Piezoelectric Thin Film Materials for Acoustic MEMS Devices

Piezoelectric thin film (PTF) materials present a number of unique properties in different applications, such as high sensitivity for micro electro mechanical systems (MEMS) microphones, and a wide dynamic range, wide displacement and low power consumption for MEMS speakers. Generation and detection of acoustic vibration can be made by piezoelectric devices which use the effects of direct piezoelectricity and inverse piezoelectricity. This paper covers popular PTFs and their applications for acoustic MEMS: lead zirconate titanate (PZT) based thin films and lead free PTFs such as aluminum nitride (AIN), zinc oxide (ZnO) and scandium doped aluminum nitride (ScAIN). The design, vibration mode, and fabrication will determine the frequency range of the acoustic MEMS devices. The performance and properties of PTF are the main parameter for certain MEMS applications are introduced. The main ideas of piezoelectric materials are reviewed and introduced for acoustic MEMS transducers.