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Publications (10 of 73) Show all publications
Akan, R., Parfeniukas, K., Vogt, C., Toprak, M. S. & Vogt, U. (2018). Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructures. RSC Advances, 8(23), 12628-12634
Open this publication in new window or tab >>Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructures
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2018 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 23, p. 12628-12634Article in journal (Refereed) Published
Abstract [en]

Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based X-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HFH2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of ≈0.7 μm min-1, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures. 

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
Keywords
Aspect ratio, Charge injection, Hydrofluoric acid, Nanocatalysts, Nanostructures, Plate metal, Processing, Silica, Silicon, X ray diffraction, Etching solutions, Metal-assisted chemical etching, Processing temperature, Reaction chemistry, Reaction parameters, Silica dissolution, Silicon interface, Silicon nano structures, Etching
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-227483 (URN)10.1039/c8ra01627e (DOI)2-s2.0-85045188242 (Scopus ID)
Funder
Swedish Research Council
Note

Export Date: 9 May 2018; Article; CODEN: RSCAC; Correspondence Address: Vogt, U.; KTH Royal Institute of Technology, Department of Applied Physics, Biomedical and X-ray Physics, Albanova University CenterSweden; email: uvogt@kth.se; Funding details: VR, Vetenskapsrådet; Funding text: This work was supported by the Swedish Research Council. We thank Adem B. Ergul for help with the cross-section images and Jussi Rahomäki for starting with MACE in our group. QC 20180516

Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2018-05-16Bibliographically approved
Seiboth, F., Schropp, A., Scholz, M., Wittwer, F., Roedel, C., Wuensche, M., . . . Schroer, C. G. (2017). Aberration Correction for Hard X-ray Focusing at the Nanoscale. In: Morawe, C Khounsary, AM Goto, S (Ed.), Advances in X-Ray/EUV Optics and Components XII: . Paper presented at Conference on Advances in XRay/ EUV Optics and Components XII held as part of the SPIE Optics + Photonics Symposium, AUG 08-09, 2017, San Diego, CA. SPIE - International Society for Optical Engineering, Article ID UNSP 103860A.
Open this publication in new window or tab >>Aberration Correction for Hard X-ray Focusing at the Nanoscale
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2017 (English)In: Advances in X-Ray/EUV Optics and Components XII / [ed] Morawe, C Khounsary, AM Goto, S, SPIE - International Society for Optical Engineering, 2017, article id UNSP 103860AConference paper, Published paper (Refereed)
Abstract [en]

We developed a corrective phase plate that enables the correction of residual aberration in reflective, diffractive, and refractive X-ray optics. The principle is demonstrated on a stack of beryllium compound refractive lenses with a numerical aperture of 0.49 x 10(-3) at three different synchrotron radiation and x-ray free-electron laser facilities. By introducing this phase plate into the beam path, we were able to correct the spherical aberration of the optical system and improve the Strehl ratio of the optics from 0.29(7) to 0.87(5), creating a diffraction-limited, large aperture, nanofocusing optics that is radiation resistant and very compact.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2017
Series
Proceedings of SPIE, ISSN 0277-786X ; 10386
Keywords
x-ray optics, compound refractive lenses, aberration correction, ptychography, wavefront sensing
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-220504 (URN)10.1117/12.2274030 (DOI)000417334200008 ()2-s2.0-85038942600 (Scopus ID)978-1-5106-1230-3 (ISBN)978-1-5106-1229-7 (ISBN)
Conference
Conference on Advances in XRay/ EUV Optics and Components XII held as part of the SPIE Optics + Photonics Symposium, AUG 08-09, 2017, San Diego, CA
Note

