Removal of inclusions from solar grade silicon using electromagnetic field

Abstract

The characteristics of the top-cut solar grade silicon (SoG-Si) scraps produced from SoG-Si ingots were investigated using optical microscope observation, SEM-EDS analysis and automatic inclusion scanning (ASPEX). Particles of SiC and Si3N4 are the main non-metallic inclusions in the SoG silicon top-cut scrap. The deeper into the scrap from the surface, the less and smaller inclusions are found. A laboratory-scale electromagnetic purification unit was used to melt the silicon scraps and remove inclusions from the melt. The experimental results indicated that the electromagnetic (EM) field efficiently pushed the non-metallic particles and less-conductive metallic impurity elements to the boundary layer.