Publications by Stuart Sherwin
2023
Stuart Sherwin
Modeling, Designing, and Measuring EUV Photomasks PhD Thesis
EECS Department, University of California, Berkeley, 2023.
@phdthesis{Sherwin:EECS-2023-37,
title = {Modeling, Designing, and Measuring EUV Photomasks},
author = {Stuart Sherwin},
url = {http://www2.eecs.berkeley.edu/Pubs/TechRpts/2023/EECS-2023-37.html},
year = {2023},
date = {2023-05-01},
number = {UCB/EECS-2023-37},
school = {EECS Department, University of California, Berkeley},
abstract = {We present a selection of topics relating to modeling, designing, and measuring EUV (Extreme Ultraviolet) photomasks, with implications for high-volume nanofabrication of integrated circuits. These EUV photomasks must be accurately designed, but rigorously modeling large domains is extremely computationally intensive; we introduce an approximate Fresnel Double Scattering model which is 10,000x faster. This approximation can predict
the trend of phase vs pitch, which is critical to designing EUV phase shift masks (PSMs). We
also explore novel mask architectures to improve efficiency and contrast, such as an etched
multilayer PSM (up to 6x throughput but restrictive applicability), aperiodic multilayers
(up to +22% throughput and more general applicability), and multilayers with minimal
propagation distance at certain angles (lower throughput but higher contrast with minimized 3D effects). Finally we explore computational metrology with EUV reflectometry,
scatterometry, and imaging for probing the phase and amplitude response of an EUV mask, with experimental demonstrations at the Advanced Light Source synchrotron. We perform reflectometry experiments on 3 masks with different architectures to infer approximately 25
physical film parameters each. Another reflectometry application to contamination monitoring achieved single-picometer precision for thickness (3σ < 6pm) and sub-degree precision for phase (3σ < 0.2deg). We compare two implementations of phase scatterometry, either applying nonlinear optimization with approximate scattering, or linearizing the rigorous scattering relationship between intensity and phase; linearization is shown to generally be more accurate, but both methods have similar precision. We apply novel software and hardware for phase imaging, using PhaseLift convex phase retrieval, combined with a set of custom Zernike Phase Contrast (ZPC) zone plates. We perform hyperspectral ZPC phase imaging on 3 masks, where we see promising agreement with reflectometry in the trend of phase vs wavelength.},
keywords = {},
pubstate = {published},
tppubtype = {phdthesis}
}
the trend of phase vs pitch, which is critical to designing EUV phase shift masks (PSMs). We
also explore novel mask architectures to improve efficiency and contrast, such as an etched
multilayer PSM (up to 6x throughput but restrictive applicability), aperiodic multilayers
(up to +22% throughput and more general applicability), and multilayers with minimal
propagation distance at certain angles (lower throughput but higher contrast with minimized 3D effects). Finally we explore computational metrology with EUV reflectometry,
scatterometry, and imaging for probing the phase and amplitude response of an EUV mask, with experimental demonstrations at the Advanced Light Source synchrotron. We perform reflectometry experiments on 3 masks with different architectures to infer approximately 25
physical film parameters each. Another reflectometry application to contamination monitoring achieved single-picometer precision for thickness (3σ < 6pm) and sub-degree precision for phase (3σ < 0.2deg). We compare two implementations of phase scatterometry, either applying nonlinear optimization with approximate scattering, or linearizing the rigorous scattering relationship between intensity and phase; linearization is shown to generally be more accurate, but both methods have similar precision. We apply novel software and hardware for phase imaging, using PhaseLift convex phase retrieval, combined with a set of custom Zernike Phase Contrast (ZPC) zone plates. We perform hyperspectral ZPC phase imaging on 3 masks, where we see promising agreement with reflectometry in the trend of phase vs wavelength.
Eric Li; Stuart Sherwin; Gautam Gunjala; Laura Waller
Exceeding the limits of algorithmic self-calibrated aberration recovery in Fourier ptychography Journal Article
In: Opt. Continuum, vol. 2, no. 1, pp. 119–130, 2023.
