X-ray photoelectron study on the adsorption of anhydrous hydrogen fluoride onto silicon native oxide

The adsorption of anhydrous hydrogen fluoride (AHF) on the surfaces of silicon native oxide was investigated by in situ X-ray photoelectron spectroscopy (XPS) in order to understand the reaction between HF and the oxide films at room temperature. A significant amount of the component is located at 670.0 eV binding energy in the observed XPS spectra, and is most likely derived from HF molecules. Moreover, the surface density of F-Si bonds slowly increases with the AHF exposure. We also attempted to accelerate the etching of the native oxide without moisture, supplying the AHF gas with remote-plasma-excited Ar, and obtained the enhanced etch rate.