温场对CZ硅单晶氧含量和径向扩展电阻均匀性的影响

利用测量熔体温度、液流模拟、红外吸收和扩展电阻探针研究了温场对硅单晶的氧含量和径向扩展电阻均匀性的影响。高温场中整个熔体的温度梯度与重力方向一致,矮温场中只有上部熔体的温度梯度与重力方向一致,而下部熔体的温度梯度与重力方向相反。高温场中整个熔体有热对流,矮温场中只有上部熔体有热对流。高温场中生长的单晶的氧含量明显高于矮温场中生长的单晶。高温场中生长的硅片,径向扩展电阻分布有中央平坦部分、剧烈起伏部分和边缘波纹起伏部分,矮温场中生长的硅片无剧烈起伏部分。这一部分可能是熔体中泰勒柱与热对流区之间的切变层是高氧熔体造成的。

THE EFFECT OF TEMPERATURE FIELD ON OXYGEN CONCENTRATION AND RADIAL SPREADING RESISTANCE PROFILE OF CZ-Si

In this paper, the effect of temperature field on oxygen concentration andradial spreading resistance profile of CZ-Si has been investigated by usingtemperature measurement of melt, flow simulation, infrared absorption and spreadingresistance probe. The direction of temperature gradient in whole melt is agreeableto the direction of gravity in high temperature field, while it is only agreeablein upper melt, but opposite in under melt in low temperature field. Thereis a thermal convection in whole melt of high temperature field, while in lowtemperature field only the upper melt has a thermal convection. The oxygenconcentration of grown crystal in high temperature field is obviously greater thanthat of grown crystal in low temperature field. The radial spreading resistanceprofile of grown silicon slice in high tempetraure field consists of three parts.They are the central uniform part, drastic fluctuational part, and edging smaller flu-ctuational part. The drastic fluctuational part does not exist in the grown slicein low temperature field. The occurence of this part is probably due to the factthat the shear layer in melt between Taylor cell and thermal convection regioncontains high oxygen concentration.