Process and apparatus for manufacturing polycrystalline silicon, and process for manufacturing silicon wafer for solar cell

摘要

PCT No. PCT/JP96/02965 Sec. 371 Date Aug. 8, 1997 Sec. 102(e) Date Aug. 8, 1997 PCT Filed Oct. 14, 1996 PCT Pub. No. WO98/16466 PCT Pub. Date Apr. 23, 1998An object of the present invention is to provide a process and apparatus for the continuous flow production of polycrystalline silicon from metallic silicon or silicon oxide as a raw material and also for the manufacture of a wafer by using it, which process and apparatus permit the mass production at a low cost. The above object can be attained by the manufacture of polycrystalline silicon and a silicon wafer for a solar cell by the following steps: (A) smelting metallic silicon under reduced pressure, carrying out solidification for the removal of the impurity components from the melt, thereby obtaining a first ingot, (B) removing the impurity concentrated portion from the ingot by cutting, (C) re-melting the remaining portion, removing boron and carbon from the melt by oxidizing under an oxidizing atmosphere, and blowing a mixed gas of argon and water to carry out deoxidization, (D) casting the deoxidized melt into a mold, and carried out directional solidification to obtain a second ingot, and (E) removing the impurity concentrated portion of the ingot obtained by directional solidification by cutting.