Integrated electrostatically resonant scan tip for an atomic force microscope

The atomic force microscope (AFM) has become a practical tool for mapping surface features with a resolution better than 10 nm. As such, in recent years the demand from industry for the AFM has increased significantly. For the AFM to be a practical instrument, however, its operation must be user friendly and its performance must be consistent. The essential element of an AFM is a microprobe which uses a cantilever mounted with a sharp stylus as a force sensor. For reproducible measurements, it is crucial that the physical dimensions of the cantilever and its stylus be consistent. Typical dimensions of the cantilever are 100–200 μm in length, 20–50 μm in width, and 0.5–1.2 μm in thickness. Typical stylus dimensions include a height of at least 3 μm and a radius of tip curvature of less than 100 nm. Silicon micromachining techniques were applied to fabricate microprobes with built‐in alternating‐current excitation of the polysilicon cantilevers in our previous work. This article presents a compatible process for the formation of a fine grained polysilicon stylus on the cantilever and an optical port for fiber‐optic interferometry readout. The process demonstrates the feasibility of integrating both electronic drive and sensing circuitry onto the microprobe for future use in multichannel AFM systems.