Electrostatically actuated double cantilever AFM probe for high speed imaging

We present the design, fabrication and characterization of an electrostatically actuated AFM probe. The probe consists of two cantilevers, a relatively long, stiff cantilever on which end a smaller and softer cantilever with a sharp tip is incorporated. The deflection of the small cantilever is controlled by an electrostatic gap-closing actuator, which is monolithically integrated on the cantilevers. A combination of a small and fast cantilever with an integrated electrostatic actuator allows for a high frequency operation and high speed AFM imaging. We have designed and fabricated a probe with the large cantilever having a stiffness of over 400 N/m and small cantilevers with a stiffness of up to 3.2 N/m and a resonance frequency up to 643 kHz. We have confirmed a proper operation of the probe using high-speed imaging (8 scan lines per second) in electrostatically driven tapping mode.