Removal Process of Insoluble Matter in High Purity Silicon

Abstract

The invention discloses a process for removing insoluble matters from high-purity silicon. The process comprises the steps of cleaning the surface of a purified silicon raw material, melting the purified silicon raw material through induction heating of an intermediate-frequency coil, controlling local temperature of a melt, so as to float the insoluble matters, then, adsorbing the floating insoluble matters by using a condenser, and finally, solidifying impurity removed silicon in directional equipment. According to the process disclosed by the invention, formed insoluble impurities, such as silicon carbide, silicon nitride and the like, can be removed from silicon, and the recycling rate is stable; moreover, no new pollutants can be generated, the integrity of purified silicon ingots is maintained, and no air holes are formed, so that the cutting is facilitated, and the production cost is effectively controlled.

Description

technical field [0001] The invention relates to a process for removing insoluble matter in high-purity silicon. Background technique [0002] High-purity polycrystalline silicon is the raw material for the preparation of single crystal and polycrystalline solar cells. The raw material for preparing monocrystalline and polycrystalline silicon wafers is 6N primary polycrystalline prepared by improved Siemens method and fluidized bed. After the production of monocrystalline and polycrystalline silicon wafers, some silicon materials that cannot be sliced ​​will be produced in each furnace, which will be put into recycling again. After multiple cycles, the content of impurities such as silicon carbide and silicon nitride in the silicon material increases, which affects the use effect and leads to defective products. In order to remove these insoluble impurities in silicon, the impurities are pushed to the top of the silicon ingot by directional solidification, and then the part...

AI Technical Summary

Problems solved by technology

If it is purified through multiple reuses, although qualified polysilicon can be obtained, in this process, the energy consumed for multiple recovery and purification increases cumulatively, and the yield of each purification is getting lower and lower. Purification, the yield drops to 65%, and the proportion of eliminated parts gradually increases, resulting in excessively high purification costs