Melt Flow Simulations of Czochralski Crystal Growth Process of Silicon for Large Crystals

Abstract

Czochralski Growth of Silicon Crystal (Cz) is extensively used for single crystal manufacturing and most of the Silicon wafers are manufactured by this process. Melt flow in large crucibles, used for growth of large diameter (300mm) crystal, is turbulent in nature. In this study, we present a model for simulating Czochralski crystal growth process for 300mm crystal. This study is mainly focused on effect of crucible rotation on flow and temperature profiles in the melt. Two-dimensional axisymmetric model was used for this purpose which accounts for generated turbulence, heat/ mass transfer with phase change. Investigations show that flow pattern in co-rotation below the crystal is totally opposite that of counter-rotation. Centrifugal force is dominant due to crystal and crucible rotation, which creates vertical upwards or downward flow below the crystal, depending upon the co-rotation or counter rotation. With increase in pull rate, depth of the predicted interface in the melt was also found to be increased. Simulated results will be helpful for optimization of process parameters to achieve better quality of crystals.