Realization and simulation of high-aspect-ratio micro/nanostructures by proton beam writing

Abstract

Among the patterning technologies proposed and applied for the realization of high-aspect-ratio structures in the micro- and nanoscale, proton beam writing (PBW) is considered to be a valuable tool for maskless patterning of such structures owing to the unique ability of protons to maintain a straight path over long distances. In this work, the PBW capabilities are demonstrated through simulation results of fine structures in resist films. These results prove the capability of PBW to produce very tall structures with almost vertical sidewalls, with the aspect ratio limited practically only by the resist performance and the beam diameter provided. The performance of PBW is explored and proved through the patterning of an aqueous base developable negative chemically amplified resist (TADEP, thick aqueous base developable epoxy based resist). By employing PBW on a 2.0-μm-thick TADEP, patterns with 110nm linewidth and an aspect ratio of 18 were resolved. © 2008 The Japan Society of Applied Physics.