Abstract

X-ray microscopy greatly bene�ts from the advances in x-ray optics. At the
Paul Scherrer Institut, developments in x-ray di�ractive optics include the manufacture and
optimization of Fresnel zone plates (FZPs) and di�ractive optical elements for both soft and
hard x-ray regimes. In particular, we demonstrate here a novel method for the production of
ultra-high resolution FZPs. This technique is based on the deposition of a zone plate material
(iridium) onto the sidewalls of a prepatterned template structure (silicon) by atomic layer
deposition. This approach overcomes the limitations due to electron-beam writing of dense
patterns in FZP fabrication and provides a clear route to push the resolution into sub-10 nm
regime. A FZP fabricated by this method was used to resolve test structures with 12 nm lines
and spaces at the scanning transmission x-ray microscope of the PolLux beamline of the Swiss
Light Source at 1.2 keV photon energy.