A comparative study of acoustic isolation configurations for pMUT array-based applications

Abstract

This paper presents an overview of state-of-the-art acoustic isolation in MEMS and compares several acoustic isolation techniques that can be applied to a pMUT array. To keep the solution for acoustic filtering relatively simple in terms of design and fabrication, several typical solutions are considered: use of mesa-type structures, machining ring-shaped pillars of different materials on the surface and combining the trenches etched on the surface with polymer deposited inside it. A direct comparison of these approaches is made using FEM analysis, and it is demonstrated that the crosstalk in pMUT array can be reduced by the value close to the one order of magnitude.