SILICON MICRO NANOMECHANICAL DEVICE FABRICATION BASED ON FOCUSED ION-BEAM SURFACE MODIFICATION AND KOH ETCHING/

Selective Ga+ ion implantation and milling by focused ion beam exposur e and subsequent wet chemical etching is used to fabricate micro/nanom echanical elements in Si. Freestanding elements with a approximate to 30 nm membrane thickness are made by controlled selective underetching between unexposed and exposed areas. Ultrahigh-frequency cantilever b eams have been made with resonances in the tens of MHz range. Using a U-shaped beam cross section, mechanical stiffness could be increased 1 00-fold, which in turn increased the beam resonance frequency to sever al hundreds of MHz. The direct-write patterning/milling technique was used to fabricate various arbitrary shapes with vertical sidewalls suc h as submicrometer-sized containers, cups, and other nanomechanical de vices.