Sumco Corporation

Mitsuo Yoshihara

Koichi Maegawa

Shinya Fukushima

Daisuke Ebi

Tomohiro Onizuka

Disclosed is an electromagnetic casting method of polycrystalline silicon which is characterized in that polycrystalline silicon is continuously cast by charging silicon raw materials into a bottomless cold mold, melting the silicon raw materials using electromagnetic induction heating, and pulling down the molten silicon to solidify it, wherein the depth of solid-liquid interface before the start of the final solidification process is decreased by reducing a pull down rate of ingot in a final phase of steady-state casting. By adopting the method, the region of precipitation of foreign substances in the finally solidified portion of ingot can be reduced and cracking generation can be prevented upon production of a polycrystalline silicon as a substrate material for a solar cell.

Electromagnetic casting method and apparatus for polycrystalline silicon

Provided is a continuous casting method of a silicon ingot for continuously casting the silicon ingot by arranging, inside an induction coil, a bottomless cold crucible having a part along an axial direction that is circumferentially divided into a plurality of strip elements, forming molten silicon inside the cold crucible through electromagnetic induction heating by the induction coil, and solidifying the molten silicon while pulling it down from the cold crucible, wherein as the cold crucible, used is a cold crucible with Ni&#x2014;B alloy plating on a portion in the inner surface thereof that faces the outer side surface of the molten silicon and the outer surface of the silicon ingot. The method can reduce the damage to the inner surface of the cold crucible, in addition to the contamination of cast ingots with impurities.

Continuous casting method of silicon ingot

Provided is a silicon electromagnetic casting apparatus that is capable of stably producing polycrystalline silicon used as a solar cell substrate material, having a bottomless cold mold and an induction heating coil, the apparatus for pulling down the silicon melted through electromagnetic induction heating by means of the induction coil and solidifying the silicon melt; further including a plasma torch for generating a transferable plasma arc and a top heater configured so as to face a top surface of the molten silicon, the top heater for generating heat through electromagnetic induction by means of the induction coil. The apparatus enables, upon production of a high quality polycrystalline silicon ingot as a solar cell substrate material along with plasma heating, stable production thereof without cracking in a final solidification portion.

Growing community of inventors

Tokyo, Japan

Mitsuo Yoshihara