Ingot casting furnace for reducing carbon content of polycrystalline silicon ingot and preparation method thereof

Abstract

The invention provides an ingot furnace for reducing the carbon content of a polycrystalline silicon ingot. The ingot furnace comprises a crucible, a protection plate and a cover plate, wherein the protection plate surrounds the periphery of the outer wall of the crucible and makes close contact with the outer wall of the crucible, and the cover plate covers the port formed by the protection plate in a surrounding mode. The outer surface, away from the crucible, of the protection plate and the outer surface, away from the crucible, of the cover plate are each provided with a coating capable of reacting with carbon. The coatings can react with carbon in the ingot furnace, the carbon content in the ingot furnace can be reduced, and therefore the carbon content in the polycrystalline silicon ingot is reduced. The invention further provides a preparation method of the ingot furnace for reducing the carbon content of the polycrystalline silicon ingot. The outer surface of the protection plate and the outer surface of the cover plate are coated with the coatings capable of reacting with carbon in a brushing or spraying mode, and therefore the carbon content in the ingot furnace is reduced, and the preparation method is simple and easy to operate.

Description

technical field [0001] The invention relates to the field of polycrystalline silicon ingots, in particular to an ingot casting furnace for reducing the carbon content of polycrystalline silicon ingots and a preparation method thereof. Background technique [0002] Since the current polycrystalline silicon ingot preparation process is: batching, charging, heating and melting the charging crucible in the ingot furnace, crystal growth, annealing, and cooling processes to produce polycrystalline silicon ingots, in order to prevent the quartz crucible from softening at high temperatures, it is necessary to use A shield made of graphite material is used to protect the surroundings of the quartz crucible. In order to prevent carbon impurities or other impurities in the graphite heater located above the crucible from falling into the quartz crucible, a cover plate is generally used in the prior art to cover the mouth surrounded by the guard plate. However, at high temperature, the ...

AI Technical Summary

Problems solved by technology

However, at high temperature, the carbon produced by the graphite structural parts will enter the silicon melt in the crucible, causing carbon pollution of the silicon melt and increasing the carbon content in the cast polysilicon material.

If the carbon content is too high, it will easily lead to the formation of carbon precipitates, silicon carbide inclusions, dislocations and other impurities or defects in the silicon solution during the directional solidification and growth process, which will not only increase the number of broken wire accidents and poor wire marks in the polysilicon ingot cutting process risk, and it will also lead to problems such as high leakage rate and low conversion efficiency of the fabricated cells

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