Design, fabrication and characterization of a high-bandwidth 2DOF MEMS nanopositioner

Abstract

There is a need for 2 DOF scanners in a variety of applications in nanotechnology, particularly in the Atomic Force Microscope (AFM). An ideal AFM stage should have a high resonance frequency, low cross coupling between the two perpendicular axes of motion and be capable of moving over a large range in either direction. To achieve these specifications, which are crucial in obtaining high quality images at high scan speeds, various designs have been proposed in the literature. The use of Microelectromechanical Systems (MEMS) technology and silicon as the structural material has resulted in the achievement of higher resonance frequencies in nanopositioning stages compared to many other conventional technologies. In this paper we report the design of a 2 DOF MEMS stage, fabricated using a Silicon on Insulator process. The scan table has dimensions of 1.6mm×1.6mm. To move the stage in two orthogonal directions, a parallel kinematic mechanism utilizing electrostatic comb actuators is used. Electrothermal sensors are incorporated to detect displacements of the stage in these directions. Characterization of the device reveals a displacement range of ±6μm and a first resonance frequency of approximately 5200 Hz in the X and Y directions.