Toward perfect on-wafer pattern placement: stitched overlay exposure tool characterization

Christopher P. Ausschnitt; Timothy A. Brunner; Nelson M. Felix; Blandine Minghetti

doi:10.1117/12.846847

3 March 2010 Toward perfect on-wafer pattern placement: stitched overlay exposure tool characterization

Christopher P. Ausschnitt, Timothy A. Brunner, Nelson M. Felix, Blandine Minghetti

Proceedings Volume 7640, Optical Microlithography XXIII; 76400U (2010) https://doi.org/10.1117/12.846847
Event: SPIE Advanced Lithography, 2010, San Jose, California, United States

Abstract

Continued lithographic pattern density scaling depends on aggressive overlay error reduction.^1,2 Double patterning processes planned for the 22nm node require overlay tolerances below 5 nm; at which point even sub-nanometer contributions must be considered. In this paper we highlight the need to characterize and control the single-layer matching among the three pattern placement mechanisms intrinsic to step&scan exposure - optical imaging, mask-to- wafer scanning, and field-to-field stepping. Without stable and near-perfect pattern placement on each layer, nanometer-scale layer-to-layer overlay tolerance is not likely to be achieved. Our approach to understanding onwafer pattern placement is based on the well-known technique of stitched field overlay. We analyze dense sampling around the field perimeter to partition the systematic contributors to pattern placement error on representative dry and immersion exposure tools.

Citation Download Citation

Christopher P. Ausschnitt, Timothy A. Brunner, Nelson M. Felix, and Blandine Minghetti "Toward perfect on-wafer pattern placement: stitched overlay exposure tool characterization", Proc. SPIE 7640, Optical Microlithography XXIII, 76400U (3 March 2010); https://doi.org/10.1117/12.846847

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