Patent ID: 7667858

Claim:
A method of controlling a process step in fabricating a structure 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; b) determining a value of the 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) the value of at the least two key profile shape variables determined in b); d) fabricating the structure in a first fabrication process cluster using the process step and the value of the at least two key profile shape variables determined in b); e) obtaining a measured diffraction signal off the structure fabricated in d); f) determining one or more profile parameters of the structure fabricated in d) based on the measured diffraction signal obtained in e) and the selected profile model selected in c); and g) transmitting the one or more determined profile parameters to the first fabrication process cluster or a second fabrication process cluster.