Investigation of interactions between metrology and lithography with a CD SEM simulator

Mark D. Smith; Chao Fang; John J. Biafore; Alessandro Vaglio Pret; Stewart A. Robertson

doi:10.1117/12.2048247

27 March 2014 Investigation of interactions between metrology and lithography with a CD SEM simulator

Mark D. Smith, Chao Fang, John J. Biafore, Alessandro Vaglio Pret, Stewart A. Robertson

Proceedings Volume 9051, Advances in Patterning Materials and Processes XXXI; 905109 (2014) https://doi.org/10.1117/12.2048247
Event: SPIE Advanced Lithography, 2014, San Jose, California, United States

Abstract

The predictive power of computational lithography is often demonstrated by showing predicted 2D pattern shapes compared with top-down SEM images. However, image formation in a SEM is a complex process [1,2,3], and for most 3D lithography and OPC simulators, line width measurements and 2D pattern shapes are based on extracted resist polygons at a fixed height above the substrate. Generating resist polygon shapes with this method is driven by computationally efficiency instead of an attempt to describe the image formation process in an actual SEM. We present PROLITH photolithography simulations combined with simulation of the CD SEM to investigate the interactions between lithography and metrology. Our CD SEM simulator is a simplification of the complicated image formation process [4], but it captures many effects seen experimentally. For example, narrow trenches and contact holes are dark at the bottom in our simulated SEM images, while for isolated lines, the sidewall of the photoresist can clearly be observed all the way to the resist foot at the substrate. This simple result has important implications when evaluating lithographic phenomena such as LWR: for polygon-based metrology, simulated LWR is approximately constant with resist thickness; by contrast, the LWR increases with decreasing thickness when the same simulated 3D resist profiles are evaluated with the CD SEM simulator.

Citation Download Citation

Mark D. Smith, Chao Fang, John J. Biafore, Alessandro Vaglio Pret, and Stewart A. Robertson "Investigation of interactions between metrology and lithography with a CD SEM simulator", Proc. SPIE 9051, Advances in Patterning Materials and Processes XXXI, 905109 (27 March 2014); https://doi.org/10.1117/12.2048247

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