Design of grazing-incidence multilayer supermirrors for hard-x-ray reflectors

Joensen, Karsten Dan; Voutov, Peter; Szentgyorgyi, Andrew; Roll, John; Gorenstein, P.; Høghøj, Peter; Christensen, Finn Erland

doi:10.1364/ao.34.007935

Cited by 131 publications

(60 citation statements)

References 15 publications

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“…33 As can be seen from Fig. 2, the Si layers ͑light bands͒ are amorphous, as are the W layers ͑dark bands͒ in all but the top three bilayers (dϾ8.8 nm) where lattice fringes from individual W crystallites are visible.…”

Section: Shown Inmentioning

confidence: 89%

Growth, structure, and performance of depth-graded W/Si multilayers for hard x-ray optics

Windt

Christensen

Craig

et al. 2000

Journal of Applied Physics

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We describe the development of depth-graded W/Si multilayer films prepared by magnetron sputtering for use as broad-band reflective coatings for hard x-ray optics. We have used specular and nonspecular x-ray reflectance analysis to characterize the interface imperfections in both periodic and depth-graded W/Si multilayer structures, and high-resolution transmission electron microscopy ͑TEM͒ and selected area electron diffraction ͑SAED͒ to characterize the interface structure and layer morphology as a function of depth in an optimized depth-graded multilayer. From x-ray analysis we find interface widths in the range ϭ0.275-0.35 nm for films deposited at low argon pressure ͑with a slight increase in interface width for multilayers having periods greater than ϳ20 nm, possibly due to the transition from amorphous to polycrystalline metal layers identified by TEM and SAED͒, and somewhat larger interface widths ͑i.e., ϭ0.35-0.4 nm͒ for structures grown at higher Ar pressures, higher background pressures, or with larger target-to-substrate distances. We find no variation in interface widths with magnetron power. Nonspecular x-ray reflectance analysis and TEM suggest that the dominant interface imperfection in these films is interfacial diffuseness; interfacial roughness is minimal ( r ϳ0.175 nm) in structures prepared under optimal conditions, but can increase under conditions in which the beneficial effects of energetic bombardment during growth are compromised. X-ray reflectance analysis was also used to measure the variation in the W and Si deposition rates with bilayer thickness: we find that the W and Si layer thicknesses are nonlinear with the deposition times, and we discuss possible mechanisms responsible for this nonlinearity. Finally, hard x-ray reflectance measurements made with synchrotron radiation were used to quantify the performance of optimized depth-graded W/Si structures over the photon energy range from 18 to 212 keV. We find good agreement between the synchrotron measurements and calculations made using either 0.3 nm interface widths, or with a depth-graded distribution of interface widths in the range ϭ0.275-0.35 nm ͑as suggested by 8 keV x-ray and TEM analyses͒ for a structure containing 150 bilayers, and designed for high reflectance over the range 20 keV ϽEϽ70 keV. We also find for this structure good agreement between reflectance measurements and calculations made for energies up to 170 keV, as well as for another graded W/Si structure containing 800 bilayers, designed for use above 100 keV, where the peak reflectance was measured at Eϭ212 keV to be Rϭ76.5Ϯ4% at a graze angle of ϭ0.08°.

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Section: Shown Inmentioning

confidence: 89%

Growth, structure, and performance of depth-graded W/Si multilayers for hard x-ray optics

Windt

Christensen

Craig

et al. 2000

Journal of Applied Physics

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“…Similarly, monochromatic light is reflected over a range of incident angles. Several approaches to obtain such depth-graded structures were considered theoretically, based on numerical optimization [24][25][26][27] or a combination of analytical designing and numerical optimization. [28][29][30][31] In both methods, solving the so-called inverse problem is usually required as the final step, which consists of the minimization of a certain merit function that characterizes the deviation of the calculated reflectivity profile from the desired one.…”

