Smooth and Narrow Nanopillars Fabricated by Ion-Beam-Induced Deposition under Charging Conditions

We investigate the formation of the irregular sidewall and halo of pillars grown by ion-beam-induced deposition (IBID) by growing platinum nanopillars on an insulating Si 3 N 4 membrane and on a semiconducting Si wafer with a thin Si 3 N 4 top layer. As compared with the pillars grown in a conductive environment, the pillars grown on an insulating membrane are smoother, higher and thinner but have the same volume. Furthermore, they are accompanied by smaller halos. These differences suggest a distinct charging effect in IBID pillar growth. This charging effect is attributed to the secondary electron emission and possibly the aggregation of precursor gas molecules.