Producing pure silicon, comprises subjecting molten silicon to a purification step in a directional solidification, heating molten silicon by bath surface, removing molten silicon from a warmed heatsink, and controlling solidification rate

摘要

Producing pure silicon, comprises: subjecting molten silicon to at least one purification step in a directional solidification, where the directional solidification takes place in a crucible; heating the molten silicon by bath surface using plasma torch; removing the molten silicon from a warmed heatsink associated with the bottom of the crucible; and controlling the solidification rate, in which the solidification is moved from the crucible bottom to the melt bath surface, by temporal change of the cooling capacity of the heatsink. An independent claim is included for a device for performing the above process, comprising a furnace (1), in which a crucible (5) is placed on a heatsink (4), where the crucible is surrounded by a thermal insulation (6) on all sides, at least one plasma torch (9) for heating silicon introduced in the crucible from the top of the crucible and a control device (13) that is controlled over the both cooling capacity of the heatsink and the heat output of the plasma torch for adjusting the speed with which the solidification front in the molten silicon moves from the bottom crucible to the down melt surface.