Frequency and Acoustic Performance Tunability for a SiN-AlScN Based PMUT Device

Abstract

This paper presents a wide frequency range and acoustic performance tunability for a Piezoelectric Micromachined Ultrasonic transducer (PMUT) device. Aluminium Scandium Nitride (AlScN) sandwiched between Aluminium (Al) electrodes is used for the piezoelectric actuation. Thin-film Silicon-Nitride (SiN) acts as an elastic layer to tune the frequency and optimize the acoustic performance of the PMUT devices. The devices are fabricated using a CMOS compatible monolithic technique. We simulated the acoustic performance of the device in a water-coupled medium and demonstrated for a cavity size of $80\mu\mathrm{m}$ the frequencies could be tuned within the range of 3.6MHz to 5.4MHz with a transmitting sensitivity ranging from 5.8 kPa/V to 7.8 kPa/V respectively.