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Proceedings Paper

Interaction of pattern orientation and lens quality on CD and overlay errors
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Paper Abstract

As product error budgets continue to shrink with decreasing ground rule, more attention is being paid to the effects of exposure tool lens aberrations. Interaction of the reticle pattern with the lens can cause both image placement shifts as well as variations of critical dimensions across the exposure field. A particularly subtle effect is the interaction of the reticle pattern orientation with lens aberrations. It can be shown that there is often a large difference in aberration-driven errors for patterns oriented differently relative to the lens axis. This paper develops the physical model behind this phenomenon as a function of pattern aspect ratio and orientation. Specific examines are given in reference to line width control and overlay for typical DRAM patterns, using both simulation and experimental dat. In addition, optimization schemes for pattern orientation are explored, as well as implications for practical implementation on exposure tools .We also show that pattern orientation can be optimized on a level-by- level basis to provide great benefit in CD and overlay error performance.

Paper Details

Date Published: 5 July 2000
PDF: 11 pages
Proc. SPIE 4000, Optical Microlithography XIII, (5 July 2000); doi: 10.1117/12.389020
Show Author Affiliations
Scott J. Bukofsky, IBM Microelectronics Div. (United States)
Christopher J. Progler, IBM Microelectronics Div. (United States)

Published in SPIE Proceedings Vol. 4000:
Optical Microlithography XIII
Christopher J. Progler, Editor(s)

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