Opportunities and challenges for optical CD metrology in double patterning process control

Daniel C. Wack; John Hench; Leonid Poslavsky; John Fielden; Vera Zhuang; Walter Mieher; Ted Dziura

doi:10.1117/12.772997

24 March 2008 Opportunities and challenges for optical CD metrology in double patterning process control

Daniel C. Wack, John Hench, Leonid Poslavsky, John Fielden, Vera Zhuang, Walter Mieher, Ted Dziura

Proceedings Volume 6922, Metrology, Inspection, and Process Control for Microlithography XXII; 69221N (2008) https://doi.org/10.1117/12.772997
Event: SPIE Advanced Lithography, 2008, San Jose, California, United States

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.

Citation Download Citation

Daniel C. Wack, John Hench, Leonid Poslavsky, John Fielden, Vera Zhuang, Walter Mieher, and Ted Dziura "Opportunities and challenges for optical CD metrology in double patterning process control", Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69221N (24 March 2008); https://doi.org/10.1117/12.772997

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