Nonequilibrium water permeation in Si0 2 thin films

d;r, _:0 films by thermal treatments in steam. Thermal oxides were grown on silicon to a t ,ickntss of 260 nm in dry 02 and were subsequently treated in steam at temperatures of 320 and 500"C for periods lasting between 390 and 6 X 10' s. The concentrations of hydrogen carried in by permeating water were then profiled with 6.4 MeV "N ions using the resonant nuclear reaction 'H(1N, ay)"C. Water was seen to penetrate the films rapidly and to slowly react with the SiO 2 uniformly throughout the films. Two distinct stages were observed in the buildup of H, indicating that the water/SiO 2 reaction involves at least two concurrent processes rather than a single-stage process.