Helium ion beam lithography on fullerene molecular resists for sub-10 nm patterning

Abstract

Helium ion beam lithography (HIBL) is an emerging technique that uses a sub-nanometre focused beam of helium ions generated in the helium ion microscope to expose resist. It benefits from high resolution, high sensitivity and a low proximity effect. Here we present an investigation into HIBL on a novel, negative tone fullerene-derivative molecular resist. Analysis of large area exposures reveals a sensitivity of ~40μC/cm2 with a 30keV helium beam which is almost three orders of magnitude higher than the sensitivity of this resist to a 30keV electron beam. Sparse line features with line widths of 7.3nm are achieved on the ~10nm thick resist. The fabrication of 8.5 half-pitched lines with good feature separation and 6nm half-pitched lines with inferior but still resolvable separation is also shown in this study. Thus, sub-10nm patterning with small proximity effect is demonstrated using HIBL using standard processing conditions, establishing its potential as an alternative to EBL for rapid prototyping of beyond CMOS devices.