A ScAlN-Based Piezoelectric MEMS Microphone With Sector-Connected Cantilevers

With increasing requirements for massive sound acquisition, piezoelectric MEMS microphones (PMMs) have attracted widespread attention due to the advantages of low power consumption, fast response, waterproof and dustproof. This work presents a PMM with sector-connected cantilevers, where the anchors are located at the center of a circular operating area of 0.5-mm2. According to theoretical analysis and finite element simulations, the proposed PMM exhibits higher sensitivity compared with conventional cantilever diaphragms fixed at the perimeter. The PMM is fabricated on a customized cavity silicon-on-insulator (CSOI) substrate with a 9.5% scandium-doped aluminum nitride (ScAlN) film. The output of the PMM assembly is amplified and filtered from 100-Hz to 20-kHz, and the measured sensitivity, minimum detectable pressure (MDP), resolution, total harmonic distortion (THD), and signal-to-noise ratio (SNR) are −37.6-dB (re: 1-V/Pa), 40-dB SPL, 40-dB SPL, 0.997%, and 54.2-dB at 1-kHz, respectively. The calculated nonlinearity of the PMM is less than 0.85% under 94-dB SPL. The receiving sensitivity and SNR of the ScAlN-based PMM are effectively improved, which shows great potential in intelligent voice acquisition and control scenarios. [2023-0110]