Patent ID: 7756677
Filing Date: 2010-07-13
Classification: G01B,G02B

Abstract:
1. A method of characterizing a diffraction structure having one or more layers sandwiched between an incident medium and a substrate, wherein L l is the lth of said layers and wherein said index l increases from incident medium to substrate, the method comprising: a) illuminating said diffraction structure with incident optical radiation, wherein said diffraction structure has one or more structural parameters; b) measuring an optical response of said diffraction structure as a function of an incident radiation parameter p; c) calculating two or more modeled optical responses of said diffraction structure corresponding to two or more sets S d) providing said two or more modeled optical responses as inputs to a procedure for providing estimates of one or more of said structural parameters; e) providing said estimates of said one or more structural parameters as an output; f) wherein said calculating is performed by nesting an inner loop running over all sets S