Tilted nanostructure fabrication by electron beam lithography

Abstract

Periodic tilted nanostructures over large area have various applications. In this work tilted nanostructures were created by SEM scanning of electron beam resists with the substrate tilted at 45°. The key to the process is the usage of the dynamic focus function that is available for most SEM systems for imaging purpose (but not for lithography), as otherwise the tilted substrate will be out of focus of the electron beam. The pattern created by this method is limited to periodic pillar or hole array using negative or positive resist, respectively, with the number of pillars or holes per scan given by the image resolution (e.g., 1024 × 768). The diameter of the pillars or holes was determined by the exposure dose, which is in turn determined by the beam current and scan speed (scanning time per frame). The array period is controlled by the magnification (that determines image area, e.g., 1 mm2) and image resolution. The pillar or hole pattern in the resist can be further transferred to another material such as Au by electroplating.