冶金法提纯多晶硅退火工艺优化的数学模型分析与试验验证

Mathematical Model Analysis and Experimental Verification of Polycrystalline-Silicon Annealing Optimization by Metallurgical Method

冶金法制备多晶硅过程中,通过对不同退火温控方案进行数学建模,探求优化的退火理论温度控制函数与曲线。数学模型表明,对硅铸锭直接进行保温,依靠自然热平衡退火,会使内部应力大于产生位错的临界应力;采用加热元件对硅铸锭适当加热保温可减缓降温速率。通过比较,选择较低的退火温度1 236℃和较短的退火时间8.52 ks作为试验退火温控方案。试验验证表明,该退火方案得到的多晶硅铸锭目视裂纹较少,少数载流子寿命与电阻率具有明显优势。

In the process of purifying polysilicon by metallurgical method,the temperature control function and curve of annealing theory are explored by mathematical modeling of different annealing temperature schemes.The mathematical model shows that the silicon ingot is directly insulated,depending on the natural thermal equilibrium annealing,the internal stress is greater than the critical stress of generating dislocation.The top heater is used to heat the top of the silicon ingot to reduce the cooling rate.By comparison,a lower annealing temperature of 1236℃and a shorter annealing time 8.52 ks is chosen as a reasonable theoretical annealing control scheme.The experimental results show that the annealing scheme has the advantages of less visual crack and a few carrier lifetime and resistivity.