Non-crucible zone melting furnace - with protective cylinder reheating recrystallised part of rod by reflected heat

摘要

In a non-crucible zone melting process a vertical silicon rod is guided in the top wall of an evacuated or inert gas-filled receptacle. The lower part of the rod which has been recrystallised by the molten zone is surrounded by a cylindrical protective case which reheats it by reflected heat radiation. This case has dia. 15-100 cm and is made at least on its inside of aluminium or silver. Prior problems of generation of considerable thermal stresses in the recrystallised part of a silicon rod, esp. at dias. of 10 cm and more, are overcome.