support 12 are provided.

  In addition, the carbon nanotube manufacturing apparatus 1 of the present invention has a visible light so as to cover the workpiece 2 when viewed from the plasma 20 generated by irradiating the process gas with the microwave introduced from the microwave introduction window 16. A plate material 18 having a transmittance of light (electromagnetic wave) having a longer wavelength of less than 5% and a porosity of more than 70% and less than 95% is disposed.

  The manufacturing apparatus 1 having the above configuration can prevent the substrate 2 from being damaged or deformed by the heat of the plasma 20 or the influence of sputtering. Further, since the plate material 18 is disposed, it is possible to suppress the mixing of impurities and the growth inhibition of carbon nanotubes. As a result, the carbon nanotube production apparatus 1 of the present invention can grow carbon nanotubes inexpensively and easily.

The carbon nanotube production apparatus 1 of the present invention is an apparatus for vapor-phase growing carbon nanotubes on the surface of a substrate 2 (non-treated body) using microwave plasma.
The vacuum processing chamber 10 includes a flat plate-like microwave introduction window 16 and maintains a predetermined pressure state while introducing a carbon-containing process gas into the internal space.
Connected to the vacuum processing chamber 10 are a gas introduction means 14 for introducing a process gas and a vacuum exhaust means 15 for maintaining a predetermined pressure state while introducing the process gas. The gas introduction means 14 communicates with a gas source (not shown) through a gas pipe.

The carbon-containing process gas introduced when the carbon nanotube is vapor-phase grown on the surface to be processed (upper surface in FIG. 1) of the object 2 is carbonized such as methane (CH ₄ ) or acetylene (C ₂ H ₂ ). Hydrogen gas or vaporized alcohol, or for dilution and catalysis in vapor phase growth, these gases include at least one of hydrogen (H ₂ ), ammonia (NH ₃ ), nitrogen (N ₂ ), or argon (Ar) A mixture of one is used. Preferably, methane or the like that does not decompose at a heated substrate temperature is used.

  In this vacuum processing chamber 10, for example, in order to generate a large-diameter plasma, a taper-type that expands from a small-diameter waveguide propagating in the fundamental mode to a large-diameter waveguide in which a plurality of higher-order modes can exist. A microwave introducing means 11 is connected. The microwave introduction means 11 and the vacuum processing chamber 10 are spatially separated by a microwave introduction window 16.

The support 12 is in the internal space of the vacuum processing chamber 10, and places, for example, a plate-like object (hereinafter also referred to as a substrate) 2 so as to be opposed to the microwave introduction window 16.
Here, the substrate 2 on which the carbon nanotubes are vapor-grown is not particularly limited, but is made of titanium (Ti), aluminum (Al), copper (Cu), nickel (Ni), etc., and the thickness is For example, it is 20-100 micrometers.
Further, as a material for the catalyst film for growing carbon nanotubes, for example, a material containing iron (Fe), cobalt (Co), or nickel (Ni) is used.

The support 12 incorporates temperature control means 13 (for example, a heater) for keeping the substrate 2 in a predetermined temperature range.
When the substrate 2 is heated by the temperature control means 13, when the carbon nanotubes are vapor-phase grown, the substrate temperature can be easily controlled, and the carbon nanotubes can be vapor-grown at a low temperature. It is preferable to control the operation of the temperature control means 13 so that the substrate 2 is maintained at a predetermined temperature within a range of 400 to 800 ° C.
The support 12 is preferably electrically grounded, but may be electrically floating as necessary.

  In the carbon nanotube production apparatus 1 of the present invention, the substrate (object to be processed) 2 is covered as seen from the plasma 20 generated by irradiating the process gas with the microwave introduced from the microwave introduction unit 11. As described above, the plate member 18 having a transmittance of light (electromagnetic wave) having a wavelength longer than that of visible light of less than 5% and a porosity of greater than 70% and less than 95% is disposed. Here, “light having a wavelength longer than visible light (electromagnetic wave)” means light having a wavelength region of 400 [nm] to 2500 [nm]. Further, “transmittance” means the transmittance of light incident perpendicularly to the surface of the plate (the carbon nanotubes are vapor-grown).

