A method and device for increasing the amount of volatile impurities removed during electron beam smelting

Abstract

The invention discloses a method and device for increasing the impurity removal amount of volatile impurities in an electron beam smelting process. According to the invention, in an electron beam smelting process, the surface of a silicon melt can be fluctuated by changing the melting mode of an electron beam, so that the evaporation surface area is increased, the evaporation surface area of a melt interface is increased, and the evaporation amount of impurities in unit time is increased; a graphite substrate is placed at the bottom of a smelting crucible, and then the temperature distributionat the bottom of the silicon melt is changed, so that flowing of the silicon melt at the bottom of the smelting crucible is promoted, convection occurs in the silicon melt, and then melt exchange between the silicon melt at the bottom and the silicon melt at the top is accelerated. Through the change of the melting mode and the experimental device of the electron beam, the evaporation surface area of the melt is increased, the evaporation amount of the impurities in unit time is increased, and therefore, the problems that a silicon melt is low in impurity evaporation amount, long in melting time, large in silicon material loss and high in cost in an impurity removal process of volatile impurities are solved.

Description

technical field [0001] The invention relates to the field of smelting and impurity removal, in particular to a method and device for increasing the amount of volatile impurities removed during electron beam smelting. Background technique [0002] Volatile impurity elements such as phosphorus, aluminum, calcium, arsenic, etc. are very common impurity elements in silicon materials. The content of impurity elements in solar-grade silicon will affect the photoelectric conversion efficiency of silicon panels. By doping trace elements in high-purity silicon It can increase the concentration of carriers, facilitate the migration and diffusion of electrons, and then improve the photoelectric performance of solar-grade silicon. Therefore, how to obtain high-purity solar-grade silicon is a research hotspot in current scientific research. In the process of purifying metallurgical-grade silicon to prepare solar-grade silicon materials by metallurgical methods, the equilibrium segregatio...

AI Technical Summary

Problems solved by technology

Electron beam smelting technology can provide a high temperature and high vacuum environment. Impurities tend to volatilize from the surface of silicon melt in the form of gas and form a gas / liquid equilibrium state with liquid phase, which is conducive to the removal of volatile impurities, but the melting time Longer, higher cleaning costs

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