Patent ID: 7912679
Filing Date: 2011-03-22
Classification: G03F,H01L

Abstract:
1. A method of examining a structure formed on a semiconductor wafer using an optical metrology model, the method comprising: a) creating an optical metrology model for the structure, the optical metrology model comprising one or more profile parameters, which characterize one or more geometric characteristics of the structure, one or more process parameters, which characterize one or more process conditions for fabricating the structure, a dispersion, which characterizes optical properties of a material of the structure; b) obtaining a dispersion function that relates the dispersion to at least one of the one or more process parameters; c) generating a simulated diffraction signal using the optical metrology model and a value for the at least one of the process parameters and a value for the dispersion, wherein the value for the dispersion is calculated using the value for the at least one of the process parameter and the dispersion function; d) obtaining a measured diffraction signal of the structure, wherein the measured diffraction signal was measured off the structure; e) comparing the measured diffraction signal to the simulated diffraction signal; and f) determining one or more profile parameters of the structure based on the comparison of the measured diffraction signal to the simulated diffraction signal.