轴向磁场对硅单晶Czochralski生长过程的影响

Effects of an axial magnetic field on silicon crystal Czochralski growth

利用有限元方法对炉内的传递过程进行了全局数值模拟,假定熔体和气相中的流动都为准稳态轴对称层流,熔体为不可压缩流体,Cz炉外壁温度维持恒定,模拟磁场强度范围为(0-0.3)T,研究了用Czochralski(Cz)法生长单晶硅轴向磁场对熔体流动和氧传输过程的影响.结果表明:轴向磁场可有效地抑制熔体内的流动,但增大加热器功率和结晶界面处晶体内的轴向温度梯度;对于常规Cz炉,轴向磁场可增大结晶界面平均氧浓度,而对于具有气体导板的Cz炉,则会减小结晶界面平均氧浓度.

In order to understand the effects of the axial magnetic field on the silicon melt flow and oxygen transport in a silicon Czochralski (Cz) furnace, a set of global numerical simulations was conducted using the finite-element method for the magnetic field strength from 0 to 0.3 T. It was assumed that the flow was axisymmetric laminar in both the melt and the gas, the melt was incompressible and a constant temperature was imposed on the outer wall of the Cz furnace. The results show that the silicon melt flow is suppressed but the heater power and the axial temperature gradient on the melt-crystal interface increase when a uniform axial magnetic field is applied. The average oxygen concentration along the melt-crystal interface increases in conventional Cz furnace but decreases with increasing of the axial magnetic field strength in Cz furnace with gas guide.