Silicon nitride spray finishing method for quartz crucible for polysilicon solar battery casting ingot

Abstract

The invention relates to a method for spraying silicon nitride on a quartz crucible used in polysilicon solar cell ingot casting. The method comprises the following steps: proportioning ultrapure silicon nitride powder and deionized water (DI water) according to a certain quantity, stirring uniformly, using a high-pressure gun to spray on the preheated inner wall of the quartz crucible in a cleaning cavity, sintering by an oven in a certain procedure, forming a compact silicon nitride film spraying coating on the quartz crucible inner wall, vacuumizing the oven, and introducing Ar air into the oven. The film can stop the reaction between a high-temperature fused silica liquid and a quartz crucible, thereby avoiding the crucible-adhesion phenomenon; a silicon nitride film is substituted for an ultrapure quartz crucible, so that the cost is saved; and the interfusion of oxygen elements and impurity elements, which are harmful to a finished cell slice, is avoided, so that the quality of a cell slice is ensured.

Description

(1) Technical field [0001] The invention relates to a method for spraying silicon nitride on a quartz crucible used for ingot casting of polycrystalline silicon solar cells. It belongs to the technical field of solar cells. (2) Background technology [0002] The polysilicon ingot uses a quartz crucible as a container, in which polysilicon is melted, cooled, annealed and crystallized. Due to the high impurity content of ordinary quartz crucibles, the cost of high-purity crucibles is too high, and the crucibles will react with molten silicon as follows: [0003] SiO 2 +Si=2SiO [0004] The sticky pot phenomenon occurs, and at the same time, oxygen elements and impurity elements that are unfavorable to the electrical properties of the finished battery sheet can also be mixed into the ingot. Therefore, the method adopted is to spray a layer of silicon nitride on the inner wall of an ordinary quartz crucible. [0005] Before the present invention was made, the silicon nitrid...

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Problems solved by technology

[0006] 1. No attention was paid to the influence of silicon nitride powder particle size on the crucible coating,

[0007] 2. No need to pay attention to the cleanliness requirements in the spraying and drying process

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