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Proceedings Paper

Opportunities and challenges for optical CD metrology in double patterning process control
Author(s): Daniel C. Wack; John Hench; Leonid Poslavsky; John Fielden; Vera Zhuang; Walter Mieher; Ted Dziura
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Paper Abstract

We review early challenges and opportunities for optical CD metrology (OCD) arising from the potential insertion of double patterning technology (DPT) processes for critical layer semiconductor production. Due to the immaturity of these new processes, simulations are crucial for mapping performance trends and identifying potential metrology gaps. With an analysis methodology similar in spirit to the recent NIST OCD extendability study1, but with aperture and noise models pertinent to current or projected production metrology systems, we use advanced simulation tools to forecast OCD precision performance of key structural parameters (eg., CD, sidewall angle) at litho (ADI) and etch (ACI) steps for a variety of mainstream optical measurement schemes, such as spectroscopic or angle-resolved, to identify strengths and weaknesses of OCD metrology for patterning process control at 32 and 22nm technology nodes. Test case geometries and materials for the simulated periodic metrology targets are derived from published DPT process flows, with ITRS-style scaling rules, as well as rather standard scanner qualification use cases. Consistent with the NIST study, we find encouraging evidence of OCD extendability through 22nm node dense geometries, a surprising and perhaps unexpected result, given the near-absence of published results for the inverse optical scattering problem for periodic structures in the deep sub-wavelength regime.

Paper Details

Date Published: 24 March 2008
PDF: 9 pages
Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69221N (24 March 2008); doi: 10.1117/12.772997
Show Author Affiliations
Daniel C. Wack, KLA-Tencor (United States)
John Hench, KLA-Tencor (United States)
Leonid Poslavsky, KLA-Tencor (United States)
John Fielden, KLA-Tencor (United States)
Vera Zhuang, KLA-Tencor (United States)
Walter Mieher, KLA-Tencor (United States)
Ted Dziura, KLA-Tencor (United States)

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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