Fabrication of nanometre sized gratings via ion irradiation

Abstract

The damage caused by irradiation of crystalline material with ions results in localized volume changes. Here, swelling is utilized to fabricate nanostructured gratings with heights below 10 nm for extreme ultraviolet radiation. Irradiations were performed through a structured layer of photoresist shadowing parts of the sample from a broad ion beam. This enabled much shorter fabrication times than comparable direct write processes with a focussed ion beam. The study presents results from first systematic investigations regarding the fabrication of nanostructured gratings by irradiation of silicon with a broad beam of helium ions with energies of 30 keV. A smaller, scanned beam is used for comparison. Fluence was varied from 0.4 to 7.5×1016 ions/cm2. Fabricated structures were measured via atomic force microscopy. This yielded a controllable method to fabricate shallow gratings with heights in the range of 0 to 10 nm.