Aln-on-SOI platform-based MEMS hydrophone with ultra-low operation frequency and ultra-high noise resolution

This paper reports a piezoelectric aluminum nitride (AlN) based MEMS hydrophone with ultra-low operation frequency and ultra-high noise resolution. The hydrophone was fabricated on a cavity SOI substrate using a 7-mask AlN-on-SOI process platform. The fabricated hydrophone achieved a non-linearity of 0.11%, a sensitivity of -182.5dB±0.3dB (ref. to 1Vrms/μPa) and a noise floor of -125dBV/√Hz, i.e. a noise resolution 57.5dB referenced to 1 μPa/√Hz within the ultra-low operation frequency of 10Hz~100Hz, the highest noise resolution of MEMS hydrophones and better than traditional bulky hydrophones[1].