Crucible pot coating for polysilicon casting ingot and preparation method

Abstract

The invention relates to a crucible coating, in particular to a ceramic crucible coating used in producing polycrystalline silicon cast ingot, and also relates to a preparation method of ceramic crucible coating used for polycrystalline silicon cast ingot. The solid content in the formulation of the crucible coating used for polycrystalline silicon cast ingot comprises 80-99% of silicon nitride and 1-20% of filming agent containing silicon element by weight percentage; after sintering the total oxygen content is 0.2-4.9% by weight percentage. The invention aims at providing a crucible coating used for polycrystalline silicon cast ingot and a preparation method; in the invention, a technique proposal in which the coating contains lower oxygen content is adopted as far as possible, so that potential pollution can be reduced, and meanwhile filming and spraying technologies are adopted to guarantee the stability of the silicon nitride layer and the quality of the silicon ingot in the use process of the crucible.

Description

technical field [0001] The invention relates to a crucible coating, in particular to a ceramic crucible coating, which is specifically applied to the production of polysilicon ingots. The invention also relates to a preparation method of a ceramic crucible coating for polycrystalline silicon ingots. Background technique [0002] Ceramic crucibles are a key necessity in the production of polysilicon ingots, and are mainly used to contain molten silicon liquid. The main chemical composition of ceramic crucibles is silica. The main reason for choosing silica as the material of the crucible is its high purity and availability. However, there are many problems with the use of ceramic crucibles. [0003] Silicon in the molten state can react with the ceramic crucible it comes in contact with. Molten silicon reacts with silicon dioxide to form silicon monoxide, which introduces oxygen to contaminate the silicon liquid. Moreover, silicon monoxide is volatile and can react with g...

AI Technical Summary

Problems solved by technology

[0004] The reaction between silicon dioxide and molten silicon promotes the adhesion of silicon to the crucible. Due to the difference in thermal expansion coefficient between the two materials, silicon dioxide and silicon, if the silicon material is tightly bonded to the walls of the ceramic crucible, it is very difficult for the crystal to cool down. May cause cracking of crystalline silicon or ceramic crucibles

Although this preparation method reduces the risk of peeling or peeling of the coating to a certain extent, since the preparation is only a simple physical mixing of silicon nitride powder and inorganic binder, although the nitriding process has been improved to a certain extent The stability of the silicon coating, but there is still a risk of coating peeling or peeling; in addition, the high oxygen content of the coating (5%-15%) will cause a certain degree of oxygen pollution to the silicon ingot, affecting Silicon ingot quality

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