Resistless patterning of sub-micron structures by evaporation through nanostencils

We describe a sub-micron shadow-mask evaporation or nanostencil technique for single-layer material patterning. The technique does not involve photoresist processing steps and is therefore applicable on arbitrary surfaces. It allows for rapid fabrication of sub-micron structures on a milimeter scale. The nanostencils used here are thin microfabricated silicon nitride membranes, 1 x 3 mm wide and 0.3 - 1.0 mu m thick. They are perforated by a regular two-dimensional array of sub-micron apertures of 1 mu m periode. Metal evaporation of 40 nm thick Cr/Au through the apertures directly onto the substrate yields the exact 1:1 replication of the aperture pattern. The smallest dot size on a flat substrate obtained is 120 nm, whereas 750 nm dots are reproduced, both on freestanding micromechanical beams and on a surface recessed by 5 - 10 mu m.