JP2008019153A - Shape processing control technology for locally removing and cutting carbon nano material by electron beam, and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology and an apparatus capable of locally removing and cutting a carbon nano material in an arbitrary position by using electron beams by means of the introduction of a carbon reactive gas, thereby processing the carbon nano material into an arbitrary shape. <P>SOLUTION: In the technology and the apparatus, the carbon nano material is processed into the arbitrary shape by introducing the gas containing an atom reactive with carbon atom, scanning the electron beams, whose acceleration voltage and irradiation current are adjusted, on the arbitrary position of the carbon nano sample placed in a working section to locally irradiate the carbon nano material in the state of controlling the gas introducing quantity by a controller and controlling the position of a gas nozzle for introducing the gas into the working section by a control stage, thereby locally destructing the atomic bonding structure of the carbon nano material to locally remove and cut the carbon nano material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique and apparatus for arbitrary shape processing by local removal and cutting of carbon nanomaterials. This technique uses an electron beam, and is used to process an arbitrary position by arbitrarily scanning the electron beam.

In Patent Document 1, a method of breaking carbon nanotubes was proposed. The present invention is characterized in that the carbon nanotube is broken by a collision between the carbon nanotube-carrying liquid and the chamber wall surface, and a shearing force, shock wave, cavitation, expansion, etc. generated when the carbon nanotube-carrying liquid collides with each other. .
Various techniques for local cutting of carbon nanotubes have been proposed (see Patent Documents 2 to 5). Patent Document 2 proposes a method of cutting carbon nanotubes by a discharge action. Patent Document 3 proposes a carbon nanotube cutting method in which a mixed solution in which carbon nanotubes are dispersed in a saccharide solution is heated and dried to solidify and then pulverized to cut the carbon nanotubes. Patent Document 4 proposed a method of breaking carbon nanotubes by locally generating stress due to heat generation due to concentration of electric charges or the like by irradiation of an electron beam and breaking the chemical bond at that portion. Patent Document 5 proposes a method of cutting carbon nanotubes with an ion beam.

JP 2006-016222 A JP 2005-059147 A Japanese translation of PCT publication No. 2004-043258 JP 2003-159700 A JP-A-7-172807

  The carbon nanomaterial has, for example, a crystal structure in which carbon atoms form a crystal structure by SP1 and SP2 bonds, and thus has a chemically stable property. However, by controlling the energy of an electron beam, Since the ionization efficiency becomes high by making it equal to the binding energy of the carbon, local removal and cutting can be performed. However, since the energy of the electron beam is originally very small, the local removal and cutting of carbon atoms is necessary. Needs to be sufficiently irradiated with an electron beam. Therefore, it took a lot of time to remove and cut the carbon nanomaterial with an electron beam and perform arbitrary shape processing.

As a result of intensive studies to solve the above problems, the present inventors have arrived at the present invention having the following configuration.
That is, by introducing a carbon reactive gas and irradiating the sample with a carbon reactive gas locally in a vacuum environment with an electron beam, C− + O− → CO, C− + O ₂ − → CO ₂ , C- + H- → CH, C- + H _2- → CH ₂ , etc., promote the generation reaction of hydrocarbon gas and hydrocarbon gas, and locally remove carbon nanomaterials using electron beam And a technology that specializes in cutting and processing any shape.
In the above configuration, the carbon reactive gas is preferably a molecule having as much reactive atom content as possible.
Further, it is preferable that the electron beam can be locally controlled at an arbitrary position by a lens system and a scanning mechanism.

According to the apparatus configured as described above, the atomic bond structure of the carbon nanomaterial can be destroyed in a short time by using a chemical reaction by a carbon reactive atom. If there are no carbon-reactive atoms, the residual molecules in the vacuum will participate in the reaction, but the number of atoms that can participate in the reaction is small, especially when using an oil diffusion vacuum pump, etc. The phenomenon of carbon atom deposition may occur. However, when carbon reactive atoms are introduced in a certain amount in a certain amount, the above reaction can be promoted, so that the atomic bond structure of the carbon nanomaterial can be easily broken by an electron beam.
Further, by irradiating an arbitrary position with an electron beam by a scanning mechanism, the carbon nanomaterial can be cut with high accuracy at an arbitrary position. This is effective for applications such as controlling the length of a carbon nanotube for an atomic force microscope probe to produce a three-dimensional shape.
Further, the carbon nanomaterial can be locally processed by irradiating the electron beam sufficiently narrowed down by the lens system.
Further, by using an electron beam having a low energy, it is possible to limit the damage of the carbon nanomaterial that has been locally removed and cut and processed into an arbitrary shape.

  A configuration capable of cutting the carbon nanomaterial of the present invention is shown in FIG. The carbon nanomaterial 7 is placed in the work chamber 1 of the electron microscope, and the work chamber is in a vacuum state 2. When processing with the electron beam 4, a point mode is used to shorten the processing time.

  In order to be able to cut with an electron beam, two main elements are necessary. One is an electron beam with low energy, and the other is introduction of oxygen gas, which is a carbon reactive gas.