When the light transmittance of the plate 18 is 5% or more, it is insufficient to reduce the influence of high energy particles and electromagnetic waves generated from plasma, and is not suitable for the growth of carbon nanotubes.
Further, when the porosity of the plate member 18 is 70% or less, the gas permeability is low, which is not suitable for the growth of carbon nanotubes. If it is 95% or more, it is difficult to maintain the structure as a plate material.
Examples of such a plate material 18 include a breathable carbon plate, carbon paper, and carbon fiber nonwoven fabric.

By arranging the plate member 18, the heat of the plasma is not directly transmitted to the substrate 2 constituting the object to be processed, but the heat is diffused through the air-permeable plate and transmitted to the substrate 2 or hardly transmitted. it can. That is, the conventional problem, that is, the problem that the substrate 2 is deformed by being heated unevenly due to the influence of locally applied heat can be solved.
In addition, by arranging the plate member 18, high energy ions generated from the plasma do not directly reach the substrate 2, and the carbon nanotubes can be efficiently grown without being sputtered.
In addition, by arranging the plate member 18, the antenna material evaporated from the antenna that generates plasma does not directly reach the substrate 2, and it is also possible to prevent the mixing of impurity fine particles.
Further, since only the plate member 18 is disposed, it is much cheaper and simpler than installing a grid electrode for controlling the potential.

  As described above, by arranging the plate material 18 having a transmittance of light (electromagnetic wave) having a wavelength longer than that of visible light of less than 5% and a porosity of more than 70% and less than 95%, the heat of plasma or sputtering The damage and deformation | transformation which are given to a to-be-processed object by influence can be prevented. In addition, impurities can be prevented and carbon nanotube growth inhibition can be suppressed. As a result, it is possible to grow carbon nanotubes inexpensively and easily.

  Further, the plate member 18 is supported by a moving means (not shown) and is movable relative to the substrate (object to be processed) 2. The presence of the moving means is effective when the plate member 18 is exchanged or when the distance from the plate member 18 is adjusted. Here, the term “relative” includes one or both of up and down (Z-axis (height) direction) and left and right (XY (in-plane) direction).

Next, a method for manufacturing carbon nanotubes using the carbon nanotube manufacturing apparatus 1 having the above configuration will be described.
In the method for producing carbon nanotubes of the present invention, a process gas containing carbon is introduced into the internal space of the vacuum processing chamber 10 and is placed on the support 12 from the plasma 20 generated by irradiating the process gas with microwaves. A method for producing carbon nanotubes, in which carbon nanotubes are vapor-grown on the surface of a substrate (object to be processed) 2, and a plate 18 made of carbon and having air permeability is disposed between the plasma 20 and the substrate 2. The carbon nanotubes are formed using the temperature control means 13 incorporated in the support 12 while keeping the substrate 2 in a predetermined temperature range.

  In the method for producing carbon nanotubes of the present invention, the substrate (object to be processed) 2 is maintained in a predetermined temperature range by the temperature control means 13 built in the support 12 so that the substrate (object to be processed) 2 is covered. Since the air-permeable plate 18 made of carbon is disposed, damage or deformation to the substrate 2 due to the influence of plasma heat or sputtering can be prevented. Further, by arranging the air-permeable plate 18, it is possible to suppress the mixing of impurities and the growth inhibition of carbon nanotubes. As a result, the carbon nanotube production method of the present invention makes it possible to grow carbon nanotubes inexpensively and easily.

  As mentioned above, although the manufacturing apparatus and manufacturing method of the carbon nanotube of this invention were demonstrated, this invention is not limited to these examples, In the range which does not deviate from the meaning of invention, it can change suitably.

Carbon nanotubes were grown on a substrate (object to be processed) using a manufacturing apparatus as shown in FIG.
Example 1
As a substrate, a titanium base material (thickness 0.04 to 0.1 mm) on which a nickel thin film was formed in advance was placed on a stage of a microwave plasma CVD apparatus in which a heater was built. Further, on the surface of the nickel thin film constituting the substrate, carbon paper as “a plate material having a transmittance of light (electromagnetic wave) having a wavelength longer than visible light of less than 5% and a porosity of greater than 70% and less than 95%”. (Toray: TGP-H-120) was put on, plasma was generated immediately above the carbon paper at an output of 300 W, and carbon nanotubes were grown on the nickel thin film of the substrate by the CVD method.
As a result, even when a very thin substrate was used, carbon nanotubes could be grown over the entire surface of the substrate without deformation. Moreover, it was confirmed that the transmittance of the carbon nanotube produced in this example is 1% or less in the wavelength region of 200 nm to 2500 nm.

