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Proceedings Paper

A non-uniform SEM contour sampling technique for OPC model calibration
Author(s): T. Shibahara; M. Oikawa; H. Shindo; H. Sugahara; Y. Hojyo
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Paper Abstract

OPC model calibration techniques that use SEM contours are a major reason for the modern day improved fitting efficiency in complex mask design compared to conventional CD-based calibration. However, contour-based calibration has a high computational cost and requires a lot of memory. To overcome this problem, in conventional contour-based calibration, the SEM contour is sampled uniformly at intervals of several nanometers. However, such sparse uniform sampling significantly increases deviations from real CD values, which are measured by CD-SEM. We also have to consider the shape errors of 2D patterns. In general, the calibration of 2D patterns requires higher frequency sampling of the SEM contour than 1D patterns do. To achieve accurate calibration results, and while considering the varied shapes of calibration patterns, it is necessary to set precise sampling intervals of the SEM contour. In response to these problems, we have developed a SEM contour sampling technique in which contours are sampled at a non-uniform rate with arbitrary mask shapes within the allowable sampling error. Experimental results showed that the sampling error rate was decreased to sub-nm when we reduced the number of contour points.

Paper Details

Date Published: 5 April 2012
PDF: 7 pages
Proc. SPIE 8324, Metrology, Inspection, and Process Control for Microlithography XXVI, 83242Q (5 April 2012); doi: 10.1117/12.913957
Show Author Affiliations
T. Shibahara, Hitachi, Ltd. (Japan)
M. Oikawa, Hitachi, Ltd. (Japan)
H. Shindo, Hitachi High-Technologies Corp. (Japan)
H. Sugahara, Hitachi High-Technologies Corp. (Japan)
Y. Hojyo, Hitachi High-Technologies Corp. (Japan)


Published in SPIE Proceedings Vol. 8324:
Metrology, Inspection, and Process Control for Microlithography XXVI
Alexander Starikov, Editor(s)

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