  The peak ionization efficiency of carbon can be obtained by irradiation with a low energy electron beam. In other words, carbon atoms are easily excited or ionized by irradiation with a low energy electron beam. Since the maximum ionization efficiency can be obtained with an electron beam of about 1 keV, it is suitable for local removal and cutting of carbon nanomaterials and processing of arbitrary shapes.

  Carbon reactive gas species, for example, oxygen gas is applied to the workpiece and reacts with carbon to produce carbon monoxide and carbon dioxide, which are then exhausted.

  When cutting in a vacuum environment such as a work room of an electron microscope, it is necessary to maintain the vacuum by introducing gas. For this reason, in order to minimize this vacuum break, and for sufficient cutting, it is necessary to introduce a small flow rate of gas locally through a tube with a narrow inner diameter at the tip. In addition, as the number of gas molecules participating in the reaction with carbon increases, it is better to have a device such as a control stage for installing the gas nozzle near the workpiece.

  In the above technique and apparatus, the carbon nanomaterial can be bent by changing the processing conditions. In other words, compared with the cutting conditions, shortening the electron beam irradiation time, increasing the electron beam acceleration voltage, decreasing the irradiation current, increasing the distance between the object to be processed and the gas nozzle, these conditions One or a plurality of items can be changed and curved.

  Furthermore, it is possible to control the shape of the carbon nanomaterial with a bending apparatus and technique. By applying this, a three-dimensional and arbitrary structure can be produced. An example of the configuration of the processing apparatus is shown in FIG.

  By using the above technique and apparatus, the electron beam irradiation mode is changed from the point mode to the area scan mode, whereby a process for removing a part of the carbon nanomaterial can be performed. A schematic diagram of this processing example is shown in FIG. At this time, it should be noted that the processing time increases or decreases depending on the size of the scan area.

Next, an example for confirming the cutting technique of the carbon nanomaterial will be described.
As carbon nanomaterials, multi-walled carbon nanotubes produced by arc discharge were used as experimental objects. Carbon nanotubes are placed in the working room of a scanning electron microscope. The working chamber is in a vacuum state.

  In order to cut the carbon nanomaterial, the electron beam emitted from the electron gun of the scanning electron microscope is irradiated to the carbon nanotube. The acceleration voltage of the electron beam was 1 kv. The probe current was 0.6 nA. Point mode was used as the electron beam mode.

  A glass tube nozzle having a tip inner diameter of 20 μm was used to introduce the carbon reactive gas into the vacuum chamber for cutting the carbon nanomaterial. The distance from the nozzle to the carbon nanotube was set at 90 μm by a control stage. The gas flow was controlled by a mass flow controller.

  For cutting the carbon nanomaterial, oxygen gas was used as a carbon reactive gas species, and the flow rate was set to 1 sccm by a mass flow controller.

  The carbon nanotube shown in FIG. 2 (a) was cut into three times. The results are shown in (b), (c) and (d). The cutting time was 1 minute in total. (B) is an electron microscopic image of the carbon nanotube after a portion having a length of 650 nm is cut by the first cutting. In (c), a 700 nm long portion was cut by the second cutting. (D) shows the result of aligning the same length as the adjacent tube in the third cut. The length of the cut part was 700 nm.

  The conditions under which the carbon nanotube can be cut within one minute after changing the acceleration voltage and the probe current are indicated by black dots. That is, cutting was performed with a low probe current with an electron beam of about 1 keV that provides the maximum ionization efficiency. On the other hand, when cutting at a high acceleration voltage, it can be said that a higher probe current is required.

An example of the bending technique of the carbon nanomaterial will be described.
Carbon nanotubes were used as the carbon nanomaterial. FIG. 4A is an electron micrograph before the carbon nanotube is bent.

  The carbon nanotubes are irradiated with an electron beam from a scanning electron microscope. The acceleration voltage of the electron beam was 1 kV. The probe current was 0.1 nA. The point mode was used as the electron beam irradiation mode.

  In order to introduce a carbon reactive gas into the vacuum chamber for bending the carbon nanomaterial, a glass tube nozzle having a tip inner diameter of 20 μm was used. The distance from the nozzle to the carbon nanotube was set to 200 μm. The flow rate of the carbon reactive gas was controlled by a mass flow controller.

  For the bending process of the carbon nanomaterial, oxygen gas was used as a carbon reactive gas species, and the flow rate was set to 1 sccm by a mass flow controller.

  FIG. 4A shows the result of bending the carbon nanomaterial, and FIG. 4B shows the result of bending the carbon nanotube. The irradiation time of the electron beam was 4 minutes. At the position irradiated with the electron beam, a fold of the carbon nanotube occurred, and the photo was bent 85 degrees upward.

  An example in which a carbon nanomaterial local removal processing technique is implemented using an electron beam scan mode will be described. Carbon nanotubes were used as the carbon nanomaterial. FIG. 7A is an electron micrograph before the carbon nanotube is bent.

