Methods And Systems For Spectral Measurements Based On Perturbed Spectra

Abstract: methods and systems for measuring structural parameters characterizing a measurement target based on changes in measurement signal values due to one or more perturbations of an effective illumination angle of incidence on the measurement target are presented herein. in some examples, a measurement model estimates values of the structural parameters based on the changes in measurement signal values. in some examples, at least one derivative of detected measurement signals with respect to effective illumination angle is determined, and values of the structural parameters are estimated based on the at least one derivative. in some examples, values of one or more tunable measurement model parameters are estimated based on at least one derivative. in some examples, the fitting performance of a measurement model is quantified based on measurements performed at both unperturbed and perturbed orientations of a structure under measurement with respect to the illumination beam.

Inventor(s): William McGahan, Shankar Krishnan

CPC Classification: G01N21/9501 ({Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step )})

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