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19 October 2016 Experimental verification of AI decomposition-based source optimization for M1 two-bar building blocks in 0.33NA EUVL
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Traditional pupil optimization for horizontal dark field two-bar building blocks yields a dipole matching its local pitch. This classical “rule” guides the placement for the illumination into a pupil area of high contrast and exposure latitude. However under these illumination conditions the feature exhibits an extremely large relative CD Bossung separation limiting its overlapping process window. Here we show experimentally that contrast-aware source optimization is necessary to lift this relative separation. The Tachyon-generated pupil applied is a very close replica of a rigorously obtained asymmetric illumination solution. The latter has emerged out of a study which evidenced that the formation of this rigorous pupil can be traced back to the interdependency of CD Bossung formation and symmetry of the intensity spectrum across the diffraction orders. Compared to standard D90Y and leaf shape illumination, the optimized pupil provides the highest simulated contrast, and experimentally obtained highest depth-of-focus and lowest pattern shift range. Finally we compare the consequences of intensity balancing versus phase aberration minimization across the diffraction orders and conclude that the balancing of the intensity spectrum is the main responsible factor for lifting the feature’s CD Bossung asymmetry and separation.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
T. Last, Z. Wang, P. van Adrichem, L. de Winter, and J. Finders "Experimental verification of AI decomposition-based source optimization for M1 two-bar building blocks in 0.33NA EUVL", Proc. SPIE 9985, Photomask Technology 2016, 99850W (19 October 2016);


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