Thermoelastic Damping in MEMS Gyroscopes at High Frequencies

TL;DR

This paper investigates thermoelastic damping in high frequency MEMS gyroscopes, combining simulations and measurements to understand its impact on device performance and reliability in harsh environments.

Contribution

It introduces a validated simulation method to predict thermoelastic damping effects on high frequency modes in MEMS gyroscopes, aiding in design optimization.

Findings

Good agreement between simulations and measurements of quality factors.

Thermoelastic damping significantly affects high frequency mode damping.

Method applicable to various nano- and micromechanical systems.

Abstract

Microelectromechanical systems (MEMS) gyroscopes are widely used, e.g. in modern automotive and consumer applications, and require signal stability and accuracy in rather harsh environmental conditions. In many use cases, device reliability must be guaranteed under large external loads at high frequencies. The sensitivity of the sensor to such external loads depends strongly on the damping, or rather quality factor, of the high frequency mechanical modes of the structure. In this paper, we investigate the influence of thermoelastic damping on several high frequency modes by comparing finite element simulations with measurements of the quality factor in an application-relevant temperature range. We measure the quality factors over different temperatures in vacuum, to extract the relevant thermoelastic material parameters of the polycrystalline MEMS device. Our simulation results show a good agreement with the measured quantities, therefore proving the applicability of our method for predictive purposes in the MEMS design process. Overall, we are able to uniquely identify the thermoelastic effects and show their significance for the damping of the high frequency modes of an industrial MEMS gyroscope. Our approach is generic and therefore easily applicable to any mechanical structure with many possible applications in nano- and micromechanical systems.