Method for producing polycrystal ingot

Abstract

The invention relates to a method for producing a polycrystal ingot, which comprises the following steps: preparing a solution of barium hydroxide or a barium salt serving as a coating solution; preheating a quartz ceramics crucible; uniformly coating the coating solution of the solution of the barium hydroxide or the barium salt on the inner surface of the preheated quartz ceramics crucible; baking the quartz ceramics crucible; spraying silicon nitride on the inner surface of the quartz ceramics crucible after baking and rotating the quartz ceramics crucible; filling a silicon material into the quartz ceramics crucible; putting the quartz ceramics crucible into a polycrystal furnace; vacuumizing the polycrystal furnace and adding a protective gas to the polycrystal furnace; heating the silicon material to smelt the silicon material; gradually crystallizing the melted silicon material from the bottom to the top by directional solidification; at last performing high temperature annealing to form the polycrystal ingot used for making a battery through slicing; slicing a crystal ingot into silicon slices; making the silicon slices into battery plates by making herbs into wool, diffusing, etching edges, PECVD filming, screen painting and sintering; and testing and grading the battery plates. The coating in the crucible prevents impurities in the crucible from diffusing to the silicon material, and improves the lifetime of minority carrier close to the crucible, the utilization rate of the crystal ingot and the battery conversion efficiency.

Description

technical field [0001] The invention relates to a production method of a solar cell ingot, in particular to a production method of a polycrystalline ingot. Background technique [0002] At present, when producing polycrystalline ingots, quartz ceramic crucibles are used as containers for polycrystalline silicon ingots. Through dual temperature zone or three temperature zone control, the temperature gradient between the upper and lower sides of the crystal ingot is used to achieve directional solidification, and silicon nitride powder coating is used as a release agent. , this method is commonly used in the solar cell ingot industry. Quartz glass crucibles for single crystals have higher purity, higher cost, and are relatively easy to deform; crucibles for polycrystalline ingots have a large amount of material, and in order to obtain higher strength, the quartz ceramic crucibles used contain a large amount of aluminum and alkaline earth metals to promote crystallization. Age...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is: in order to solve the problem that the silicon nitride powder layer cannot effectively inhibit the diffusion of impurity elements such as metals in the quartz ceramic crucible during polycrystalline ingot casting, a method for surface surface treatment of quartz ceramic crucible for ingot casting is proposed. A method of producing polycrystalline ingots to prevent the diffusion of impurities in the crucible, thereby improving the utilization rate of the ingot and the conversion efficiency of the battery

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