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Journal of Micro/Nanolithography, MEMS, and MOEMS

Phase-sensitive structured illumination to detect nanosized asymmetries in silicon trenches
Author(s): Ahmad Faridian; Valeriano Ferreras Paz; Karsten Frenner; Giancarlo Pedrini; Arie den Boef; Wolfgang Osten
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Paper Abstract

A metrology approach to detect nanoscale asymmetries in structures on a silicon wafer is being introduced through simulation investigations. The simulations were performed based on a rigorous coupled-wave analysis. A structured spot focused on the wafer with a high-numerical aperture (NA=0.7) has been scanned over the wafer. Having access to the complex amplitude of the wavefront over the field, both the intensity and the phase profile of the spot have been investigated in the far-field image plane. To show the proof of concept, we considered a 10-nm asymmetry that appears in the radius of the bottom roundings of a trench on the wafer. The results have been compared to the case of using a conventional spot and it has been shown that the structured illumination provides more sensitivity to the presence of asymmetry. In both illumination cases, the phase distribution along the spot was shown to be more sensitive to the changes due to the presence of asymmetry in the wafer.

Paper Details

Date Published: 10 April 2015
PDF: 7 pages
J. Micro/Nanolith. 14(2) 021104 doi: 10.1117/1.JMM.14.2.021104
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 14, Issue 2
Show Author Affiliations
Ahmad Faridian, Univ. Stuttgart (Germany)
Valeriano Ferreras Paz, Univ. Stuttgart (Germany)
Karsten Frenner, Univ. Stuttgart (Germany)
Giancarlo Pedrini, Univ. Stuttgart (Germany)
Arie den Boef, ASML Netherlands B.V. (The Netherlands)
Wolfgang Osten, Univ. Stuttgart (Germany)

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