THE GROWTH DYNAMICS OF THICK SPUTTERED COPPER COATINGS UNDER THE INFLUENCE OF SURFACE-DIFFUSION - A QUANTITATIVE ATOMIC-FORCE MICROSCOPY STUDY

The evolution of surface features during the growth of a coating is of vital importance for the resulting overall film structure and morphology. In the low substrate temperature regime (T/T-M<0.3) the growth front of a single component material roughens due to fluctuations in the incoming particle beam (kinetic roughening) and relaxes via surface diffusion. The continuous deposition process thus leads to the evolution of surface features of large lateral extensions compared to the extension of the film-forming particles. A detailed experimental study of the surface evolution of sputtered copper coatings with thicknesses ranging from 300 to 10(5) Angstrom for a working gas pressure of 0.4 Pa is presented. The roughening as well as the relaxation of the film growth front is studied by means of atomic force microscopy (AFM). The increasing lateral extension of the surface features during growth (coarsening) can well be described by a deterministic continuum model of surface diffusion. The model is capable of predicting the evolution of the surface profile's Fourier transform for increasing deposition times (i.e., increasing film thickness). A retransformation from k space to real space allows for a direct comparison of surface profiles obtained from AFM scans with those resulting from the continuum model and gives good qualitative agreement of the profile shapes. (C) 1995 American Institute of Physics.