5 November 2005 Comparison of different approaches for the correction of residual mask proximity effects
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Abstract
Linearity- and proximity effects do exist on actual masks even if manufactured with current state-of-the-art processes. The impact of these short-range mask effects on the results of the optical lithography for features sizes relevant in the 90nm-node is investigated. For this purpose, an approach is chosen which employs mask process simulations in combination with simulations of optical lithography. Two mask models are deduced and verified from measurement data of an existing mask process. The lithographic results are simulated using parameters of current optical- and process models. Both mask models are used to evaluate the impact of the mask proximity effects on the printing results of optical lithography for critical pattern geometries. The differences in the mask proximity characteristics lead to additional pattern-dependent CD-offtargets after wafer lithography. Additionally, a mask-process dependent sensitivity of the CD-offtarget on the presence of optical sub-resolution assist features is observed. Based on these simulation results, the efficiencies of two techniques for the correction of the mask proximity signatures are evaluated. The application of mask sub-resolution features is compared with model-based data correction on mask level. Mask sub-resolution assist features reduce the influence of the mask process significantly and provide an enhanced stability against mask process fluctuations. Data correction yields even better correction results at the cost of an increased complexity due to the susceptibility to changes of the mask processes characteristics.
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E. Mittermeier, T. Franke, "Comparison of different approaches for the correction of residual mask proximity effects", Proc. SPIE 5992, 25th Annual BACUS Symposium on Photomask Technology, 59925I (5 November 2005); doi: 10.1117/12.637363; https://doi.org/10.1117/12.637363
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