A Decoupling Design with T-Shape Structure for the Aluminum Nitride Gyroscope.

Yang Yang,Han Han,Zhao Zhao,Ning Ning,Wang Wang,Zhang Zhang,Si Si

doi:10.3390/mi10040244

Abstract

This paper reports a novel design for the decoupling of microelectromechanical systems (MEMS) gyroscopes. The MEMS gyroscope is based on piezoelectric aluminum nitride (AlN) film, and the main structure is a mass hung by T-shape beams. A pair of parallel drive electrodes are symmetrically placed on the surface of the vertical bar for driving the oscillating mass. A serpentine sense electrode is placed on the lateral bar. When the gyroscope is oscillating in drive mode, charges with equal quantity and opposite sign will be polarized and distributed symmetrically along the lateral bar. These charges neutralize each other at the sense electrode. Therefore, no coupling signals can be detected from the sense electrode. This design can realize the decoupling between the drive mode and sense mode. In this work, the T-shape decoupled structure was designed as the key component of an AlN piezoelectric gyroscope and the whole structure was simulated by COMSOL Multiphysics 5.2a. The working principle of the decoupling is described in detail. Electrical properties were characterized by the dynamic signal analyzer. According to the test results, the drive mode and the sense mode are decoupled. The coefficient of orthogonal coupling is 1.55%.

Highlights

Microelectromechanical systems (MEMS) gyroscopes play an important role in inertial navigation systems
There are some factors limiting the performance of MEMS gyroscopes
Different ICP etching processes are performed on the Ti/Pt, aluminum nitride (AlN), Mo, SiO2 and Si successively; (d) The releasing process is performed by inductively coupled plasma (ICP) isotropic etching process of Si

Summary

Introduction

Microelectromechanical systems (MEMS) gyroscopes play an important role in inertial navigation systems. The working principles of these gyroscopes are based on the Coriolis’ effect [5]. There are some factors limiting the performance of MEMS gyroscopes. Orthogonal coupling is one of the main restrictions for the sensitivity and bias instability of MEMS gyroscopes [9–11]. Owing to the manufacturing tolerances or design of the structure, the mechanical crosstalk of the drive mode couples to the sense electrodes. There is a mechanical coupling between the drive mode structure and sense electrode, the charge neutralization can realize the

Results

Conclusion