| 主权项 |
1. A method for enhancing accuracy in 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 first library comprising Jones and/or Mueller matrices or components (JMMOC) and corresponding profile parameters, the library generated using ray tracing based on a selected representative ray and a first set of beam propagation parameters; (b) using the processor, generating a first difference library comprising difference JMMOC for each ray of a set of rays, each difference JMMOC calculated by subtracting the JMMOC of each ray of the set of rays from the selected representative ray JMMOC; (c) obtaining a measured diffraction signal off the sample structure using the optical metrology tool; and (d) using the processor, regenerating the JMMOC of the representative ray using the first library and regenerating the JMMOC of each ray of the set of rays using the first difference library; (e) obtaining a simulated diffraction signal of the sample structure using the regenerated JMMOC of the representative ray, regenerated JMMOC of each ray of the set of rays, and the optical metrology model; (f) determining one or more profile parameters of the sample structure using the measured diffraction signal, the simulated diffraction signal, and a matching algorithm. |
