MULTILAYER FILM STABILITY

We apply a linear stability analysis to examine the effect of misfit s tress on the interface diffusion controlled morphological stability of multilayer microstructures. The stresses could be the result of misfi t strains between the individual film layers and/or between film and s ubstrate. We find that misfit between the layers in the film can desta bilize the multilayer structure in cases where the thinner layer is el astically stiffer than the thicker layer. The rate at which these inst abilities develop increase with increasing misfit and decreasing inter facial energy. Even when there is no misfit between layers, the misfit between the multilayer film and substrate can destabilize the interfa ces. This type of instability occurs whether the thinner layers are st iffer or more compliant, than the thicker ones. By appropriate choice of the elastic moduli mismatch between layers and relative layer thick nesses, the presence of an interlayer misfit call suppress the instabi lity caused by the substrate misfit. We present stability diagram that can be used to design stable, multilayer films using all of the degre es of freedom commonly available in multilayer film deposition. (C) 19 97 American Institute of Physics.