Release Time:2022-06-21  Hits:

Date of Publication: 2017-01-01

Journal: 无机材料学报

Institution: 材料科学与工程学院

Volume: 32

Issue: 3

Page Number: 281-286

ISSN: 1000-324X

Abstract: Preparation of 6N grade polycrystalline silicon materials using raw materials of industrial silicon was explored by medium melting, directional solidification and electron beam melting. The contents of impurities B and P in the samples are both lower than 0.20 ppmw, while the total content of metal impurity (TM) is less than 0.23 ppmw. Dur-ing the process of removing B by medium melting, a large proportion of Al and Ca is simultaneously removed through the redox reaction. During the process of electron beam melting, volatile impurities including P, Al and Ca are fur-ther effectively removed by using saturated vapor pressure. Meanwhile, other metal impurities are removed by de-creasing beam power, which induces the occurrence of directional solidification. Coupling of metallurgical methods reduces the purification process of polycrystalline silicon, and provides the technical support for continuous and large-scale production.

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