真空感应熔炼和定向凝固制备多晶硅中铝的除杂

Purification Behavior of Impurity Aluminum in Multicrystalline Silicon by Vacuum Induction Melting and Directional Solidification Method

用真空感应熔炼和定向凝固法制备多晶硅,通过成分测定和理论计算研究了铝杂质的除杂机理。结果表明,在真空熔炼保温阶段(T≥1723 K),硅中的铝杂质明显蒸发;在随后的定向凝固过程中,铝杂质的分凝偏析是主要的,但仍有部分铝蒸发。建立了一个包括铝分凝和蒸发机制的新模型,模拟铝在硅中的分布曲线。模拟结果与铝在硅中的实际分布符合得很好。

Purification mechanism of impurity aluminum in multicrystalline silicon ingot made from metallurgical-grade silicon was investigated by composition analysis and theoretical analysis of vacuum induction melting and directional solidification.The results showed that the content of impurity aluminum was significantly decreased due to the obviously evaporation in the stage of thermal insulation （T≥1723 K）.The segregation of impurity aluminum plays an important role in the distribution of aluminum in subsequent directional solidification process,but a little amount aluminum evaporation still happened.A new theoretical model including segregation phenomenon and evaporation mechanism was developed to simulate the distribution of aluminum in multicrystaliine silicon.The result of simulation was well consistent with the measured distribution of aluminum in the obtained ingot.