Fabrication of Fresnel zone plates by ion-beam lithography and application as objective lenses in extreme ultraviolet microscopy at 13 nm wavelength.

Fresnel zone plates are used for imaging at extreme ultraviolet and soft x-ray wavelengths. Fabricating these zone plates is challenging due to small structure sizes (<150  nm) and complex nanostructuring processes. Fabrication techniques such as electron-beam lithography followed by etching and electroplating processes have been developed over the years. We are reporting on the development of a technique incorporating focused gallium ion-beam lithography to fabricate Fresnel zone plates with 120 nm outermost structure size in a process that combines pattern exposure and structure transfer in one single step. The fabricated zone plates were successfully applied in a microscopic setup at λ=13  nm wavelength.