The diffusion and reactivity of H, which had been incorporated into SiOxNy films during low-pressure chemical vapor deposition at 800C, was studied by using elastic recoil detection and infra-red spectroscopic methods at temperatures ranging from 700 to 1000C. The experiments were based upon the determination of the H and D depth profiles in layer structures in which H and D had been incorporated in different layers. Such double layers could be produced directly during deposition or by the exchange of incorporated H with gas-phase D. The diffusion coefficient of H (or D) ranged from 3 x 10-18 to 10-13cm2/s, at temperatures of between 700 and 1000C, and was characterized by a single activation energy of 3eV, for [O]/([O]+[N]) ratios of up to 0.45. The diffusion coefficient, and therefore the rate of exchange of incorporated H and gas-phase D, increased with the [O]/([O]+[N]) ratio when the latter was higher than 0.3. On the basis of the results, a model was proposed in which the rate-limiting step in the process of H diffusion in the present samples was the breaking of N-H bonds. After the bond breaking, the H atom became trapped in a N-related trapping site or exchanged with a N-bonded H (D) atom. If the bond breaking occurred within about 10nm of the immediate surface, the H atom was able to desorb into the gas phase. The presence of a SiO2 capping layer did not prevent the desorption.

W.M.Arnoldbik, C.H.M.Marée, A.J.H.Maas, M.J.Van den Boogaard, F.H.P.M.Habraken, A.E.T.Kuiper: Physical Review B, 1993, 48[8], 5444-56