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Method for purification of silicon and silicon purified by said method

A technology for melting silicon and gas, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of long refining time, large size, expensive, etc., and achieve the effect of simple and low-cost refining process

Inactive Publication Date: 2007-06-20
SHARP KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] According to this method, although boron oxide can be evaporated and removed at high temperature, the portion used for plasma reaction is limited because of the structure of the device
Therefore, the device is large in size, expensive, and requires a long refining time

Method used

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  • Method for purification of silicon and silicon purified by said method
  • Method for purification of silicon and silicon purified by said method
  • Method for purification of silicon and silicon purified by said method

Examples

Experimental program
Comparison scheme
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Embodiment 1

[0063] In this example, 1Kg MG-Si was placed in the crucible 2 in Fig. 1, and then silicon dioxide powder, lithium silicate powder and calcium silicate powder were mixed in an amount equivalent to 20% by weight of MG-Si Mix and place it in crucible 2. The silica powder, lithium silicate powder and calcium silicate powder were converted into silica:lithium oxide:calcium oxide=67:16:17 (mass ratio), and mixed. Next, the inside of the furnace 1 was set to an Ar atmosphere of 0.10 MPa, and the crucible 2 was heated using the electromagnetic induction heating device 3 to melt the MG-Si and keep it at 1550°C. In order to measure the boron content before processing, about 20 g of molten silicon 8 were extracted, 5 g of which were used for the measurement.

[0064] As the purge gas, a gas in which 60% by volume of water vapor was mixed with respect to a carrier gas composed of a mixed gas of Ar and hydrogen (4% by volume of hydrogen) was used. Refined gas was introduced into the gas...

no. 2 example

[0067] The refining process was performed in a manner similar to that of the first embodiment, except that a treating gas containing only Ar was used in order to clarify the role of hydrogen in the treating gas. The results are shown in Figure 3. As shown in FIG. 3, in this embodiment in which hydrogen is not added to the process gas, although the concentration of boron is slightly higher than that of the first embodiment, boron removal can be effectively performed without reducing the concentration of boron. removal speed.

no. 3 example

[0069] In this embodiment, the refining process is carried out in a manner similar to that of the first embodiment except that the composition of the refining additive is changed. As refining additives, silica powder and lithium silicate powder were converted into silica:lithium oxide=80:20 (mass ratio) and mixed. The results are shown in Figure 3. As shown in Fig. 3, the concentration of boron is slightly higher than that of the first embodiment. The reason for this is conceived as follows. Compared with the first embodiment, since the specific gravity of the refining additive of silicon dioxide: lithium oxide=80:20 (present embodiment) is lighter than the refining additive of silicon dioxide: lithium oxide: calcium oxide=67:16:17 ( First embodiment), so the slag is easy to float on the surface of the melt, and the evaporation removal rate of boron oxide is reduced. However, by performing the process gas blowing process, boron removal can be effectively achieved without re...

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Abstract

This invention provides a method for purification of silicon that can purify silicon efficiently without sacrificing the purification rate and can provide silicon for solar cells at a low cost. The method for purification of silicon is a method for purifying molten silicon (8) containing impurity elements and comprises, in one aspect, a step of bringing a purification gas containing a component reactive with the impurity elements into contact with the molten silicon (8) to remove an impurity element-containing product from the molten silicon (8) and a step of bringing a treatment gas having a low level of reactivity with the molten silicon (8) into contact with the molten silicon (8) to remove the product of the reaction between the molten silicon (8) and the purification gas.

Description

technical field [0001] The present invention relates to a silicon refining process for the production of silicon raw material for use in solar cells. Background technique [0002] In consideration of environmental issues, the use of natural energy instead of petroleum and the like has attracted attention. Among them, a solar cell using the principle of photoelectric conversion of a silicon semiconductor has such a feature that it can easily convert solar energy into electricity. However, in order to popularize solar cells, it is necessary to reduce the cost of solar cells, especially semiconductor silicon. [0003] As for high-purity silicon for semiconductor integrated circuits, trichlorosilane (SiHCl 3 ), which is then purified by distillation and thereafter refined (Siemens method) to obtain high-purity silicon of about 11N(9), the metallic silicon being obtained by reduction of silicon dioxide with carbon. However, such high-purity silicon requires complicated manufac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
CPCC01B33/037
Inventor 福山稔章和田健司
Owner SHARP KK