A Low-Cost Fabrication and Numerical Simulation of a MEMS Acoustic Transducer Using Polyimide Membrane on FR4 Substrate

Micro-electromechanical system (MEMS)-based acoustic transducers are also known as microphones. The membrane materials on MEMS microphones are metal, polysilicon, silicon, and silicon nitride. The existing technology and materials used for the microphones involve expensive materials and complex process steps. This paper proposed a low-cost fabrication process and studies a MEMS acoustic transducer device using polyimide as a membrane on FR4 substrate (non-silicon substrate). The numerical simulation is carried out for the proposed device and considers the following parameters such as thickness of membrane, diameter of diaphragm cavity, resistor length and applied pressure. This device has four resistors which are linked in the method of Wheatstone bridge. The resistance change is observed due to membrane deformation when applying pressure, and output is measured on corresponding nodes. Based on the operating parameters studied the change in resistance, displacement, frequency response, sensitivity and operating bandwidth.