QC 20171222

Available from: 2017-12-22 Created: 2017-12-22 Last updated: 2018-01-31Bibliographically approved
Vogt, U., Parfeniukas, K., Stankevic, T., Kalbfleisch, S., Liebi, M., Matej, Z., . . . Johansson, U. (2017). First x-ray nanoimaging experiments at NanoMAX. In: Lai, B Somogyi, A (Ed.), X-Ray Nanoimaging: Instruments and Methods III 2017. Paper presented at X-Ray Nanoimaging: Instruments and Methods III 2017, San Diego, United States, 7 August 2017 through 8 August 2017. SPIE - International Society for Optical Engineering, 10389, Article ID 103890K.
Open this publication in new window or tab >>First x-ray nanoimaging experiments at NanoMAX
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2017 (English)In: X-Ray Nanoimaging: Instruments and Methods III 2017 / [ed] Lai, B Somogyi, A, SPIE - International Society for Optical Engineering, 2017, Vol. 10389, article id 103890KConference paper (Refereed)
Abstract [en]

NanoMAX is a hard x-ray nanoimaging beamline at the new Swedish synchrotron radiation source MAX IV that became operational in 2016. Being a beamline dedicated to x-ray nanoimaging in both 2D and 3D, NanoMAX is the first to take full advantage of MAX IVs exceptional low emittance and resulting coherent properties. We present results from the first experiments at NanoMAX that took place in December 2016. These did not use the final experimental stations that will become available to users, but a temporary arrangement including zone plate and order-sorting aperture stages and a piezo-driven sample scanner. We used zone plates with outermost zone widths of 100 nm and 30 nm and performed experiments at 8 keV photon energy for x-ray absorption and fluorescence imaging and ptychography. Moreover, we investigated stability and coherence with a Ronchi test method. Despite the rather simple setup, we could demonstrate spatial resolution below 50 nm after only a few hours of beamtime. The results showed that the beamline is working as expected and experiments approaching the 10 nm resolution level or below should be possible in the future.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2017
Series
Proceedings of SPIE, ISSN 0277-786X ; 10389
Keywords
X-ray microscopy, x-ray nanoimaging, x-ray zone plates
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-220505 (URN)10.1117/12.2272960 (DOI)000417335200006 ()2-s2.0-85034272848 (Scopus ID)978-1-5106-1236-5 (ISBN)978-1-5106-1235-8 (ISBN)
Conference
X-Ray Nanoimaging: Instruments and Methods III 2017, San Diego, United States, 7 August 2017 through 8 August 2017
Funder
Swedish Research Council
Note

QC 20171222

Available from: 2017-12-22 Created: 2017-12-22 Last updated: 2018-03-09Bibliographically approved
Parfeniukas, K., Giakoumidis, S., Akan, R. & Vogt, U. (2017). High-aspect ratio zone plate fabrication for hard x-ray nanoimaging. In: Morawe, C Khounsary, AM Goto, S (Ed.), Advances in X-Ray/EUV Optics and Components XII: . Paper presented at Conference on Advances in XRay/ EUV Optics and Components XII held as part of the SPIE Optics + Photonics Symposium, AUG 08-09, 2017, San Diego, CA. SPIE - International Society for Optical Engineering, 10386, Article ID UNSP 103860S.
Open this publication in new window or tab >>High-aspect ratio zone plate fabrication for hard x-ray nanoimaging
2017 (English)In: Advances in X-Ray/EUV Optics and Components XII / [ed] Morawe, C Khounsary, AM Goto, S, SPIE - International Society for Optical Engineering, 2017, Vol. 10386, article id UNSP 103860SConference paper (Refereed)
Abstract [en]

