Measuring line-edge roughness of masks with DUV light

Stan Stokowski; David Alles

doi:10.1117/12.633184

8 November 2005 Measuring line-edge roughness of masks with DUV light

Stan Stokowski, David Alles

Proceedings Volume 5992, 25th Annual BACUS Symposium on Photomask Technology; 59924P (2005) https://doi.org/10.1117/12.633184
Event: SPIE Photomask Technology, 2005, Monterey, California, United States

Abstract

Line edges on masks are not perfectly smooth and straight due to writer shot placement errors and randomness in photo-resist processes. This mask roughness may affect local CD defects and CD non-uniformity on the printed wafer. We are able to measure some aspects of line edge roughness using line-space patterns and DUV light in an inspection tool. Analyzing inspection images can make visible both edge placement errors with periodic character (writer generated) and more-random, higher-spatial frequency variations (photo-resist process generated). Our technique observes relative edge placement errors of <1 nm. For example, on one mask the periodic peak-to-peak writer errors are 4 nm, the random edge noise has a standard deviation of about 1.3 nm, and there are ~7 nm steps in the edge position, about one per 200 micron mask field. These values are affected by the inspection tool lateral resolution and thus are actually higher than these values. However, this method is useful in monitoring mask relative edge quality.

Citation Download Citation

Stan Stokowski and David Alles "Measuring line-edge roughness of masks with DUV light", Proc. SPIE 5992, 25th Annual BACUS Symposium on Photomask Technology, 59924P (8 November 2005); https://doi.org/10.1117/12.633184

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