@article{Li:23,
title = {Exceeding the limits of algorithmic self-calibrated aberration recovery in Fourier ptychography},
author = {Eric Li and Stuart Sherwin and Gautam Gunjala and Laura Waller},
url = {https://opg.optica.org/optcon/abstract.cfm?URI=optcon-2-1-119},
doi = {10.1364/OPTCON.475990},
year = {2023},
date = {2023-01-01},
journal = {Opt. Continuum},
volume = {2},
number = {1},
pages = {119--130},
publisher = {Optica Publishing Group},
abstract = {Fourier ptychographic microscopy is a computational imaging technique that provides quantitative phase information and high resolution over a large field-of-view. Although the technique presents numerous advantages over conventional microscopy, model mismatch due to unknown optical aberrations can significantly limit reconstruction quality. A practical way of correcting for aberrations without additional data capture is through algorithmic self-calibration, in which a pupil recovery step is embedded into the reconstruction algorithm. However, software-only aberration correction is limited in accuracy. Here, we evaluate the merits of implementing a simple, dedicated calibration procedure for applications requiring high accuracy. In simulations, we find that for a target sample reconstruction error, we can image without any aberration corrections only up to a maximum aberration magnitude of $łambda$/40. When we use algorithmic self-calibration, we can tolerate an aberration magnitude up to $łambda$/10 and with our proposed diffuser calibration technique, this working range is extended further to $łambda$/3. Hence, one can trade off complexity for accuracy by using a separate calibration process, which is particularly useful for larger aberrations.},
keywords = {},
pubstate = {published},
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}
2021
Stuart Sherwin; Isvar Cordova; Ryan Miyakawa; Markus Benk; Laura Waller; Andrew Neureuther; Patrick Naulleau
Picometer sensitivity metrology for EUV absorber phase Journal Article
In: Journal of Micro/Nanopatterning, Materials, and Metrology, vol. 20, no. 3, pp. 1 – 19, 2021.
@article{10.1117/1.JMM.20.3.031011,
title = {Picometer sensitivity metrology for EUV absorber phase},
author = {Stuart Sherwin and Isvar Cordova and Ryan Miyakawa and Markus Benk and Laura Waller and Andrew Neureuther and Patrick Naulleau},
url = {https://doi.org/10.1117/1.JMM.20.3.031011},
doi = {10.1117/1.JMM.20.3.031011},
year = {2021},
date = {2021-01-01},
journal = {Journal of Micro/Nanopatterning, Materials, and Metrology},
volume = {20},
number = {3},
pages = {1 -- 19},
publisher = {SPIE},
keywords = {},
pubstate = {published},
tppubtype = {article}
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Stuart Sherwin; Isvar A Cordova; Ryan H Miyakawa; Markus P Benk; Laura Waller; Andrew R Neureuther; Patrick Naulleau
Picometer sensitivity metrology for EUV absorber phase Journal Article
In: Journal of Micro/Nanopatterning, Materials, and Metrology, vol. 20, no. 3, pp. 1 – 19, 2021.
@article{10.1117/1.JMM.20.3.031011b,
title = {Picometer sensitivity metrology for EUV absorber phase},
author = {Stuart Sherwin and Isvar A Cordova and Ryan H Miyakawa and Markus P Benk and Laura Waller and Andrew R Neureuther and Patrick Naulleau},
url = {https://doi.org/10.1117/1.JMM.20.3.031011},
doi = {10.1117/1.JMM.20.3.031011},
year = {2021},
date = {2021-01-01},
journal = {Journal of Micro/Nanopatterning, Materials, and Metrology},
volume = {20},
number = {3},
pages = {1 -- 19},
publisher = {SPIE},
keywords = {},
pubstate = {published},
tppubtype = {article}
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2020
Gautam Gunjala; Antoine Wojdyla; Stuart Sherwin; Aamod Shanker; Markus P. Benk; Kenneth A. Goldberg; Patrick P. Naulleau; Laura Waller
Extreme ultraviolet microscope characterization using photomask surface roughness Journal Article
In: Scientific Reports, vol. 10, no. 1, pp. 11673, 2020.
