直拉法硅单晶生长时晃动的分析及控制

Analysis and Control of Oscillation Phenomenon During the Czochralski Silicon Growth

晃动是直拉法硅单晶生长中的常见现象。晃动会导致晶体生长控制系统出现异常,提拉速度波动幅度大,同时还引起熔体对流的不稳定以及杂质微观扩散的紊乱。这不仅对硅单晶的无位错生长造成一定的困难,而且对硅单晶的品质有十分不利的影响。分析了直拉硅单晶生长时晃动的影响因素。利用MATLAB软件及现有振动激励下的单摆动力学模型对CG6000型单晶炉进行单晶晃动的理论计算,理论上分析了各参数变化对单晶晃动的影响。在此基础上提出了改变晶体转速的工艺来控制单晶晃动及晶体形变的方法,并总结了若干减少晶体晃动的措施。

Oscillation is the common phenomenon in czochralski silicon growth.Oscillation causes the abnormal auto-diameter-control and a big fluctuation of the pulling rate,also leads to the convectional instability in the silicon melts and the diffusion disturbance of the microscopic impurity.It causes the difficulty to the dislocation-free growth,and leads to a very adverse impact on the quality of single crystal silicons.The oscillation phenomenon during the czochralski silicon growth was studied.Based on this,the influence factors of the oscillation were analyzed.The oscillation theory was counted to fit the single-crystal growth furnace of CG6000 type using MATLAB software and existing simple pendulum dynamic model.The impact of parameters variation on the crystal oscillation was analyzed based on the theoretical analysis.For this reason,the method of reducing crystal oscillation and crystal deformation during the crystal growth was proposed with the technology of changing crystal rotate speed.Some effective measures to reduce the crystal oscillation were summarized.