Thermal and Photochemical Promotion of Silicon and Silicon Dioxide Etching by Carbonyl Difluoride

摘要

Silicon surfaces that were cleaned and characterized in ultrahigh vacuum were exposed to carbonyl difluoride. After adsorption of carbonyl difluoride the silicon crystal was desorption of silicon tetrafluoride. Si surfaces covered with a native oxide layer were also exposed to carbonyl difluoride. Dissociation of COF 2, using high fluences from the CO2 laser, caused etching of the SiO2 surface. Volatile SiF4 was detected by transmission Fourier transform infrared spectroscopy. Two mechanisms, for the thermally enhanced etching of silicon by COF2 and the photochemically promoted etching of silicon dioxide by COF2, are proposed.