Silicon casting apparatus

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.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a silicon casting apparatus suitable for production of a solar-cell silicon ingot and the like. The silicon casting apparatus includes an electrically-conductive copper-alloy cold crucible divided into a plurality of elements in a circumferential direction, and is used when silicon as raw material is melted by electromagnetic induction heating and solidified to perform continuous casting of a polycrystalline silicon.[0003]2. Description of the Related Art[0004]A silicon crystal is used as a substrate material in almost all currently-produced solar cells. The silicon crystal is classified into a single crystal and a polycrystal. Usually, solar cells having higher efficiency in converting incident light energy into electric energy can be obtained when the single crystal is used as the substrate.[0005]The single-crystal silicon is produced by the Czochralski method, and a high-quality dislo...

AI Technical Summary

Benefits of technology

[0024]In the silicon casting apparatus according to the present invention, it is preferable that said copper alloy contains beryllium of 0.1 to 5 mass %, since a cold crucible life extension effect is clearly recognized without accompanying any difficulty in preparing the cold crucible.

[0025]The silicon casting apparatus according to the present invention, as a vessel for melting the raw material, includes a bottomless cold crucible made of copper alloy containing beryllium, in which the crucible is divided into a plurality of elements in a circumferential direction. In performing the electromagnetic casting, the silicon casting appa

Problems solved by technology

However, when compared with the polycrystalline silicon, solar-cell production costs are increased since the silicon production costs are increased.

However, since the cast method is an ingot making method of solidifying the molten silicon with a quartz crucible or a graphite mold, impurity contamination is generated due to contact of the molten silicon with the wall of a container such as the crucible.

There is also a problem that a mold lubricant used to prevent fusion between the ingot and the mold is mixed into the molten silicon.

Additionally, since continuous casting can be hardly performed by the cast method, production efficiency is inevitably lowered.

However, in the actual operation, warping or damagin

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