Spatial signature in local overlay measurements: what CD-SEM can tell us and optical measurements can not

Scott Halle; Daniel Moore; Chas Archie; Shoji Hotta; Takumichi Sutani; Akiyuki Sugiyama; Masahiko Ikeno; Atsuko Yamaguchi; Kazuyoshi Torii

doi:10.1117/12.846665

1 April 2010 Spatial signature in local overlay measurements: what CD-SEM can tell us and optical measurements can not

Scott Halle, Daniel Moore, Chas Archie, Shoji Hotta, Takumichi Sutani, Akiyuki Sugiyama, Masahiko Ikeno, Atsuko Yamaguchi, Kazuyoshi Torii

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Proceedings Volume 7638, Metrology, Inspection, and Process Control for Microlithography XXIV; 76381V (2010) https://doi.org/10.1117/12.846665
Event: SPIE Advanced Lithography, 2010, San Jose, California, United States

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, Daniel Moore, Chas Archie, Shoji Hotta, Takumichi Sutani, Akiyuki Sugiyama, Masahiko Ikeno, Atsuko Yamaguchi, and 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); https://doi.org/10.1117/12.846665

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