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Proceedings Paper

Slope-integrated methodology for OPC model calibration
Author(s): Liang Zhu; Mark Lu; Dion King; Yili Gu; Steve Yang; Gensheng Gao
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Paper Abstract

As the semiconductor industry scales down to 90nm and below, Model-Based OPC has become a standard practice to compensate for optical proximity effects and process variations occurring when printing features below the exposure wavelength. For parametric OPC models, it is assumed that the empirical data are accurate and the model parameter space is sufficiently well sampled. In spite of advanced metrology tools, the measurement uncertainty for 1D small critical dimensions and 2D patterns remains to be a challenge. Traditionally, the weight of SEM measurement points are based on either statistical method such as standard deviations, or engineers' judgment, which is either time consuming or individual-dependent. In this paper, the slope-integrated OPC model calibration methodology is proposed, which takes into account the slope as a weighting indicator. The additional measurement objects per calibration structure are economically feasible, as most metrology tool time is spent on addressing and auto-focusing. When we consider one measurement point with both CD and slope measurements, the slightly increased time is tolerable for FAB, which requires a short turn around time (TAT). By this approach, we can distinguish measurement points with low confidence from those accurate ones. Furthermore, we check the fitting differences among equal-weighted data sheets, empiricalweighted data sheets and slope-weighted data sheets, by using the same variable threshold model form. From the edge placement error (EPE) of fitting results and the overlap between simulated contours and SEM images, it is found that the proposed slope-integrated methodology results in a more accurate and stable model.

Paper Details

Date Published: 21 November 2007
PDF: 8 pages
Proc. SPIE 6827, Quantum Optics, Optical Data Storage, and Advanced Microlithography, 682725 (21 November 2007); doi: 10.1117/12.755663
Show Author Affiliations
Liang Zhu, Shanghai Institute of Microsystem And Information Technology (China)
Graduate School of Chinese Academy of Science (China)
Grace Semiconductor Manufacturing Corp. (China)
Mark Lu, Grace Semiconductor Manufacturing Corp. (China)
Dion King, Grace Semiconductor Manufacturing Corp. (China)
Yili Gu, Grace Semiconductor Manufacturing Corp. (China)
Steve Yang, Grace Semiconductor Manufacturing Corp. (China)
Gensheng Gao, Mentor Graphics Corp. (China)

Published in SPIE Proceedings Vol. 6827:
Quantum Optics, Optical Data Storage, and Advanced Microlithography
Chris A. Mack; Jinfeng Kang; Jun-en Yao; Guangcan Guo; Song-hao Liu; Osamu Hirota; Guofan Jin; Kees A. Schouhamer Immink; Keiji Shono, Editor(s)

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