@article{gunjala2020extreme,
title = {Extreme ultraviolet microscope characterization using photomask surface roughness },
author = {Gautam Gunjala and Antoine Wojdyla and Stuart Sherwin and Aamod Shanker and Markus P. Benk and Kenneth A. Goldberg and Patrick P. Naulleau and Laura Waller },
url = {https://doi.org/10.1038/s41598-020-68588-w},
doi = {10.1038/s41598-020-68588-w},
year = {2020},
date = {2020-07-15},
journal = {Scientific Reports},
volume = {10},
number = {1},
pages = {11673},
keywords = {},
pubstate = {published},
tppubtype = {article}
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Stuart Sherwin; Isvar Cordova; Ryan Miyakawa; Laura Waller; Andrew Neureuther; Patrick Naulleau
Quantitative phase retrieval for EUV photomasks Inproceedings
In: Felix, Nelson M; Lio, Anna (Ed.): Extreme Ultraviolet (EUV) Lithography XI, pp. 234 – 243, International Society for Optics and Photonics SPIE, 2020.
@inproceedings{10.1117/12.2552967,
title = {Quantitative phase retrieval for EUV photomasks},
author = {Stuart Sherwin and Isvar Cordova and Ryan Miyakawa and Laura Waller and Andrew Neureuther and Patrick Naulleau},
editor = {Nelson M Felix and Anna Lio},
url = {https://doi.org/10.1117/12.2552967},
doi = {10.1117/12.2552967},
year = {2020},
date = {2020-03-23},
booktitle = {Extreme Ultraviolet (EUV) Lithography XI},
volume = {11323},
pages = {234 -- 243},
publisher = {SPIE},
organization = {International Society for Optics and Photonics},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
2019
Stuart Sherwin; Isvar Cordova; Laura Waller; Andrew R Neureuther; Patrick P Naulleau
Measuring the Phase of EUV Photomasks Inproceedings
In: International Conference on Extreme Ultraviolet Lithography 2019, pp. 111471F, International Society for Optics and Photonics 2019.
@inproceedings{sherwin2019measuring,
title = {Measuring the Phase of EUV Photomasks},
author = { Stuart Sherwin and Isvar Cordova and Laura Waller and Andrew R Neureuther and Patrick P Naulleau},
url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11147/111471F/Measuring-the-Phase-of-EUV-Photomasks/10.1117/12.2538107.full},
year = {2019},
date = {2019-11-11},
booktitle = {International Conference on Extreme Ultraviolet Lithography 2019},
volume = {11147},
pages = {111471F},
organization = {International Society for Optics and Photonics},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Stuart Sherwin; Laura Waller; Andrew R Neureuther; Patrick P Naulleau
Advanced multilayer mirror design to mitigate EUV shadowing Inproceedings
In: Extreme Ultraviolet (EUV) Lithography X, pp. 1095715, International Society for Optics and Photonics 2019.
@inproceedings{sherwin2019advanced,
title = {Advanced multilayer mirror design to mitigate EUV shadowing},
author = { Stuart Sherwin and Laura Waller and Andrew R Neureuther and Patrick P Naulleau},
url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10957/1095715/Advanced-multilayer-mirror-design-to-mitigate-EUV-shadowing/10.1117/12.2515095.full},
year = {2019},
date = {2019-03-26},
booktitle = {Extreme Ultraviolet (EUV) Lithography X},
volume = {10957},
pages = {1095715},
organization = {International Society for Optics and Photonics},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
2018
Stuart Sherwin; Andrew Neureuther; Patrick Naulleau
EUV mask characterization with actinic scatterometry Inproceedings
In: Ronse, Kurt G; Hendrickx, Eric; Naulleau, Patrick P; Gargini, Paolo A; Itani, Toshiro (Ed.): International Conference on Extreme Ultraviolet Lithography 2018, pp. 122 – 135, International Society for Optics and Photonics SPIE, 2018.
@inproceedings{10.1117/12.2501970,
title = {EUV mask characterization with actinic scatterometry},
author = {Stuart Sherwin and Andrew Neureuther and Patrick Naulleau},
editor = {Kurt G Ronse and Eric Hendrickx and Patrick P Naulleau and Paolo A Gargini and Toshiro Itani},
url = {https://doi.org/10.1117/12.2501970},
doi = {10.1117/12.2501970},
year = {2018},
date = {2018-10-03},
booktitle = {International Conference on Extreme Ultraviolet Lithography 2018},
volume = {10809},
pages = {122 -- 135},
publisher = {SPIE},
organization = {International Society for Optics and Photonics},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Gautam Gunjala; Stuart Sherwin; Aamod Shanker; Laura Waller
Aberration recovery by imaging a weak diffuser Journal Article
In: Optics express, vol. 26, no. 16, pp. 21054–21068, 2018.
