Patent ID: 8570531
Filing Date: 2013-10-29
Classification: G01N

Abstract:
1. A method for enhancing accuracy of an optical metrology system, the optical metrology system including an optical metrology tool, an optical metrology model, and a profile extraction algorithm, the optical metrology model including a model of the optical metrology tool and a profile model of the sample structure; the sample structure formed on a substrate, the profile model having profile parameters, the optical metrology model having an illumination beam, the method comprising: (a) using a processor, generating a library comprising Jones and/or Mueller matrices or components (JMMOC) and corresponding profile parameters, the library generated using ray tracing and a selected range of beam propagation parameters in the optical metrology model; (b) obtaining a measured diffraction signal off the sample structure using the optical metrology tool; and (c) calculating an original simulated diffraction signal for the sample structure using the optical metrology model; (d) setting an error and precision criteria for a regenerated simulated diffraction signal; (e) if the error and precision criteria for the regenerated simulated diffraction signal compared to the original simulated diffraction signal are met: