摘要
以实验室10 t/a VODS型多晶炉为原型,对其凝固过程的热场、固液界面和热应力进行了瞬态模拟与实验验证。结果表明:在坩埚底部有水冷热交换块的真空定向凝固系统中硅料凝固会产生较大的热应力,增加环形保温结构使热区封闭后可改变炉内换热过程,从而改变硅料凝固情况;硅料在坩埚底部为石墨热交换块的系统中凝固时产生的热应力相对较小,但固液界面的形状会发生较大的改变,影响晶粒的生长。炉膛内径适当变宽有利于炉内热区温度分布更合理,使得硅料凝固时的固液界面更加理想。通过实验验证了多晶硅在坩埚底部无需进行水冷换热情况下进行真空定向凝固能达到冶金法生产太阳能级多晶硅的要求,这为提高冶金法制备太阳能级多晶硅质量、降低系统能耗具有一定的指导意义。
We conducted transient simulation and experimental on the temperature field,solid-liquid interface and thermal stress in the solidification process of a laboratory 10 t/a VODS polysilicon furnace. The results show that the larger thermal stress in the silicon ingot in the vacuum directional solidification system with water-cooling heat exchanger under the bottom of crucible produces,and sealing the heat zone by adding an annular insulation can change the heat transfer process inside the furnace and improve the solidification sate of silicon.The smaller thermal stress in the silicon ingot in the system with the graphite block heat exchanger under the crucible bottom,but the solid-liquid interface in the solidification process vary obviously,affecting the growth of crystal. Broadening the inner diameter of the furnace chamber can improve the temperature distribution in the hot zone and is favorable for the solid-liquid interface. The experiments show that solar-grade polysilicon can be produced by the improved vacuum directional solidification system with graphite block heat exchanger under the bottom of crucible.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2015年第5期230-236,共7页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金(51466005
U1137601)
关键词
多晶硅
真空定向凝固
数值模拟
固液界面
少子寿命
polysilicon
vacuum directional solidification
numerical simulation
solid-liquid interface
minority carrier lifetime
