Electron beam mastering system using a vacuum-compatible hydrodynamic spindle

Abstract

Nanoscale patterning used in disk media is a promising technology for storage devices (patterned media) and optical devices (Fresnel lens, X-ray zone plate). Electron beam (EB) lithography is a candidate technique for writing nanoscale patterns. Patterned media and X-ray zone plates are fabricated using an EB mastering system with a vacuum chamber. The EB mastering system requires a positioning mechanism to put a workpiece such as a semiconductor wafer in an appropriate position. This positioning mechanism must be vacuum-compatible and have properties such as low out-gassing and high positional accuracy. We propose an EB mastering system using a compact hydrodynamic spindle lubricated by an ionic liquid, which has a low vapor pressure. In addition, this spindle could be easily installed as an attachment to an existing scanning electron microscope (SEM). In our experiments, the proposed EB system could fabricate concentric circular grooves with a width of 40nm, track pitch of 180nm and a diameter of 1200μm under a vacuum pressure of 10−4Pa. It was confirmed that the ionic liquid had no effect on the EB machining in the SEM and that the proposed hydrodynamic spindle was very suitable for creating an EB mastering system that was simple, small and able to achieve high accuracy.