热屏结构对大直径单晶硅生长影响的数值分析

Numerical Analysis of the Effect of Heat Shield Structure on Growth of Large Diameter Monocrystalline Silicon

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。

During the process of growth 300 nm monocrystalline Silicon, the effect of heat shield on the furnace body tmperature, flow shield and the thermal load in crystal were calculated by finite element method. The present numerical model incorporates the most important physical phenomena of the Cz growth process including latent heat generation during crystallization, crystal-melt interface deflection, turbulent heat and mass transport, oxygen transport, etc. The result demonstrates that using steep heat shield can flat the crystal-melt interface, and reduce the Von Mises stress without increase of macro- dislocation probability, and reduce the oxygen concentration in melt.