End of thresholds: subwavelength optical linewidth measurement using the flux-area technique

Peter Fiekowsky

doi:10.1117/12.392075

19 July 2000 End of thresholds: subwavelength optical linewidth measurement using the flux-area technique

Peter Fiekowsky

Proceedings Volume 4066, Photomask and Next-Generation Lithography Mask Technology VII; (2000) https://doi.org/10.1117/12.392075
Event: Photomask and Next Generation Lithography Mask Technology VII, 2000, Kanagawa, Japan

Abstract

The patented Flux-Area technique of metrology with optical images has been proven to provide accurately and repeatable measurements of defect sizes as small as 0.08 (mu) , and is in use in 12 leading edge mask shops and wafer fabs around the world. This paper describes the extension of this technique for linewidth measurement and the result of test on photomasks, using lines as narrow as 0.25 micrometers . Linewidths were measured with SEM and optical images analyzed with the Flux-Area technique. Results show that the new technique provides linear measurements on even the smallest lines, using visible as well as UV illumination. This technique promises to allow mask makers to continue measuring their masks optically, even as linewidths shrink much smaller than the optical wavelengths used in the measurement. Further, this technique allows older visible light system to be used for measuring even DUV masks. Finally, this technique does not require thresholds: it only requires an image and that the optical magnification be known. The technique simply measures the amount of light absorbed by a feature, the fundamental optical quality of any photomask feature.

Citation Download Citation

Peter Fiekowsky "End of thresholds: subwavelength optical linewidth measurement using the flux-area technique", Proc. SPIE 4066, Photomask and Next-Generation Lithography Mask Technology VII, (19 July 2000); https://doi.org/10.1117/12.392075

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