The self-diffusion of N was measured with secondary ion mass spectrometry in isotopically enriched polycrystalline and amorphous Si314N4/Si315N4/Si314N4 isotope heterostructures which were produced by reactive magnetron sputtering. The N diffusivities of polycrystalline films, at 1130 to 1700C, follow an Arrhenius law over 4 orders of magnitude with a single activation enthalpy of 4.9eV and a pre-exponential factor of 10–6m2/s. A calculated entropy of diffusion of about 0k indicated a diffusion mechanism with localized point defects, in contrast to extended point defects usually found in semiconductors, like Si, Ge, and GaAs. The diffusivities in the amorphous state between 1130 and 1180C did not differ significantly from those in the polycrystalline state.

Nitrogen Self-Diffusion in Silicon Nitride Thin Films Probed with Isotope Heterostructures. H.Schmidt, G.Borchardt, M.Rudolphi, H.Baumann, M.Bruns: Applied Physics Letters, 2004, 85[4], 582-4