Brugger, JBeljakovic, GDespont, Mde Rooij, N FVettiger, P2005-11-022005-11-022005-11-02199710.1016/S0167-9317(96)00210-9https://infoscience.epfl.ch/handle/20.500.14299/218596Selective Ga + ion implantation and miring by focused ion beam exposure and subsequent wet chemical etching is used to fabricate micro/nanomechanical elements in Si. Freestanding elements with a ~ 30 nm membrane thickness are made by controlled selective underetching between unexposed and exposed areas. Ultrahigh-frequency cantilever beams have been made with resonances in the tens of MHz range. Using a U-shaped beam cross section, mechanical stiffness could be increased 100-fold, which in turn increased the beam resonance frequency to several hundreds of MHz. The direct-write patterning/milling technique was used to fabricate various arbitrary shapes with vertical sidewalls such as submicrometer-sized containers, cups, and other nanomechanical devices.text::journal::journal article::research article