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在氟化物电解质体系下,把Cu与冶金级多晶硅熔配成合金作为阳极,利用杂质与硅析出电位的差别,通过控制电解工艺条件和参数,对冶金硅进行了电解精炼提纯研究.结果表明,阳极铜硅合金对硅中的杂质有滞留作用,且在大电流密度下Cu不会随着合金中硅的减少而溶解到电解质中;预电解对电解质净化效果明显,XRF分析表明P含量从10降为1ppmw;阴极电沉积的硅呈颗粒状,并与电解质混杂,随着电解时间的延长,分散的硅的颗粒聚集成1—2cm直径的大尺寸硅球.ICP-AES分析表明,最后得到的产物硅与冶金级硅相比,硼含量由12·7降低到2·2ppmw,磷含量由98·6减少到4·1ppmw,说明电解精炼除杂进行多晶硅的提纯是有效和可行的.
In the fluoride electrolyte system, Cu and metallurgical grade polycrystalline silicon are alloyed as the anode, and the difference between the impurity and the precipitation potential of silicon is used. By controlling the electrolysis process conditions and parameters, the metallurgical silicon is refined by electrolytic refining. Anode copper-silicon alloy has a retention effect on the impurities in silicon, and Cu does not dissolve into the electrolyte with the decrease of silicon in the alloy at high current density. The pre-electrolysis has a clear effect on electrolyte purification. XRF analysis shows that the P content is increased from 10 Reduced to 1ppmw; Cathode electrodeposition of silicon was granular and mixed with the electrolyte, with the electrolysis time, scattered silicon particles aggregated into 1-2cm diameter large-size silicon ball.ICP-AES analysis showed that the final Compared with metallurgical grade silicon, the content of boron decreased from 12.7 to 2.2 ppmw, and the phosphorus content decreased from 98.6 to 4.1 ppmw. This shows that it is effective and feasible to purify polycrystalline silicon by electrolytic refining and impurity removal.