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Proceedings Paper

From nightmares to sweet dreams: inspection of aggressive OPC on 14nm reticles (and beyond) using a novel high-NA and low-NA dual method
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Paper Abstract

To prevent catastrophic failures in wafer manufacturing lines from reticle defects, mask manufacturers employ sophisticated reticle inspection systems to examine every shape on every reticle for defects. The predominant inspection systems in use today compare the reticle directly with the design database using high-NA optics (typically 3x higher resolution at the reticle plane than advanced wafer scanners).

High-NA optical inspection with its high signal to noise ratio (SNR) can readily detect small defects before they have lithographic impact, thus ensuring reticle quality. However, when inspecting certain aggressive OPC, high-NA inspection can overload on small OPC defects which do not have lithographic impact and thus, should generally be ignored.

Whereas, inspecting a reticle as imaged in the wafer plane (low-NA in the reticle plane) will generally ignore such small OPC defects; however, the SNR is often too low for certain defect types to provide the needed defect detection sensitivity to ensure reticle quality.

This paper discusses the design and performance of a novel reticle inspection method using high-NA and low-NA dual optical imaging and processing. This method offers the high defect sensitivity of high-NA inspection with the OPC tolerance of low-NA inspection. These two imaging methods are blended together into a seamless inspection mode suitable for aggressive OPC of the 14nm generation and beyond. The test reticles include 14nm logic designs containing aggressive OPC and native defects, as well as a 14 nm test reticle containing relevant programmed defects. Defect lithographic significance is judged using a Zeiss AIMS™ system.

Paper Details

Date Published: 23 October 2015
PDF: 15 pages
Proc. SPIE 9635, Photomask Technology 2015, 963511 (23 October 2015); doi: 10.1117/12.2197729
Show Author Affiliations
Karen D. Badger, GLOBALFOUNDRIES Inc. (United States)
Michael Hibbs, GLOBALFOUNDRIES Inc. (United States)
Kazunori Seki, Toppan Photomasks, Inc. (United States)
William Broadbent, KLA-Tencor Corp. (United States)
Trent Hutchinson, KLA-Tencor Corp. (United States)
Vincent Redding, KLA-Tencor Corp. (United States)

Published in SPIE Proceedings Vol. 9635:
Photomask Technology 2015
Naoya Hayashi, Editor(s)

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