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采用有限元法计算了300 mm硅单晶生长过程中,热屏结构对炉体内温度分布、熔体中流场以及晶体内热应力的影响。计算所用的模型涵盖了晶体生长过程中的主要物理现象,包括结晶潜热的释放、结晶前沿的形变、熔体中热和质的传输以及氧的输运等。计算结果表明使用直壁式热屏时,晶体-熔体界面变得更加平坦同时结晶前沿处的热应力大幅度下降,减少了发生宏观位错的可能性,此外熔体中的氧含量显著降低。
The influence of the thermal screen structure on the temperature distribution in the furnace, the flow field in the melt and the thermal stress in the crystal was calculated by the finite element method. The model used in the calculation covers the major physical phenomena during crystal growth, including the release of latent heat of crystallization, the deformation of the crystal front, the heat and mass transport in the melt, and the transport of oxygen. The calculated results show that when the straight wall heat shield is used, the crystal-melt interface becomes more flat and the thermal stress at the crystal front decreases greatly, reducing the possibility of macroscopic dislocation. In addition, the oxygen content in the melt decreases significantly .