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利用有限元分析软件对Φ300 mm直拉硅单晶生长过程进行模拟,分析了保持CUSP磁场对称面与熔体坩埚界面交点处的径向分量不变的情况下,硅单晶中氧浓度分别随CUSP磁场通电线圈距离、通电线圈半径的变化规律。随着通电线圈距离和半径的增大,晶体熔体固液界面氧浓度均逐渐降低。随着通电线圈距离和半径的增大,硅熔体径向磁场强度逐渐增大,对坩埚底部熔体向晶体熔体固液界面处对流的抑制作用加强,固液界面下方熔体轴向流速减小,使得从坩埚底部运输上来的富氧熔体减少,继而固液界面处的氧浓度降低。随着线圈距离和半径的增大,为保持所需磁场强度,施加电流也逐渐增大,从而能耗增大,与增大通电线圈距离相比,增大通电线圈半径所需的电流较大。通过实验,将CUSP磁场对单晶中氧浓度分布影响的数值模拟结果与实际晶体生长进行了对比,实验结果验证了数值模拟的结果。
The finite element analysis software was used to simulate the growth of Φ300 mm Czochralski silicon crystal. The analysis of the oxygen concentration in the silicon single crystal was carried out with the constant radial component at the intersection of the symmetry plane of the CUSP magnetic field and the melt crucible CUSP magnetic field coil distance, coil coil radius variation. With the increase of the distance and radius of the energized coil, the oxygen concentration in the solid-liquid interface of the crystal melt gradually decreases. With the increase of the distance and radius of the energized coil, the radial magnetic field strength of the silicon melt gradually increases, and the inhibition of convection at the bottom of the crucible to the solid-liquid interface of the crystal melt is strengthened. The axial velocity of the melt below the solid- Decreases so that the oxygen-rich melt transported from the bottom of the crucible decreases and the oxygen concentration at the solid-liquid interface decreases. As the coil distance and radius increase, the applied current also increases to maintain the desired magnetic field strength, resulting in increased energy consumption and greater current required to increase the energized coil radius compared to increasing the energized coil distance . The numerical simulation results of the effect of CUSP magnetic field on the distribution of oxygen concentration in the single crystal are compared with the actual crystal growth through experiments. The experimental results verify the numerical simulation results.