Roughening kinetics of reactively sputter-deposited Ti-Al-N films on Si(100)

The roughening kinetics of Ti_1-xAl_xN (0 ≤ x ≤ 1) films 600 nm thick synthesized by reactive dc magnetron sputtering on Si(100) substrates has been investigated by atomic force microscopy (AFM). The quantification of surface roughening was achieved by calculation of both vertical root-mean-square roughness and lateral correlation lengths of the film surface using the height-height correction functions of measured AFM images. For all the Ti_1-xAl_xN films, a steady roughness exponent α = 0.94 ± 0.03 was determined. The evolution of the surface topography as a function of Al concentration is discussed in terms of the competition between surface diffusion and shadowing instability during sputter deposition.