Diffractive Optics manufactured w. EBL

Patterning of Tungsten using EBL and negative resist HSQ



Values indicate half pitch size. 90 nm pattern height.

Courtesy Julia Reinspach, Anders Holmberg, Biomedical & X-ray Physics, KTH.

High resolution nickel zone plate for soft x-ray microscopy


Outermost part of the zone plate with 16 nm half-pitch, 60 nm high.

Courtesy Julia Reinspach, Anders Holmberg, Biomedical & X-ray Physics, KTH.

13-nm nickel zone plates fabricated using
cold-developed electron-beam patterned Zep 7000

High-aspect-ratio processing is needed to obtain zone plates with both high resolution and high diffraction efficiency. To fabricate such optics we use a tri-layer resist process in combination with electroplating. Si3 N4 - membranes are used as substrates since they have a high x-ray transmission

The patterning is performed with 25 keV electron-beam lithography (Raith 150 system) followed by two steps of reactive ion etching (RIE) to provide a mold. The mold is filled with the zone-plate material by electroplating, after which the mold is removed.


Overview image of a nickel zone plate with 14 nm outermost zone width.
The pattern quality is high and uniform over the entire zone plate area.


The outer part of a nickel zone plate with 13 nm outermost zone width.
The nickel thickness is 35 nm.

Cold development was applied in the nanofabrication process and the resolution improvement enabled the fabrication of zone plates with outermost zone widths down to 13 nm.

SEM images of electroplated nickel zone plates are shown above. The zone plate with 15 nm outermost zone width was fabricated using Ti as hardmask material. For higher resolution SiO2 was used since it provided a more reproducible pattern transfer.

Courtesy Julia Reinspach, Magnus Lindblom, Anders Holmberg, Biomedical & X-ray Physics, KTH.

Anders Liljeborg Nanostructure Physics, KTH.