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EUV-FP+
Fourier ptychography is a computational imaging technique that consists in collecting coherent images with a variety of illumination angles, and recombining the data to reconstruct the complex electric field of the sample in the image plane – that is with high resolution amplitude and quantitative phase information.
We applied this very powerful technique to the most extreme wavelength (13.5 nm – the so-called Extreme UltraViolet regime) in order to achieve extreme resolution (down to 26 nm) by compensating aberrations below state-of-the art manufacturing capabilities and beating the diffraction limit.
The Sharp microscope (credit K. Goldberg)
Optical layout of the Sharp EUV microscopue (credit C. Gu)
The Sharp EUV microscope
at ALS beamline 11.3.2
photograph of a EUV photomask
View of the Sharp EUV micrsocope
We have adapted this technique to the field of EUV lithography, where we use the Sharp EUV microscope at ALS beamline 11.3.2 to collect data on EUV photomask and reconstruct high resolution images of the photomasks, and allow to simulate arbitrary illumination conditions based on real data to study was to increase the yield and the density of transistors during the manufacturing of leading edge microelectronics chips for AI, corresponding roughly to the A5 node (planned for 2035 on the ASML roadmap.)
Image acquisition process – imaging a sample defect with various imaging angle before recombining it
Example of high-resolution, quantitative phase of a defect on a EUV photomask
(left: conventional imaging right: Fourier ptychogr.)
The roughness on these images is caused by substrate variations at the atomic scale (2Å)
We have been collaborating with Laura Waller's Computational Imaging Lab at UC Berkeley, and Chaoying Gu recently expended those demonstration to show that EUV Fourier ptychography could be used to expand the field of view of the EUV microscope (a full field imaging microscople is based on a single zoneplate.)
Selected dream work:
Selected dream work:
Enhanced extreme ultraviolet mask imaging with Fourier ptychographic microscopy,
Chaoying Gu, Markus P. Benk, Antoine Islegen-Wojdyla, Kenneth A. Goldberg, Laura Waller,
J. Micro/Nanopattern. Mater. Metrol. 25(3), 031606 (2026)
doi.org/10.1117/1.JMM.25.3.031606 - submitted draftEnhanced EUV Mask Imaging Using Fourier Ptychographic Microscopy
Chaoying Gu, Antoine Islegen-Wojdyla, Markus Benk, Kenneth A. Goldberg, and Laura Waller
Optical and EUV Nanolithography XXXVIII, Proc. of SPIE Vol. 13424, 134240S (2025)
Extreme ultraviolet microscope characterization using photomask surface roughness
Gautam Gunjala, Antoine Wojdyla, Stuart Sherwin, Aamod Shanker, Markus P. Benk, Kenneth A. Goldberg, Patrick P. Naulleau & Laura Waller
Scientific Reports volume 10, Article number: 11673 (2020)
https://doi.org/10.1038/s41598-020-68588-w
EUV photolithography mask inspection using Fourier ptychography
Antoine Wojdyla, Markus P. Benk, Patrick P. Naulleau, Kenneth A. Goldberg
Proceedings of SPIE Volume 10656 (2018),
https://doi.org/10.1117/12.2307860
Fourier ptychography at short wavelength with a synchrotron-based microscope
Antoine Wojdyla, Markus P. Benk, Kenneth A. Goldberg, Patrick P. Naulleau
Proceedings of SPIE Volume 10669 (2018),
https://doi.org/10.1117/12.2303447
Resources:
Resources:
Github repository: https://github.com/ArianaGu/EUV_FPM
Room to shrink, Berkeley Science Review (2020)
Characterization of EUV Optics using Intrinsic Mask Roughness – ALS News (2020)
Basic to Breakthrough: Pushing the Boundaries of Moore’s Law with Extreme Ultraviolet Lithography (DOE BES, 2026)
Accelerating the future of Microelectronics – Berkeley Lab news (2026)
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