Dense high aspect ratio hydrogen silsesquioxane nanostructures by 100 keV electron beamlithography

Abstract

We investigated the fabrication of dense, high aspect ratio hydrogen silsesquioxane (HSQ)nanostructures by 100 keV electron beam lithography. The samples were developed using ahigh contrast developer and supercritically dried in carbon dioxide. Dense gratings withline widths down to 25 nm were patterned in 500 nm-thick resist layers and semi-densegratings with line widths down to 10 nm (40 nm pitch) were patterned in 250 nm-thick resistlayers. The dense HSQ nanostructures were used as molds for gold electrodeposition, andthe semi-dense HSQ gratings were iridium-coated by atomic layer deposition. We usedthese methods to produce Fresnel zone plates with extreme aspect ratio for scanningtransmission x-ray microscopy that showed excellent performance at 1.0 keV photon energy.