Impact of slanted absorber side wall on printability in EUV lithography

Minoru Sugawara; Iwao Nishiyama

doi:10.1117/12.632419

8 November 2005 Impact of slanted absorber side wall on printability in EUV lithography

Minoru Sugawara, Iwao Nishiyama

Proceedings Volume 5992, 25th Annual BACUS Symposium on Photomask Technology; 59923V (2005) https://doi.org/10.1117/12.632419
Event: SPIE Photomask Technology, 2005, Monterey, California, United States

Abstract

In EUV lithography, when off-axis incident light illuminates an absorber pattern on a reflective multilayer substrate, the side wall of the pattern facing the illumination reflects and absorbs the light, and the side wall on the opposite side casts a shadow. These effects reduce the energy used to create a printed image on a wafer, thereby lowering the image contrast. In addition, when an absorber pattern has a vertical taper, the taper complicates the reflection, absorption and shadowing characteristics. This paper reports on an investigation of how a vertically tapered absorber pattern influences those characteristics and printability based on an analysis of diffracted rays. The printability results revealed that the taper introduces a new error source, namely, the CD (critical dimension) difference on wafer between parallel and perpendicular incidences. The allowable CD difference was found to determine the latitude in the side-wall angle. Moreover, it was found that a thinner absorber increases both the allowable CD difference and the latitude in the side-wall angle at the same time.

Citation Download Citation

Minoru Sugawara and Iwao Nishiyama "Impact of slanted absorber side wall on printability in EUV lithography", Proc. SPIE 5992, 25th Annual BACUS Symposium on Photomask Technology, 59923V (8 November 2005); https://doi.org/10.1117/12.632419

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