We present our results in fabricating Fresnel zone plate optics for the NanoMAX beamline at the fourth-generation synchrotron radiation facility MAX IV, to be used in the energy range of 6-10 keV. The results and challenges of tungsten nanofabrication are discussed, and an alternative approach using metal-assisted chemical etching (MACE) of silicon is showcased. We successfully manufactured diffraction-limited zone plates in tungsten with 30 nm outermost zone width and an aspect ratio of 21:1. These optics were used for nanoimaging experiments at NanoMAX. However, we found it challenging to further improve resolution and diffraction efficiency using tungsten. High efficiency is desirable to fully utilize the advantage of increased coherence on the optics at MAX IV. Therefore, we started to investigate MACE of silicon for the nanofabrication of high-resolution and high-efficiency zone plates. The first type of structures we propose use the silicon directly as the phase-shifting material. We have achieved 6 mu m deep dense vertical structures with 100 nm linewidth. The second type of optics use iridium as the phase material. The structures in the silicon substrate act as a mold for iridium coating via atomic layer deposition (ALD). A semi-dense pattern is used with line-to-space ratio of 1:3 for a so-called frequency-doubled zone plate. This way, it is possible to produce smaller structures with the tradeoff of the additional ALD step. We have fabricated 45 nm-wide and 3.6 mu m-tall silicon/iridium structures.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2017
Series
Proceedings of SPIE, ISSN 0277-786X ; 10386
Keywords
zone plate, high-aspect ratio, etching, RIE, MACE, tungsten, silicon, gold
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-220503 (URN)10.1117/12.2272695 (DOI)000417334200016 ()2-s2.0-85038958242 (Scopus ID)978-1-5106-1230-3 (ISBN)978-1-5106-1229-7 (ISBN)
Conference
Conference on Advances in XRay/ EUV Optics and Components XII held as part of the SPIE Optics + Photonics Symposium, AUG 08-09, 2017, San Diego, CA
Funder
Swedish Research Council, C0242401Knut and Alice Wallenberg Foundation
Note

QC 20171222

Available from: 2017-12-22 Created: 2017-12-22 Last updated: 2018-03-09Bibliographically approved
Stankevic, T., Engblom, C., Langlois, F., Alves, F., Lestrade, A., Jobert, N., . . . Kubsky, S. (2017). Interferometric characterization of rotation stages for X-ray nanotomography. Review of Scientific Instruments, 88(5), Article ID 053703.
Open this publication in new window or tab >>Interferometric characterization of rotation stages for X-ray nanotomography
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2017 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 88, no 5, article id 053703Article in journal (Refereed) Published
Abstract [en]

The field of three-dimensional multi-modal X-ray nanoimaging relies not only on high-brilliance X-rays but also on high-precision mechanics and position metrology. Currently available state-of-the-art linear and rotary drives can provide 3D position accuracy within tens to hundreds of nm, which is often insufficient for high resolution imaging with nanofocused X-ray beams. Motion errors are especially troublesome in the case of rotation drives and their correction is more complicated and relies on the metrology grade reference objects. Here we present a method which allows the characterisation and correction of the radial and angular errors of the rotary drives without the need for a highly accurate metrology object. The method is based on multi-probe error separation using fiber-laser interferometry and uses a standard cylindrical sample holder as a reference. The obtained runout and shape measurements are then used to perform the position corrections using additional drives. We demonstrate the results of the characterization for a piezo-driven small rotation stage. The error separation allowed us to measure the axis runout to be approximately +/-1.25 mu m, and with active runout compensation this could be reduced down to +/-42 nm.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-210504 (URN)10.1063/1.4983405 (DOI)000402801900036 ()28571450 (PubMedID)2-s2.0-85019598560 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20170704

Available from: 2017-07-04 Created: 2017-07-04 Last updated: 2017-07-04Bibliographically approved
Parfeniukas, K., Rahomäki, J., Giakoumidis, S., Seiboth, F., Wittwer, F., Schroer, C. G. & Vogt, U. (2016). Improved tungsten nanofabrication for hard X-ray zone plates. Microelectronic Engineering, 152, 6-9
Open this publication in new window or tab >>Improved tungsten nanofabrication for hard X-ray zone plates
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2016 (English)In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 152, p. 6-9Article in journal (Refereed) Published
Abstract [en]

We present an improved nanofabrication method of high aspect ratio tungsten structures for use in high efficiency nanofocusing hard X-ray zone plates. A ZEP 7000 electron beam resist layer used for patterning is cured by a second, much larger electron dose after development. The curing step improves pattern transfer fidelity into a chromium hard mask by reactive ion etching using Cl2/O2 chemistry. The pattern can then be transferred into an underlying tungsten layer by another reactive ion etching step using SF6/O2. A 630 nm-thick tungsten zone plate with smallest line width of 30 nm was fabricated using this method and characterized. At 8.2 keV photon energy the device showed an efficiency of 2.2% with a focal spot size at the diffraction limit, measured at Diamond Light Source I-13-1 beamline.

