TIS-WIS Interaction Characterization on Overlay Measurement Tool

摘要

Modern overlay metrology tools achieve the required metrology accuracy by controlling critical asymmetries in the imaging optics, and by compensating for the remaining asymmetries through TIS-calibration. We extend our study on the TIS-WIS interaction in stepper alignment optics to the overlay metrology tool, and propose a new method for characterizing residual TIS. This method is based on the examination of the through-focus behavior of the metrology tool on a wafer with a simple, TIS-sensitive structure.