Characterizing Variation in EUV Contact Hole Lithography

Local critical dimension uniformity (LCDU) for contact holes may be correlated with stochastic defects (missing or merged holes), but metrology noise will bias the LCDU measured by a CD-SEM. In this work, large contact hole data sets will be collected with varying SEM measurement recipes, such as different numbers of frames of averaging. Additionally, multiple measurements of the same after-etch features will be used to quantify the impact of metrology noise on the biasing of measured LCDU. Finally, a recommendation will be made as to an approach that minimizes, or eliminates, bias in LCDU measurements.