Unlocking the potential of piezoelectric films grown on vertical surfaces for inertial MEMS

Abstract

Devices based on piezoelectric actuation are some of the most promising among the microelectromechanical systems (MEMS). Commonly, piezoelectric materials, such as aluminum nitride (AlN), are utilized to perform out-of-the-plane motion due to a clear and simple fabrication process. However, in-plane actuation is essential for inertial sensors, such as gyroscopes, where actuation and sensing directions are strongly perpendicular. Moreover, in-plane actuation and sensing can also find applications beyond inertial sensors. This paper presents the finite-element-modeling (FEM) of the MEMS gyroscope with the AlN thin films on vertical sidewalls that demonstrate in-plane actuation and unleash the full potential of piezoelectric AlN MEMS devices. Current work focuses on inertial sensing with the half-fork MEMS gyroscope’s FEM simulation. This device has a significant advantage in scaling, while its output is in a competitive range among existing commercial angular rate sensors. The FEM simulations in COMSOL Multiphysics (COMSOL) allow to measure the angular rate sensitivity and perform further design optimization. Ultimately, this research shows the potential of the AlN sidewall structures in MEMS gyroscopes by optimizing the angular rate sensitivity in the range of [− 64.64] degrees per second (dps) with the peak value of 1 mV/dps.