KR100519397B1 - Processing method of carbon nanotube - Google Patents

Abstract

The present invention relates to a method for producing carbon nanotubes, which enables the production of carbon nanotubes on pyramidal structures using a metal catalyst. The present invention relates to a process of forming a structure on an upper surface of a silicon substrate, and AFM (Atomic). Applying a metal catalyst to an end of a force microscope tip, placing an AFM tip coated with the metal catalyst on top of the structure, transferring the metal catalyst on the structure, In the method of manufacturing a carbon nanotube comprising the step of growing a carbon nanotube on the structure of the structure on which the silicon substrate and the metal catalyst is placed in an environment capable of applying carbon gas and heat,

The upper portion of the structure,

A chemical agent of Au having a feature of fixing a metal catalyst, which is transferred to the metal catalyst, to be fixed on the structure is applied.

Description

Processing method of carbon nanotube

The present invention relates to a method for producing carbon nanotubes, and more particularly, to a method for producing carbon nanotubes, which enables the production of carbon nanotubes in pyramidal structures using metal catalysts.

In general, a carbon nanotube (carbon nanotube) is bonded to three carbon atoms adjacent to one carbon (carbon) atom, the hexagonal ring is formed by the bond between these carbon atoms, these planes are repeated in a honeycomb form It is a rolled material that forms a cylindrical tube.

In particular, carbon nanotubes have the form of hollow tubes recently discovered. These carbon nanotubes are very useful for making electrical, chemical, physical and mechanical devices. Accordingly, research is being conducted on various applications such as electric devices, chemical, physical and mechanical sensors, hydrogen storage devices, and field-emitted devices.

In addition, carbon nanotubes have a diameter of several tens of micrometers to several tens of nm, and the length thereof is tens of times to several thousand times. Much research is being done on carbon nanotube synthesis because of its morphological properties and excellent thermal, mechanical and electrical properties resulting from chemical bonding. By using the above characteristics, it is expected that not only the existing materials can develop many products that have hit technical limitations, but also give the already developed products characteristics that have not been shown so far.

In addition, various methods such as arc discharge, laser evaporation, chemical vapor deposition (CVD), catalytic synthesis, and plasma synthesis have been proposed as methods for synthesizing carbon nanotubes. (Reference, USP 5,424,054 (arc discharge); Chem. Phys. Lett. 243, 1-12 (1995) (laser vaporization); Science, 273: 483-487 (1996) (laser vaporization); USP 6,210,800 (catalyst) Synthesis method); USP 6,221,330 (gas phase synthesis); WO 00/26138 (gas phase synthesis)).

On the other hand, carbon nanotubes are also used as a tip of AFM (Atomic Force Microscope).

Here, AFM is used in various fields, from basic research and nanotechnology to process equipment for production, and the core technology of AFM is at the probe tip. Depending on the shape and size of the probe tip, the resolution and reproducibility of the image of the AFM vary.

In addition, AFM has been widely used in the field of measurement and observation up to nano units, and recently, many studies have been conducted on soft lithography.

In addition, AFM generally uses a pyramid-shaped pointed shape at the end of the cantilever, but carbon nanotubes are also attached to the end of the pyramid. This is because using the tip with atomically very high aspect ratio and large elasticity is advantageous for the measurement. Carbon nanotube tips offer performance in the measurement, manipulation, and manufacturing of AFM due to their sharpness, high aspect ratio and high mechanical stiffness, high elasticity, and control of chemical components. It is known to have ideal properties to improve. These nanotube tips are advantageous for measuring long lifetimes, narrow and deep structures, and have a high resolution of less than 1 nm.

However, it is very difficult to obtain a single SWNT (Single Wall NanoTube) with such a good quality and make it to a desired shape in a desired position. Conventional methods, such as laser vaporization or arc discharge, can produce nanotubes that are primarily tangled, but it is almost impossible to refine, separate and manipulate these entangled nanotubes in one device. It's work.

As the conventional method described above, mass production of MWNT (Multi Wall NanoTube) by CNT (Carbon NanoTube) deposition method (US pat. 5,482,601), Mandeville, etc., by the arc discharge method presented by Oshima et al. Catalytic method (US pat. 5,500,200).

However, these methods are effective in developing new composite materials by producing large quantities of carbon nanotubes or carbon fibrils, but it is almost impossible to separate individual nanotubes and attach the tubes one by one exactly to the desired position. There was this.

Therefore, it can be said that it is not suitable as a method of attaching a nanotube tip to an AFM probe. Recently, a method of directly growing MWNTs or SWNTs by the CVD method proposed by Hafner et al. (US Patent application ser No. 09 / 133,948) has been developed. In this method, catalyst particles are applied to grow AFM probe tips individually, followed by growth on a high temperature hydrocarbon gas. In this way, a bundle of MWNTs or SWNTs are attached to the ends of the AFM.

