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Proceedings Paper

CD-SEM contour-based process monitoring in DRAM production environment
Author(s): Uwe Kramer; David Jackisch; Robert Wildfeuer; Stefan Fuchs; Franck Jauzion-Graverolle; Gilad Ben-Nahumb; Ovadya Menadeva; Stefano Ventola
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Paper 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.

Paper Details

Date Published: 24 March 2008
PDF: 12 pages
Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69221C (24 March 2008); doi: 10.1117/12.774114
Show Author Affiliations
Uwe Kramer, Qimonda Dresden GmbH and Co. OHG (Germany)
David Jackisch, Qimonda Dresden GmbH and Co. OHG (Germany)
Robert Wildfeuer, Qimonda Dresden GmbH and Co. OHG (Germany)
Stefan Fuchs, Qimonda Dresden GmbH and Co. OHG (Germany)
Franck Jauzion-Graverolle, Qimonda Dresden GmbH and Co. OHG (Germany)
Gilad Ben-Nahumb, Applied Materials, Inc. (Israel)
Ovadya Menadeva, Applied Materials, Inc. (Israel)
Stefano Ventola, Applied Materials, Inc. (Israel)

Published in SPIE Proceedings Vol. 6922:
Metrology, Inspection, and Process Control for Microlithography XXII
John A. Allgair; Christopher J. Raymond, Editor(s)

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