GLOBAL ANALYSIS OF HEAT-TRANSFER IN CZ CRYSTAL-GROWTH OF OXIDE

For the crystal growth of LiNbO3, a global analysis of heat transfer in an inductively heated CZ furnace was carried out by use of the finite element method. The effects of the temperature dependency of physical properties such as viscosity and surface tension of the melt, as well as the effect of processing parameters such as crystal rotation, on the flow and temperature fields in the furnace and on the melt/crystal interface shape were investigated. With the mathematical model developed in the present work, the interface inversion caused by crystal rotation was demonstrated theoretically. It is found that the effect of the temperature dependency of viscosity on CZ crystal growth is not significant under the conditions used here, and that the thermocapillary force strongly affects crystal growth. The critical crystal rotation rate at which the interface inversion occurs becomes much larger, and the RF coll current required to keep the crystal diameter constant becomes smaller, in comparison with those without thermocapillary flow in the melt.