Keywords
High aspect ratio, Reactive ion etching, Tungsten, X-ray diffractive optics, Zone plate
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-180917 (URN)10.1016/j.mee.2015.12.015 (DOI)2-s2.0-84952359520 (Scopus ID)
Note

QC 20160128

Available from: 2016-01-28 Created: 2016-01-25 Last updated: 2018-03-09Bibliographically approved
Selin, M., Fogelqvist, E., Holmberg, A., Guttmann, P., Vogt, U. & Hertz, H. M. (2014). 3D simulation of the image formation in soft x-ray microscopes. Optics Express, 22(25), 30756-30768
Open this publication in new window or tab >>3D simulation of the image formation in soft x-ray microscopes
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2014 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 22, no 25, p. 30756-30768Article in journal (Refereed) Published
Abstract [en]

In water-window soft x-ray microscopy the studied object is typically larger than the depth of focus and the sample illumination is often partially coherent. This blurs out-of-focus features and may introduce considerable fringing. Understanding the influence of these phenomena on the image formation is therefore important when interpreting experimental data. Here we present a wave-propagation model operating in 3D for simulating the image formation of thick objects in partially coherent soft x-ray microscopes. The model is compared with present simulation methods as well as with experiments. The results show that our model predicts the image formation of transmission soft x-ray microscopes more accurately than previous models.

Place, publisher, year, edition, pages
Optical Society of America, 2014
Keywords
Wave propagation, X ray microscopes, 3D simulations, Depth of focus, Out-of-focus, Partially coherent, Propagation modeling, Soft X-ray, Soft x-ray microscopy
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-160068 (URN)10.1364/OE.22.030756 (DOI)000346368800068 ()2-s2.0-84919663855 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20150227

QC 20160324

Available from: 2015-02-27 Created: 2015-02-13 Last updated: 2017-12-04Bibliographically approved
Seiboth, F., Schropp, A., Hoppe, R., Meier, V., Patommel, J., Lee, H. J., . . . Schroer, C. G. (2014). Focusing XFEL SASE pulses by rotationally parabolic refractive x-ray lenses. Paper presented at 22nd International Congress on X-Ray Optics and Microanalysis, ICXOM 2013; Hamburg; Germany; 2 September 2013 through 6 September 2013. Journal of Physics, Conference Series, 499(1), 012004
Open this publication in new window or tab >>Focusing XFEL SASE pulses by rotationally parabolic refractive x-ray lenses
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2014 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 499, no 1, p. 012004-Article in journal (Refereed) Published
Abstract [en]

Using rotationally parabolic refractive x-ray lenses made of beryllium, we focus hard x-ray free-electron laser pulses of the Linac Coherent Light Source (LCLS) down to a spot size in the 100 nm range. We demonstrated efficient nanofocusing and characterized the nanofocused wave field by ptychographic imaging [A. Schropp, et al., Sci. Rep. 3, 1633 (2013)] in the case of monochromatic LCLS pulses produced by a crystal monochromator that decreases the LCLS bandwidth down to ΔE/E 1.4 · 10-4. The full spectrum of LCLS pulses generated by self-amplified spontaneous emission (SASE), however, fluctuates and has a typical bandwidth of a few per mille (ΔE/E 2 · 10-3). Due to the dispersion in the lens material, a polychromatic nanobeam generated by refractive x-ray lenses is affected by chromatic aberration. After reviewing the chromaticity of refractive x-ray lenses, we discuss the influence of increased bandwidth on the quality of a nanofocused SASE pulse.