However, it is very difficult to attach catalyst particles to the ends of the silicon pyramid.

In addition, the SWNT grown at the end of the pyramid has a size of 1 μm to 20 μm, but in order to use the SWNT attached to the actual AFM, the SWNT usually has a size of about 30 nm to 100 nm. In order to shorten this size, a discharge method is used, but it is very difficult to accurately adjust the size.

In particular, the method developed by Dai (US Pat. 6,401,526) is a very effective method of coating a liquid phase precursor at the tip of an AFM tip, growing it by CVD, and then adjusting the size to control the size. The charge process creates an AFM tip with carbon nanotubes attached. In this case, the liquid phase precursor is made by mixing a salt containing metal, a long-chain molecular compound, and a solvent. In addition, a method of coating the ends of many paramides at once by using micro contact printing in order to attach precursors more effectively.

Recently, the precursor is applied by spin coating on a wafer equipped with a large amount of silicon pyramids for AFM, and then the precursor remains only in the pyramid, and the remainder is removed by etching. Only make the precursor remain. Subsequently, carbon nanotubes are grown using a CVD method in a gas containing carbon (Paper: Wafer scale production of carbon nanotube scanning probe tips for atomic force microscopy, Applied Physics letters, Vol. 80, No. 12, Erhan Yenilmez etc., 2002, march, pp2225-2227).

However, both of these methods have a problem that it is very difficult to coat exactly the desired amount of precursor because of the mechanical and chemical properties.

Therefore, the present invention has been proposed to solve the above-mentioned problems according to the prior art, an object of the present invention is to prepare carbon nanotubes that can produce carbon nanotubes in a pyramidal structure using a metal catalyst To provide a method.

Features of the carbon nanotube manufacturing method according to the present invention for achieving the above object, the step of forming a structure on the upper surface of the silicon substrate, AFM (Atomic Force Microscope) A tip of the tip (tip) applied to the metal catalyst And placing the AFM tip coated with the metal catalyst on the upper portion of the structure, transferring the metal catalyst on the structure, and placing the silicon substrate and the metal catalyst on the structure. In the manufacturing method of the carbon nanotube comprising a step of growing in the environment to which the carbon nanotubes on top of the structure, the upper part of the structure,

A chemical agent of Au having a feature of fixing a metal catalyst, which is transferred to the metal catalyst, to be fixed on the structure is applied.

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Hereinafter, with reference to the accompanying drawings a preferred embodiment of the method for producing a carbon nanotube according to the present invention.

1A, 1B, 1C, and 1D are flowcharts of a first embodiment showing a method of manufacturing carbon nanotubes according to the present invention.

First, as shown in FIG. 1A, a structure 110 such as a pyramid having a tower shape is formed on an upper surface of a silicon substrate 100 having a constant thickness and length, and the upper portion of the structure moves a metal catalyst. Flatten it so you can put it.

And, as shown in Figure 1b, the liquid metal catalyst 130 is applied to the end of the AFM tip 120, the metal catalyst 130 is applied to the AFM tip 120 is applied to the structure 110 Position it at the top.

Here, the AFM tip 120 is shaped like a pyramid or cone. In addition, the metal catalyst 130 uses an electrochemical dip pen technique.

Accordingly, the upper portion of the structure 110, as shown in Figure 1c, when the metal catalyst 130, as if the ink is written on the paper by writing a pen, the ink is transferred to the paper (transfer) is transferred (transfer) over the paper in the same principle Will be moved.

At this time, the metal catalyst 130 located above the structure 110 is in the form of water droplets.

Thereafter, the structure 110 on which the silicon substrate 100 and the metal catalyst 130 in the form of water droplets are located is placed in a chamber type CVD reactor (not shown).

In addition, carbon gas is injected into a chamber (not shown) of the chamber-type CVD reactor. Here, the chamber maintains a high temperature.

In addition, the metal catalyst 130 located on the upper portion of the structure 110 causes a chemical reaction with the carbon gas injected into the chamber, and as shown in FIG. 1D, the carbon nanotubes on the upper portion of the structure 110. 140 grows.

At this time, the carbon nanotubes 140 grow only in one direction.

Here, in order to control the length of the manufactured carbon natotube 140, the length is adjusted using a discharge.

On the other hand, Figures 2a, 2b and 2c shows a process that allows the metal catalyst to be fixed well on top of the structure, as shown in Figure 2b, on top of the structure 110, such as a pyramid in the form of a tower The support material 150 such as Au is uniformly applied to a certain thickness and length.

As shown in FIG. 2C, the liquid metal catalyst 130 is applied to the end of the AFM tip 120, and the structure 110 is applied to the AFM tip 120 to which the metal catalyst 130 is applied. It is located on the upper surface of the induction material 150 located in the upper portion of the.

