The challenge of wafer-scale integration of silicon nanowires into microsystems is addressed by developing a fabrication approach that utilizes a combination of Bosch-process-based nanowire fabrication with surface micromachining and chemical-mechanical-polishing-based metal electrode/contact formation. Nanowires up to a length of 50 μm are achieved while retaining submicron nanowire-to-electrode gaps. The scalability of the technique is demonstrated through using no patterning method other than optical lithography on conventional SOI substrates. Structural integrity of double-clamped nanowires is evaluated through a three-point bending test, where good clamping quality and fracture strengths approaching the theoretical strength of the material are observed. Resulting devices are characterized in resonator and switch applications-two areas of interest for CMOS-compatible solutions-with all-electrical actuation and readout schemes. Improvements and tuning of obtained performance parameters such as resonance frequency, quality factor and pull-in voltage are simply a question of conventional design and process adjustments. Implications of the proposed technique are far-reaching including system-level integration of either single-nanowire devices within thick Si layers or nanowire arrays perpendicular to the plane of the substrate.
Fabrication of ultra-high aspect ratio exchangeable and customizable tips for atomic force microscopy (AFM) using lateral focused ion beam (FIB) milling is presented. While on-axis FIB milling does allow high aspect ratio (HAR) AFM tips to be defined, lateral milling gives far better flexibility in terms of defining the shape and size of the tip. Due to beam-induced deformation, it has so far not been possible to define HAR structures using lateral FIB milling. In this work we obtain aspect ratios of up to 45, with tip diameters down to 9 nm, by a deformation-suppressing writing strategy. Several FIB milling strategies for obtaining sharper tips are discussed. Finally, assembly of the HAR tips on a custom-designed probe as well as the first AFM scanning is shown.
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