Abstract: Process and apparatus for refining silicon by treatment in a graphite vessel with irradiation with an electron beam while removing impurity elements by evaporation. A single graphite vessel is used, or plural graphite vessels are arranged in sequence. During treatment in successive graphite vessels, molten silicon is poured in succession from one vessel to another. Use of graphite vessels improves heat efficiency, prevents contamination and produces refined silicon containing very low contents of impurities.

Abstract: Method for producing highly purified silicon for use in solar cells by a single solidification purification, pouring silicon into a mold and gradually fractionally solidifying it while solidifying the liquid surface, followed by purifying the solidified silicon by zone melting or continuous casting using an electromagnetic mold, or by zone melting in combination with continuous casting, and optionally causing directional solidification to concentrate impurities, leaching and recycling.

Abstract: An 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.

Abstract: Disclosed herein are a method and apparatus for purifying silicon, which are suitable for economical and mass production of high-purity silicon for solar cells from regular-grade silicon containing boron and carbon in large quantities. The method comprises directing a plasma jet stream of an inert gas toward the surface of molten silicon held in a container lined with silica or a silica-based refractory. For improved purification, the inert gas as the plasma gas is mixed with 0.1-10 vol % steam and/or less than 1 g of silica powder per liter of the inert gas at normal state. Alternatively, the container may have a bottom opening and is provided with an electrode having a cooling means underneath the bottom of the container, with the electrode and the cathode of the plasma torch connected to a power source for plasma generation, so that the plasma jet and electron beam are directed toward the surface of molten silicon.