Three Dimensional Modeling of Piezoelectric Micromachined Transducers Built on Top of Integrated Circuits

Rapid advancements in the field of ultrasound sensing and imaging necessitates fast and realistic modeling of piezoelectric micromachined ultrasound transducers (PMUTs) and arrays to facilitate their design. This paper reports on the modeling and simulation of single piezoelectric micromachined transducers and arrays designed by Universitat Autonoma de Barcelona UAB [1] and using the MEMs-on-CMOS process from SilTerra [2]. We demonstrate a tightly coupled workflow performing coupled 3D mechanical-piezoelectric analyses on the cloud directly from virtual fabrication of PMUT mask layouts. The comparison of S21 parameters with data from fabricated devices shows agreement between measured and simulated data for the resonance frequency amplitude and the phase within 1% for simulations in air and 3% for water and FC-70. Results of calculating the pulse-echo response for a 6x6 PMUT array under a
$\mathbf{950}\mu\mathbf{m}$
thick FC-70 loading are presented detailing the simulation time and memory requirements, and showing the simulation speed up achievable using the Cloud. The workflow demonstrates that full 3D finite element analysis (FEA) of high-fidelity 3D PMUT array models is possible in less than a few hours enabling designers to evaluate and optimize designs for pressure, receive sensitivity, and bandwidth for pulse-echo applications, reducing the time and costs of prototyping.