METHOD FOR CONTROLLING FLOATING MELTING ZONE OF SEMICONDUCTOR ROD

摘要

PURPOSE:To enable control of the zone length and diameter of a formed crystal with quick responsiveness and stability, by regulating moving speed of a semiconductor rod on the melting out side, controlling the length of a melting zone in the axial direction and regulating electric power supplied to a heater. CONSTITUTION:The lowering speed (Vp) of a semiconductor rod (upper rod) is kept at a constant value and supply electric power (P) is increased stepwise to temporarily increase the diameter (Dsi) of a formed crystal. The zone length (L) is then delayingly increased to subsequently reduce the diameter (Dsi) of the formed crystal and almost equal to the original value. That is the Dsi is not changed simply by increasing the supply electric power (P). On the other hand, if the supply electric power is kept at a constant value and the lowering speed of the upper rod is increased stepwise, the zone length (L) is relatively rapidly reduced to simultaneously increase the diameter (Dsi) of the formed crystal. The diameter (Dsi) of the formed crystal is controlled by the supply electric power (P) and the zone length (L) is controlled by the lowering speed (Vp) of the upper rod. Thereby effective diameter control can be carried out.