Crucible cover plate for polysilicon ingot furnace and cover plate surface coating method

Abstract

The invention relates to a crucible cover plate for a polysilicon ingot furnace and a cover plate surface coating method. The crucible cover plate for the polysilicon ingot furnace and the cover plate surface coating method have the advantages that a dense SiC coating high in bonding strength is prepared on the outer surface of the cover plate made of carbon-carbon composites by a technological method combining chemical vapor deposition with high-temperature treatment, so that carbon content of polysilicon ingots is reduced, service life of the cover plate is prolonged and the method is particularly applicable to development and application of the cover plate for the polysilicon ingot furnace.

Description

technical field [0001] The invention relates to a crucible cover plate for polycrystalline silicon ingots. Background technique [0002] Polycrystalline silicon materials account for more than half of the demand in the field of solar cells. The quality of silicon wafers is directly related to the quality of solar photovoltaic cells. Therefore, it is of great significance to produce high-quality silicon wafers. At present, the polycrystalline silicon ingot casting process mostly adopts the directional solidification method, and the production process temperature is as high as 1500 ° C. The crucible and cover plate in the ingot casting furnace mostly use heat-resistant structural parts such as graphite and carbon / carbon composite materials. In a high temperature environment, residual oxygen, silicon oxide and other impurities in the ingot furnace react with the carbon surface of heat-resistant structural parts such as crucibles and cover plates to easily generate carbon monoxi...

AI Technical Summary

Problems solved by technology

In a high temperature environment, residual oxygen, silicon oxide and other impurities in the ingot furnace react with the carbon surface of heat-resistant structural parts such as crucibles and cover plates to easily generate carbon monoxide gas, which then reacts with silicon melt to release carbon, resulting in silicon melt Carbon pollution, the carbon content in the ingot is increased, and in the subsequent slicing process, the number of carbon hard spots is increased, which affects the polysilicon yield and quality

In addition, the free silicon released in the ingot casting process causes silicon dissolution to the graphite crucible and the carbon / carbon composite material cover plate, destroys the internal carbon fiber and carbon matrix, and reduces the service life of the graphite crucible and carbon / carbon composite cover plate

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