Oxidation of silicon by low energy oxygen ions

This paper gives an overview of recent studies of the oxidation of silicon during oxygen bombardment. In secondary ion mass spectrometry measurements, oxygen builds up to stoichiometric SiO ₂ under appropriate conditions. When this occurs, some elements are segregated at the SiSiO ₂ interface during subsequent sputtering. Temperature-dependent studies have shown that there is a strong chemical driving force to form SiO ₂ layers even under liquid nitrogen temperature bombardment. Oxygen is not mobile in Si during bombardment but is highly mobile in SiO ₂. Fast diffusing metals such as Cu, Au and Pd appear to be mobile in an amorphous-Si layer beyond the beam-induced SiO ₂ layer if the bombardment temperature is sufficiently high. These metals also exhibit low solubility in SiO ₂ but high solubility in amorphous or disordered Si. Thus, there is a driving force for segregation at a moving SiSiO ₂ interface.