A piezoelectric MEMS microphone with proof mass and its array

• Published in: Sensors and actuators. A. Physical. 2024-10, Vol.377, p.115735, Article 115735
• Main Authors: Lu, Liangyu, Liu, Wenjuan, Hu, Bohao, Yang, Chaoxiang, Wang, Zekai, Liu, Yan, Cai, Yao, Wang, Jian, Guo, Shishang, Sun, Chengliang
• Format: Article
• Language: English
• Subjects: Array; Piezoelectric MEMS Microphone (PMM); Proof mass; Scandium-doped Aluminum Nitride (ScAlN)
• ISSN: 0924-4247
• DOI: 10.1016/j.sna.2024.115735

Piezoelectric MEMS microphones (PMMs) have attracted increased attention in home automation, wearable devices and autonomous driving, since the high linearity, dustproof and waterproof, and easy manufacturing. In this paper, a hexagonal PMM with proof mass and its array in parallel are proposed using a 20 % Scandium-doped Aluminum Nitride (ScAlN) thin film on a Silicon-on-insulator (SOI) wafer. The theoretical analysis, simulation, fabrication and verification test were discussed. The performance of the devices was simulated using the finite element simulation, and the resonant frequency is 102.85 kHz. The sensitivity of element and its array were measured up to −68.3 dB and −68.4 dB, respectively (re: 1 V/Pa). And the sensitivities of the element and array were −38.6 dB and −37.9 dB at 1 kHz (re: 1 V/Pa) after amplification and filtering. The SNR of the array was increased to 55.3 dB since the increased capacitance of array. Besides, the total harmonic distortion (THD) was measured 1.7 % and 1.14 %, respectively. The PMM and its array with high SNR and good THD is suitable to commercial acoustic fields, especially the high-noise scenarios. [Display omitted] •A hexagonal MEMS microphone with proof mass and its array were proposed.•The microphones were fabricated on films of Aluminum Nitride doped with 20 % Scandium.•The SNR of the parallel array is 55.3 dB, much higher than that of the element.