Effect of Interface Inversion on Thermal Stress Field in CZ Crystal Growth of Oxide

Abstract

For CZ crystal growth of an oxide (Al₂O₅), finite element analyses of the thermal stress field in the crystal are carried out, and the effect of interface shape on the maximum shear stress in the crystal is investigated.
When the crystal rotation rate increases, with other operating conditions unchanged, the melt/crystal interface changes its shape from convex to concave toward the melt at the critical Reynolds number (Re_s^*). When Re_s < Re_s^*, the maximum value of the thermal stress on the interface is insensible to Re_s and its radial profile is an inversed W-shape. When Re_s exceeds Re_s^*, however, thermal stress on the interface increases very rapidly and its radial profile becomes W-shaped.