12 April 2013 Pupil wavefront manipulation to compensate for mask topography effects in optical nanolithography
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As semiconductor nanolithography is pushed to smaller dimensions, process yields can suffer from three dimensional sub-wavelength imaging effects. Mask topography can influence the propagating diffracted field causing errors such as pitch dependent defocus and degraded useable depth of focus (UDOF). In this work, the compensation of diffracted phase error is realized through the manipulation of the wavefront in the projection lens pupil. Mask exposure data is presented showing how such manipulation can increase the UDOF for several mask structure types, leading to UDOF improvement between 18% and 83%. An analytical model is presented to understand trends seen in experimental data through pitch. Results also show that an asymmetric wavefront can be tuned to particular geometries, providing a UDOF improvement for line ends under restricted processing conditions.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Monica Kempsell Sears, Monica Kempsell Sears, Bruce W. Smith, Bruce W. Smith, "Pupil wavefront manipulation to compensate for mask topography effects in optical nanolithography", Proc. SPIE 8683, Optical Microlithography XXVI, 86830G (12 April 2013); doi: 10.1117/12.2010034; https://doi.org/10.1117/12.2010034


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