| 摘要 |
<PICT:0900562/III/1> The diameter of a rod being pulled from a melt is controlled by an electrostatic field produced by a ring electrode around the solid-liquid interface. The rod may be of silicon or genmanium. In the former case, the component of the field strength normal to the rod should be at least 5 kv./cm. As shown, a rod 1 is pulled from a molten drop 2 adhering to a rod 3, rod 1 being surrounded at the solid-liquid interface by a ring electrode 14 in electrical communication therewith via a direct current source 15. Drop 2 is maintained molten by an induction heating coil 4 and the drop is replenished by upward movement of rod 3. Pulling is effected in a vessel 16 containing a vacuum or a protective gas atmosphere. The capacitance between the rod and the ring electrode, which is proportional to the diameter of the rod, may be measured and utilized to control further the diameter of the rod by varying the speed of pulling or the strength of the electrostatic field. In a further embodiment (not shown), a rod is pulled through a perforated diaphragm from a molten mass in a crucible. |
