Electrostatically Actuated Cantilever With SOI-MEMS Parallel Kinematic $XY$ Stage

This paper presents the design, analysis, fabrication, and characterization of an active cantilever device integrated with a high-bandwidth 2-DOF translational (XY) micropositioning stage. The cantilever is actuated electrostatically through a separate electrode that is fabricated underneath the cantilever. Torsion bars that connect the cantilever to the rest of the structure provide the required compliance for the cantilever's out-of-plane rotation. The active cantilever is carried by a micropositioning stage, which enables high-bandwidth scanning to allow manipulation in three dimensions. The design of the microelectromechanical system stage is based on a parallel kinematic mechanism (PKM). The PKM design decouples the motion in the X- and Y-directions while allowing for an increased motion range with linear kinematics in the operating region (or workspace). The trusslike structure of the PKM also results in increased stiffness and reduced mass of the stage. The integrated cantilever device is fabricated on a silicon-on-insulator (SOI) wafer using surface micromachining and deep reactive ion etching processes. The actuation electrode of the cantilever is fabricated on the handle layer, while the cantilever and the XY stage are at the device layer of the SOI wafer. Two sets of electrostatic linear comb drives are used to actuate the stage mechanism in the X- and Y-directions. The cantilever provides an out-of-plane motion of 7 mum at 4.5 V, while the XY stage provides a motion range of 24 mum in each direction at the driving voltage of 180 V. The resonant frequency of the XY stage under ambient conditions is 2090 Hz. A high quality factor (~210) is achieved from this parallel kinematic XY stage. The fabricated stages will be adapted as chip-scale manufacturing and metrology devices for nanomanufacturing and nanometrology applications.