JP2009161404A - Method for manufacturing silicon nanowire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a silicon nanowire of high purity at a low temperature. <P>SOLUTION: [1] The silicon nanowire is manufactured by allowing a mixed gas of silicon tetrachloride gas and an inert gas or silicon tetrachloride gas 5 to flow through a high temperature region 3 into a region at a temperature lower than that of the high temperature region (low temperature region 4), providing aluminum at the high temperature region 3, and crystallizing the silicon nanowire at the region 4 at a temperature lower than that of the high temperature region. [2] The method is characterized by setting a temperature in a high temperature region at 700 to 1,100°C in the method described in [1]. [3] The method is characterized by setting a temperature in the region with a temperature lower than that of the high temperature region at 600 to 900°C in the method described in [1] or [2]. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing silicon nanowires.

Silicon nanowires are attracting attention as members for nanomachines and semiconductor information communication devices.
Conventionally, it is known that silicon nanowires are produced by a melting method (Patent Document 1), an evaporation method (Patent Document 2), and a catalytic method (Patent Document 3).

JP 2003-142680 A (claims, paragraphs 0006, 0014 to 0016, 0019 to 0021) JP 2004-296750 A (Claims, paragraphs 0011 to 0015) JP 2006-117475 A (Claims, paragraphs 0014 to 0018)

However, the melting method requires a high temperature exceeding 1500 K, and the evaporation method also requires a temperature exceeding 1300 ° C. in order to evaporate silicon. When the temperature is high, there is a problem that the material of the device that can withstand use is restricted or the energy consumption is large.
On the other hand, although it is possible to manufacture silicon nanowires at a low temperature by the catalytic method, there is a problem that a catalyst component is contained in the silicon nanowires because a catalyst is required in the manufacturing method.

  An object of the present invention is to provide a method for producing high-purity silicon nanowires at a low temperature.

  As a result of intensive studies on a method for producing silicon nanowires, the present inventors have completed the present invention.

That is, the present invention provides: [1] A mixed gas of silicon tetrachloride gas and an inert gas or silicon tetrachloride gas is circulated through a high temperature region to a region having a temperature lower than that of the high temperature region. The present invention relates to a method for producing silicon nanowires in which aluminum is supplied and silicon nanowires are deposited in a region having a temperature lower than that of the high temperature region.
Furthermore, the present invention provides [2] the method according to [1], wherein the temperature in the high temperature region is 700 ° C. or higher and 1100 ° C. or lower.
[3] The method according to [1] or [2], wherein a temperature in a region lower than the high temperature region is 600 ° C. or higher and 900 ° C. or lower.
In the present invention, the silicon nanowire refers to a linear material having a diameter of nanometer order made of silicon. For example, a linear material having a diameter of 1 to 500 nm or 20 to 300 nm made of silicon can be used.

  According to the production method of the present invention, high-purity silicon nanowires can be produced at a low temperature.

[Silicon tetrachloride]
The method for producing silicon nanowires of the present invention uses a mixed gas of silicon tetrachloride gas and an inert gas or silicon tetrachloride gas.
Silicon tetrachloride gas is easily available as a high purity product of 6N or more.
Silicon tetrachloride gas may be supplied alone, or in order to control reactivity, silicon tetrachloride is diluted with an inert gas and supplied as a mixed gas of silicon tetrachloride gas and an inert gas. Also good. The silicon tetrachloride gas concentration in the mixed gas is preferably 5 vol% or more, more preferably 20 vol% or more, and further preferably 50 vol% or more. Examples of the inert gas include argon and helium, and argon is preferable.
A known method can be used as a method for supplying the silicon tetrachloride gas. Specifically, a method of supplying an inert gas into a container filled with liquid silicon tetrachloride and bubbling it to supply as a mixed gas of silicon tetrachloride gas and an inert gas, or liquid silicon tetrachloride There is a method in which liquid is supplied to a container (vaporizer) heated by a metering pump and supplied as silicon tetrachloride gas.

〔aluminum〕
In the present invention, aluminum is supplied to the high temperature region.
The aluminum used in the present invention is preferably high-purity from the viewpoint of improving the purity of the obtained silicon. For example, the purity is preferably 99.9% or more, more preferably 99.99%.
Examples of such high-purity aluminum include those obtained by purifying general-purpose products by a known method. For example, high-purity aluminum can be obtained by refining electrolytically reduced aluminum (ordinary aluminum) by a segregation solidification method, a three-layer electrolytic method, or the like.
In the present invention, the shape of the aluminum used is preferably fine particles from the viewpoint of increasing the reactivity. The aluminum fine particles are usually particles having a particle size of 500 μm or less by sieving, preferably 212 μm or less, more preferably 150 μm or less.
The aluminum fine particles may be kept in the high temperature region, but if the temperature is high, the reactivity may decrease due to melting. Therefore, preferably, aluminum is supplied in the fine particle state to the high temperature region immediately. You may make it react. Specifically, there is a method in which molten aluminum is sprayed to a high temperature region with a spray nozzle or the like and supplied to the high temperature region.

