Silicon microcantilevers with MOSFET detection

Abstract

We report the fabrication of silicon microcantilevers with MOSFET detection, to be used in force measurements for biomolecular detection. Thin cantilevers are required for a high force sensitivity. Therefore the source and drain of the transistors have been fabricated by As implantation to obtain shallow PN junctions. The cantilevers have been oriented on the non-standard (100) crystallographic direction of silicon, to maximize the stress response of the NMOS transistors. The force sensitivity and resolution of the cantilevers have been tested by applying a force with an AFM tip. Values of 25 μV/pN and 56 pN respectively have been obtained for a force applied at the tip of a cantilever with a length of 200 μm, a width of 24 μm and a silicon thickness of 340 nm.