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Proceedings Paper

Novel methodology to optimize wafer alignment to enhance 14nm on product overlay
Author(s): Pavan Samudrala; Woong Jae Chung; Lokesh Subramany; Haiyong Gao; Nyan Aung; Seung Chul Oh; Shawn Lee; Erik Delvigne; Blandine Minghetti
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Paper Abstract

With continuous shrink in feature dimensions, overlay tolerance for fabrication of transistors is getting more stringent. Achieving good overlay is extremely critical in getting good yield in HVM environment. It is widely understood that good alignment during exposure is critical for better on product overlay [1]. Conventional methods to choose alignment marks on ASML scanners are based on comparing alignment key performance indicators (KPIs) including signal quality, grid repeatability, etc. It is possible that even with good alignment KPIs, OPO is still impacted. In this paper, we propose aspects that need to be monitored to choose proper alignment marks. LIS (Litho In-Sight) alignment, Ideal overlay/APC parameter signatures are used to determine and validate wafer alignment. LIS alignment ‘Target and Profile selection’ analysis enables us to determine best alignment strategy between multiple strategies/marks based on overlay measurements. Analysis includes examining wafer to wafer OPO variation which is key indicator for alignment robustness. Varying overlay parameters within lot would indicate either large process instability or alignment mark signal instability. It is possible that alignment marks depending on their segmentation can be very differently impacted with the process. Ideal overlay/APC signature stability indicates healthy process and wafer alignment. Having similar APC signatures at corresponding layers would mean that there is no major process or alignment issue.

Paper Details

Date Published: 24 March 2017
PDF: 6 pages
Proc. SPIE 10147, Optical Microlithography XXX, 101471U (24 March 2017); doi: 10.1117/12.2258137
Show Author Affiliations
Pavan Samudrala, GLOBALFOUNDRIES Inc. (United States)
Woong Jae Chung, GLOBALFOUNDRIES Inc. (United States)
Lokesh Subramany, GLOBALFOUNDRIES Inc. (United States)
Haiyong Gao, GLOBALFOUNDRIES Inc. (United States)
Nyan Aung, GLOBALFOUNDRIES Inc. (United States)
Seung Chul Oh, ASML (United States)
Shawn Lee, ASML (United States)
Erik Delvigne, ASML (United States)
Blandine Minghetti, ASML (United States)


Published in SPIE Proceedings Vol. 10147:
Optical Microlithography XXX
Andreas Erdmann; Jongwook Kye, Editor(s)

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