A High-Bandwidth MEMS Nanopositioner for On-Chip AFM: Design, Characterization, and Control

We report the design, characterization, and control of a high-bandwidth microelectromechanical systems (MEMS) nanopositioner for on-chip atomic force microscopy (AFM). For the fabrication, a commercially available process based on silicon-on-insulator is used. The device consists of a scan table, moved in the x-y plane by two sets of electrostatic comb actuators, capable of generating strokes in excess of ±5 μm. The first resonance frequencies of the nanopositioner are approximately 4.4 and 5.3 kHz in lateral directions. Electrothermal sensors are used to measure the displacement of the scan table. To enable fast scans, a dynamic model of the system is identified and used to design a feedback controller that damps the oscillatory behavior of the device. The nanopositioner is tested as the scanning stage of an AFM to perform high-speed scans.