  For local removal processing of the carbon nanomaterial, an electron beam of a scanning electron microscope is irradiated to the carbon nanotube. The acceleration voltage of the electron beam was 2 kV. The probe current was 0.3 nA. The electron beam irradiation mode was a scan mode, and the scan area was 800 nm in length and 200 nm in width.

  In order to introduce the carbon reactive gas into the vacuum chamber for the local removal processing of the carbon nanomaterial, a glass tube nozzle having a tip inner diameter of 20 μm was used. The distance from the nozzle to the carbon nanotube was set to 170 μm. The flow rate of the carbon reactive gas was controlled by a mass flow controller.

  For local removal processing of the carbon nanomaterial, oxygen gas was used as a carbon reactive gas species, and the flow rate was set to 1 sccm by a mass flow controller.

  FIG. 7B and FIG. 7C show the results of removing the local parts of the carbon nanotubes from the sample of FIG. 7A. The electron beam irradiation time was 30 minutes. FIG.7 (c) is an enlarged photograph of the processing part of FIG.7 (b). As shown in FIG. 7C, the outer layer of the long axis range of about 200 nm of the carbon nanotube was removed.

The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications may be included in the present invention as long as those skilled in the art can easily conceive without departing from the description of the scope of claims.
For example, the electron gun of all electron microscopes may be used. Further, an electron beam generated by any kind of emitter without using an electron gun of an electron microscope may be used.
The electron beam mode may be various scanning methods such as spot mode, line mode, and area mode.
Further, the carbon reactive gas species may be a gas species capable of reacting with carbon instead of oxygen gas. That is, it may be water vapor or hydrogen.

FIG. 1 is an example of the configuration of a processing apparatus for cutting a carbon nanomaterial. FIG. 2 shows a schematic example in which carbon nanotubes are cut. FIG. 3 shows experimental conditions when carbon nanotubes are cut in one minute. FIG. 4 shows a schematic example in which a carbon nanomaterial is curved. FIG. 5 shows an example of the configuration of an apparatus for processing a carbon nanomaterial three-dimensionally into an arbitrary shape. FIG. 6 shows an example of a configuration in which carbon nanomaterials are locally removed. FIG. 7 shows the results of an experiment in which carbon nanotubes were locally removed.

Explanation of symbols

1 vacuum chamber 2 vacuum 3 substrate 4 electron beam 5 electron gun 6 gas nozzle 7 carbon nanomaterial

Claims (12)

  An electron in which carbon reactive gas is introduced into the work chamber, the amount of introduction is controlled by a control device, and the position of the nozzle for introducing the carbon reactive gas into the work chamber is controlled to adjust the acceleration voltage and irradiation current. The carbon nanomaterial installed in the working room is scanned with an electron beam at an arbitrary position using a wire, and the carbon nanomaterial is irradiated locally, thereby locally linking the carbon nanomaterial's atomic bond structure. Technology that destroys, removes and cuts parts locally, and processes any shape.   An electron in which carbon reactive gas is introduced into the work chamber, the amount of introduction is controlled by a control device, and the position of the nozzle for introducing the carbon reactive gas into the work chamber is controlled to adjust the acceleration voltage and irradiation current. The carbon nanomaterial installed in the working room is scanned with an electron beam at an arbitrary position using a wire, and the carbon nanomaterial is irradiated locally, thereby locally linking the carbon nanomaterial's atomic bond structure. A device that breaks, removes, cuts, and processes any shape.   The apparatus according to claim 1, wherein the electron beam is produced by an electron gun apparatus capable of controlling an acceleration voltage and an irradiation current.   The apparatus according to claim 2, wherein the electron beam is produced by an electron gun apparatus capable of controlling an acceleration voltage and an irradiation current.   The apparatus according to claim 1, wherein the carbon nanomaterial is a nanomaterial having a crystalline structure composed of carbon atoms, an amorphous structure, or a mixed structure thereof.   The apparatus according to claim 2, wherein the carbon nanomaterial is a nanomaterial having a crystalline structure composed of carbon atoms, an amorphous structure, or a mixed structure thereof.   The apparatus according to claim 1, wherein the carbon reactive gas is made of a material that can have a molecular composition rich in reactivity with carbon, such as an oxygen atom and a hydrogen atom.   The apparatus according to claim 2, wherein the carbon reactive gas is made of a material capable of having a molecular composition rich in reactivity with carbon such as an oxygen atom and a hydrogen atom.   The apparatus according to claim 1, wherein the carbon reactive gas can be set to an arbitrary value by a flow rate control mechanism when introduced into a working chamber placed in a vacuum environment.   The apparatus according to claim 2, wherein the carbon reactive gas can be set to an arbitrary value by a flow rate control mechanism when introduced into a working chamber placed in a vacuum environment.   The carbon reactive gas can be installed at an arbitrary position with respect to the carbon nanomaterial by the control stage mechanism when introduced into the working chamber placed in a vacuum environment. The apparatus according to 1.   The carbon reactive gas can be installed at an arbitrary position with respect to the carbon nanomaterial by the control stage mechanism when introduced into the working chamber placed in a vacuum environment. 2. The apparatus according to 2.

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