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Proceedings Paper

Mechanistic model of line edge roughness
Author(s): Mark D. Smith
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Paper Abstract

Physically-based photoresist models, such as those in PROLITH, have been very successful in describing photolithography from a continuum standpoint. These models allow engineers to accurately predict the final resist CD on the wafer and to analyze process robustness, such as calculation of focus-exposure process windows. However, as feature sizes continue to shrink, we are beginning to see yield-limiting phenomena that are due to the molecular nature of photoresist materials. One example of this is line-edge roughness (LER). LER is believed to be due to fluctuations during the exposure process (shot noise) and post-exposure bake (thermal diffusion and reaction). We present a model that explicitly takes into account the molecular nature of the photoresist during the exposure and post-exposure bake processes. We do this by writing a master equation that describes the probability that acid molecules are generated during exposure, and then describes the evolution of the acid, quencher, and blocking-group probability distributions during the bake process. We show how all the parameters in this model can be simply derived from the parameters in a calibrated PROLITH continuum model. Finally, we demonstrate prediction of LER from an accurately tuned PROLITH continuum model and compare the LER predictions with experimental results.

Paper Details

Date Published: 29 March 2006
PDF: 11 pages
Proc. SPIE 6153, Advances in Resist Technology and Processing XXIII, 61530X (29 March 2006); doi: 10.1117/12.659627
Show Author Affiliations
Mark D. Smith, KLA-Tencor Corp. (United States)

Published in SPIE Proceedings Vol. 6153:
Advances in Resist Technology and Processing XXIII
Qinghuang Lin, Editor(s)

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