Purification of metallurgical grade silicon by a microwave-assisted plasma process

• Published in: Separation and purification technology 2013-01, Vol.102 (4), p.82-85
• Main Authors: Wang, Jiangtao, Li, Xiaodong, He, Yongmin, Feng, Na, An, Xiuyun, Teng, Feng, Gao, Caitian, Zhao, Changhui, Zhang, Zhenxing, Xie, Erqing
• Format: Article
• Language: English
• Subjects: Emission analysis; Impurities; Impurity concentrations; Inductively coupled plasma; Metallurgical grade silicon; Metallurgy; Microwave; Microwave plasmas; microwave treatment; phosphorus; Plasma; Purification; Silicon; Spectroscopy
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2012.09.035

► A new microwave plasma purification technique was proposed. ► The purification effect was significant after treatment for 15min. ► The removal rate of the element P is 100% only for 5min treatment. ► The experimental temperature was 1000°C, lower than other plasma techniques. A new microwave plasma process is developed to refine and purify metallurgical grade silicon (MG-Si) effectively. Inductively coupled plasma-atomic emission spectrometry analysis (ICP-AES) indicates that the concentrations of impurities in silicon decrease significantly in the process, particularly for phosphorus, whose average removal rate is close to 100% after microwave plasma treatment of only 5min. The underlying mechanisms of the ultra-high removal rate of impurity atoms are discussed in detail in this paper. The photoresponse switching behavior of n+-Si wafers that are made of as-purified silicon provides further evidence for the unique advantage arising from the use of microwave plasma in the purification of MG-Si.