The high temperature region can be appropriately formed by a known method. For example, a method using a high frequency induction heating method, a resistance heating method, or the like can be given.
The temperature in the high temperature region is preferably 800 ° C. or higher and 1000 ° C. or lower. When the temperature in the high temperature region is lower than 800 ° C., the yield of silicon may decrease, and when it exceeds 1000 ° C., the cost may increase. The silicon tetrachloride concentration in the atmosphere in the high temperature region is preferably 5 vol% or more, more preferably 20 vol% or more, and further preferably 50 vol% or more. The atmosphere in the high temperature region preferably contains no gas such as water and oxygen from the viewpoint of reaction progress.

[Deposition of silicon nanowires]
In the method for producing silicon nanowires of the present invention, it is a flow downstream region of a mixed gas of silicon tetrachloride gas and an inert gas or silicon tetrachloride gas and has a lower temperature than the high temperature region (hereinafter referred to as a low temperature). In this case, silicon nanowires are deposited. The temperature in the low temperature region is preferably 600 ° C to 1000 ° C.

  The production of silicon nanowires in the present invention is usually carried out in a container made of a material that has heat resistance at a temperature in a high temperature region and does not contaminate silicon nanowires that are products. Examples of the material of the container include carbon, silicon carbide, silicon nitride, aluminum nitride, alumina, and quartz.

  FIG. 1 is a configuration diagram showing an example of an apparatus for carrying out the manufacturing method of the present invention. In FIG. 1, in a reaction tube 1 installed in a heating furnace 2, a mixed gas of silicon tetrachloride gas and an inert gas or a silicon tetrachloride gas 5 is passed from the lower side to the upper side, through the high temperature region 3, and at a low temperature. Distribute to the area. When aluminum fine particles are held in the high temperature region 3, silicon nanowires are deposited in the low temperature region 4.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention disclosed above are merely examples, and the scope of the present invention is not limited to these embodiments. The scope of the present invention is defined by the terms of the claims, and includes all modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1
In FIG. 1, carbon paper was laid on a portion corresponding to the high temperature region 3, and aluminum fine particles (particles having a particle size of 150 μm or less by sieving, 30 mg) were held thereon.
The temperature in the high temperature region was raised to 895 ° C., and the temperature in the low temperature region was raised to 790 ° C.
Argon was passed at a flow rate of 80 ml / min through a container filled with silicon tetrachloride (manufactured by Trichemical Laboratories) maintained at 45 ° C., and a mixed gas of silicon tetrachloride and argon gas was sent to the high temperature region. In this way, the high temperature region was a mixed gas atmosphere of silicon tetrachloride and argon gas.
After supplying a mixed gas of silicon tetrachloride gas and argon gas for 10 minutes, the gas was switched to argon gas, and the temperature was lowered to room temperature.
When the inside of the apparatus was checked after cooling, it was confirmed that a cotton-like substance was deposited on the surface of the carbon nozzle (corresponding to a low temperature region). As a result of analysis by an electron probe micro-analysis (EPMA) method, the cotton-like substance was confirmed to be silicon. The cotton-like substance was linear, and as a result of transmission electron microscope observation, it was an aggregate of linear objects having a diameter of 20 nm to 300 nm, and the production of silicon nanowires was confirmed.

The block diagram which illustrated the reaction apparatus. The scanning electron microscope image of the silicon nanowire produced | generated in Example 1. FIG.

Explanation of symbols

1 Reaction tube 2 Heating furnace 3 High temperature zone (reaction zone)
4 Low temperature region (precipitation part)
5 Mixed gas of silicon tetrachloride gas and inert gas or silicon tetrachloride gas

Claims (3)

  A mixed gas of silicon tetrachloride gas and an inert gas or silicon tetrachloride gas is passed through a high temperature region to a region having a temperature lower than that of the high temperature region, and aluminum is supplied to the high temperature region. A method for producing silicon nanowires, comprising depositing silicon nanowires in a region where the temperature is lower than that.   The method according to claim 1, wherein the temperature in the high temperature region is 700 ° C. or higher and 1100 ° C. or lower.   3. The method according to claim 1, wherein a temperature in a region lower than the high temperature region is 600 ° C. or more and 900 ° C. or less.

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