Optical metrology of lithographic processes using asymmetric sub-resolution features to enhance measurement

摘要

A process of calibrating a model, the process including: obtaining training data including: scattered radiation information from a plurality of structures, individual portions of the scattered radiation information being associated with respective process conditions being characteristics of a patterning process of the individual structures; and calibrating a model with the training data by determining a ratio relating a change in one of the process characteristics to a corresponding change in scattered radiation information.