| 摘要 |
<PICT:0926497/III/1> In the production of a monocrystalline rod of silicon by the upward passage of a molten zone 3 (produced by a pancake coil 4) a plurality of times through a monocrystalline seed 5 and an adjoining polycrystalline rod 2 supported between holders, a rod free from crystal imperfection is produced by a final passage at a speed of 7-15 m.m./min. through seed 5, at a gradually reduced speed through the conical portion 2a of rod 2, and a final speed of less than 7 m.m./min. through the main portion of rod 2, the two holders being moved apart at a speed of at least 25 m.m./min. while the molten zone is at the junction of seed 5 and rod 2 to produce a restriction 6. The diameter of rod 2 may be 12 m.m., that of seed 5 may be 3-5 m.m., and that of the constriction may be 2 m.m. A second similar constriction may be produced a few m.m. above the first. An incandescent zone may initially be formed in rod 2 by conduction from an inductively heated molybdenum holder or by radiation, passed down into seed 5, and converted there into the first molten zone. An incandescent zone may similarly precede each subsequent molten zone. The speed of travel of molten zone through rod 2 may be 4 m.m./min. and that of the incandescent zone may be 200 m.m./min. One of the holders may be rotated during each passage of the molten zone (preferably not the last). The induction coil may be fed at a frequency of 4 megacycles per sec. Specifications 888,148 and 889,160 are referred to. |
