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

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.

Sensitivity enhancement of piezoelectric force sensors by using multiple piezoelectric effects

“…7 The force measurement based on the piezoelectric principle has been significantly improved in the measurement performance and application range extension. [8][9][10][11] In this paper, the force measurement based on the piezoelectric principle is investigated for the purpose of the sensitivity enhancement because a higher sensitivity is required for the measurement of small or micro forces. A method based on multiple piezoelectric effects is put forward to enhance the sensitivity of piezoelectric force sensors.…”

Low temperature aluminum nitride thin films for sensory applications

“…[2][3][4][5][6][7][8][9] Most common applications include bulk resonators, ultrasonic transducers, sensors, actuators, bandpass filters and energy harvesters. 10 Non-epitaxial AlN films are usually prepared by means of chemical and/or physical vapor deposition (CVD and PVD) techniques. Particularly, magnetron sputtering from an aluminum target in a reactive atmosphere is a well-established process, where the desired film properties are achieved by variation of the sputtering parameters, bottom electrode (seed layer) material and process temperature.…”

Stress controlled pulsed direct current co-sputtered Al1−xScxN as piezoelectric phase for micromechanical sensor applications

“…Because of its superior voltage response and low dielectric loss, 1 the non-toxic III-V semiconductor aluminum nitride is a preferred piezoelectric material for micro-electro-mechanical system (MEMS) sensor applications. 2 AlN MEMS sensor devices can facilitate the detection of a multitude of phenomena from basic acceleration 3 over sound waves 4 to magnetic fields 5 with high accuracy. Commonly realized by thinning the substrate in their sensitive area in order to maximize the strain mediated to the piezoelectric film, MEMS sensors stringently require to control residual stress introduced by this layer.…”