Vorrichtung zum Schmelzen von reinstem Silizium und anderen reinen Halbleiterstoffen

Elemental silicon, boron or selenium is melted in a crucible made of a material of good thermal conductivity and lined with a layer of the element, the crucible material and lining being maintained solid by cooling. The apparatus shown in Fig. 1 comprises a copper crucible surrounded by, and joined to, a copper casing 11 the space between the crucible and casing being for the passage of a cooling fluid around a baffle 15. A layer 12 of pure semi-conductor substance is provided in the crucible, e.g. by heating the crucible in an atmosphere of pure hydrogen and of a halide of the substance. The substance 13 to be melted may be heated from above by radiation, gas discharge, electron beam, or by a high-frequency induction coil 16 in vacuum or in an inert gas such as argon, helium or hydrogen. In a modification (Fig. 2, not shown), the crucible walls are formed by an induction coil of copper tubing through which the cooling medium flows, the space between adjacent coils is filled with a sealing substance, e.g. silicon, and a layer of ultra-pure semi-conductor substance is provided on the inner surface. In a further modification (Fig. 3a) crucible 31 has a longitudinally extending slot 33 which preferably extends to the axis of the crucible. The crucible acts to couple highfrequency energy from coil 35 to the substance 36 to be melted. The crucible wall is hollow and receives a static or circulating cooling agent. The crucible may be used in the production of semi-conductor crystals by drawing from the molten material in the crucible.