Manufacturing method for silicon nitride coating

Abstract

The invention discloses a manufacturing method for a silicon nitride coating. The manufacturing method comprises the following steps: mixing micron-sized silicon nitride particles and nano-sized silicon nitride particles in purified water, and adding a surfactant and a silica sol so as to form a mixture; uniformly mixing the mixture under stirring; spraying the uniformly-mixed mixture onto the surface of a to-be-coated object; and heating the mixture to remove moisture therein so as to form the silicon nitride coating. The silicon nitride coating manufactured by using the above-mentioned method has the following advantages: through mutual cooperation of the nano-sized silicon nitride particles and the micron-sized silicon nitride particles in the interior of the silicon nitride coating, gaps among particles are smaller, and the compactness of the silicon nitride coating is improved, so the problem of low compactness due to only use of the micron-sized silicon nitride particles for manufacturing of the silicon nitride coating in the prior art is avoided; and impurities can be avoided from diffusing into a silicon material from the gaps in the silicon nitride coating by penetrating through a crucible in the process of ingotting, and the phenomenon of sticking of the impurities to the crucible is avoided from occurrence, so the quality of a product is improved, and the cost of production is reduced.

Description

Technical field [0001] The invention belongs to the technical field of photovoltaic equipment manufacturing, and particularly relates to a manufacturing method of a silicon nitride coating. Background technique [0002] In the process of polycrystalline ingot casting, it is necessary to use a quartz crucible as an ingot container. Because quartz reacts with polycrystalline silicon at high temperature and produces adhesion, impurities such as Fe, Al, O enter the silicon material and the viscous crucible will crack and cause cracking. Therefore, the quartz crucible needs to be coated with a silicon nitride coating before the ingot is cast to prevent the liquid phase silicon from chemically reacting with the quartz to cause sticking, and it also prevents metal impurities and oxygen from entering the silicon material. [0003] In the prior art, the silicon nitride sprayed in the quartz crucible used for solar polysilicon ingots is all micron-sized. Since silicon nitride is a particulat...

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Problems solved by technology

[0003] In the prior art, the silicon nitride sprayed in the quartz crucible used for solar polysilicon ingots is all micron-sized, and since silicon nitride is a particulate matter, the process for making this silicon nitride coating includes: Make a slurry first, and then spray it on the inner wall of the crucible. The particles in the silicon nitride coating obtained in this way are easy to form holes. Silicon coating affects the compactness of the coating and forms "channels". Impurity elements such as Fe, Al, and O in the crucible will diffuse into the silicon material, causing pollution to the bottom and sides of the silicon ingot, resulting in a red zone, and ultimately affecting the silicon wafer quality, and the obtained polycrystalline ingot coating has poor compactness and a high proportion of silicon ingot impurities, which will cause a high proportion of broken wires and line marks during diamond wire cutting, reducing the quality of silicon wafers and Increased manufacturing cost of silicon wafers

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