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Proceedings Paper

Quantitative phase imaging of EUV masks
Author(s): Ryan H. Miyakawa; Stuart Shwerwin; Wenhua Zhu; Markus Benk; Patrick Naulleau
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Paper Abstract

In this paper, we present two methods for directly measuring the effective complex reflectance function of a patterned EUV mask. Obtaining this measurement can provide important insight into a number of key areas in EUV mask development, including obtaining a deeper understanding of mask 3-D effects, and characterizing and quantifying the amplitude and phase generated by attenuated and etched phase shift masks. The first method, Quantitative Zernike Phase Contrast Microscopy (QZPCM), works by modulating the imaging pupil function with several known phase shifts, and obtaining through-focus images of a target area for each pupil setting. The second method, Lateral Shearing Imaging (LSI), works by splitting and interfering two copies of the complex amplitude function in the image plane separated by a distance s. The resulting fringe pattern gives information about the derivative of the complex amplitude in the direction of the shift. We present results from two experiments: the first demonstrates QZPCM at EUV on the Berkeley SHARP microscope, and the second utilizes LSI in an optical prototype using a visible light laser source.

Paper Details

Date Published: 20 April 2020
PDF: 6 pages
Proc. SPIE 11323, Extreme Ultraviolet (EUV) Lithography XI, 113231H (20 April 2020); doi: 10.1117/12.2553133
Show Author Affiliations
Ryan H. Miyakawa, Lawrence Berkeley National Lab. (United States)
Stuart Shwerwin, Lawrence Berkeley National Lab. (United States)
Univ. of California, Berkeley (United States)
Wenhua Zhu, Lawrence Berkeley National Lab. (United States)
Markus Benk, Lawrence Berkeley National Lab. (United States)
Patrick Naulleau, Lawrence Berkeley National Lab. (United States)

Published in SPIE Proceedings Vol. 11323:
Extreme Ultraviolet (EUV) Lithography XI
Nelson M. Felix; Anna Lio, Editor(s)

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