High-resolution x-ray microscopy lenses made using atomic layer deposition.

The fabrication of small, tall nanostructures is one of the key challenges in developing highly resolving diffractive x-ray optics. For nanodevices like diffractive x-ray lenses, feature sizes of below 10 nm are required to enter a new regime in high resolution x-ray microscopy.

Using a novel fabrication approach, the Laboratory for Micro- and Nanotechnology at the Paul Scherrer Institute has succeeded in manufacturing Fresnel zone plates with structure sizes as small as 6.4 nm.

These new lenses will be exploited by the scanning transmission x-ray microscopes PolLux at the Swiss Light Source and Hermes at Synchrotron Soleil, France.

The fabrication process consists of several steps. First, a template structure is written by electron beam lithography. The template is then coated with iridium metal using atomic layer deposition. Caps are removed with argon milling, followed by etching with hydrofluoric acid to leave double the number of iridium metal nanostructures.

It is anticipated that this new fabrication capability will have a major impact on x-ray microscopy through a notable enhancement in resolution.

References

Rösner B, Koch F, Döring F, Bosgra J, Guzenko VA, Kirk E, Meyer M, Ornelas JL, Fink RH, Stanescu S, Swaraj S, Belkhou R, Watts B, Raabe J, David C
Exploiting atomic layer deposition for fabricating sub-10 nm x-ray lenses
Microelectronic Engineering. 2018;191:91-96
https://doi.org/10.1016/j.mee.2018.01.033