1 April 2010 Spatial signature in local overlay measurements: what CD-SEM can tell us and optical measurements can not
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Abstract
This work explores the applications of CD-SEM overlay metrology for double patterned one-dimensional (1D) pitch split features as well as double patterned ensembles of two-dimensional (2D) complex shapes. Overlay model analysis of both optical overlay and CD-SEM is compared and found to give nearly equivalent results. Spatial correlation of the overlay vectors is examined over a large range of spatial distances. The smallest spatial distances are shown to have the highest degree of correlation. Correlation studies of local overlay in a globally uniform environment, suggest that the smallest sampling of overlay vectors need to be ~10-15μm, within the spatial sampling of this experiment. The smallest spatial distances are also found to have to tightest mean distributions. The distribution width of the CD-SEM overlay is found to scale linearly with log of the spatial distances over 4-5 orders of magnitude of spatial length. Methodologies are introduced to examine both the overlay of double pattern contacts at the edge of an array and lithographic process-induced overlay shift of contacts. Finally, a hybrid optical- CD-SEM overlay metrology is introduced in order to capture a high order, device weighted overlay response.
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Scott Halle, Scott Halle, Daniel Moore, Daniel Moore, Chas Archie, Chas Archie, Shoji Hotta, Shoji Hotta, Takumichi Sutani, Takumichi Sutani, Akiyuki Sugiyama, Akiyuki Sugiyama, Masahiko Ikeno, Masahiko Ikeno, Atsuko Yamaguchi, Atsuko Yamaguchi, Kazuyoshi Torii, Kazuyoshi Torii, } "Spatial signature in local overlay measurements: what CD-SEM can tell us and optical measurements can not", Proc. SPIE 7638, Metrology, Inspection, and Process Control for Microlithography XXIV, 76381V (1 April 2010); doi: 10.1117/12.846665; https://doi.org/10.1117/12.846665
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