@article{gunjala2018aberration,
title = {Aberration recovery by imaging a weak diffuser},
author = { Gautam Gunjala and Stuart Sherwin and Aamod Shanker and Laura Waller},
url = {https://doi.org/10.1364/OE.26.021054},
doi = {10.1364/OE.26.021054},
year = {2018},
date = {2018-08-06},
journal = {Optics express},
volume = {26},
number = {16},
pages = {21054--21068},
publisher = {Optical Society of America},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Gautam Gunjala; Antoine Wojdyla; Aamod Shanker; Stuart Sherwin; Markus P Benk; Kenneth A Goldberg; Patrick P Naulleau; Laura Waller
Field-varying aberration recovery in EUV microscopy using mask roughness Inproceedings
In: Computational Optical Sensing and Imaging, pp. CW2E–2, Optical Society of America 2018.
@inproceedings{gunjala2018field,
title = {Field-varying aberration recovery in EUV microscopy using mask roughness},
author = { Gautam Gunjala and Antoine Wojdyla and Aamod Shanker and Stuart Sherwin and Markus P Benk and Kenneth A Goldberg and Patrick P Naulleau and Laura Waller},
url = {https://www.osapublishing.org/abstract.cfm?uri=COSI-2018-CW2E.2},
year = {2018},
date = {2018-06-25},
booktitle = {Computational Optical Sensing and Imaging},
pages = {CW2E--2},
organization = {Optical Society of America},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Stuart Sherwin; Andrew Neureuther; Patrick Naulleau
Actinic EUV scatterometry for parametric mask quantification Inproceedings
In: Goldberg, Kenneth A (Ed.): Extreme Ultraviolet (EUV) Lithography IX, pp. 323 – 334, International Society for Optics and Photonics SPIE, 2018.
@inproceedings{10.1117/12.2299271,
title = {Actinic EUV scatterometry for parametric mask quantification},
author = {Stuart Sherwin and Andrew Neureuther and Patrick Naulleau},
editor = {Kenneth A Goldberg},
url = {https://doi.org/10.1117/12.2299271},
doi = {10.1117/12.2299271},
year = {2018},
date = {2018-03-19},
booktitle = {Extreme Ultraviolet (EUV) Lithography IX},
volume = {10583},
pages = {323 -- 334},
publisher = {SPIE},
organization = {International Society for Optics and Photonics},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
2017
Stuart Sherwin; Andrew Neureuther; Patrick Naulleau
Modeling high-efficiency extreme ultraviolet etched multilayer phase-shift masks Journal Article
In: Journal of Micro/Nanolithography, MEMS, and MOEMS, vol. 16, no. 4, pp. 1 – 15, 2017.
@article{10.1117/1.JMM.16.4.041012,
title = {Modeling high-efficiency extreme ultraviolet etched multilayer phase-shift masks},
author = {Stuart Sherwin and Andrew Neureuther and Patrick Naulleau},
url = {https://doi.org/10.1117/1.JMM.16.4.041012},
doi = {10.1117/1.JMM.16.4.041012},
year = {2017},
date = {2017-12-09},
journal = {Journal of Micro/Nanolithography, MEMS, and MOEMS},
volume = {16},
number = {4},
pages = {1 -- 15},
publisher = {SPIE},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Stuart Sherwin; Thomas V Pistor; Andrew Neureuther; Patrick Naulleau
Rigorous 3D electromagnetic simulation of ultrahigh efficiency EUV contact-hole printing with chromeless phase shift mask Inproceedings
In: Panning, Eric M (Ed.): Extreme Ultraviolet (EUV) Lithography VIII, pp. 232 – 240, International Society for Optics and Photonics SPIE, 2017.
@inproceedings{10.1117/12.2260412,
title = {Rigorous 3D electromagnetic simulation of ultrahigh efficiency EUV contact-hole printing with chromeless phase shift mask},
author = {Stuart Sherwin and Thomas V Pistor and Andrew Neureuther and Patrick Naulleau},
editor = {Eric M Panning},
url = {https://doi.org/10.1117/12.2260412},
doi = {10.1117/12.2260412},
year = {2017},
date = {2017-03-24},
booktitle = {Extreme Ultraviolet (EUV) Lithography VIII},
volume = {10143},
pages = {232 -- 240},
publisher = {SPIE},
organization = {International Society for Optics and Photonics},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}