Accordingly, the metal catalyst 130 is well fixed to the top of the structure 110 by the inducer 150.

In addition, the amount of the metal catalyst 130 applied to the AFM tip 120 can be adjusted to be well fixed to the structure (110).

On the other hand, as shown in Figure 1d, in order to control the direction of the carbon nanotubes growing on top of the structure, the shape of the top of the structure in various forms as shown in Figures 3, 4, 5 and 6 Can be changed to

3A, 3B, 3C and 3D are flowcharts of a second embodiment showing a method of manufacturing carbon nanotubes according to the present invention.

First, as shown in Figure 3a, to form a structure 110, such as a pyramid in the form of a tower on the upper surface of the silicon substrate 100 having a constant thickness and length, the upper portion of the structure by moving a metal catalyst (Metal Catalyst) The groove 110-1 is formed in the center thereof so as to be placed thereon.

And, as shown in Figure 3b, the liquid metal catalyst 130 is applied to the end of the AFM tip 120, and the AFM tip 120, the metal catalyst 130 is applied to the structure 110 It is located in the groove (110-1).

Accordingly, the groove 110-1 of the structure 110, as shown in Figure 3c, when the metal catalyst 130 as if the ink to write on the paper by writing a pen, as if the ink is transferred to the paper transfer To the principle.

In this case, the metal catalyst 130 located in the groove 110-1 of the structure 110 has a droplet shape.

Thereafter, the structure 110 on which the silicon substrate 100 and the metal catalyst 130 in the form of water droplets are located is placed in a chamber type CVD reactor (not shown).

In addition, when the carbon gas is injected into the chamber (not shown) of the chamber-type CVD reactor (not shown), the metal catalyst 130 located above the structure 110 is chemically reacted with the carbon gas injected into the chamber. In addition, as shown in FIG. 3D, the carbon nanotubes 140 grow in the grooves 110-1 of the structure 110.

4A, 4B, 4C and 4D are flowcharts of a third embodiment showing a method of manufacturing carbon nanotubes according to the present invention.

First, as shown in FIG. 4A, a structure 110 such as a pyramid having a tower shape is formed on an upper surface of a silicon substrate 100 having a constant thickness and length, and the upper portion of the structure moves a metal catalyst. It forms a slanted inclined groove (110-3) to the center inside so that it can be placed.

And, as shown in Figure 4b, the liquid metal catalyst 130 is applied to the end of the AFM tip 120, and the AFM tip 120, the metal catalyst 130 is applied to the structure 110 Place in the inclined groove (110-3).

Accordingly, as shown in Figure 4c, the inclined groove (110-3) of the structure 110, when the metal catalyst 130, as if the ink is written on the paper with a pen, the ink is transferred to the paper and transferred The same goes for.

In this case, the metal catalyst 130 located in the inclined groove 110-3 of the structure 110 has a water droplet shape.

Thereafter, the structure 110 on which the silicon substrate 100 and the metal catalyst 130 in the form of water droplets are located is placed in a chamber type CVD reactor (not shown).

In addition, when the carbon gas is injected into the chamber (not shown) of the chamber-type CVD reactor (not shown), the metal catalyst 130 located above the structure 110 is chemically reacted with the carbon gas injected into the chamber. In addition, as shown in FIG. 4D, the carbon nanotubes 140 grow in the inclined grooves 110-1 of the structure 110.

5A, 5B, 5C and 5D are flowcharts of a fourth embodiment showing a method of manufacturing carbon nanotubes according to the present invention.

First, as shown in FIG. 5A, a structure 110 such as a pyramid having a tower shape is formed on an upper surface of a silicon substrate 100 having a constant thickness and length, and the upper portion of the structure moves a metal catalyst. The stepped portion 110-5 is formed to be etched inclined at one edge thereof so as to be placed.

And, as shown in Figure 5b, the liquid metal catalyst 130 is applied to the end of the AFM tip 120, the metal catalyst 130 is applied to the AFM tip 120 is applied to the structure 110 The stepped portion 110-5 of.

Accordingly, as illustrated in FIG. 5C, when the metal catalyst 130 writes ink with a pen and writes it on paper, the ink is transferred and transferred onto the paper as shown in FIG. 5C. The same goes for.

In this case, the metal catalyst 130 located at the stepped portion 110-5 of the structure 110 has a droplet shape.

Thereafter, the structure 110 on which the silicon substrate 100 and the metal catalyst 130 in the form of water droplets are located is placed in a chamber type CVD reactor (not shown).

