Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects

Microscopes and various forms of interferometers have been used for decades in optical metrology of objects that are typically larger than the wavelength of light λ. Metrology of sub-wavelength objects, however, was deemed impossible due to the diffraction limit. We report the measurement of the phy...

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Main Authors: Rendón-Barraza, Carolina, Chan, Eng Aik, Yuan, Guanghui, Adamo, Giorgio, Pu, Tanchao, Zheludev, Nikolay, I.
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2022
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Online Access:https://hdl.handle.net/10356/154947
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1549472023-02-28T19:27:33Z Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects Rendón-Barraza, Carolina Chan, Eng Aik Yuan, Guanghui Adamo, Giorgio Pu, Tanchao Zheludev, Nikolay, I. School of Physical and Mathematical Sciences Centre for Disruptive Photonic Technologies (CDPT) The Photonics Institute Science::Physics Deep Learning Optical Metrology Microscopes and various forms of interferometers have been used for decades in optical metrology of objects that are typically larger than the wavelength of light λ. Metrology of sub-wavelength objects, however, was deemed impossible due to the diffraction limit. We report the measurement of the physical size of sub-wavelength objects with deeply sub-wavelength accuracy by analyzing the diffraction pattern of coherent light scattered by the objects with deep learning enabled analysis. With a 633 nm laser, we show that the width of sub-wavelength slits in an opaque screen can be measured with an accuracy of ∼λ/130 for a single-shot measurement or ∼λ/260 (i.e., 2.4 nm) when combining measurements of diffraction patterns at different distances from the object, thus challenging the accuracy of scanning electron microscopy and ion beam lithography. In numerical experiments, we show that the technique could reach an accuracy beyond λ/1000. It is suitable for high-rate non-contact measurements of nanometric sizes of randomly positioned objects in smart manufacturing applications with integrated metrology and processing tools. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Published version The authors acknowledge the Singapore Ministry of Education (Grant No. MOE2016-T3-1-006); the Agency for Science, Technology and Research (A∗ STAR), Singapore (Grant No. SERC A1685b0005); and the Engineering and Physical Sciences Research Council UK (Grants No. EP/N00762X/1 and No. EP/M0091221), and the European Research Council (Advanced grant FLEET786851). T.P. acknowledges support from the China Scholarship Council (CSC No. 201804910540). 2022-03-25T06:41:42Z 2022-03-25T06:41:42Z 2021 Journal Article Rendón-Barraza, C., Chan, E. A., Yuan, G., Adamo, G., Pu, T. & Zheludev, N. I. (2021). Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects. APL Photonics, 6(6), 066107-. https://dx.doi.org/10.1063/5.0048139 2378-0967 https://hdl.handle.net/10356/154947 10.1063/5.0048139 2-s2.0-85108678515 6 6 066107 en MOE2016-T3-1-006 SERC A1685b0005 APL Photonics © 2021 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Physics
Deep Learning
Optical Metrology
spellingShingle Science::Physics
Deep Learning
Optical Metrology
Rendón-Barraza, Carolina
Chan, Eng Aik
Yuan, Guanghui
Adamo, Giorgio
Pu, Tanchao
Zheludev, Nikolay, I.
Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects
description Microscopes and various forms of interferometers have been used for decades in optical metrology of objects that are typically larger than the wavelength of light λ. Metrology of sub-wavelength objects, however, was deemed impossible due to the diffraction limit. We report the measurement of the physical size of sub-wavelength objects with deeply sub-wavelength accuracy by analyzing the diffraction pattern of coherent light scattered by the objects with deep learning enabled analysis. With a 633 nm laser, we show that the width of sub-wavelength slits in an opaque screen can be measured with an accuracy of ∼λ/130 for a single-shot measurement or ∼λ/260 (i.e., 2.4 nm) when combining measurements of diffraction patterns at different distances from the object, thus challenging the accuracy of scanning electron microscopy and ion beam lithography. In numerical experiments, we show that the technique could reach an accuracy beyond λ/1000. It is suitable for high-rate non-contact measurements of nanometric sizes of randomly positioned objects in smart manufacturing applications with integrated metrology and processing tools.
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Rendón-Barraza, Carolina
Chan, Eng Aik
Yuan, Guanghui
Adamo, Giorgio
Pu, Tanchao
Zheludev, Nikolay, I.
format Article
author Rendón-Barraza, Carolina
Chan, Eng Aik
Yuan, Guanghui
Adamo, Giorgio
Pu, Tanchao
Zheludev, Nikolay, I.
author_sort Rendón-Barraza, Carolina
title Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects
title_short Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects
title_full Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects
title_fullStr Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects
title_full_unstemmed Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects
title_sort deeply sub-wavelength non-contact optical metrology of sub-wavelength objects
publishDate 2022
url https://hdl.handle.net/10356/154947
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