Fremgangsmåde til trækning af et krystallinsk legeme fra et mindst til smeltetemperaturen opvarmet smeltegods samt apparat til gennemførelse af fremgangsmåden

1284068 Crystal-pulling SIEMENS AG 23 Sept 1970 [24 Sept 1969] 45193/70 Heading B1S In a crystal-pulling process where a sealcrystal is used, the material from which the crystal is to be pulled is, prior to melting, heated to a temperature such that it becomes a good enough conductor of electricity for induction heating to occur. This is accomplished by heating the seed-crystal so that its free end at least is heated and presenting the heated crystal to the material when the conductivity has risen high enough as a result of this treatment, the material is melted by an induction coil and conventional crystal-pulling occurs. In the illustrated embodiment, crucible 2 is kept in a shielding gas and cooled by water passing along tubes and rings 6, 3a, 4a, 5, 4b, 3b and 7. Induction coil 8 is wound around the crucible 2. Seed crystal 11 is mounted in holder 10 and shaft 19. Induction coil 13 is mounted on movable shaft 12. Holder 10 is made of highly conductive steel and at the start of the operation is coupled electrically to the field of coil 13. This heats crystal 11 so that its conductivity rises to the point where it may be heated by coil 13. By moving the coil 13 relative to crystal 11, the tip of the crystal may be melted. The crystal is then moved down so that the melt touches the material 9 and heats it. Conventional crystal-pulling may then occur. The coil of the process to obtain a crystal of silicon, which does not couple satisfactorily until at a temperature above 600‹C is described.