Piezoelectric MEMS sensors: state-of-the-art and perspectives

TLDR

Over the past two decades, micromachined sensors and actuators have advanced, creating a need to integrate non‑silicon materials such as piezoelectric films, whose high energy density and favorable scaling have spurred interest and led to commercialized aluminum‑nitride FBAR resonators, while future innovations in inertial sensors, oscillators, filters, microactuators, and chip‑scale chemical analysis rely on successful miniaturization and integration of piezoelectrics and metals. This article provides a comprehensive review of micromachined piezoelectric transducer technology. The review covers bulk and thin‑film piezoelectric materials, fabrication techniques for integrating them into microsensors, recent advances illustrated by specific examples, and concludes with a critical assessment of future trends and promise.

Abstract

Over the past two decades, several advances have been made in micromachined sensors and actuators. As the field of microelectromechanical systems (MEMS) has advanced, a clear need for the integration of materials other than silicon and its compounds into micromachined transducers has emerged. Piezoelectric materials are high energy density materials that scale very favorably upon miniaturization and that has led to an ever-growing interest in piezoelectric films for MEMS applications. At this time, piezoelectric aluminum-nitride-based film bulk acoustic resonators (FBAR) have already been successfully commercialized. Future innovations and improvements in inertial sensors for navigation, high-frequency crystal oscillators and filters for wireless applications, microactuators for RF applications, chip-scale chemical analysis systems and countless other applications hinge upon the successful miniaturization of components and integration of piezoelectrics and metals into these systems. In this article, a comprehensive review of micromachined piezoelectric transducer technology will be presented. Piezoelectric materials in bulk and thin film forms will be reviewed and fabrication techniques for the integration of these materials for microsensor applications will be presented. Recent advances in various piezoelectric microsensors will be presented through specific examples. This review will conclude with a critical assessment of the future trends and promise of this technology.