Oxynitride diffusion barriers were produced at 400 to 725C by annealing Ag/Al bilayers, on oxidized Si substrates, in an NH3 ambient. Rutherford back-scattering spectrometry showed that the out-diffused Al reacted with NH3 and O in the ambient, and encapsulated the Ag films. The thermal stability of the diffusion barriers was evaluated by depositing 50nm of Cu film onto the encapsulated sample, and annealing in vacuum or flowing He-0.5%H2. The results showed that these barriers sustained interdiffusion, between Cu and Ag, for at least 0.5h at up to 620C in either ambient.

Formation of Aluminum Oxynitride Diffusion Barriers for Ag Metallization. Y.Wang, T.L.Alford: Applied Physics Letters, 1999, 74[1], 52-4