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Proceedings Paper

Enhancing native defect sensitivity for EUV actinic blank inspection: optimized pupil engineering and photon noise study
Author(s): Yow-Gwo Wang; Andrew Neureuther; Patrick Naulleau
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Paper Abstract

In this paper, we discuss the impact of optimized pupil engineering and photon noise on native defect sensitivity in EUV actinic blank inspection. Native defects include phase-dominated defects, absorber defects, and defects with a combination of phase and absorption behavior. First, we extend the idea of the Zernike phase contrast (ZPC) method and study the impact of optimum phase shift in the pupil plane on native defect sensitivity, showing a 23% signal-to-noise ratio (SNR) enhancement compare to bright field (BF) for a phase defect with 20% absorption. We also describe the possibility to increase target defect SNR on target defect sizes at the price of losing the sensitivity on smaller (non-critical) defects. Moreover, we show the advantage of the optimized phase contrast (OZPC) method over BF EUV actinic blank inspection. A single focus scan from OZPC has better inspection efficiency over BF. Second, we make a detailed comparison between the phase contrast with apodization (AZPC) method and dark field (DF) method based on defect sensitivity in the presence of both photon shot noise and camera noise. Performance is compared for a variety of photon levels, mask roughness conditions, and combinations of defect phase and absorption.

Paper Details

Date Published: 11 April 2016
PDF: 8 pages
Proc. SPIE 9776, Extreme Ultraviolet (EUV) Lithography VII, 97761D (11 April 2016); doi: 10.1117/12.2220277
Show Author Affiliations
Yow-Gwo Wang, Univ. of California, Berkeley (United States)
Lawrence Berkeley National Lab. (United States)
Andrew Neureuther, Univ. of California, Berkeley (United States)
Lawrence Berkeley National Lab. (United States)
Patrick Naulleau, Lawrence Berkeley National Lab. (United States)


Published in SPIE Proceedings Vol. 9776:
Extreme Ultraviolet (EUV) Lithography VII
Eric M. Panning, Editor(s)

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