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Proceedings Paper

A scatterometry based CD metrology solution for advanced nodes, including capability of handling birefringent layers with uniaxial anisotropy
Author(s): Chih-Ming Ke; Jimmy Hu; Willie Wang; Jacky Huang; H. L. Chung; C. R. Liang; Victor Shih; H. H. Liu; H. J. Lee; John Lin; Y. D. Fan; Tony Yen; Noelle Wright; Ruben Alvarez Sanchez; Wim Coene; Marc Noot; Kiwi Yuan; Vivien Wang; Kaustuve Bhattacharyya; Karel van der Mast
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Paper Abstract

A brand new CD metrology technique that can address the need for accuracy, precision and speed in near future lithography is probably one of the most challenging items. CDSEMs have served this need for a long time, however, a change of or an addition to this traditional approach is inevitable as the increase in the need for better precision (tight CDU budget) and speed (driven by the demand for increase in sampling) continues to drive the need for advanced nodes. The success of CD measurement with scatterometry remains in the capability to model the resist grating, such as, CD and shape (side wall angle), as well as the under-lying layers (thickness and material property). Things are relatively easier for the cases with isotropic under-lying layers (that consists of single refractive or absorption indices). However, a real challenge to such a technique becomes evident when one or more of the under-lying layers are anisotropic. In this technical presentation the authors would like to evaluate such CD reconstruction technology, a new scatterometry based platform under development at ASML, which can handle bi-refringent non-patterned layers with uniaxial anisotropy in the underlying stack. In the RCWA code for the bi-refringent case, the elegant formalism of the enhanced transmittance matrix can still be used. In this paper, measurement methods and data will be discussed from several complex production stacks (layers). With inclusion of the bi-refringent modeling, the in-plane and perpendicular n and k values can be treated as floating parameters for the bi-refringent layer, so that very robust CD-reconstruction is achieved with low reconstruction residuals. As a function of position over the wafer, significant variations of the perpendicular n and k values are observed, with a typical radial fingerprint on the wafer, whereas the variations in the in-plane n and k values are seen to be considerably lower.

Paper Details

Date Published: 23 March 2009
PDF: 7 pages
Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72723R (23 March 2009); doi: 10.1117/12.814909
Show Author Affiliations
Chih-Ming Ke, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Jimmy Hu, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Willie Wang, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Jacky Huang, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
H. L. Chung, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
C. R. Liang, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Victor Shih, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
H. H. Liu, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
H. J. Lee, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
John Lin, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Y. D. Fan, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Tony Yen, Taiwan Semiconductor Manufacturing Co. Ltd. (Taiwan)
Noelle Wright, ASML Netherlands B.V. (Netherlands)
Ruben Alvarez Sanchez, ASML Netherlands B.V. (Netherlands)
Wim Coene, ASML Netherlands B.V. (Netherlands)
Marc Noot, ASML Netherlands B.V. (Netherlands)
Kiwi Yuan, ASML Netherlands B.V. (Netherlands)
Vivien Wang, ASML Netherlands B.V. (Netherlands)
Kaustuve Bhattacharyya, ASML Netherlands B.V. (Netherlands)
Karel van der Mast, ASML Netherlands B.V. (Netherlands)


Published in SPIE Proceedings Vol. 7272:
Metrology, Inspection, and Process Control for Microlithography XXIII
John A. Allgair; Christopher J. Raymond, Editor(s)

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