STRUCTURE OF TEMPERATURE AND VELOCITY-FIELDS IN THE SI MELT OF A CZOCHRALKSI CRYSTAL-GROWTH SYSTEM

Non-axisymmetric temperature and velocity profiles attributed to crucible rotation in the Si melt of a Czochralski (Cz) system were studied numerically by using three-dimensional (3D) numerical simulation and experimentally by measuring temperature. Two types of non-axisymmetric temperature and velocity profiles were found to exist in the melt. The type observed at low rotation rates occurs under conditions in which Rayleigh-Benard instability occurs, and the other type of non-axisymmetric flow observed at high rotation rates occurs under conditions corresponding to the occurrence of the baroclinic instability in the rotating annulus. The 3D structure of the temperature field was studied experimentally to confirm the possibility of baroclinic instability in the melt. The predominant trend was a tilt of the temperature field in the same direction as crucible rotation. It was found that the temperature field tilted along the azimuthal direction under conditions in which baroclinic instability occurs.