Effect of silicon wafer surface stains on copper-assisted chemical etching

Abstract

Silicon wafer slicing is a crucial process of solar cell fabrication, this process often stains the silicon wafer surface, Thus, this work systematically investigated the composition, source, cleaning method of typical white spot stains on silicon wafer surface. The EDS and XPS results showed that the white spot stains contained CaCO3 and SiO2 that are basically consistent with the filler components in sticky stick glue. Meanwhile, The effects of stains on copper deposition and copper-assisted chemical etching were systematically studied, the white spot stain was still attached on silicon after the deposition and the etching process, we have fond that the stains can affect the uniform deposition of copper particles on the surface of the silicon wafer, it also impede the catalytic etching process of copper particles. Finally, the KOH solution combined with the ultrasonic field was proposed to remove the surface stains of the silicon wafer. This study has important guidance on knowledge and cleaning of silicon wafer contamination for fabricating high-efficiency solar cells.