Recent developments show that Scanning Helium Ion Beam Lithography (SHIBL) with a sub-nanometer beam diameter is a promising alternative fabrication technique for high-resolution nanostructures at high pattern densities. Key principles and critical conditions of the technique are explained. From existing data, the fundamental factors underlying the sensitivity gain by 1-2 orders of magnitude and the prospects for high resolution at high pattern densities are analysed. State-of-The-Art performance of the technique is illustrated with experimental achievements in HSQ and PMMA resists. Exploratory SHIBL work on aluminum oxide resist is presented as a novel approach to overcome potential shot noise effects in pattern definition and to improve masking capabilities in subsequent pattern transfer.