Comparative study of c-axis AlN films sputtered on metallic surfaces

Abstract We have investigated the crystal quality, the residual stress and the composition of AlN thin films with {00·2} preferred orientation sputtered on metallic surfaces (Al 0.9 Si 0.1 , Cr, Mo and Ti) and, for comparison, on oxidized Si wafers. The AlN films deposited on metallic surfaces showed values of strain and residual stress significantly lower than on the oxidized Si wafers. The AlN films with the best crystal quality were achieved on Mo, with grain sizes ranging from 20 nm to 60 nm. In the case of AlN sputtered on Al 0.9 Si 0.1 substrates, an unexpected behavior was observed, consisting in the reaction between the Al substrate and the nitrogen from the plasma to form stoichiometric AlN. For the AlN films deposited on Ti, we found that a large concentration of nitrogen (up to 10%) had been incorporated into the Ti layer, although we did not observe the formation of TiN x polytypes. No chemical reactions were observed for the AlN films sputtered on Cr and Mo substrates.