Aluminum oxynitride (AlxOyNz) diffusion barriers have been formed in the temperature range of 400-725 °C by annealing Ag/Al bilayers on oxidized Si substrates in an ammonia (NH3) ambient. Rutherford backscattering spectrometry showed that the out-diffused Al reacted with ammonia and oxygen in the ambient and encapsulated the Ag films. The resulting Ag resistivity values are 1.75±0.35 μ cm. Higher processing temperatures and thinner original Al layers showed to improve the resistivity of the encapsulated Ag layers. The thermal stability of these diffusion barriers was evaluated by depositing 50 nm of Cu films onto the encapsulated samples, and then annealing in either vacuum or flowing He-0.5%H2. Results showed that these barriers sustained interdiffusion between Cu and Ag up to 620 °C at least for 30 min in either ambient. This temperature is a 200 °C improvement over previously reported values for the self-encapsulated Cu and Ag films.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)