CD-SEM contour-based process monitoring in DRAM production environment

Uwe Kramer; David Jackisch; Robert Wildfeuer; Stefan Fuchs; Franck Jauzion-Graverolle; Gilad Ben-Nahumb; Ovadya Menadeva; Stefano Ventola

doi:10.1117/12.774114

24 March 2008 CD-SEM contour-based process monitoring in DRAM production environment

Uwe Kramer, David Jackisch, Robert Wildfeuer, Stefan Fuchs, Franck Jauzion-Graverolle, Gilad Ben-Nahumb, Ovadya Menadeva, Stefano Ventola

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Proceedings Volume 6922, Metrology, Inspection, and Process Control for Microlithography XXII; 69221C (2008) https://doi.org/10.1117/12.774114
Event: SPIE Advanced Lithography, 2008, San Jose, California, United States

Abstract

As design rules shrink, there is an increase in the complexity. OPC/RET have been facilitating unprecedented yield at k₁ factors, they increase the mask complexity and production cost, and can introduce yield-detracting errors. Currently OPC modeling techniques are based on extensive CD-SEM measurements which are limited to one dimensional structures or specific shape structures e.g. contact holes. As a result the measured information is not representing the whole spatial 2D change in the process. Therefore the most common errors are found in the OPC design itself and in the resulting patterning robustness across the process window. A new methodology for OPC model creation and verification is to extract contours from complex test structures which beside the CD values contain further information about e.g. various proximities. In this work we use 2D contour profiles extracted automatically by the CD-SEM over varying focus and exposure conditions. We will show that the measurement sensitivity and uncertainty of that algorithm through the whole process window fulfills the requirements of the ITRS with respect to CD-SEM metrology tools. This will be done on various test structures normally being used for OPC model generation and OPC stability monitoring. Furthermore a study on systematic influences on the quality of the extracted contours has been started. This study includes the evaluation of various parameters which are considered as possible contributors to the uncertainty of the edge contour extraction. As one of the parameters we identified the pixel size of the SEM images. Furthermore, a new metric for calculating repeatability and reproducibility determination for 2D contour extraction algorithms will be presented. By applying this contour extraction based methodology to different CD-SEM tool generations the influence of SEM beam resolution to the quality of the contours will be evaluated.

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Uwe Kramer, David Jackisch, Robert Wildfeuer, Stefan Fuchs, Franck Jauzion-Graverolle, Gilad Ben-Nahumb, Ovadya Menadeva, and Stefano Ventola "CD-SEM contour-based process monitoring in DRAM production environment", Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69221C (24 March 2008); https://doi.org/10.1117/12.774114

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