坩埚厚度对多晶硅定向凝固的影响

Effects of Crucible Thickness on Directional Solidification of Polysilicon

运用Comsol Multiphysics有限元软件对多晶硅的定向凝固过程进行了模拟,分析了不同坩埚厚度(15、20、25 mm)对多晶硅熔化、结晶过程及晶体热应力的影响。结果表明:当坩埚厚度为15 mm时,熔化所需要的时间最短,比坩埚厚度为20 mm和25 mm时分别少31 min和74 min;结晶初期,坩埚厚度为25 mm时的固液界面最为平坦,最有利于晶体的生长;多晶硅晶体底部边缘和顶部边缘区热应力高;坩埚厚度为15 mm时,晶体内热应力最大,且随着坩埚厚度的增大,两个区域的应力都减小。

The directional solidification process of polysilicon was simulated by using the finite element software Comsol Multiphysics, and the effects of the crucible thickness （15, 20, 25 mm） on the melting, crystallization of polysilicon and the thermal stress of the crystal were analyzed. The results show that when the crucible thickness is 15mm, the melting time is the shortest, which is 31 min and 74rain less than that of the crucible with thickness of 20 mm and 25 mm respectively. When the crucible thickness is 25mm, the solid-liquid interface is the flat test at the initial stage of crystallization, which is beneficial to the crystal growth. The thermal stresses at bottom edge and top edge of the polysilicon crystal are high. When the crucible thickness is 15 mm, the thermal stress is maximum,and with the increase of the crucible thickness, the thermal stresses in the two regions reduce.