Abstract:We have investigated the suitability of atomic layer deposition (ALD) for SiO 2 optical coatings and applied it to broadband antireflective multilayers in combination with HfO 2 as the high refractive index material. SiO 2 thin films were successfully grown using tris [dimethylamino]silane (3DMAS), bis [diethylamino]silane (BDEAS) with plasma activated oxygen as precursors, and the AP-LTO 330 precursor with ozone, respectively. The amorphous SiO 2 films show very low optical losses within a spectral range of 200 nm to 1100 nm. Laser calorimetric measurements show absorption losses of 300 nm thick SiO 2 films of about 1.5 parts per million at a wavelength of 1064 nm. The films are optically homogeneous and possess a good scalability of film thickness. The film surface porosity -which correlates to a shift in the transmittance spectra under vacuum and air conditions -has been suppressed by optimized plasma parameters or Al 2 O 3 sealing layers. and TiO 2 multilayers for applications as bandpass filters and antireflection coatings," Appl. Opt. 48(9), 1727-1732 (2009). 7. N. T. Gabriel, S. S. Kim, and J. J. Talghader, "Control of thermal deformation in dielectric mirrors using mechanical design and atomic layer deposition," Opt. Lett. 34(13), 1958-1960 (2009 4675-4685 (2012). 25. K. J. Hughes and J. R. Engstrom, "Nucleation delay in atomic layer deposition on a thin organic layer and the role of reaction thermochemistry," J.

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A significant challenge to the wide utilization of X-ray microscopy lies in the difficulty in fabricating adequate high-resolution optics. To date, electron beam lithography has been the dominant technique for the fabrication of diffractive focusing optics called Fresnel zone plates (FZP), even though this preparation method is usually very complicated and is composed of many fabrication steps. In this work, we demonstrate an alternative method that allows the direct, simple, and fast fabrication of FZPs using focused Ga(+) beam lithography practically, in a single step. This method enabled us to prepare a high-resolution FZP in less than 13 min. The performance of the FZP was evaluated in a scanning transmission soft X-ray microscope where nanostructures as small as sub-29 nm in width were clearly resolved, with an ultimate cutoff resolution of 24.25 nm, demonstrating the highest first-order resolution for any FZP fabricated by the ion beam lithography technique. This rapid and simple fabrication scheme illustrates the capabilities and the potential of direct ion beam lithography (IBL) and is expected to increase the accessibility of high-resolution optics to a wider community of researchers working on soft X-ray and extreme ultraviolet microscopy using synchrotron radiation and advanced laboratory sources.

material is achieved, kinoform lenses exhibit focusing effi ciencies of 100% [ 10 ] and concentrate all the incident light into a single focus. This very desirable property is of crucial importance for many applications such as laboratory based X-ray microscopy where every single photon is important due to limited source brightness. Unfortunately, to date the fabrication of kinoform lenses for X-ray microscopy mainly relies on approximations, which reduce their potential effi ciency. Approximations based on step profi les have been developed including a variety of routes such as optical gray scale lithography, [ 2b,c ] multilevel/multilayer quasi-Kinoforms, [ 11 ] consecutive overlaid e-beam lithographic steps, [ 10 ] direct ion beam writing of steps profi les, [ 12 ] 2D approximations, [ 13 ] and stacking of two binary FZPs. [ 14 ] Recently, progress was made in structuring of continuous linear and circular blazed profi les via combining focused ion beam implantation and reactive ion etching, [ 15 ] and diamond tool based micro-machining [ 16 ] sometimes also in combination with reactive ion etching. [ 17 ] A few attempts toward Fresnel lenses using direct write gray scale ion beam lithography (IBL) were already reported but with rather large feature sizes, small apertures and dedicated mostly to the optical wavelength range, [ 18 ] while infrared applications were also reported. [ 19 ] Overall, the preparation of the fabled circularly symmetric, continuous kinoform 3D surface profi le remains a daunting task especially for X-ray applications and was recently considered impossible with current fabrication methods. [ 14a ] Here, for the fi rst time, we demonstrate a simple and singlestep fabrication strategy for X-ray kinoform lenses approaching the ideal profi le and we show their performance for X-ray microscopy (XRM) supported with imaging and effi ciency measurements in a state of the art X-ray microscope (STXM) located at BESSY II synchrotron radiation facility. [ 20 ] XRM has developed as a powerful analytical tool used in various research fi elds ranging from biology-biochemistry and materials science/engineering to information technology with applications including for instance, imaging of ultracellular structure, [ 21 ] in situ and in operando examination of chemical reactions via spectroscopy and imaging, [ 22 ] and investigation of ultrafast A kinoform lens is a highly effi cient photonic device capable of focusing a wide range of electromagnetic radiation. Unfortunately, its realization without the need of any approximation remained elusive for a very long time. A direct, simple and precise fabrication method was still missing. Here, an effi cient preparation scheme is presented for the fi rst time. Two kinoform lenses made out of polycrystalline gold and nano-crystalline PdSi, are successfully fabricated, thoroughly characterized and tested for their ultimate focusing performances at soft X-ray energies. The fabrication is made possible by means of gray-scale direct-write ion beam lithograph...

