Polysilicon directional solidification device

Abstract

The invention relates to the field of polysilicon purification, in particular to a polysilicon directional solidification device which comprises a furnace body, a quartz crucible is placed in the furnace, a graphite heating unit, an insulating sleeve and a induction coil are arranged on the outer wall of the quartz crucible from inside to outside in sequence in a surrounding manner, an ingot mechanism communicated with the bottom of the furnace body is arranged at the bottom of the quartz crucible, the height of the insulating sleeve is 1.5 to 2 time higher of that of the quartz crucible, a graphite spiral plate is arranged at the upper part of the ingot mechanism, a spiral channel built in the graphite spiral plate is communicated with the inlet of the ingot mechanism, and outlets are formed in the edge of the two sides of the graphite spiral plate. According to the device, thermal radiation of the sidewall of the quartz crucible generated in the pulling process can be better intercepted, thermal radiation of the sidewall of the quartz crucible is effectively decreased, and the directional solidification effect is better than conventional solidification method. The device is short in warming up time, small in insulating energy consumption, controllable in cooling speed, the crystal growth is better in cooling method when compared with conventional mode, and can better realize directional solidification effect.

Description

technical field [0001] The invention belongs to the field of polysilicon purification, and in particular relates to a polysilicon directional solidification device. 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 proportion is increasing. According to the Medium and Long-te...

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Problems solved by technology

[0005] At present, the directional solidification technology basically uses the pull-down method of the quartz crucible to directional solidify the polysilicon. The pull-down is to gradually pull the quartz crucible out of the thermal field area. Since the height of the current insulation sleeve is basically the same as that of the quartz crucible, the part of the pulled-down quartz crucible is exposed. In the furnace body, a large amount of heat will be dissipated from the surroundings, causing the temperature of the outer wall of the quartz crucible in the pull-down part to be lower than the central temperature. In this way, polysilicon will grow along the side wall toward the center, causing the metallic impurities in the polysilicon to move from the surrounding to the center. Enrichment will affect the effect of directional solidification and impurity removal in light cases, and lead to the failure of qualitative solidification to purify polysilicon in severe cases

In addition, the directional solidification technology basically adopts the design of the water-cooled copper plate on the upper part of the ingot pulling mechanism to cool the bottom of the quartz crucible with circulating water, so that the silicon melt can be directional solidified. The cold source of this method exists in the whole process of smelting. , this method will take away a large amount of heat energy, thereby increasing energy consumption

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