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Proceedings Paper

Exploring the sources of MEEF in contact SRAMs
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Paper Abstract

Optical Proximity Correction (OPC) relies on predictive modeling to achieve consistent wafer results. To that end, understanding all sources of variation is essential to the successful implementation of OPC. This paper focuses on challenging SRAM layouts of contacts to study the sources of wafer variation. A range of shape geometries and contact configurations are studied. Contact shapes are no longer restricted to simple rectangles on the mask, some more complex OPC outputs may include shapes like H's or T's or even more fragmented figures. The result is a large group of parameters that can be measured at both mask and wafer level. The dependence of mask variation on geometry is studied through the statistical distributions of parameter variations. The mask metrology output is expanded from traditional linear dimensional measurements to include area, line edge roughness, corner rounding, and shape-to-shape metrics. Wafer mask error enhancement factor (MEEF) is then calculated for the various contact geometries. This collection of data makes it possible to study variation on many levels and determine the underlying source of wafer variations so that, ultimately, they can be minimized.

Paper Details

Date Published: 30 October 2007
PDF: 9 pages
Proc. SPIE 6730, Photomask Technology 2007, 67302I (30 October 2007); doi: 10.1117/12.746801
Show Author Affiliations
Emily Gallagher, IBM Corp. (United States)
Ian Stobert, IBM Corp. (United States)
Masaru Higuchi, Toppan Electronics Inc. (United States)
Donald Samuels, IBM Corp. (United States)

Published in SPIE Proceedings Vol. 6730:
Photomask Technology 2007
Robert J. Naber; Hiroichi Kawahira, Editor(s)

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