Abstract
The principal role of silicon-fluorine bonds in the chemical nature of HF-etched Si surfaces has been studied by angle resolved X-ray photoelectron spectroscopy. The fluorine coverage and the native oxide growth thickness have been systematically measured as functions of HF concentration, pure water rinse time, air or N2+O2 gas exposure time and gas phase H2O concentration. It is found that the existence of Si-F bonds of about 0.12 monolayers on the surface strongly suppresses the native oxide growth. This is explained by a model in which Si-F bonds chemically stabilize the surface reactive sites such as atomic steps as supported by the result of the layer-by-layer oxidation of Si.
