Silicon purification method

Abstract

The invention refers to a silicon purification method which utilizes eutectic reaction to separate out crystals of silicon crystal from Al-Si meltwater at a temperature lower than a silicon melting point. Solid materials composed of aluminum, silicon and other elements are thrown into a cooling crucible. The cooling crucible is a bottomless conductive cooling crucible (7) and at least part of the cooling crucible in a direction of principal axis is divided into a plurality of parts in a peripheral direction; the periphery of the cooling crucible is enclosed with inductance coils (8) and a support table (14) is arranged below the cooling crucible. Meanwhile, electromagnetic induction caused through the inductance coils at a temperature lower than a silicon melting point and higher than an eutectic temperature in the cooling crucible melts the solid materials to cool crystals and separate out silicon crystals on a solidification interface below the Al-Si meltwater and the support table is used for pulling down crystallized silicon crystals to realize continuous unidirectional solidification and manufacture silicon ingot (3). The silicon purification method can simply and accurately implement unidirectional solidification and devices are not complicated and have the characteristics of high efficiency, low energy consumption and costs; metal grade silicon can be used as raw materials to produce solar polycrystalline silicon.

Description

technical field [0001] The present invention relates to a silicon purification method for producing silicon ingots used in solar cells and the like. Background technique [0002] With the recent significant increase in solar cell production, the demand for silicon for solar cells is expanding. Silicon for solar cells uses semiconductor silicon for devices, out-of-standard varieties of semiconductor silicon, scrap, and the like. In order to cope with the expected increase in the production volume of solar cells in the future, a manufacturing method capable of mass production with the aim of stably supplying inexpensive silicon for solar cells is required. So far, although metallurgy is developing methods for refining cheap metal silicon, it is still necessary to seek lower costs. [0003] However, in an aluminum-silicon melt with a silicon atomic fraction of 12.2% or more, if silicon is crystallized when the eutectic point temperature is above 577°C and the silicon melting ...

AI Technical Summary

Problems solved by technology

In addition, in the aluminum electromagnetic casting method, it is not disclosed to use the eutectic reaction to crystallize silicon

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