A micromachined silicon scan tip for an atomic force microscope

Abstract

The development of single-channel and multichannel scan tips for use in atomic force microscopy is described. A combination of bulk and surface micromachining techniques has been utilized to fabricate a heavily doped single-crystal silicon microprobe with integrated polysilicon scan tips. Polysilicon beams, configured both as cantilevers and as double-end-clamped structures 75-200 mu m long and approximately 30 mu m wide with a thickness of 1-1.5 mu m have been fabricated. The fabrication process utilizes an undoped polysilicon sacrificial layer and a boron-doped polysilicon release structure. By careful choice of the passivation layers, the strain in the structure can be reproducibly controlled. The beams are driven electrostatically, and the response amplitude is sensed using interferometric techniques.