The surface chemistry of silicon bombarded with a CF+3 ion beam has been studied using X-ray photoemission and Auger electron spectroscopy. The chemical species and their depth distribution in a surface exposed to CF+3 ions of different energies (0.5 kV and 2 kV) are analyzed and are related to the etching behavior of silicon. The phenomenon of electron-induced desorption of surface fluorine is examined. XPS binding energies and the relative photoionization cross sections are also determined for a number of Si, C and F containing compounds, and these are used for chemical identification of the surface species. © 1979.