Understanding the impact of CD-SEM artifacts on metrology via experiments and simulations

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

doi:10.1117/12.2087106

19 March 2015 Understanding the impact of CD-SEM artifacts on metrology via experiments and simulations

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

Author Affiliations +

Proceedings Volume 9424, Metrology, Inspection, and Process Control for Microlithography XXIX; 94242A (2015) https://doi.org/10.1117/12.2087106
Event: SPIE Advanced Lithography, 2015, San Jose, California, United States

Abstract

Scanning Electron Microscopy (SEM) is widely used to measure Critical Dimensions (CD) in semiconductor lithography processes. Correlation between the CD-SEM metrology and target profile has drawing attention from metrology community [1]. In this paper, we use a recently developed CD-SEM simulator [2-3] to investigate some artifacts of SEM metrology. The simulation consists of two parts. First part is a stochastic resist modeling for lines and spaces through pitch, exposure dose and focus. Second part is CD-SEM simulation. Both CD and LWR extracted from experimental CD-SEM images were used to train the SEM model. Two types of artifacts were found to be metrology dependent: the first artifact is that a CD-SEM measures CD at various heights across pitch for the same SEM threshold. The second artifact is a misleading CD measurement for trenches not fully developed. By overlapping the CD-SEM simulation with 3D lithography simulation, correlation between CD-SEM metrology and target 3D profile is studied. Finally, a Process Window (PW) analysis based on both experiment and simulation is presented, using the simulated features and SEM images to correct the experimental PW.

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Chao Fang, Chao Fang, Alessandro Vaglio Pret, Alessandro Vaglio Pret, Mark D. Smith, Mark D. Smith, John J. Biafore, John J. Biafore, Stewart A. Robertson, Stewart A. Robertson, Joost Bekaert, Joost Bekaert, "Understanding the impact of CD-SEM artifacts on metrology via experiments and simulations", Proc. SPIE 9424, Metrology, Inspection, and Process Control for Microlithography XXIX, 94242A (19 March 2015); doi: 10.1117/12.2087106; https://doi.org/10.1117/12.2087106

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