In the low temperature deposition regime (T<0.3 Tm) the surface evolution of a growing film is determined by the interplay of kinetic roughening and the smoothing mechanism of surface diffusion.

In this paper we report on the surface evolution of Cu-coatings sputter deposited on Si (100)-substrates. Film thicknesses ranged from 300 Å (deposition time = 18 s) to 10 Å (deposition timeó.lO s). The ratio T/TM was 0.3. The RMS (Root Mean Square) roughness values ξ and the surface morphology of the films were determined by AFM (Atomic Force Microscopy). The dependence of the RMS roughness-values on the deposition time t was found to be non-linear according to the scaling expression ξα with =;π = 1/3. This non-linear behavior indicates a growth situation with an increasing lateral extension of surface features. Their lateral extension is quantified by a continuum approach of mass transport by surface diffusion proposed by Mullins. Calculated and experimentally observed feature extensions are in good agreement in the entire considered range of deposition times and vary from 800 Åto 10 Å.