[12a-M111-1~9] 15.7 Crystal characterization, impurities and crystal defects

▲ [12a-M111-2] Numerical analysis of asymmetric three-phase line in the floating zone silicon

〇Xuefeng Han¹, Satoshi Nakano¹, Xin Liu¹, Hirofumi Harada¹, Yoshiji Miyamura¹, Koichi Kakimoto¹ (1.RIAM, Kyushu Univ.)

Keywords:silicon, floating zone, simulation

Numerical calculation has been conducted to investigate the asymmetric heat transfer, fluid flow and three-phase line in the floating zone (FZ) silicon crystal growth. In the FZ method, a needle-eye inductor is used to grow the large-diameter (100 mm) single crystal silicon. The needle-eye inductor has one main slit and three side slits. This asymmetric configuration induces the asymmetric heating on the free surface of the silicon melt and three-phase line. R. Menzel et al. [1] observed that the spillage down of melt occurred during the crystal growth because of the inhomogeneous heating on the three-phase line. To investigate the effect of asymmetric heating on the deflection of three-phase line, electromagnetic (EM) and heat transfer calculations are conducted [2]. The results show that the current density distribution along the three-phase line is not homogeneous as a result of asymmetric high-frequency inductor. The asymmetric current density caused asymmetric heating and defection of three-phase line. The deflection of three-phase line is calculated to compare with the experimentally observed results. Both the calculation and experimental results show a trend that along the rotation direction, the three-phase line descends quickly and ascends slowly below the current supplier. The inhomogeneous local growth rate at the three-phase line causes the asymmetric deflection of the three-phase line below the current supplier. When the local growth rate is lower than the pulling rate, the re-melting phenomenon occurs.
[1] R. Menzel, Growth Conditions for Large Diameter FZ Si Single Crystals, PhD thesis, (2013).
[2] X.F. Han, X. Liu, S. Nakano, H. Harada, Y. Miyamura, K. Kakimoto, Crystal Research and Technology, (2018) 1700246.