Roughness effect on the measurement of interface stress

Stimulated by a recent paper by Spaepen (Acta mater. 48 (2000) 31) we conce ntrate on the effect of roughness parameters on stress measurements in thin films for self-affine and mound rough interfaces. A self-affine interface is characterized by a lateral correlation length xi, an rms roughness ampli tude sigma, and a roughness exponent H (0 < H < 1). With increasing long wa velength roughness ratio sigma/xi the ratio between the measured and the ac tual interface stress decreases. It decreases with a decreasing roughness e xponent H that leads to rougher interfaces at short roughness wavelengths ( < xi). For mound roughness which is characterised besides cr by an average mound separation;1 and a system correlation length zeta, the force ratio d ecays in an oscillatory manner as a function of sigma/lambda as long as lam bda < zeta. it is concluded that for both cases a more precise knowledge of roughness morphology is required in order to address the influence of inte rface roughness on the interface stress in thin films. (C) 2000 Acid Metall urgica Inc. Published bf Elsevier Science Lid. All rights reserved.