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Journal of Micro/Nanolithography, MEMS, and MOEMS

Mueller matrix measurement of asymmetric gratings
Author(s): Jie Li; Justin J. Hwu; Yongdong Liu; Silvio Rabello; Zhuan Liu; Jiangtao Hu
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Paper Abstract

Scatterometry has been used extensively for the characterization of critical dimensions (CDs) and detailed sidewall profiles of periodic structures in microelectronics fabrication processes. In most cases devices are designed to be symmetric, although errors could occur during the fabrication process and result in undesired asymmetry. Conventional optical scatterometry techniques have difficulties distinguishing between left and right asymmetries. We investigate the possibility of measuring grating asymmetry with Mueller matrix spectroscopic ellipsometry (MM-SE) for a patterned hard disk sample prepared by a nanoimprint technique. The relief image on the disk sometimes has an asymmetrical sidewall profile, presumably due to the uneven separation of the template from the disk. Cross section SEM reveals that asymmetrical resist lines are typically tilted toward the outer diameter direction. Simulation and experimental data show that certain Mueller matrix elements are proportional to the direction and amplitude of profile asymmetry, providing a direct indication to the sidewall tilting. The tilting parameter can be extracted using rigorous optical critical dimension (OCD) modeling or calibration methods. We demonstrate that this technique has good sensitivity for measuring and distinguishing left and right asymmetry caused by sidewall tilting, and can therefore be used for monitoring processes for which symmetric structures are desired.

Paper Details

Date Published: 1 October 2010
PDF: 8 pages
J. Micro/Nanolith. MEMS MOEMS 9(4) 041305 doi: 10.1117/1.3514708
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 9, Issue 4
Show Author Affiliations
Jie Li, Nanometrics Inc. (United States)
Justin J. Hwu, Seagate Technology LLC (United States)
Yongdong Liu, Nanometrics Inc. (United States)
Silvio Rabello, Nanometrics Inc. (United States)
Zhuan Liu, Nanometrics Inc. (United States)
Jiangtao Hu, Nanometrics Inc. (United States)

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