Alignment optimization and residual analysis for critical DUV photolithography

This work examines the alignment residual data for photolithography imaging in relationship to the maximum-minimum measured overlay values with linear factors corrected. Within the scope of this work, the relationships of maximum and minimum overlay vectors are examined instead of a three-sigma value characterizing the overlay. (The maximum vector is very close to a three sigma number, and the effective analysis would not be very different if three-sigma metric had been considered.) Such evaluation can lead to the understanding of what levels of alignment residuals are required to meet corresponding overlay budgets. It can be used to choose the alignment strategy or as a filter of real-time production alignment data.