A Capacitive-type MEMS Acoustic Sensor with a Diaphragm of Al/Si3N4/Al Based on a Polyimide Sacrificial layer

Abstract

A capacitive-type micro-electro-mechanical system (MEMS) acoustic sensor with a diaphragm of Al/Si₃N₄/Al (0.1/0.4/0.1 µm) multi layer on a sacrificial layer of 3.0 µm polyimide is presented. It can make the total fabrication process simpler due to using O₂ gas as a releasing material. Furthermore, equivalent circuit modeling for the MEMS acoustic sensor is implement with a lumped model. the acoustic sensor had a modeled open-circuit sensitivity of –38.5 dBV/Pa at 1 ㎑ with a bias of 10.0 V, which shows good agreement with the measured one in the range from 100 ㎐ to 16 ㎑.