A comparative Raman spectroscopy study on silicon surface in HF, HF/H2O2 and HF/NH4F aqueous solutions

The nature of Si(100) surfaces during immersion in dilute hydrofluoric acids (DHF), HF/H2O2/H2O mixture and buffered hydrofluoric acids (BHF) has been comparatively investigated using confocal Raman spectroscopy. In DHF solution, silicon surfaces are covered mainly with silicon trihydrides (SiH3) at the beginning of etching. As the etching goes on, silicon dihydrides (SiH2) become main surface bonds, and silicon monohydride (SiH) signal appears clearly. In HF/H2O2/H2O solution, silicon surfaces are terminated with hydrides, oxides and hydrogen-associated silicon fluorides. In BHF solution, silicon surfaces are covered with hydrides and hydrogen-associated silicon fluorides.