(Comparative Example 1)
Carbon nanotubes were grown on the substrate by CVD under the same conditions as in Example 1 except that no carbon paper was placed on the substrate.
As a result, the substrate was deformed by the heat of the plasma, and the carbon nanotubes grew only on the substrate edge away from the plasma. When the plasma output was lowered to 200 W, deformation of the substrate was suppressed, but carbon nanotubes did not grow by sputtering at the center of the substrate. When the plasma output was further reduced to 100 W, the plasma became unstable and the carbon nanotubes did not grow.

(Example 2)
A titanium substrate (thickness 0.04 to 0.1 mm) on which a nickel thin film was formed was placed on a stage in which a heater was built in a microwave plasma CVD apparatus. Further, carbon paper (manufactured by Toray Industries, Inc.) was placed on the titanium substrate, plasma was generated at the tip of a tungsten antenna placed directly on the carbon paper with an output of 300 W, and carbon nanotubes were grown on the substrate by CVD.
As a result, it was possible to grow carbon nanotubes on the entire surface without the tungsten fine particles of the antenna material being mixed into the carbon nanotubes and without deforming the substrate.

(Comparative Example 2)
Carbon nanotubes were grown on the substrate by CVD under the same conditions as in Example 2 except that no carbon paper was placed on the substrate.
As a result, tungsten fine particles of the antenna material were mixed into the carbon nanotubes on the upper surface of the carbon nanotubes.

As is clear from the above results, in Examples 1 and 2, in which a breathable plate material made of carbon is arranged so as to cover the substrate, damage and deformation to the substrate due to the effects of plasma heat and sputtering are prevented. I was able to. In addition, the contamination of impurities and the growth inhibition of carbon nanotubes could be suppressed.
On the other hand, in Comparative Examples 1 and 2 in which no plate material was arranged, the substrate was damaged and deformed by the influence of plasma heat and sputtering. In addition, impurities are mixed in and the growth of carbon nanotubes is inhibited.
Therefore, it has been found that carbon nanotubes can be grown easily and inexpensively in the present invention.

  The present invention is widely applicable to a carbon nanotube manufacturing apparatus and manufacturing method.

  DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus, 2 Substrate (object to be processed), 10 Vacuum processing chamber, 11 Microwave introduction part, 12 Support body, 13 Temperature control means, 14 Gas introduction means, 15 Vacuum exhaust means, 18 Plate material, 20 Plasma.

Claims (3)

A vacuum processing chamber provided with microwave introduction means and maintaining a predetermined pressure state while introducing a carbon-containing process gas into the internal space;
A support in which the plate-like object is placed so as to be opposed to the plate-like microwave introduction window attached to the microwave introduction means in the internal space;
A temperature control means built in the support, and at least a carbon nanotube production apparatus comprising:
The transmittance of light having a wavelength longer than visible light is less than 5% so as to cover the object to be processed as seen from the plasma generated by irradiating the process gas with the microwave introduced from the microwave introduction window The carbon nanotube production apparatus is characterized in that a plate material having a porosity of greater than 70% and less than 95% is disposed.   2. The carbon nanotube manufacturing apparatus according to claim 1, wherein the plate member is supported by a moving means and is movable relative to the object to be processed. A carbon-containing process gas is introduced into the internal space of the vacuum processing chamber, and carbon nanotubes are vapor-phased on the surface of the target object mounted on the support from the plasma generated by irradiating the process gas with microwaves. A method for producing carbon nanotubes to be grown, comprising:
A plate material having a transmittance of light having a wavelength longer than visible light of less than 5% and a porosity of greater than 70% and less than 95% is disposed between the plasma and the object to be processed, A method for producing carbon nanotubes, characterized in that carbon nanotubes are formed while maintaining the object to be treated in a predetermined temperature range using a built-in temperature control means.

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