温度梯度对多晶硅感应熔炼除杂效果的影响

EFFECT OF TEMPERATURE GRADIENT ON IMPURITY REMOVAL IN INDUCTION MELTING OF POLYCRYSTALLINE SILICON

以低硼工业硅为原料,基于真空感应熔炼技术,通过调控界面前沿的温度梯度,比较分析固液前沿温度梯度的变化对多晶硅铸锭定向凝固过程中金属杂质分凝的影响。温度梯度为473.62 K/m时,铸锭出成率达到63%,当温度梯度增大到940.51 K/m时,提纯区比例提高至88%。以Fe、Ni、Cu、Ti为研究元素,分别计算温度梯度增大前后杂质的扩散层厚度和有效分凝系数,结果表明,随着温度梯度的增大,杂质的扩散层厚度和有效分凝系数均减小,可大大提高杂质的分凝去除效果及铸锭的出成率。

The influence of temperature gradient on impurity segregation of metal impurities in polycrystalline silicon during directional solidification is analyzed by regulating the temperature gradient at the front of the solid-liquid boundary interface. When the temperature gradient was 473.62 K/m,the yield of silicon was 63%. When the temperature gradient increased to 940.51 K/m,the proportion of the purification area increased to 88%. The thickness of diffusion layer and effective segregation coefficient of Fe,Ni,Cu and Ti were calculated under different temperature gradient conditions. The results show that the diffusion layer thickness and the effective segregation coefficient of metal impurities decreased with the increase of temperature gradient,which greatly improves the removal of impurity segregation,and improves the yield.