Modeling and Fabrication Aspects of PVDF as a Membrane Material for Air Borne PMUT Applications

This paper reports a thorough analysis on the viability of polyvinylidene difluoride (PVDF) as a membrane material for Piezoelectric Micromachined Ultrasonic Transducers using a well developed multiphysics finite element modeling approach. Key metrics such as frequency modes, membrane displacement sensitivity, generated acoustic pressure were analyzed not only for PVDF but also for other piezoelectric materials like Zinc Oxide (ZnO) and Aluminium Nitride (AIN). Based on the affirmative conclusions, fabrication of PMUT using PVDF as membrane material was carried out. One of the major bottlenecks encountered in the process is the poor adhesion between PVDF and metal. This generic issue not limited this particular process flow was resolved using simple chemical surface modification of metal surface. This resulted in the successful demonstration of PVDF based PMUT.