FLOW INSTABILITY OF THE MELT DURING CZOCHRALSKI SI CRYSTAL-GROWTH - DEPENDENCE ON GROWTH-CONDITIONS - A NUMERICAL-SIMULATION STUDY

Flow instability of molten Si during Czochralski (CZ) Si crystal growt h has been studied utilizing a 3D heat- and mass-transfer model togeth er with global heat- and mass-transfer calculation. It is found that t he phase transition from an axisymmetric to a non-axisymmetric mode of the flow occurs depending critically on the growth parameters, such a s temperature distribution, crucible as well as crystal rotation rates . In order to prevent the non-axisymmetric instability, low crucible r otation and large temperature difference between the crucible and the crystal are found to be desired. These tendencies are well characteriz ed by the thermal Rossby number and the Taylor number, which represent the relative strengths of Coriolis force to buoyancy force and inerti al force. The calculated results are compared and discussed with the e xperimental observation obtained for the same growth condition.