Patent ID: 7480062
Filing Date: 2009-01-20
Classification: G03F

Abstract:
1. A method of controlling a photolithography cluster using a trained a machine learning system to determine photomask structure parameters of a photomask covered with a pellicle using optical metrology, the photomask being used to fabricate a structure on a wafer, the method comprising: a) obtaining a set of different values of one or more photomask structure parameters, the photomask covered with a pellicle; b) obtaining a set of diffraction signals using the set of different values of the one or more photomask structure parameters; c) training a machine learning system using the set of diffraction signals as inputs to the machine learning system and the set of different values of the one or more photomask structure parameters as expected outputs of the machine learning system; (d) obtaining a measured diffraction signal off an examined structure; and (e) after the machine learning system has been trained, inputting the measured diffraction signal into the machine learning system to obtain one or more values of one or more photomask structure parameters as an output of the machine learning system.