Polycrystalline silicon directional solidification method and device for improving impurity removal effect

Abstract

The invention belongs to the field of polycrystalline silicon purification, and particularly relates to a polycrystalline silicon directional solidifying method and device capable of improving the impurity removal effect. A curved graphite heater is additionally arranged in an existing device, when silicon liquid is directionally solidified by 75% to 85%, the silicon liquid on the upper portion is influenced by the curved graphite heater above a quartz crucible in a heat radiating mode, and therefore the curved degree of a solid liquid interface inside the quartz crucible is enlarged. The polycrystalline silicon directional solidifying method and device have the advantages that distribution of metal impurities has the directionality in a directionally solidified silicon ingot and can be conveniently cut off, and the cutting rate of waste on the tail portion is reduced; the device is easily transformed, on the basis of the existing device, only the curved graphite heater is additionally arranged above the quartz crucible, and the cost is well controlled; waste of raw materials is reduced, and the cost of polycrystalline silicon raw materials is greatly reduced.

Description

technical field [0001] The invention belongs to the field of polysilicon purification, and in particular relates to a polysilicon directional solidification method and a device for improving the impurity removal effect. Background technique [0002] At present, my country has become the world's largest energy production and consumption country, but the per capita energy consumption level is still very low. With the continuous development of the economy and society, my country's energy demand will continue to grow. In response to the current energy shortage, countries around the world are thinking deeply, and are working hard to improve energy efficiency, promote the development and application of renewable energy, and reduce the impact on energy consumption. Reliance on imported oil to enhance energy security. [0003] As one of the important development directions of renewable energy, solar photovoltaic power generation has developed rapidly in recent years, and its proport...

AI Technical Summary

Problems solved by technology

[0005] In the current directional solidification process of polysilicon, when the directional solidification reaches 75-85%, the solid-liquid interface in the quartz crucible tends to be horizontal and continues until the end of directional solidification, so the tail waste is cut along the horizontal direction during the final cut. Contains high metal impurities in the waste, and the metal impurities are distributed in various parts of the waste, resulting in low waste recycling rate

Generally, the removal rate of tail waste is 20-25%, that is, the yield is only 75-80%, which causes a great waste of energy and raw materials, and thus increases the manufacturing cost.

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