Dependence of Si melt flow in a crucible on surface tension variation in the Czochralski process

In order to study the kinetic transportation mechanism of oxygen into crystals, the silicon melt flow used in the Czochralski method has been investigated using a numerical analysis in conjunction with Marangoni flow due to the temperature dependence of the surface tension, and the actual temperature measurement in the melt during crystal growth with a large Czochralski facility. Consequently, the following was revealed. The numerical analysis revealed that the high-velocity surface flow towards the growing crystal from the crucible was generated by the Marangoni effect due to the temperature dependence of the surface tension. On the other hand, it was clear from the temperature measurement that a high-temperature region existed 60-70 mm below the melt surface. This high-temperature region moved towards the crystal from the crucible wall, and the end of the region terminated under the growing crystal. When we compared the result of the actual temperature measurement with the result of the numerical analysis, it was inferred that the high-temperature region formed between the Rayleigh-Prantru convection and the Rayleigh-Benard convection. We have studied the numerical analysis of melt flow in a crucible and the actual temperature measurement in the melt during the crystal growing process. It has been found that there are at least two different flow modes in the melt during the crystal growth. (C) 2002 Published by Elsevier Science B.V.