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Fresnel Zone Plates (FZP) are to date very successful focusing optics for X-rays. Established methods of fabrication are rather complex and based on electron beam lithography (EBL). Here, we show that ion beam lithography (IBL) may advantageously simplify their preparation. A FZP operable from the extreme UV to the limit of the hard X-ray was prepared and tested from 450 eV to 1500 eV. The trapezoidal profile of the FZP favorably activates its 2 nd order focus. The FZP with an outermost zone width of 100 nm allows the visualization of features down to 61, 31 and 21 nm in the 1 st , 2 nd and 3 rd order focus respectively. Measured efficiencies in the 1 st and 2 nd order of diffraction reach the theoretical predictions. References and links1. D. T. Attwood, Soft X-rays and extreme ultraviolet radiation (Cambridge University Press, 1999). 2. A. Sakdinawat and D. Attwood, "Nanoscale X-ray imaging," Nature Photonics 4, 840-848 (2010). 3. R. Falcone, C. Jacobsen, J. Kirz, S. Marchesini, D. Shapiro, and J. Spence, "New directions in X-ray microscopy," Contemp. Phys. 52, 293-318 (2011). 4. B. Kaulich, P. Thibault, A. Gianoncelli, and M. Kiskinova, "Transmission and emission x-ray microscopy: operation modes, contrast mechanisms and applications," J. (12) in this article (equation (13) and (14)

X-ray microscopy is a successful technique with applications in several key fields. Fresnel zone plates (FZPs) have been the optical elements driving its success, especially in the soft X-ray range. However, focusing of hard X-rays via FZPs remains a challenge. It is demonstrated here, that two multilayer type FZPs, delivered from the same multilayer deposit, focus both hard and soft X-rays with high fidelity. The results prove that these lenses can achieve at least 21 nm half-pitch resolution at 1.2 keV demonstrated by direct imaging, and sub-30 nm FWHM (fullpitch) resolution at 7.9 keV, deduced from autocorrelation analysis. Reported FZPs had more than 10% diffraction efficiency near 1.5 keV. ©2014 Optical Society of AmericaOCIS codes: (340.7460) X-ray microscopy; (340.0340) X-ray optics; (340.6720) Synchrotron radiation; (340.7480) X-rays, soft x-rays, extreme ultraviolet (EUV); (050.1965) Diffractive lenses; (220.4241) Nanostructure fabrication. References and links1. J. Vila-Comamala, Y. Pan, J. J. Lombardo, W. M. Harris, W. K. S. Chiu, C. David, and Y. Wang, "Zonedoubled Fresnel zone plates for high-resolution hard X-ray full-field transmission microscopy," J. Synchrotron Radiat. 19(5), 705-709 (2012). 2. E. Zschech, C. Wyon, C. E. Murray, and G. Schneider, "Devices, materials, and processes for nanoelectronics: characterization with advanced x-ray techniques using lab-based and synchrotron radiation sources," Adv. Eng. Mater. 13(8), 811-836 (2011 Schütz, "Fast spin-wave-mediated magnetic vortex core reversal," Phys. Rev. B 86(13), 134426 (2012). 5. J. Kirz and C. Jacobsen, "The history and future of X-ray microscopy," J. Phys. Conf. Ser. 186, 012001 (2009). 6. P. Kirkpatrick and A. V. Baez, "Formation of optical images by X-Rays," J. Opt. Soc. Am. 38(9), 766-774 (1948 International Journal of Optics 31(4), 403-413 (1984). 46. A. A. Michelson, Studies in Optics (Dover Publications, Incorporated, 1995. 47. G. R. Morrison, "Phase contrast and darkfield imaging in x-ray microscopy," Proc. SPIE 1741, 186-193 (1993).

Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ∼10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD.Viathe use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricatedviathis combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al2O3/Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV.