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Title: Optical modeling of Fresnel zoneplate microscopes

Abstract

Defect free masks remain one of the most significant challenges facing the commercialization of extreme ultraviolet (EUV) lithography. Progress on this front requires high-performance wavelength-specific metrology of EUV masks, including high-resolution and aerial-image microscopy performed near the 13.5 nm wavelength. Arguably the most cost-effective and rapid path to proliferating this capability is through the development of Fresnel zoneplate-based microscopes. Given the relative obscurity of such systems, however, modeling tools are not necessarily optimized to deal with them and their imaging properties are poorly understood. Here we present a modeling methodology to analyze zoneplate microscopes based on commercially available optical modeling software and use the technique to investigate the imaging performance of an off-axis EUV microscope design. The modeling predicts that superior performance can be achieved by tilting the zoneplate, making it perpendicular to the chief ray at the center of the field, while designing the zoneplate to explicitly work in that tilted plane. Although the examples presented here are in the realm of EUV mask inspection, the methods described and analysis results are broadly applicable to zoneplate microscopes in general, including full-field soft-x-ray microscopes routinely used in the synchrotron community.

Authors:
; ;
Publication Date:
OSTI Identifier:
22036642
Resource Type:
Journal Article
Journal Name:
Applied Optics
Additional Journal Information:
Journal Volume: 50; Journal Issue: 20; Other Information: (c) 2011 Optical Society of America; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0003-6935
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DEFECTS; DESIGN; EXTREME ULTRAVIOLET RADIATION; FRESNEL REFLECTORS; IMAGES; INSPECTION; MICROSCOPES; MICROSCOPY; PERFORMANCE; RESOLUTION; RESPIRATORS; SIMULATION; SOFT X RADIATION; SYNCHROTRONS; WAVELENGTHS

Citation Formats

Naulleau, Patrick P., Mochi, Iacopo, and Goldberg, Kenneth A. Optical modeling of Fresnel zoneplate microscopes. United States: N. p., 2011. Web. doi:10.1364/AO.50.003678.
Naulleau, Patrick P., Mochi, Iacopo, & Goldberg, Kenneth A. Optical modeling of Fresnel zoneplate microscopes. United States. doi:10.1364/AO.50.003678.
Naulleau, Patrick P., Mochi, Iacopo, and Goldberg, Kenneth A. Sun . "Optical modeling of Fresnel zoneplate microscopes". United States. doi:10.1364/AO.50.003678.
@article{osti_22036642,
title = {Optical modeling of Fresnel zoneplate microscopes},
author = {Naulleau, Patrick P. and Mochi, Iacopo and Goldberg, Kenneth A.},
abstractNote = {Defect free masks remain one of the most significant challenges facing the commercialization of extreme ultraviolet (EUV) lithography. Progress on this front requires high-performance wavelength-specific metrology of EUV masks, including high-resolution and aerial-image microscopy performed near the 13.5 nm wavelength. Arguably the most cost-effective and rapid path to proliferating this capability is through the development of Fresnel zoneplate-based microscopes. Given the relative obscurity of such systems, however, modeling tools are not necessarily optimized to deal with them and their imaging properties are poorly understood. Here we present a modeling methodology to analyze zoneplate microscopes based on commercially available optical modeling software and use the technique to investigate the imaging performance of an off-axis EUV microscope design. The modeling predicts that superior performance can be achieved by tilting the zoneplate, making it perpendicular to the chief ray at the center of the field, while designing the zoneplate to explicitly work in that tilted plane. Although the examples presented here are in the realm of EUV mask inspection, the methods described and analysis results are broadly applicable to zoneplate microscopes in general, including full-field soft-x-ray microscopes routinely used in the synchrotron community.},
doi = {10.1364/AO.50.003678},
journal = {Applied Optics},
issn = {0003-6935},
number = 20,
volume = 50,
place = {United States},
year = {2011},
month = {7}
}