The diffusion of O in thin films was studied by using O which was isotopically enriched with 18O. The films were prepared by using a direct current magnetron and reactive sputtering techniques. In order to produce 18O-enriched material, a Si wafer was reactively sputtered by using 95% 18O gas as the plasma feed. The films were characterized by using Rutherford back-scattering spectrometry and secondary ion mass spectrometry to establish stoichiometry and purity. The films were then exposed to an air-derived O plasma for up to 10h. The concentration of 16O as a function of depth was determined by using secondary ion mass spectrometry profiling, and was compared with a control sample. The O diffusivity near to the surface of the films was then found to be about 10-15cm2/s at 50C.

D.A.Gulino, L.A.Kren, T.M.Dever: Thin Solid Films, 1990, 188[2], 237-46