防止重掺砷CZ单晶硅组分过冷的探讨

在探讨组分过冷数学模型的基础上,针对重掺砷CZ单晶硅的生长,理论计算了防止组分过冷时固液界面处晶体温度梯度G_S的临界值为51.32~33.10 K/cm.以此为依据,设计了具有较大温度梯度的18寸(60 cm)晶体生长热场,以数值模拟的方法,给出了固液界面处晶体的温度梯度G_S的模拟值为54.68~38.14 K/cm.在晶体等径生长的各个阶段,固液界面处晶体的温度梯度G_S的模拟值均在防止组分过冷的临界值之上,可以有效避免晶体生长过程中组分过冷的发生,并利用实际晶体生长试验的结果验证了以上分析的有效性.

Discussionon Preventing Heavily Arsenic-doped Czochralski Silicon Crystal from Constitutional Supercooling

After the mathematical model of constitutional supercooling was discussed,the critical value of crystals' temperature gradient G_S on the solid-liquid interface that could avoid constitutional supercooling phenomenon was theoretically calculated to be 51.32-33.10 K/cm as heavily Arsenic-doped CZ silicon crystal grew.Based on the results above,a thermal field of 60 cm with relatively greater temperature gradient was designed.The simulation value of temperature gradient G_S was calculated to be 54.68-38.14 K/cm through computer numerical simulation.The simulation value of temperature gradient G_S is always greater than the corresponding critical value at each stage of crystals' constant diameter growth,which ensured that constitutional super cooling could be effectively prevented during crystal growth.The actual crystals' growth experiments demonstrated the effectiveness of the above analysis.