Patent ID: 8248607

Claim:
A computer controlled method of characterizing ellipsometric parameters for samples with non-ideal surfaces in that reflections therefrom comprise a non-specular component, comprising the steps of: a) said computer system controlling an ellipsometer system which comprises: a polarization state generator; a stage for supporting a sample; a polarization state detector; and said computer system; to acquire ellipsometric data from a non-ideal sample surface comprising: a bare surface; a surface comprising a thin film coating thereupon; a surface comprising a thin film coating thereupon of a known thickness; on said stage for supporting a sample in a known orientation, said computer system causing said polarization state generator to direct a polarized beam of electromagnetic radiation so that it impinges on a non-ideal surface of said sample resulting in non-specular reflection, and then enters the polarization state detector, such that ellipsometric data is acquired and saved; b) computer regressing saved data acquired in step a onto a mathematical model for the sample in the known orientation thereof, said mathematical model being expressed as a matrix which relates orthogonal components of the beam which is provided by the polarization state generator and which is caused to impinge on the non-ideal surface of the sample, to those determined by the polarization state detector, and said mathematical model further comprising a correction factor or scattering matrix comprising elements, which correction factor or scattering matrix at least partially corrects for errors in the determination of said ellipsometric parameters which characterize said sample because the surface thereof is non-ideal; to the end that parameters in the mathematical model are evaluated and tangibly presented by said computer.