Lithography

Impact of tool design on defect detection sensitivity in extreme ultraviolet actinic blank inspection

[+] Author Affiliations
Yow-Gwo Wang, Andrew R. Neureuther

University of California, Berkeley, Department of Electrical Engineering and Computer Sciences, Berkeley, California, United States

Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California, United States

Patrick P. Naulleau

Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California, United States

J. Micro/Nanolith. MEMS MOEMS. 16(2), 023502 (May 16, 2017). doi:10.1117/1.JMM.16.2.023502
History: Received March 21, 2017; Accepted April 26, 2017
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Abstract.  We discuss the impact of various tool design perspectives on defect detection sensitivity for dark-field-based extreme ultraviolet (EUV) actinic blank inspection. We consider the impact of pixel size, EUV source type, and photon collection efficiency on critical defect signal-to-noise ratio (SNR) performance. The results show that as the pixel size approaches the target defect image size, defect SNR increases, and that pixel size also determines the dominant noise source in the inspection system. Moreover, the choice of the EUV source affects the optimal numerical aperture (NA) and illumination settings. For plasma-discharged sources, more photons provided by larger partial coherent illumination can improve the defect SNR, while coherent illumination is needed to get a higher defect SNR for synchrotron-based source. In the end, we show that simply increasing the photon collection efficiency by using high-NA optics or increasing the source power cannot always improve the defect SNR. In a speckle-noise dominated situation, larger outer NA includes more noise than defect signal, thus resulting in a lower SNR. The impact of source power also saturates at a certain level as the system becomes speckle-noise limited compared to photon-noise limited.

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© 2017 Society of Photo-Optical Instrumentation Engineers

Citation

Yow-Gwo Wang ; Andrew R. Neureuther and Patrick P. Naulleau
"Impact of tool design on defect detection sensitivity in extreme ultraviolet actinic blank inspection", J. Micro/Nanolith. MEMS MOEMS. 16(2), 023502 (May 16, 2017). ; http://dx.doi.org/10.1117/1.JMM.16.2.023502


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