Abstract: 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.

Abstract: 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.

Abstract: In a silicon casting apparatus according to the present invention, silicon melted by electromagnetic induction heating is continuously solidified using an electrically-conductive bottomless cold crucible and an induction coil surrounding the cold crucible. The cold crucible is made of copper alloy containing beryllium (desirably containing beryllium of 0.1 to 5 mass %), whereby the generation of electric-discharge flaw can be effectively prevented in performing electromagnetic casting. The use of the silicon casting apparatus according to the present invention can greatly extend a crucible life to reduce facility costs. Additionally, a solar-cell silicon ingot can be produced with high quality.

Abstract: In a casting method for polycrystalline silicon in which a bottomless cooling crucible with a part of a certain length in an axial direction being circumferentially and plurally sectioned is provided inside an induction coil, producing a silicon melt within the cooling crucible by means of electromagnetically induced heating by the induction coil, and withdrawing the silicon melt in a downward direction while being solidified, an alternating current with a frequency of 25-35 kHz is applied on the induction coil. According to the casting method for polycrystalline silicon of the present invention, in addition to preventing rapid cooling of the ingot surface at the time of solidifying the molten silicon and producing the ingot, the stirring of the molten silicon inside the crucible is suppressed to thereby promote the growth of large diameter crystals, with the result that the conversion efficiency of the cast polycrystalline silicon used as solar cells is increased.