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Proceedings Paper

SEM image contouring for OPC model calibration and verification
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Paper Abstract

Lithography models for leading-edge OPC and design verification must be calibrated with empirical data, and this data is traditionally collected as a one-dimensional quantification of the features acquired by a CD-SEM. Two-dimensional proximity features such as line-end, bar-to-bar, or bar-to-line are only partially characterized because of the difficulty in transferring the complete information of a SEM image into the OPC model building process. A new method of two-dimensional measurement uses the contouring of large numbers of SEM images acquired within the context of a design based metrology system to drive improvement in the quality of the final calibrated model. Hitachi High-Technologies has continued to develop "full automated EPE measurement and contouring function" based on design layout and detected edges of SEM image. This function can measure edge placement error everywhere in a SEM image and pass the result as a design layout (GDSII) into Mentor Graphics model calibration flow. Classification of the critical design elements using tagging scripts is used to weight the critical contours in the evaluation of model fitness. During process of placement of the detected SEM edges of into the coordinate system of the design, coordinate errors inevitably are introduced because of pattern matching errors. Also, line edge roughness in 2D features introduces noise that is large compared to the model building accuracy requirements of advanced technology nodes. This required the development of contour averaging algorithms. Contours from multiple SEM images are acquired of a feature and averaged before passing into the model calibration. This function has been incorporated into the prototype Calibre Workbench model calibration flow. Based on these methods, experimental data is presented detailing the model accuracy of a 45nm immersion lithography process using traditional 1D calibration only, and a hybrid model calibration using SEM image contours and 1D measurement results. Error sources in the contouring are assessed and reported on including systematic and random variation in the contouring results.

Paper Details

Date Published: 27 March 2007
PDF: 11 pages
Proc. SPIE 6520, Optical Microlithography XX, 652019 (27 March 2007); doi: 10.1117/12.714389
Show Author Affiliations
Cyrus Tabery, Advanced Micro Devices, Inc. (United States)
Hidetoshi Morokuma, Hitachi High-Technologies Corp. (Japan)
Ryoichi Matsuoka, Hitachi High-Technologies Corp. (Japan)
Lorena Page, Hitachi High-Technologies America, Inc. (United States)
George E. Bailey, Mentor Graphics Corp. (United States)
Ir Kusnadi, Mentor Graphics Corp. (United States)
Thuy Do, Mentor Graphics Corp. (United States)

Published in SPIE Proceedings Vol. 6520:
Optical Microlithography XX
Donis G. Flagello, Editor(s)

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