OXIDATION OF SILICON BY LOW-ENERGY OXYGEN BOMBARDMENT

High resolution Rutherford backscattering and channeling has been used to study the formation of surface oxides during room temperature bomb ardment of silicon with oxygen in a secondary ion mass spectrometry sy stem. Stoichiometric SiO2 is formed at angles of incidence (to the sur face normal) less-than-or-equal-to 25-degrees and the angular dependen ce is adequately modeled using the PROFILE code. A linear dependence o f oxide thickness on energy is obtained in the energy range 3-40 keV ( per oxygen ion) and this is consistent with TRIM code calculations. Th e suboxide damage has also been measured and studied during annealing. Our data are consistent with a simple model of oxygen build up and fo rmation of strong Si-O bonds during room temperature bombardment. Once a buried SiO2 layer is reached and Si bonds are saturated, oxygen can migrate in SiO2 to extend the oxide towards the surface.