Aluminum and gold nanowires were fabricated using 100 mm stencil wafers containing nanoslits fabricated with a focused ion beam. The stencils were aligned and the nanowires deposited on a substrate with predefined electrical pads. The morphology and resistivity of the wires were studied. Nanowires down to 70 nm wide and 5 µm long have been achieved showing a resistivity of 10 µΩcm for Al and 5 µΩcm for Au and maximum current density of ∼10 8 A/cm 2 . This proves the capability of stencil lithography for the fabrication of metallic nanowires on a full wafer scale.An important objective in nanotechnology is the development of alternative nanopatterning methods and the fabrication of novel nanoscale structures and materials. Among such structures, nanowires (NWs) have shown potential and applications in a broad range of fields such as electronics, 1,2 magnetic memories, 3 thermoelectric, 4,5 nanomechanical, 6 optoelectronic, 7 and biosensing devices 8-10 due to their physical properties and surface to volume ratio. In particular, metallic nanowires can be applied for interconnects, magnetic memories based on spin-polarized current 3 and biosensors. 9 To fabricate NWs, the two approaches used are the chemical synthesis (bottom-up) and the nanopatterning methods (topdown).

The fabrication of gold nanodots by stencil lithography and its application for optical biosensing based on localized surface plasmon resonance are presented. Arrays of 50-200 nm wide nanodots with different spacing of 50-300 nm are fabricated without any resist, etching, or lift-off process. The dimensions and morphology of the nanodots were characterized by scanning electron and atomic force microscopy. The fabricated nanodots showed localized surface plasmon resonance in their extinction spectra in the visible range. The resonance wavelength depends on the periodicity and dimensions of the nanodots. Bulk refractive index measurements and model biosensing of streptavidin were successfully performed based on the plasmon resonance shift induced by local refractive index change when biomolecules are adsorbed on the nanodots. These results demonstrate the potential of stencil lithography for the realization of plasmon-based biosensing devices.

A quantitative analysis of blurring and its dependence on the stencil-substrate gap and the deposition parameters in stencil lithography, a high resolution shadow mask technique, is presented. The blurring is manifested in two ways: first, the structure directly deposited on the substrate is larger than the stencil aperture due to geometrical factors, and second, a halo of material is formed surrounding the deposited structure, presumably due to surface diffusion. The blurring is studied as a function of the gap using dedicated stencils that allow a controlled variation of the gap. Our results show a linear relationship between the gap and the blurring of the directly deposited structure. In our configuration, with a material source of ∼5 mm and a source-substrate distance of 1 m, we find that a gap size of ∼10 μm enlarges the directly deposited structures by ∼50 nm. The measured halo varies from 0.2 to 3 μm in width depending on the gap, the stencil aperture size and other deposition parameters. We also show that the blurring can be reduced by decreasing the nominal deposition thickness, the deposition rate and the substrate temperature.

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Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al(2)O(3)/SiO(2) (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al(2)O(3) (positive) and SiO(2) (negative), the membrane exhibits clear rectification of ion current in electrolyte solutions with very low aspect ratios compared to previous approaches. Our hetero-structured nanopore arrays provide a valuable platform for high throughput applications such as molecular separation, chemical processors and energy conversion.