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Proceedings Paper

Diffraction based overlay metrology for alpha-carbon applications
Author(s): Chandra Saru Saravanan; Asher Tan; Prasad Dasari; Gary Goelzer; Nigel Smith; Seouk-Hoon Woo; Jang Ho Shin; Hyun Jae Kang; Ho Chul Kim
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Paper Abstract

Applications that require overlay measurement between layers separated by absorbing interlayer films (such as α- carbon) pose significant challenges for sub-50nm processes. In this paper scatterometry methods are investigated as an alternative to meet these stringent overlay metrology requirements. In this article, a spectroscopic Diffraction Based Overlay (DBO) measurement technique is used where registration errors are extracted from specially designed diffraction targets. DBO measurements are performed on detailed set of wafers with varying α-carbon (ACL) thicknesses. The correlation in overlay values between wafers with varying ACL thicknesses will be discussed. The total measurement uncertainty (TMU) requirements for these layers are discussed and the DBO TMU results from sub-50nm samples are reviewed.

Paper Details

Date Published: 26 March 2008
PDF: 12 pages
Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69222W (26 March 2008); doi: 10.1117/12.775811
Show Author Affiliations
Chandra Saru Saravanan, Nanometrics Inc. (United States)
Asher Tan, Nanometrics Inc. (United States)
Prasad Dasari, Nanometrics Inc. (United States)
Gary Goelzer, Nanometrics Inc. (United States)
Nigel Smith, Nanometrics Inc. (United States)
Seouk-Hoon Woo, Samsung Electronics Co., Ltd. (South Korea)
Jang Ho Shin, Samsung Electronics Co., Ltd. (South Korea)
Hyun Jae Kang, Samsung Electronics Co., Ltd. (South Korea)
Ho Chul Kim, Samsung Electronics Co., Ltd. (South Korea)

Published in SPIE Proceedings Vol. 6922:
Metrology, Inspection, and Process Control for Microlithography XXII
John A. Allgair; Christopher J. Raymond, Editor(s)

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