多晶硅冷却过程中入口流速及隔热底板运动对硅锭内热应力影响

摘要

为了提高大尺寸多晶硅锭质量，本文对多晶硅定向凝固系统冷却过程进行瞬态数值模拟，研究了不同冷却时刻炉体内温度场、流场及硅锭内应力场瞬态变化，隔热底板位移按直线、正弦及抛物线规律变化时，硅锭内部最大米塞斯力及无位错面积百分比随时间的变化，以及不同入口气体速率对硅锭内部最大米塞斯力的影响。计算结果表明：隔热底板位移按正弦规律变化更有助于提高多晶硅锭质量；冷却结束时硅锭内最大米塞斯力随入口流速的增加而增大；冷却初始阶段，增大入口气体速率有利于降低硅锭内部最大米塞斯力。%To improve the quality of large-scale polycrystalline silicon ingot,a global transient model was carried out to investigate the cooling process of polycrystalline silicon directional solidification systems.The main contents include:Firstly,the transient development of the thermal field,flow field and the stress distribution of silicon ingot at different cooling time.Secondly,the maximum von Mises stress and area fraction of the dislocation-free regions under different motions of the bottom insulated plate. Thirdly,the effect of the inlet gas velocity on the maximum von Mises.The results show that a sinusoidal variation for the bot-tom insulated plate displacement may be better to improve the ingot quality.At the end of the cooling process,the maximum von Mises stress goes up as the inlet gas velocity increases,howerver,in the initial stage,it is helpful to decrease the maximum stress with small inlet gas velocity.