Section: B Broadband Multilayer Mirrormentioning

confidence: 99%

Spectral tailoring of nanoscale EUV and soft x-ray multilayer optics

Huang

Медведев

Kruijs

et al. 2017

Applied Physics Reviews

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Extreme ultraviolet and soft X-ray (XUV) multilayer optics have experienced significant development over the past few years, particularly on controlling the spectral characteristics of light for advanced applications like EUV photolithography, space observation, and accelerator- or lab-based XUV experiments. Both planar and three dimensional multilayer structures have been developed to tailor the spectral response in a wide wavelength range. For the planar multilayer optics, different layered schemes are explored. Stacks of periodic multilayers and capping layers are demonstrated to achieve multi-channel reflection or suppression of the reflective properties. Aperiodic multilayer structures enable broadband reflection both in angles and wavelengths, with the possibility of polarization control. The broad wavelength band multilayer is also used to shape attosecond pulses for the study of ultrafast phenomena. Narrowband multilayer monochromators are delivered to bridge the resolution gap between crystals and regular multilayers. High spectral purity multilayers with innovated anti-reflection structures are shown to select spectrally clean XUV radiation from broadband X-ray sources, especially the plasma sources for EUV lithography. Significant progress is also made in the three dimensional multilayer optics, i.e., combining micro- and nanostructures with multilayers, in order to provide new freedom to tune the spectral response. Several kinds of multilayer gratings, including multilayer coated gratings, sliced multilayer gratings, and lamellar multilayer gratings are being pursued for high resolution and high efficiency XUV spectrometers/monochromators, with their advantages and disadvantages, respectively. Multilayer diffraction optics are also developed for spectral purity enhancement. New structures like gratings, zone plates, and pyramids that obtain full suppression of the unwanted radiation and high XUV reflectance are reviewed. Based on the present achievement of the spectral tailoring multilayer optics, the remaining challenges and opportunities for future researches are discussed.

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“…However for many applications it is desirable that either the spectral or angular bandwidth is essentially increased as compared to conventional MMs. The typical examples include X-ray astronomy [1], synchrotron radiation beam steering [2], Göbel optics for increasing the flux from X-ray tubes [3], and EUV lithography [4].…”

Section: Introductionmentioning

confidence: 99%

“…This way radiation of different wavelengths λ or of different angles φ incident onto the MM, according to the Bragg law, are reflected from stacks of layers placed at different depth. Several theoretical approaches were developed to design MM with any desired reflectivity profile R(λ) or R(φ) (see, e.g., [1,2,[5][6][7][8] and references therein). Notice that all approaches result in non-monotonic oscillating variation of the layer thickness with depth, even though the desired profile of the reflectivity curve is very simple (for example, constant).…”

Section: Introductionmentioning

confidence: 99%

Wideband multilayer mirrors with minimal layer thicknesses variation

Кожевников¹,

Yakshin²,

Bijkerk³

2015

Opt. Express

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Wideband multilayers designed for various applications in hard X-ray to Extreme UV spectral regions are based on a layered system with layer thicknesses varying largely in depth. However, because the internal structure of a thin film depends on its thickness, this will result in multilayers in which material properties such as density, crystallinity, dielectric constant and effective thickness vary from layer to layer. This variation causes the fabricated multilayers to deviate from the model and negatively influences the reflectivity of the multilayers. In this work we solve this problem by developing designs of wideband multilayers with strongly reduced layer thickness variations in depth, without essential degradation of their optical characteristics. 158(1-6), 127-140 (1998). 7. P. van Loevezijn, R. Schlatmann, J. Verhoeven, B. A. van Tiggelen, and E. M. Gullikson, "Numerical and experimental study of disordered multilayers for broadband x-ray reflection," Appl. Opt. 35(19), 3614-3619 (1996). 8. X. Cheng, Z. Wang, Z. Zhang, F. Wang, and L. Chen, "Design of X-ray supermirrors using simulated annealing algorithm," Opt. Commun. 265(1), 197-206 (2006) Ragozin, Zh. Wang, Zh. Zhong, and F. Wang, "Design, fabrication, and study of wideband multilayer x-ray mirrors," Crystallogr. Rep. 51(6), 1075-1081 (2006). 12. R. van der Meer, I. Kozhevnikov, B. Krishnan, J. Huskens, W. van der Wiel, P. Hegeman, C. Brons, B.Bastiaens, K. Boller, and F. Bijkerk, "Single-order operation of lamellar multilayer gratings in the soft x-ray spectral range," AIP Adv. 3(1), 012103 (2013). 13. I. V. Kozhevnikov, L. Peverini, and E. Ziegler, "Development of a self-consistent free-form approach for studying the three-dimensional morphology of a thin film," Phys. Rev. B 85(12), 125439 (2012). 14. L. Peverini, E. Ziegler, T. Bigault, and I. Kozhevnikov, "Dynamic scaling of roughness at the early stage of tungsten film growth," Phys. Rev. B 76(4), 045411 (2007).

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Design of grazing-incidence multilayer supermirrors for hard-x-ray reflectors

Cited by 131 publications

References 15 publications

Growth, structure, and performance of depth-graded W/Si multilayers for hard x-ray optics

Growth, structure, and performance of depth-graded W/Si multilayers for hard x-ray optics

Spectral tailoring of nanoscale EUV and soft x-ray multilayer optics

Wideband multilayer mirrors with minimal layer thicknesses variation

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