Flare and its effects on imaging

Flare continues to be a concern in the imaging performance of KrF and ArF scanners, both in new tools and in previous-generation tools used for non-critical layers. We have performed a systematic study of the effects of flare, parametrizing it in terms of its amplitude and range, and looking at modeled effects on different features. We have also collected flare data on newer and older scanners, and the modeling allows us to place those data in context and assess their impact on scanner performance. Results show that flare is not a big driver in scanner imaging.