三层液精炼法提纯多晶硅的研究

Removal of Boron and Phosphorus from Silicon by Three-layer Refining

在高温下利用密度差别,以熔硅、熔渣和熔铁(或铜)构建Si/Slag/Me三层液体系。冶金硅中的B和P杂质扩散到熔渣和底层金属中,达到提纯冶金硅的目的。热力学计算结果证明了这种方法具有可行性。实验研究分析了底层金属类型、炉渣成分及反应温度对B和P去除率的影响。结果表明:底层金属可有效吸收冶金硅中的P,其中铁比铜有更好的P吸收效果。底层金属对B的吸收效果不佳,B的去除主要归功于造渣提纯过程。在炉渣中加入10 wt%的CaF_(2),降低了渣黏度,可显著提高B和P的去除率。1600~1700℃温度范围内,提高反应温度有利于B的去除,对P的去除无显著作用。

A new refining concept aims to remove both B and P simultaneously in silicon has been proposed in Si/Slag/Me(Me:Fe or Cu)system.Both liquid Si and liquid Fe/Cu phases are separated by the molten slag phase spontaneously based on their physicochemical properties.Equilibrium evaluations indicate that both the B and P,the most difficult impurities to be removed from ultra-pure silicon,can be redistributed to the slag and another metal phase.It is experimentally shown that the simultaneous removal of both B and P via a single metallurgical refining process is possible by three-layer refining.The metal phase plays an P impurity collector role in the system,but has little effect on B adsorptions.Liquid Fe works better than the molten Cu for P adsorptions.Addition of CaF_(2) to the binary CaO-SiO 2 slag increase significantly the remove rates of B and P,due to CaF_(2) can reduce the viscosity of slag.Increasing temperature from 1600℃to 1700℃improves the B remove rate significantly,but has little effect on P remove.