Surface roughness interpretation of ellipsometer measurements using the generalized Maxwell Garnett theory

Abstract

The generalized Maxwell Garnett theory developed in the preceding paper is utilized here to specify the state of roughness of a surface. Both thick and thin metal samples are measured on the ellipsometer. In the interpretation, the surface roughness layer is replaced by a smooth but anisotropic medium whose optical behavior is assumed to be governed by the generalized Maxwell Garnett theory which specifies a roughness layer by two parameters d and q. Success of the interpretation is judged according to the degree of independence existing between the two parameters d and q and the angle of incidence. Experimental results on several metals indicate that in many cases the surface roughness and not an oxide layer is responsible for the variation of ellipsometer parameters ψ and Δ from that of a truly smooth bulk material surface.