AN INVERSION METHOD FOR THE COMPLETE CHARACTERIZATION OF TRANSPARENT FILM-ABSORBING SUBSTRATE SYSTEMS USING MULTIPLE ANGLE ELLIPSOMETRY

Multiple angle ellipsometry is used to develop a new inversion procedure that allows the entire characterization of transparent film-absorbing substrate structures. The thickness and refractive index of the film as well as the complex index of the substrate are thus extracted. The procedure finds out unambiguously and rapidly these physical parameters as a result of the numerical techniques introduced and owing to the reduction of the four-parameter problem to a 3-D search. A quantitative experimental sensitivity analysis equally carried out serves to optimize the experimental conditions under which the propagation of errors is minimum. The range of applicability of the procedure is illustrated by simulating the random experimental errors in the ellipsometric measurements on various reflecting systems. Consequently, an approximate method is proposed for obtaining the parameters of weakly absorbing substrate systems which require a high order of accuracy.