Patent ID: 7596422
Filing Date: 2009-09-29
Classification: G01N,G03F,H01L

Abstract:
1. A method of determining one or more profile parameters of a structure fabricated on a wafer in a wafer application, the wafer application having one or more process steps, each process step having a set of process parameters, the method comprising: a) for a selected process step of the wafer application, developing a correlation between a set of profile models and at least two key profile shape variables, wherein each profile model is defined using a set of profile parameters to characterize the shape of the structure, wherein different sets of profile parameters define the profile models in the set, and wherein the at least two key profile shape variables are selected from the set of profile parameters and from the set of process parameters having the most effect on the profile shape after the process step of the wafer application is performed, the selection based on sampling of profile shape changes resulting from changes of two process parameters, changes of two profile parameters, or a change of one or more process parameters and/or a change of one or more profile parameters, wherein the correlation between a set of profile models and at least two key profile shape variables is performed using ranges of the set of profile parameters of the structure; b) determining a value of at least two key profile shape variables of the process step of the wafer application to be used in fabricating the structure; c) selecting one profile model from the set of profile models based on the correlation determined in a) and the value of the at least two key profile shape variable determined in b); d) fabricating the structure using the process step and the value of the at least one key profile shape variable determined in b); e) obtaining a measured diffraction signal off the structure fabricated in d); and f) determining one or more profile parameters of the structure fabricated in d) based on the measured diffraction signal obtained in e) and the profile model selected in c).