National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-145481 (URN)10.1088/1742-6596/499/1/012004 (DOI)000338041300004 ()2-s2.0-84899584839 (Scopus ID)
Conference
22nd International Congress on X-Ray Optics and Microanalysis, ICXOM 2013; Hamburg; Germany; 2 September 2013 through 6 September 2013
Note

QC 20140522

Available from: 2014-05-22 Created: 2014-05-21 Last updated: 2017-12-05Bibliographically approved
Uhlén, F., Nilsson, D., Rahomäki, J., Belova, L., Schroer, C. G., Seiboth, F., . . . Vogt, U. (2014). Nanofabrication of tungsten zone plates with integrated platinum central stop for hard X-ray applications. Microelectronic Engineering, 116, 40-43
Open this publication in new window or tab >>Nanofabrication of tungsten zone plates with integrated platinum central stop for hard X-ray applications
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2014 (English)In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 116, p. 40-43Article in journal (Refereed) Published
Abstract [en]

We present a nanofabrication process for producing tungsten zone plates used in hard X-ray applications including a method of integrating a high-energy absorbing central stop with the optic. Tungsten zone plates are structured with electron-beam lithography and subsequent reactive ion etching. The central stop originates from a platinum wire. It is cut to dimension by focused ion beam etching, and afterwards attached to the zone plate center using ion beam induced deposition of platinum. A zone plate with integrated central stop will simplify alignment in hard X-ray scanning microscope arrangements where the 0th order light must be eliminated. The focusing performance of the zone plate device was investigated by scanning coherent diffraction imaging (ptychography) at 8 keV photon energy. We could demonstrate a diffraction-limited focus size of 53 nm diameter full-width-at-half-maximum. Tungsten zone plates with integrated central stops show promising results for use in hard X-ray microscopes at high-brightness facilities.

Keywords
Hard X-ray microscopy, Platinum, Ptychography, Tungsten, X-ray diffractive optics, Zone plates
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-137224 (URN)10.1016/j.mee.2013.10.011 (DOI)000331161300008 ()2-s2.0-84892374286 (Scopus ID)
Funder
Swedish Foundation for Strategic Research Swedish Research CouncilEU, FP7, Seventh Framework Programme, 226716
Note

QC 20140228

Available from: 2013-12-12 Created: 2013-12-12 Last updated: 2017-12-06Bibliographically approved
Uhlén, F., Rahomäki, J., Nilsson, D., Seiboth, F., Sanz, C., Wagner, U., . . . Vogt, U. (2014). Ronchi test for characterization of X-ray nanofocusing optics and beamlines. Journal of Synchrotron Radiation, 21, 1105-1109
Open this publication in new window or tab >>Ronchi test for characterization of X-ray nanofocusing optics and beamlines
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2014 (English)In: Journal of Synchrotron Radiation, ISSN 0909-0495, E-ISSN 1600-5775, Vol. 21, p. 1105-1109Article in journal (Refereed) Published
Abstract [en]

A Ronchi interferometer for hard X-rays is reported in order to characterize the performance of the nanofocusing optics as well as the beamline stability. Characteristic interference fringes yield qualitative data on present aberrations in the optics. Moreover, the visibility of the fringes on the detector gives information on the degree of spatial coherence in the beamline. This enables the possibility to detect sources of instabilities in the beamline like vibrations of components or temperature drift. Examples are shown for two different nanofocusing hard X-ray optics: a compound refractive lens and a zone plate.

Keywords
zone plate, compound refractive lens, Ronchi interferometer
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-153856 (URN)10.1107/S160057751401323X (DOI)000341687000025 ()
Funder
Knut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research
Note

QC 20141010

Available from: 2014-10-10 Created: 2014-10-09 Last updated: 2017-12-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4394-0591

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