Microelectromechanical z-axis out-of-plane stopper

摘要

The present invention relates to a microelectromechanical structure, and more particularly, to systems, devices and methods of incorporating z-axis out-of-plane stoppers that are controlled to protect the structure from both mechanical shock and electrostatic disturbance. The z-axis out-of plane stoppers include shock stoppers and balance stoppers. The shock stoppers are arranged on a cap substrate that is used to package the structure. These shock stoppers are further aligned to a proof mass in the structure to reduce the impact of the mechanical shock. The balance stoppers are placed underneath the proof mass, and electrically coupled to a balance voltage, such that electrostatic force and torque imposed by the shock stoppers is balanced by that force and torque generated by the balance stoppers. This structure is less susceptible to mechanical shock, and shows a negligible offset that may be induced by electrostatic disturbance caused by the shock stoppers.

主权项

1. A microelectromechanical structure comprising:
a sensor substrate; a proof mass suspended above the sensor substrate via at least one elastic element, the proof mass displacing and titling in response to acceleration of the structure; a cap substrate coupled to the sensor substrate, the cap substrate being bonded to the sensor substrate to form a cavity that encloses the proof mass, the cap substrate further comprising a plurality of shock stoppers that are arranged above the proof mass to push back the proof mass at specific locations upon a shock load; and a plurality of balance stoppers coupled underneath the proof mass, each of the plurality of balance stoppers being arranged according to a position of one of the plurality of shock stoppers and electrically driven by a balance voltage, each of the plurality of balance stoppers generating first electrostatic force and torque on the proof mass to balance second force and torque generated by a corresponding shock stopper.