Sub-15 nm beam confinement by two crossed x-ray waveguides

Abstract

We have combined two high transmission planar x-ray waveguides glued onto each other in a crossed geometry to form an effective quasi-point source. From measurements of the far-field diffraction pattern, the phase and amplitude of the near-field distribution is retrieved using the error-reduction algorithm. In agreement with finite difference field simulations (forward calculation), the reconstructed exit wave intensity distribution (inverse calculation) exhibits a full width at half maximum (FWHM) below 15 nm in both dimensions. Finally, holographic imaging is successfully demonstrated for the crossed waveguide device by translation of a lithographic test structure through the waveguide beam.

Advanced x-ray multilayer waveguide optics

“…The theoretical limits for beam collimation was shown to be in the range of 10 nm depending on the material [26], and experimental values in the predicted range have been demonstrated, notably 8 nm [27,28] in a planar thin film waveguide with an optimized cladding material (Mo/C /Mo structure embedded in Ge [29]). Several different ways have been used to generate x-ray modes, or more precisely to couple x-ray beams into WGs.…”

“…Using phase retrieval method, the amplitude and phase in the object plane can be reconstructed, enabling a direct visualization of the near-field interference pattern. Three different, well established phase retrieval algorithms are used to reconstruct the wave in the object plane from the measured far-field pattern: the error reduction (ER) algorithm [27,61,62], hybrid input-output (HIO) algorithm [61,62] and the HIO+ER algorithm [63].…”

“…In particular, smaller slits result in full coherence and a broadening of a focal spot by diffraction. For alignment of the KB, the reference 2DWG [12,27] was placed on a custom-designed hexapod system (Smaract) in the focal plane of the KB mirrors. By translating the aligned 2DWG, the beamsize of the KB was measured.…”

“…For example, the theoretical limits for beam collimation was shown and demonstrated to be in the range of 10 nm depending on the material [26]. With thin film deposition techniques, notably 8 nm [27,28] for the given material could be reached in a planar thin film waveguide with an optimized cladding material (Mo/C /Mo structure embedded in Ge wafers [29]). Furthermore, the single guiding film [30,31] or the cladding film [32,33] can be generalized to a multilayer structure.…”

Feasibility study of broadband efficient “water window” source

“…In addition, we should use a dot Bi target with a diameter less than 20 µm to generate a microplasma (to fulfill the requirements for high brightness and a point source) as the expected focal spot size will be ~100 µm in the case of the longer wavelength CO 2 laser beam. Since, because of the broad band nature of the emission zone plate components cannot be used, one possible solution would be to use a transmission planar x-ray nanowaveguide to image the sample [23]. To achieve high resolution in the recorded image, we should also switch the recording device from x-ray CCD cameras to sensitive EUV resists to overcome the resolution limitation of the CCD pixel size, coupled with Schwarzschild optics, consisting of Sc/Cr MLMs with a reflection coefficient of the order of 15% around 3.2 nm.…”