Optimal selection of dielectric film in piezoelectric MEMS microphone

Abstract

This paper focusses on selecting the best piezoelectric material as a dielectric film using multi-criteria decision making (MCDM) material selection techniques. These techniques include Ashby’s approach and technique for order preference by similarity to an ideal solution (TOPSIS) methodology. This selection will ensure the maximized MEMS Microphone performance assuming a capacitor model based design. Several piezoelectric material properties have been identified and co-related using mathematical equations to model key output microphone device parameters like signal to noise ratio (SNR), impedance and bandwidth. Contour plots were generated to identify optimal intersection regions of different piezoelectric thin film materials based on device performance parameters as output responses and key material properties as input factors. Comparison of results from both these MCDM techniques shows that aluminum nitride (AlN) and zinc oxide (ZnO) serve as the best piezoelectric dielectric films to achieve optimal microphone performance. This outcome also considered the intrinsic material properties and fabrication compatibility with complementary metal oxide semiconductor (CMOS)-technology processing for commercial microphone applications.