Analysis of Micromachined Piezoelectric Transducers Operating in a Flexural Mode

Abstract

Micromachined acoustic transducers have recently emerged in multiple application domains. Bulk acoustic resonators, for example, are extensively used as filters in the cellular handset industry. As another example, silicon capacitive microphones are rapidly replacing electret-condenser devices in consumer electronics platforms. Piezoelectric materials are commonly used in acoustic sensing applications. Combining micromaching with piezoelectric thin-films opens up possibilities of multiple new applications, in addition to the miniaturization of existing sensors. Applications may be as diverse as nondestructive test, acoustic imaging, vibration sensing, acceleration/force sensing, or electroacoustics. This paper presents analysis and measured behavior of micromachined devices constructed as a molybdenum, aluminum nitride, molybdenum trilayer and operating in a flexural mode. A theoretical analysis is derived using thin-plate bending theory. Finite-element simulation results of plate dynamics are examined, and sensitivities and linearity of manufactured devices are shown.

The electromechanical behavior of piezoelectric thin film composite diaphragms possessing in-plane stresses

“…In this section, measurements of an AlN-based microphone [15,16] are compared with the analytical solution with and without film stress. Fabrication was performed by Avago Technologies in Fort Collins, CO, using a variant of their film bulk acoustic resonator (FBAR) process [35][36][37][38]. The crosssection with geometric dimensions is shown in figure 4.…”

“…Equations (37) and (36) require expressions for the radial moment and force, M r and N r , respectively. They are found from plugging (26) and (27) into (3) and (4) and the result into (12).…”

Design Approaches of MEMS Microphones for Enhanced Performance

“…In the literature, most of the piezoelectric microphones are either ZnO [31,33,34], AlN [35][36][37], or PZT [38,39] based having targeted consumer applications. Microphones with a wide bandwidth for aeroacoustic applications have been proposed in [23,[40][41][42][43], and their detailed analyses have been performed, and the parameters have been tabulated in Section 2.1.4 of this paper.…”