Method for removing boron and phosphorus impurities in industrial silicon by ferrous compounds

An industrial silicon and compound technology, which is applied in silicon compounds, chemical instruments and methods, inorganic chemistry, etc., can solve the problems of high equipment requirements, high cost, and high power consumption of the process, and achieve low energy consumption, low cost, and easy operation Effect

Inactive Publication Date: 2011-08-03
SHANDONG SHENHUAGUANGFU MATERIAL
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  • Summary
  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

US Patent 5182091 (Yuge, Noriyoshi et al. Method and apparatus for purifying silicon) and the paper "Removal of boron from metallurgical-grade silicon by applying the plasma treatment" (Tomonori Kumagai et al. ISIJ International, Vol.32 (1992). No. 5, pp.630~634) all disclose a method of applying plasma to the surface of molten silicon, which has a remarkable effect of removing impurities, especially B, but the above process consumes a lot of power, requires high equipment, and is expensive

Method used

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Examples

Experimental program
Comparison scheme
Effect test

specific Embodiment 1

[0037] 1. Coat a dense SiC coating on the surface of the graphite crucible as the inner layer, and then coat the SiC coating with Y 2 o 3 The coating is used as the outer layer to increase the service life of the graphite crucible.

[0038] 2. Weigh Fe 2 o 3 (20%wt)-SiO 2 (60%wt)-CaF 2 (20%wt) total 130kg of slagging agent, put into the graphite of coating. Close the furnace cover and turn on the power to 120KW to melt the slag.

[0039] 3. After the slag material is melted, add 25Kg industrial silicon (B content is 8.6ppmw, P content is 15ppmw). After the slag and silicon materials are completely melted, reduce the power to 90KW, and the reaction temperature at this time is 1550°C as measured by an infrared thermometer.

[0040] 4. Introduce the mixed gas Ar+H into the system 2 O, where the volume fraction of Ar is 60%, H 2 The volume fraction of O is 40%. The ventilation rate is 2L / min, and the melt is fully stirred.

[0041] After 5.30 minutes, the ventilation wa...

specific Embodiment 2

[0043] Technological process is with embodiment 1. Add slagging agent Fe 3 o 4 (40%wt)-SiO 2 (45%wt)-CaF 2 (15%wt) 100kg in total. The slag is melted at a power of 150KW, and then 45kg of industrial silicon is added. After complete melting, reduce the power to 120KW, and the reaction temperature is 1850°C. Pass 90%Ar+10%H 2 O stir the melt, the ventilation rate is 1L / min. After the slagging continued for 15 minutes, 45Kg of industrial silicon was added again, for a total of 15 times. A total of 573Kg of refined polysilicon was obtained. The average B content measured by ICP-MS is 0.25ppmw, and the average P content is 1.5ppmw.

specific Embodiment 3

[0044] Technological process is with embodiment 1. Add slagging agent Fe(OH) 3 (35%wt)-SiO 2 (40%wt)-CaF 2 (25%wt) 100kg in total. The slag is melted at a power of 130KW, and then 35kg of industrial silicon is added. After complete melting, reduce the power to 110KW, and the reaction temperature is 1750°C. Pass 70%Ar+30%H 2 O Stir the melt, the ventilation rate is 1.5L / min. After the slagging continued for 20 minutes, 25Kg of industrial silicon was added again for a total of 10 times. A total of 212Kg of refined polysilicon was obtained. The average B content measured by ICP-MS is 0.12ppmw, and the average P content is 0.7ppmw.

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Abstract

The invention provides a method for removing boron and phosphorus impurities in industrial silicon by ferrous compounds; the method comprises the following steps: selecting FeR (Fe2O3, Fe (OH) 3, Fe3O4 and the like)-SiO2-CaF2 as main components of slag forming agent, greatly increasing the distribution coefficient ratio of metal slags by combining a new process flow to lead the removal rate of boron to reach more than 95% and the removal rate of phosphorus to reach more than 90%. After the completion of slag forming, the directional solidification process is needed to be carried out so as to purify industrial silicon to form solar-grade polycrystalline silicon. The method has the characteristics of low cost and low energy consumption, is easy to operate, and is suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of semiconductor material technology and metallurgy, and specifically relates to a method for removing boron and phosphorus impurities in industrial silicon by using iron-containing compounds. Background technique [0002] In today's society, the energy crisis and the environmental pollution of traditional energy are becoming more and more serious. The development of clean and environmentally friendly energy has become a major problem facing mankind. Therefore, new energy has become one of the important fields of scientific research in the 21st century. The idea of ​​using solar energy, an inexhaustible clean energy, has been around for a long time. At first, it was directly converted into thermal energy utilization. Later, the discovery of the photovoltaic effect made the field of solar energy utilization more flexible and broad. Silicon is an element that is extremely abundant on earth and can be said to be inexhaus...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 陈建华
Owner SHANDONG SHENHUAGUANGFU MATERIAL
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