We have fabricated new and robust nanostencil membranes for the surface patterning of 100-nm scale At wires on full wafer scale. The stencil membranes are mechanically reinforced with corrugations, making them more stable against accumulated stress. The apertures in the stencil are fabricated by a combination of UV lithography and focused ion beam milling, ranging from sub-100 nm to several microns. The presence of a gap between the stencil aperture and the substrate results in a blurring of the pattern, on the order of 100-300 nm. A gentle At dry etch is applied to reduce the blurring, achieving sub-100 nm wide structures. 80 nm wide nanowires connected to micrometer-scale contact pads are fabricated and shown. The clogging of the stencil apertures is quantified and a cleaning procedure is presented.