Papers by Keyword: Si Thinning

Abstract: The HF/HNO₃ mixture Si etching process is widely used to remove stress and damaged layers after Si wafer back grinding. Although there have been many reports on the dip process, there have been few detailed reports on the single-spin process. In a single spin process, Si etch rate distributions largely differ with different HF/HNO₃ concentrations. On the other hand, thermal SiO₂ etch rate distributions are similar even with different HF/HNO₃ concentrations. In this work, we analyzed Si surfaces with XPS (X-ray Photoelectron Spectroscopy) after processing various HF/HNO₃ mixture concentrations. SiO_x stays steady in any wafer position and HNO₃ concentration, whereas SiO₂ thickens depending on HNO₃ concentration at the center. We assumed that Si etch rate distributions were caused by HF or HNO₃ consumption and confirmed this assumption was correct in a wafer center SiN cover experiment.