Multilayer Fresnel zone plate for soft X-ray microscopy resolves sub-39 nm structures

Best resolutions in X-ray focusing are obtained to date by using diffractive lenses called Fresnel zone plates (FZPs). Their further improvement is nevertheless hindered by fundamental limitations in the employed manufacturing techniques. Here, we show a novel method to fabricate FZPs based on multilayer deposition with atomic layer deposition (ALD) and subsequent sectioning with focused ion beam (FIB). For the first time a multilayer FZP working in the soft X-ray range was prepared and could achieve the best resolution obtained so far for multilayer FZPs by resolving features below 39 nm in size in a scanning soft X-ray microscope. The new technique presents high potential for high resolution microscopy in both the soft and hard X-ray range.