Patent ID: 7239391

Claim:
A method of evaluating a sample comprised of stacked layers of at least: material 1 and material 2 ; present on at least one surface of a substrate having first and second substantially parallel sides; said method sequentially comprising the steps of: a) using published data, and/or separate samples of material from each layer and/or educated guessing determining starting values for n and k for said materials 1 and 2 seperately over a range of wavelengths, wherein n is the index of refraction and k is the extinction coefficient, and therefrom determining initial values for parameters in a parameterized mathematical model therefore; practicing steps b and c in either order or simultaneously: b) obtaining reflective spectroscopic ellipsometric data from both first and second sides of said sample, and transmission data from at least one side thereof to provide two PSI, two DELTA and transmision intensity data sets; c) providing a mathematical model of said sample comprising n and k and thickness for each of the material layers, said n and k being parameterized over a plurality of wavelengths as determined in step a; d) utilizing starting values determined in step a regressing said mathematical model identified in step c, simulaneously onto the five data sets identified in step b; to evaluate said n, k and thickness defining parameters for the material 1 and material 2 layers in the wavelength range over which said n and k values are parameterized; said method being characterized in that the obtained data is insufficient to directly one for one evaluate all parameters of the mathematical model over the wavelength range; and e) displaying at least one selection from the group consisting of: n; k; real part of dielectic function; imaginary part of dielectic function; thickness; PSI; and DELTA; for at least one selection from the group consisting of: material 1 ; and material 2 ; over at least part of the wavelength range over which said n and k values are parameterized.