Characterisation of engineered defects in extreme ultraviolet mirror substrates using lab-scale extreme ultraviolet reflection ptychography
Characterisation of engineered defects in extreme ultraviolet mirror substrates using lab-scale extreme ultraviolet reflection ptychography
Ptychography is a lensless imaging technique that is aberration-free and capable of imaging both the amplitude and the phase of radiation reflected or transmitted from an object using iterative algorithms. Working with extreme ultraviolet (EUV) light, ptychography can provide better resolution than conventional optical microscopy and deeper penetration than scanning electron microscope. As a compact lab-scale EUV light sources, high harmonic generation meets the high coherence requirement of ptychography and gives more flexibilities in both budget and experimental time compared to synchrotrons. The ability to measure phase makes reflection-mode ptychography a good choice for characterising both the surface topography and the internal structural changes in EUV multilayer mirrors. This paper describes the use of reflection-mode ptychography with a lab-scale high harmonic generation based EUV light source to perform quantitative measurement of the amplitude and phase reflection from EUV multilayer mirrors with engineered substrate defects. Using EUV light at 29.6 nm from a tabletop high harmonic generation light source, a lateral resolution down to ~88nm and a phase resolution of 0.08 rad (equivalent to topographic height variation of 0.27 nm) are achieved. The effect of surface distortion and roughness on EUV reflectivity is compared to topographic properties of the mirror defects measured using both atomic force microscopy and scanning transmission electron microscopy. Modelling of reflection properties from multilayer mirrors is used to predict the potential of a combination of on-resonance, actinic ptychographic imaging at 13.5 nm and atomic force microscopy for characterising the changes in multilayered structures.
EUV, HHG, Inspection, Multilayer mirror, Ptychography
Lu, Haoyan
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Odstrčil, Michal
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Pooley, Charles
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Biller, Jan
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Mebonia, Mikheil
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He, Guanze
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Praeger, Matthew
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Juschkin, Larissa
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Frey, Jeremy
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Brocklesby, William
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1 July 2023
Lu, Haoyan
c38a2802-437c-4b1a-b639-c784eb76d543
Odstrčil, Michal
fd47ae03-651c-42c3-922e-f209cd9ef0c4
Pooley, Charles
6ceb17a6-c2b3-4b9f-9c71-6c6df77fc018
Biller, Jan
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Mebonia, Mikheil
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He, Guanze
1c748b92-3215-4594-8728-52e828105843
Praeger, Matthew
84575f28-4530-4f89-9355-9c5b6acc6cac
Juschkin, Larissa
5c7e1507-20c3-45a7-826a-82f1e31fd146
Frey, Jeremy
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Brocklesby, William
c53ca2f6-db65-4e19-ad00-eebeb2e6de67
Lu, Haoyan, Odstrčil, Michal, Pooley, Charles, Biller, Jan, Mebonia, Mikheil, He, Guanze, Praeger, Matthew, Juschkin, Larissa, Frey, Jeremy and Brocklesby, William
(2023)
Characterisation of engineered defects in extreme ultraviolet mirror substrates using lab-scale extreme ultraviolet reflection ptychography.
Ultramicroscopy, 249, [113720].
(doi:10.1016/j.ultramic.2023.113720).
Abstract
Ptychography is a lensless imaging technique that is aberration-free and capable of imaging both the amplitude and the phase of radiation reflected or transmitted from an object using iterative algorithms. Working with extreme ultraviolet (EUV) light, ptychography can provide better resolution than conventional optical microscopy and deeper penetration than scanning electron microscope. As a compact lab-scale EUV light sources, high harmonic generation meets the high coherence requirement of ptychography and gives more flexibilities in both budget and experimental time compared to synchrotrons. The ability to measure phase makes reflection-mode ptychography a good choice for characterising both the surface topography and the internal structural changes in EUV multilayer mirrors. This paper describes the use of reflection-mode ptychography with a lab-scale high harmonic generation based EUV light source to perform quantitative measurement of the amplitude and phase reflection from EUV multilayer mirrors with engineered substrate defects. Using EUV light at 29.6 nm from a tabletop high harmonic generation light source, a lateral resolution down to ~88nm and a phase resolution of 0.08 rad (equivalent to topographic height variation of 0.27 nm) are achieved. The effect of surface distortion and roughness on EUV reflectivity is compared to topographic properties of the mirror defects measured using both atomic force microscopy and scanning transmission electron microscopy. Modelling of reflection properties from multilayer mirrors is used to predict the potential of a combination of on-resonance, actinic ptychographic imaging at 13.5 nm and atomic force microscopy for characterising the changes in multilayered structures.
Text
1-s2.0-S0304399123000372-main
- Accepted Manuscript
More information
Accepted/In Press date: 14 March 2023
e-pub ahead of print date: 21 March 2023
Published date: 1 July 2023
Additional Information:
This work builds on the investment and research from the EPSRC Basic Technology, UK grant GR/R87307/01 . H.L. acknowledges Erasmus Mundus Joint Doctorate Programme EXTATIC scholarship from EACEA grant 2012-0033 .
L.J. acknowledges financial support from the Helmholtz Association, Germany for a Helmholtz professorship as part of the Initiative and Network Fund. C.P. acknowledges the EPSRC scholarship.
Keywords:
EUV, HHG, Inspection, Multilayer mirror, Ptychography
Identifiers
Local EPrints ID: 476707
URI: http://eprints.soton.ac.uk/id/eprint/476707
ISSN: 0304-3991
PURE UUID: 6fa2df2b-3907-4e34-a72c-2a394513b125
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Date deposited: 11 May 2023 17:00
Last modified: 17 Mar 2024 03:16
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Contributors
Author:
Haoyan Lu
Author:
Michal Odstrčil
Author:
Charles Pooley
Author:
Jan Biller
Author:
Mikheil Mebonia
Author:
Guanze He
Author:
Larissa Juschkin
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