A protective device for polysilicon ingot crucible

Abstract

The invention discloses a protective device for a polysilicon ingot casting crucible. The protective device comprises a guard board formed by enclosure of vertical plates mutually connected and a cover plate and base plate respectively arranged at the upper end and the lower end of the guard board, wherein the cover plate is covered on an opening of the upper end of the guard board through buckling to form internal space used for disposing the polysilicon ingot casting crucible and is mainly composed of a C / C plate and a metal plate bonded with the lower surface of the C / C plate, the melting point of the metal plate is greater than 1800 K, the upper part of the guard board is provided with an air outlet which is correspondingly arranged above the polysilicon ingot casting crucible, the cover plate is provided with an air inlet penetrating the C / C plate and the metal plate, and air-exchanging and ventilation for the internal space is realized through the air inlet and the air outlet so as to improve gas cycle in the process of ingot casting to purify a fusing and re-growth environment of polysilicon. According to the invention, the content of impurities like C and O in polysilicon is greatly reduced, the utilization rate of a silicon material and a slice yield rate are improved, and transfer efficiency of a silicon chip can be improved by more than 0.2%.

Description

technical field [0001] The invention relates to the technical field of photovoltaic utilization of crystalline silicon solar energy, in particular to a protective device for a polycrystalline silicon ingot crucible. Background technique [0002] Among the various preparation methods of polysilicon used in the solar photovoltaic industry, the silicon ingot produced by the directional solidification method has a large weight in a single furnace and low average energy consumption, so it is widely used. However, when using directional solidification method for polysilicon casting, the following two problems are usually encountered: First, due to the quality problems of the crucible itself, or abnormalities such as knocking on the crucible during the charging process, the crucible may break and occur. The accident of liquid silicon overflow brought losses to production; secondly, when casting polysilicon ingots, most manufacturers used crucible guard plates instead of cover plate...

AI Technical Summary

Problems solved by technology

However, when using directional solidification method for polysilicon casting, the following two problems are usually encountered: First, due to the quality problems of the crucible itself, or abnormalities such as knocking on the crucible during the charging process, the crucible may break and occur. The accident of liquid silicon overflow brought losses to production; secondly, when casting polysilicon ingots, most manufacturers used crucible guard plates instead of cover plates, or used ordinary C / C plates as cover plates, This method will cause impurities in the C / C insulation material and C / C plate in the ingot furnace to enter the silicon melt, affecting the quality of polysilicon

As stated in the second question, during the polysilicon ingot casting process, impurities in insulating materials, graphite shields and C / C plates, especially C, will enter the polysilicon in large quantities, which will greatly affect the quality of the polysilicon

In order to solve this problem, the method of improving the material of the insulation material is generally adopted, and the C / C material with high purity and solid material is used. This method has a certain effect on the control of impurities in polysilicon, but it inevitably increases the production cost.

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