Systems and Methods for Automated Multi-Zone Detection and Modeling

A semiconductor tool comprising:

• an illumination source configured to generate an illumination beam;
• one or more illumination optical elements configured to direct a portion of the illumination beam to a sample;
• a detector;
• one or more collection optical elements configured to direct radiation emanating from the sample to the detector;
• and
• a controller communicatively coupled to the detector, the controller including one or more processors configured to execute program instructions configured to cause the one or more processors to:
• measure alignment at a plurality of locations across the sample to generate alignment data based on the collection of radiation emanating from the sample by the detector in response to illumination from the illumination beam;
• select an analysis area for alignment zone determination, the analysis area representative of at least a portion of the sample;
• define a sweep parameter such that each value of the sweep parameter bounded by the analysis area divides the analysis area into a first region and a second region;
• select a value of the sweep parameter as a zone boundary to minimize, within a specified tolerance, a difference between an alignment signal metric applied to the first region and the alignment signal metric applied to the second region, wherein the zone boundary divides the analysis area into a first alignment zone and a second alignment zone;
• model the alignment data of the first alignment zone using a first alignment model;
• and
• model the alignment data of the second alignment zone using a second alignment model different than the first alignment model.

A method comprising:

• measuring, with a semiconductor tool, alignment at a plurality of locations across a sample to generate alignment data based on radiation emanating from the sample collected by a detector of the semiconductor tool in response to illumination from an illumination beam;
• selecting an analysis area for alignment zone determination, the analysis area representative of at least a portion of the sample;
• dividing the analysis area into two or more alignment zones having different alignment signatures;
• modeling the alignment data of at least a first alignment zone of the two or more alignment zones using a first alignment model;
• and
• modeling the alignment data of at least a second alignment zone of the two or more alignment zones using a second alignment model different than the first alignment model.