Wide-field broadband extreme ultraviolet transmission ptychography using a high-harmonic source

Baksh, Peter; Odstrčil, Michal; Kim, Hyun-Su; Boden, Stuart A.; Frey, Jeremy G.; Brocklesby, W.S.

doi:10.1364/ol.41.001317

Cited by 33 publications

(25 citation statements)

References 19 publications

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“…However, the use of a beamstop often complicates the experimental design and is very time-consuming. Second approach is to stitch different diffraction patterns recorded for various exposure durations, while removing the oversaturated signal 44 . Care must be considered in reading the sensor output, because artefacts (e.g., saturation trail) might occur for oversaturated CCD sensors.…”

Section: Resultsmentioning

confidence: 99%

“…So far, only a few groups have been able to demonstrate ptychographical imaging with tabletop EUV sources, mostly at around 30 nm 43 – 46 and 13 nm 47 , 48 . In an attempt to achieve a 100 μm–wide field of view within a single ePIE reconstruction, a polychromatic EUV beam around 29 nm was employed to provide a sufficient photon flux 44 . A breakthrough has been recently made by Gardner et al .…”

Section: Introductionmentioning

confidence: 99%

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Coherent Tabletop EUV Ptychography of Nanopatterns

Trường

Safaei

Cardin

et al. 2018

Sci Rep

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Coherent diffraction imaging (CDI) or lensless X-ray microscopy has become of great interest for high spatial resolution imaging of, e.g., nanostructures and biological specimens. There is no optics required in between an object and a detector, because the object can be fully recovered from its far-field diffraction pattern with an iterative phase retrieval algorithm. Hence, in principle, a sub-wavelength spatial resolution could be achieved in a high-numerical aperture configuration. With the advances of ultrafast laser technology, high photon flux tabletop Extreme Ultraviolet (EUV) sources based on the high-order harmonic generation (HHG) have become available to small-scale laboratories. In this study, we report on a newly established high photon flux and highly monochromatic 30 nm HHG beamline. Furthermore, we applied ptychography, a scanning CDI version, to probe a nearly periodic nanopattern with the tabletop EUV source. A wide-field view of about 15 × 15 μm was probed with a 2.5 μm−diameter illumination beam at 30 nm. From a set of hundreds of far-field diffraction patterns recorded for different adjacent positions of the object, both the object and the illumination beams were successfully reconstructed with the extended ptychographical iterative engine. By investigating the phase retrieval transfer function, a diffraction-limited resolution of reconstruction of about 32 nm is obtained.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Coherent Tabletop EUV Ptychography of Nanopatterns

Trường

Safaei

Cardin

et al. 2018

Sci Rep

View full text Add to dashboard Cite

show abstract

“…The variable aberration was simulated by the first-order Zernike polynomials resulting in a sinusoidal shift of the diffraction pattern in Fourier space with amplitude of 1 pixel and a period of 100 positions. Similar level of instability can be observed in high-resolution laboratory-based EUV microscopy [27,39] or free electron lasers [40]. The wavefront refinement was performed as it is described in Section 2.3.3.…”

Section: Wavefront Variation Refinementmentioning

confidence: 87%

Iterative least-squares solver for generalized maximum-likelihood ptychography

2018

Self Cite

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Although ptychography does not require a precise knowledge of the illumination wavefront, common implementations rely upon assumptions such as accurate knowledge of the scan positions and constant illumination. Limited validity of these assumptions results in deterioration of the reconstruction quality. We present a generalized ptychography method that optimizes the reconstruction along multiple directions. In our manuscript, we demonstrate that the additional flexibility not only helps to amend imprecisions of the ptychography model in a self-consistent way but additionally leads to faster convergence without a significant increase of the computational cost per iteration.

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“…Sufficient coherence of the illumination, short term illumination stability and sufficient sampling of the measured patterns are also crucial requirements of ptychography 32,33 and in spite of ptychography offers method to deal with these effects 26,27,34,35 , if these conditions are not met, reconstruction quality will be degraded for a given dose. In particular partially coherent illumination may seem to be an easy way to increase the flux and thus to reduce the exposure time needed to reach a target resolution 36,37 . However, low coherence, similarly to setup vibrations or insufficient diffraction sampling, leads to loss of speckle visibility.…”

Section: Scanning Precisionmentioning

confidence: 99%

High resolution 3D imaging of integrated circuits by x-ray ptychography

Odstrčil

Holler

Raabe

et al. 2018

Image Sensing Technologies: Materials, Devices, Systems, and Applications V

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Significant advances in lithography and chip manufacturing in recent years have resulted in new challenges in metrology of electronic microdevices. Manufacturing process for the 10 nm node is already available and in combination with complex three-dimensional structured interconnections, there is a lack of methods for verification that the final products correspond to the original specifications. X-ray ptycho-tomography is a locally nondestructive imaging method that could potentially help to fill the gap between electron microscopy and conventional X-ray tomography. Quantitativeness of ptycho-tomography provides detailed device geometries and corresponding sensitivity to elemental composition through the complex-valued refractive index. In order to tackle the experimental challenges and improve the imaging quality, new computational methods need to be developed for both ptychography and tomography that can account for a wide range of imperfections such as sample drifts, illumination changes or sample changes during the scan. Here, we will mention the most important of them and possible ways how to deal with them.

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Wide-field broadband extreme ultraviolet transmission ptychography using a high-harmonic source

Cited by 33 publications

References 19 publications

Coherent Tabletop EUV Ptychography of Nanopatterns

Coherent Tabletop EUV Ptychography of Nanopatterns

Iterative least-squares solver for generalized maximum-likelihood ptychography

High resolution 3D imaging of integrated circuits by x-ray ptychography

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