Method of improving quality of polysilicon material

Abstract

The invention discloses a method of improving the quality of a polysilicon material. The method comprises the following steps: putting a plurality of polished polysilicon materials in an acid and alkali resistance soaking vessel, separating every two adjacent polysilicon materials by a spacer bar, then pouring hydrofluoric acid, and slowly pouring nitric acid after all the polysilicon materials are immersed by the acid liquid, so that the internal impurities of the polysilicon materials are reacted in the mixed acid liquid, and discharged through induction; and after reaction is finished, taking out the polysilicon materials, brushing, then soaking the polysilicon materials into the mixed acid liquid which is used in normal acid pickling for 1-2h, then taking out again, and brushing for standby. According to the method disclosed by the invention, polished silicon mixtures are corroded by strong acid so that the internal impurities of the silicon mixtures are discharged from internal gaps under induction when the strong acid is reacted with the silicon mixtures, and then the silicon mixtures are brushed to eliminate the internal impurities, so that the impurities in the silicon mixtures are controlled, the crystallization ratio of ingot and the growth success rate of silicon crystal are increased, and the quality of the silicon crystal is obviously improved.

Description

technical field [0001] The invention relates to the technical field of solar crystalline silicon manufacturing, in particular to a method for improving the quality of polycrystalline silicon materials. Background technique [0002] Silicon single crystal and silicon polycrystalline are the most commonly used materials for crystalline silicon solar cells. The source of polycrystalline silicon used in solar cell ingots needs to be cleaned of impurities. Pickling. However, the pass rate of finished ingots is not high after inspection. Through research, it is found that the appearance of the silicon material after pickling and removal of impurities looks clean and has a good finish. In fact, some impurities inside the silicon block have not been removed from the body during the pickling process. The reason is that the reaction time of the silicon material in contact with the acid is short, and the surface is slightly oxidized or some dirty impurities on the surface can be remov...

AI Technical Summary

Problems solved by technology

However, the pass rate of finished ingots is not high after inspection. Through research, it is found that the appearance of the silicon material after pickling and removal of impurities looks clean and has a good finish. In fact, some impurities inside the silicon block have not been removed from the body during the pickling process. The reason is that the reaction time of the silicon material in contact with the acid is short, and the surface is slightly oxidized or some dirty impurities on the surface can be removed, but it is difficult to remove some deeper impurities inside the silicon material, such as polycrystalline edge skin, T1 material, head Impurities such as rubber traces, graphite, silicon carbide, and metal powders that exist in the tailings and leftovers have not been removed, and these all affect the resistance, the minority, and the yield in the ingot casting process. Various sources of polysilicon used in large-scale ingots are subjected to deep-level impurity removal treatment to make the impurity removal effect better, thereby improving its quality and cleanliness