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Proceedings Paper

Lithography overlay control improvement using patterned wafer geometry for sub-22nm technology nodes
Author(s): Joel Peterson; Gary Rusk; Sathish Veeraraghavan; Kevin Huang; Telly Koffas; Peter Kimani; Jaydeep Sinha
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Paper Abstract

The semiconductor industry continues to push the limits of immersion lithography through multiple patterning techniques for printing features with critical dimension 20 nm and below. As a result overlay has become one of the critical lithography control parameters impacting device performance and has a stringent budget for yielding at smaller half pitch nodes. Overlay has several sources of errors related to scanner, lens, mask, and wafer. Lithographers have developed both linear and higher order field and wafer models to successfully compensate for the static fingerprints from different sources of error. After the static modeled portion of the fingerprint is removed, the remaining overlay error can be characterized as unstable modeled error or un-modeled error, commonly called uncorrectable residual error. This paper explores the fundamental relationship of overlay to wafer geometry through mechanisms of process-induced contributions to the wafer overlay, categorized as plastic and elastic wafer deformation. Correlation of overlay to local features such as slip lines is proven experimentally. The paper describes methodologies and geometry-induced overlay metrics for the application of wafer geometry to perform overlay feedback and feed forward applications. Feedback applications allow for process development and controlling semiconductor processes through in-line monitoring of wafers. Feed forward applications could include geometrybased corrections to the scanner for compensating non-static wafer geometry related overlay errors, and grouping wafers based on higher-order geometry.

Paper Details

Date Published: 19 March 2015
PDF: 11 pages
Proc. SPIE 9424, Metrology, Inspection, and Process Control for Microlithography XXIX, 94240N (19 March 2015); doi: 10.1117/12.2086525
Show Author Affiliations
Joel Peterson, Micron Technology, Inc. (United States)
Gary Rusk, Micron Technology, Inc. (United States)
Sathish Veeraraghavan, KLA-Tencor Corp. (United States)
Kevin Huang, KLA-Tencor Corp. (United States)
Telly Koffas, KLA-Tencor Corp. (United States)
Peter Kimani, KLA-Tencor Corp. (United States)
Jaydeep Sinha, KLA-Tencor Corp. (United States)

Published in SPIE Proceedings Vol. 9424:
Metrology, Inspection, and Process Control for Microlithography XXIX
Jason P. Cain; Martha I. Sanchez, Editor(s)

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