A CD-gap-free contour extraction technique for OPC model calibration

T. Shibahara; T. Minakawa; M. Oikawa; H. Shindo; H. Sugahara; Y. Hojyo

doi:10.1117/12.878583

20 April 2011 A CD-gap-free contour extraction technique for OPC model calibration

T. Shibahara, T. Minakawa, M. Oikawa, H. Shindo, H. Sugahara, Y. Hojyo

Proceedings Volume 7971, Metrology, Inspection, and Process Control for Microlithography XXV; 79710O (2011) https://doi.org/10.1117/12.878583
Event: SPIE Advanced Lithography, 2011, San Jose, California, United States

Abstract

Recently, optical proximity correction model calibration techniques that use SEM contours have enabled possibly significant improvements in complex mask design. However, compared to conventional CD-based calibration, contour-based calibration results in increased errors in 1D features. In fact, our research shows that there is a ~1-nm gap, which we call "CD-gap," between CD measurements directly calculated from a SEM image and CD measurements calculated from SEM contours. To achieve accurate calibration, SEM contours must match the corresponding CD measurements. We have developed a CD-gap-free contour extraction technique in response to this problem. In our technique, a mask edge is classified into shape structures and an optimized SEM contour extraction method is prepared for each shape structure to reduce the CD-gap. Experimental results show that the CD-gap can be decreased to sub-nm, which clearly demonstrates the potential of our proposed technique to play a vital role in the lithography process.

Citation Download Citation

T. Shibahara, T. Minakawa, M. Oikawa, H. Shindo, H. Sugahara, and Y. Hojyo "A CD-gap-free contour extraction technique for OPC model calibration", Proc. SPIE 7971, Metrology, Inspection, and Process Control for Microlithography XXV, 79710O (20 April 2011); https://doi.org/10.1117/12.878583

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