Preparation method of ultrahigh-purity quartz ceramic crucible

Abstract

The invention mainly discloses an ultrahigh-purity quartz ceramic crucible and a preparation method thereof. The ultrahigh-purity quartz ceramic crucible is mainly applied to polycrystalline silicon ingots in the solar photovoltaic industry. The preparation method comprises the steps of treating solar-grade purity silica powder (6N) with different grain sizes, and then, adding silica sol, deionized water, additives and the like according to a certain ratio to prepare slurry with good dispersibility, wherein the solar-grade purity silica powder (6N) with different grain sizes is used as the main raw material; after further treating a common quartz crucible, placing the slurry on the inner surface of the common quartz crucible in a way of coating, brushing and the like; and after drying, oxidizing and sintering in a kiln with an oxidizing atmosphere to obtain the ultrahigh-purity quartz ceramic crucible. By using the preparation method, the ultrahigh-purity quartz ceramic crucible can be obtained, an ultrahigh-purity crucible is produced by breaking the bottleneck of an ultrahigh-purity quartz raw material, impurities are more effectively prevented from entering ingots, side red areas are thoroughly eliminated, bottom red areas are reduced, the conversion efficiency is increased, the cost is reduced while the stability is kept, the porosity is lower, the volume density is higher, the property is more stable, the service life is greatly prolonged, and the using cost is effectively reduced.

Description

technical field [0001] The invention relates to a method for manufacturing a quartz crucible, in particular to a method for preparing an ultrahigh-purity quartz ceramic crucible. Background technique [0002] The polysilicon ingot uses a quartz crucible as a container, and successively undergoes processes such as heating, melting, crystal growth, annealing, and cooling. At present, the purity of polysilicon is greater than 6N (99.9999wt%) while the purity of ordinary quartz crucible is less than 3N (99.9wt%). Although there is a silicon nitride coating to isolate the ingot, there are still a lot of impurities that penetrate into the silicon ingot, especially Fe, etc. Metals have a serious impact on the quality of silicon ingots, resulting in a low minority carrier lifetime, which appears red in the scan image of the minority carrier lifetime, which is called the red zone. As a result, the photoelectric conversion efficiency of the small square ingot near the four corners ...

AI Technical Summary

Problems solved by technology

At present, the purity of polysilicon is greater than 6N (99.9999wt%) while the purity of ordinary quartz crucible is less than 3N (99.9wt%). Although there is a silicon nitride coating to isolate the ingot, there are still a lot of impurities that penetrate into the silicon ingot, especially Fe, etc. The metal has a serious impact on the quality of the silicon ingot, resulting in a low minority carrier lifetime, which appears red in the scan image of the minority carrier lifetime, which is called the red zone

As a result, the photoelectric conversion efficiency of the small square ingot near the four corners of the crucible (A region) and the small silicon ingot near the front side (B region) is much lower than that of the center (C region), so that the conversion of the whole ingot The efficiency will be greatly reduced, and it will become a bottleneck restricting the development of polysilicon cells. Reducing or even eliminating the pollution of crucibles to silicon ingots is a key part of improving the conversion efficiency of polysilicon cells.

The purity of high-purity quartz sand on the market is mostly 4.5N, and the price is expensive. The high-purity quartz sand above 6N is hundreds or even thousands of yuan per kilogram, and the cost of making an overall high-purity crucible is too unbearable.

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