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Method for preparing solar grade polysilicon by metallurgy method and polysilicon prepared thereby

A technology of solar-grade and metallurgical methods, applied in the growth of polycrystalline materials, chemical instruments and methods, crystal growth, etc., can solve the problem of insufficient purity of solar-grade polycrystalline silicon

Inactive Publication Date: 2012-07-25
SOUTH CHINA NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to solve the problem that the purity of solar-grade polysilicon prepared by the existing metallurgical method is not high enough, and to provide a method for preparing solar-grade polysilicon by a metallurgical method with low cost, convenient operation, and simple process suitable for industrial production and the method. Polysilicon

Method used

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Examples

Experimental program
Comparison scheme
Effect test

specific Embodiment 1

[0021] Specific embodiment 1: The technical solution of this embodiment is realized according to the following steps: put the metal silicon block in a high-purity quartz crucible, under the protection of inert argon, turn on the medium frequency induction heating, melt the metal silicon, and then add the oxidizing electrode Strong alkaline slagging agent, oxidized slagging in a directional solidification furnace, the treatment temperature is 1400-1800°C, the reaction time is 0.5-2 hours, then close the argon device, open the vacuum butterfly valve, start after the vacuum reaches 600Pa Roots pump, until the vacuum degree reaches 0.2Pa, keep the temperature at 0.2Pa and let it stand for 15-60 minutes, then turn on the water cooling plate at the bottom of the directional solidification, continue to give the smelting a bottom-up condensation gradient, strictly control the solidification process Preferably, the cooling rate is 2-10K / min, and the melting speed is 0.25-1mm / min to obta...

specific Embodiment 2

[0022] Specific embodiment 2: the technical scheme of this embodiment is realized according to the following steps: take a 441# metal silicon block with a weight of 100g, and under the protection of inert argon, turn on the medium frequency induction heating, melt the metal silicon, and then add a slag-gold ratio of 0.20 Alkaline slagging agent SiO 2 -KHCO 3 -CuO-CaF 2(60%-25%-10%-5%) 20g, oxidized and slag-forming in a 60KW medium-frequency directional solidification furnace, and kept at 1500°C for 1h. Then close the argon device, open the vacuum butterfly valve, and when the vacuum reaches about 600Pa, start the Roots pump until the vacuum reaches 0.2Pa, and then keep it for about 30 minutes. Then turn on the water cooling plate at the bottom of the directional solidification, and continue to give the smelting a bottom-up condensation gradient. During the solidification process, the cooling rate is strictly controlled to 4K / min, and the melting speed is 0.8mm / min to obtain...

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Abstract

The invention discloses a method for preparing solar grade polysilicon by a metallurgy method and the polysilicon prepared thereby and relates to a preparation method of the polysilicon and the polysilicon prepared by the method. The invention aims to solve the problem that the purity of the solar grade polysilicon prepared by the traditional metallurgy method is not high enough. Through oxidation and scorification, namely a slag forming constituent is added to oxidize impurities in a silicon melt and then the impurities float on the upper layer of the silicon melt; a freezing gradient from top down is applied to the melt so that the silicon melt is better separated from slags; at the same time, vacuum unidirectional solidification contributes to further removal of the impurities; a silicon ingot is crushed; and the impurities gathered at the crystal boundary is further removed with hydrofluoric acid to obtain solar grade silicon. Compared with the traditional chemical method, the metallurgy method greatly reduces the energy consumption, shortens the production period and is suitable for industrial production. In the whole production process, no pollution is caused; and scraps in an acid leaching process can be discharged after simple neutralization. In the invention, metallurgical silicon can be purified to produce the solar grade silicon.

Description

technical field [0001] The invention relates to a method for preparing polysilicon and polysilicon prepared by the method, belonging to the technical field of semiconductor processing. Background technique [0002] At present, the global energy shortage, environmental pollution and climate warming are increasingly plaguing human society. "Seeking green alternative energy to achieve sustainable development" has become a common issue faced by all countries in the world. Solar energy because it does not emit CO 2 and SO 2 , and without the noise, solid waste and other pollution of conventional power generation, it is regarded as one of the most important renewable energy sources at present. It is estimated that by 2020, the world's solar photovoltaic production will reach the level of 18GW per year, dozens of times higher than the 278MW in 2000. There are many kinds of materials for preparing solar cells, but silicon has become the most important raw material in solar power ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/037C30B29/06
Inventor 陈红雨胡玉燕卢东亮
Owner SOUTH CHINA NORMAL UNIVERSITY