In addition, when the carbon gas is injected into the chamber (not shown) of the chamber-type CVD reactor (not shown), the metal catalyst 130 located above the structure 110 is chemically reacted with the carbon gas injected into the chamber. In addition, as shown in FIG. 5D, the carbon nanotubes 140 grow at the stepped portions 110-5 of the structure 110.

6A, 6B, 6C and 6D are flowcharts of a fifth embodiment showing a method of manufacturing carbon nanotubes according to the present invention.

First, as shown in FIG. 6A, a structure 110 such as a pyramid having a tower shape is formed on an upper surface of a silicon substrate 100 having a constant thickness and length, and a metal catalyst (Metal) is formed on the left / right side of the upper portion of the structure. The uneven portion 110-7 is formed at the center thereof so as to replace the catalyst.

And, as shown in Figure 6b, the liquid metal catalyst 130 is applied to the end of the AFM tip 120, the metal catalyst 130 is applied to the AFM tip 120 is applied to the structure 110 To the left and right of the uneven portion (110-7).

Accordingly, the left and right sides of the uneven portion 110-7 of the structure 110, as shown in FIG. 6C, when the metal catalyst 130 takes ink with a pen and writes it on the paper, the ink is transferred onto the paper. It is transferred on the same principle as it is.

At this time, the metal catalyst 130 located at the left / right side of the uneven parts 110-7 of the structure 110 has a water droplet shape.

Thereafter, the structure 110 on which the silicon substrate 100 and the metal catalyst 130 in the form of water droplets are located is placed in a chamber type CVD reactor (not shown).

In addition, when the carbon gas is injected into the chamber (not shown) of the chamber-type CVD reactor (not shown), the metal catalyst 130 located above the structure 110 is chemically reacted with the carbon gas injected into the chamber. In addition, as shown in FIG. 6D, the carbon nanotubes 140 grow on the left and right sides of the uneven parts 110-7 of the structure 110.

Thus, as shown in FIG. 6D, a plurality of carbon nanotubes may be grown on the top surface of the structure 110.

As described above, the method of manufacturing the carbon nanotubes according to the present invention has an advantage of controlling the amount of metal that rises on the tip of the AFM by applying the metal catalyst directly to the AFM tip.

Therefore, all carbon nanotubes grown by CVD on each AFM tip can grow with a constant direction and size, thereby producing high quality AFM tips.

In addition, when the shape of the tip of the AFM tip is changed so that the CNT grows well, or when it is desired to grow at a desired angle, there is an easy access effect.

1a, 1b, 1c and 1d is a process diagram of a first embodiment showing a method for producing a carbon nanotube according to the present invention,

2a, 2b and 2c is a process diagram showing the introduction of an inducer for the delivery of a metal catalyst well in the production of carbon nanotubes according to the present invention,

3a, 3b, 3c and 3d is a process diagram of a second embodiment showing a method for producing a carbon nanotube according to the present invention,

4a, 4b, 4c and 4d is a process diagram of a third embodiment showing a method of manufacturing carbon nanotubes according to the present invention;

5a, 5b, 5c and 5d is a process diagram of a fourth embodiment showing a method of manufacturing a carbon nanotube according to the present invention,

6A, 6B, 6C and 6D are flowcharts of a fifth embodiment showing a method of manufacturing carbon nanotubes according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: silicon substrate

110: structure

120: AFM Tips

130: metal catalyst

140: carbon nanotubes

Claims (7)

The process of forming the structure 110 on the upper surface of the silicon substrate 100, AFM (Atomic Force Microscope) tip (tip) A metal catalyst 130 is applied to the end of the tip, AFM tip coated with the metal catalyst 130 Placing 120 on top of the structure 110, transferring a metal catalyst 130 on the structure 110, and the silicon substrate 100 and the metal catalyst 130. In the manufacturing method of the carbon nanotubes comprising a step of growing the carbon nanotubes 140 on the upper portion of the structure 110 by placing the structure 110 is located in an environment capable of applying carbon gas and heat. , The upper portion of the structure, The method of producing a carbon nanotubes, characterized in that the coating of a chemical agent of Au having a feature that is fixed to the metal catalyst to be transferred to the metal catalyst (Metal Catalyst) to be fixed well on the structure. delete delete delete The method of claim 1, In order to control the length of the prepared nanotubes, Method for producing carbon nanotubes, characterized in that the length can be adjusted by using a discharge (discharage). The method of claim 1, In order to control the direction and the number of carbon nanotubes growing on the structure 110, Method of producing a carbon nanotubes, characterized in that the shape of the upper portion of the structure 110 can be changed in various forms. The method of claim 1, The metal catalyst 130 is applied to the end of the AFM tip 120, Method of producing a carbon nanotube, characterized in that to form a structure of the structure to be fixed to the structure 110, the inner groove, the slanted inclined groove inward to the center, irregularities or grooves.