硅单晶提拉生长中拉速稳定性研究

Study on Stability of the Pull Rate in the Czochralski Growth Process of Single Silicon

为解决硅单晶提拉生长过程中拉速不稳定、波动较大的问题,在分析晶体生长界面热量及质量传输的基础上,通过控制温度补偿速率来抑制拉速大幅波动。采取基于遗传算法优化隶属度函数的模糊控制策略,对温度补偿速率进行控制,调节加热功率,使炉内热环境处于适宜晶体生长的范围。实验结果表明,在提高系统控径精度的同时,拉速稳定性也有显著提高,大幅波动明显减少。

For the purpose of reducing the pull rate fluctuation during the Czochralski crystal growth process of single silicon, the approach of controlling the temperature compensation rate was presented based on analyzing the energy and mass balance at the solid-liquid interface. A new fuzzy control method was proposed of which the membership function parameters were optimized using the genetic algorithm to tune the power input, thus the inner circumstance of the furnace was more suitable for the crystal growth. Experiment data verifies that with this approach, the precision of the crystal diameter was improved and the pull rate fluctuation was considerable reduced also.