Mr. Tao Shen Profile

Tao Shen

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Publications (10)

Proceedings Article | 10 April 2024 Presentation + Paper

EUV reflectometry and scatterometry for thin layer and periodic structure characterization

Tao Shen, Iacopo Mochi, Paolo Ansuinelli, Dongmin Jeong, Jinho Ahn, Yasin Ekinci

Proceedings Volume 12955, 129550D (2024) https://doi.org/10.1117/12.3010875

KEYWORDS: Extreme ultraviolet, Reflectometry, Scatterometry, Grazing incidence, Diffraction, Diffraction gratings, Reflectivity, Overlay metrology

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Proceedings Article | 15 August 2023 Presentation + Paper

EUV reflective coherent diffraction imaging system for wafer metrology

Tao Shen, Paolo Ansuinelli, Iacopo Mochi, Young Woo Kang, Jinho Ahn, Yasin Ekinci

Proceedings Volume 12618, 126180N (2023) https://doi.org/10.1117/12.2673832

KEYWORDS: Scatterometry, Reflectometry, Reflectivity, Diffraction gratings, Semiconducting wafers, Coherence imaging, Metrology, Extreme ultraviolet, Diffraction, Imaging systems

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Proceedings Article | 27 April 2023 Presentation + Paper

EUV grazing-incidence lensless imaging wafer metrology

Tao Shen, Paolo Ansuinelli, Iacopo Mochi, Yasin Ekinci

Proceedings Volume 12496, 124960Z (2023) https://doi.org/10.1117/12.2658436

KEYWORDS: Extreme ultraviolet, Diffraction, Semiconducting wafers, Metrology, Scatterometry, Grazing incidence, Diffraction gratings, Reflectometry

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Proceedings Article | 1 December 2022 Presentation + Paper

Reflective grazing incidence EUV nanoscope for wafer metrology

Tao Shen, Yasin Ekinci, Iacopo Mochi

Proceedings Volume 12292, 122920O (2022) https://doi.org/10.1117/12.2641776

KEYWORDS: Metrology, Extreme ultraviolet, Grazing incidence, Diffraction, Semiconducting wafers, Mirrors, Reflectivity, Scatterometry, Microscopes, Reflectometry

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SPIE Journal Paper | 20 September 2022

Photon flux dependent image resolution of reflective ptychographic microscope for extreme ultraviolet actinic mask metrology

Hyun-Su Kim, Ricarda Nebling, Atoosa Dejkameh, Tao Shen, Yasin Ekinci, Iacopo Mochi

JM3, Vol. 21, Issue 03, 034002, (September 2022) https://doi.org/10.1117/12.10.1117/1.JMM.21.3.034002

KEYWORDS: Extreme ultraviolet, Diffraction, Photomasks, Image resolution, Microscopes, Reflectivity, Image quality, Nanoimprint lithography, Sensors, High dynamic range imaging

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Proceedings Article | 26 May 2022 Paper

EUV mask defect material characterization through actinic lensless imaging

Tao Shen, Dimitrios Kazazis, Hyun-Su Kim, Atoosa Dejkameh, Ricarda Nebling, Yasin Ekinci, Iacopo Mochi

Proceedings Volume 12053, 120530H (2022) https://doi.org/10.1117/12.2613337

KEYWORDS: Photomasks, Extreme ultraviolet, Absorption, Inspection, Multilayers, Extreme ultraviolet lithography, Defect detection, Coherence imaging, Material characterization

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Proceedings Article | 12 October 2021 Presentation + Paper

Resolution limit and photon flux dependency in EUV ptychography

H. Kim, R. Nebling, A. Dejkameh, S. Tao, I. Mochi, Y. Ekinci

Proceedings Volume 11855, 1185506 (2021) https://doi.org/10.1117/12.2601246

KEYWORDS: Photomasks, Extreme ultraviolet, Image quality, High dynamic range imaging, Diffraction, Linear filtering, Sensors, Inspection, Stars, Image resolution

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Proceedings Article | 14 September 2021 Presentation + Paper

A priori information in ptychographic image reconstruction for EUV mask metrology

Ricarda Nebling, Iacopo Mochi, Hyun-Su Kim, Atoosa Dejkameh, Tao Shen, Yasin Ekinci

Proceedings Volume 11875, 118750M (2021) https://doi.org/10.1117/12.2600233

KEYWORDS: Reconstruction algorithms, Extreme ultraviolet, Photomasks, Metrology, Inspection, Computer simulations, Diffraction

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Proceedings Article | 12 September 2021 Presentation

Missing frequency recovery through ptychography

Atoosa Dejkameh, Iacopo Mochi, Ricarda Nebling, Hyun-su Kim, Tao Shen, Yasin Ekinci

Proceedings Volume 11875, 118750J (2021) https://doi.org/10.1117/12.2597060

KEYWORDS: Reconstruction algorithms, Sensors, Diffraction, Detection and tracking algorithms, Signal attenuation, Optics manufacturing, Extreme ultraviolet, Coherence imaging, X-rays, X-ray astronomy

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High-resolution imaging at short wavelengths from extreme ultraviolet to hard X-rays has many applications in a plethora of fields from astronomy to biology and semiconductor metrology. Unfortunately, efficient optics for these wavelengths are difficult to manufacture or have limited resolution. For this reason, in the past few years, coherent diffraction imaging (CDI) applications become widely used. In CDI, the object is illuminated by a coherent beam and the diffraction intensity is collected by a 2D pixel detector. In this process, the phase information of the diffracted light is lost. A phase retrieval algorithm is then used to reconstruct the object’s complex amplitude. Ptychography is a scanning version of coherent diffraction imaging and it is based on an iterative reconstruction algorithm that relies on the quality of the recorded diffraction intensity to converge. To obtain diffraction patterns with a high signal-to-noise ratio, a beam stop is used in many ptychography setups to avoid over-saturation and blooming effects on the detector. While using a beam stop in a ptychography setup has become common practice, the limits of affordable data loss due to beam stop have not been systematically investigated. Pixel masking is the conventional method to recover the lost frequencies. In this method, when enforcing the Fourier domain constraint, the invalid pixels are ignored. In the missing data region, the algorithm is allowed to keep the guess from the previous iteration. The illumination conditions of the ptychography experiment play a critical role in the signal recovery procedure. The diffraction pattern on the detector is the convolution of the Fourier transform of the object and the illumination. An illumination with a finite numerical aperture encodes the object information over a larger detector area. This makes the reconstruction algorithm more robust to pixel loss. We provide simulation and experimental results to demonstrate this theory.

Proceedings Article | 12 March 2021 Presentation + Paper

Lensless EUV mask inspection for anamorphic patterns

Iacopo Mochi, Hyun-Su Kim, Atoosa Dejkameh, Ricarda Nebling, Dimitrios Kazazis, Uldis Locans, Tao Shen, Yasin Ekinci

Proceedings Volume 11609, 116090M (2021) https://doi.org/10.1117/12.2584518

KEYWORDS: Photomasks, Inspection, Extreme ultraviolet, Reticles, Reflectivity, Microscopes, Lithography, Light sources, Image restoration, Diffraction

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Showing 5 of 10 publications

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