AlN driven microcantilever actuators: modeling, fabrication, characterization

The subject of this paper is the use of aluminum nitride (AlN) as an actuation layer in MEMS/MOEMS systems. This material shows a good piezoelectric properties related to deposition conditions. AlN is a promising candidate for the acoustic wave devices, MEMS applications and sensors what have been already proposed. Up to now, AlN is still a technological challenge and many of its micromechanical and piezoelectric properties are not precisely described. That is why our study has been focused on the determination of the material parameters like Young's modulus, residual thin film stress, piezoelectric coefficient d31 and mechanical behaviour of especially designed cantilevers. To ensure the optimum design, functionality and reliability of those actuators the theoretical solution and the numerical simulations of mechanical performance by the Finite Element Method (FEM) were performed. The created model of device takes into account multiple film stacking. For the characterization it was chosen a full-field optical technique applied in a multifunctional interferometric platform. Proposed set-up performs the measurement in static and dynamic regimes with nanometer sensitivity and high spatial resolution. The hybrid method of analysis combining the experimental and numerical results has been used to better understand the properties of these microdevices, facilitate their designing and to optimize their technological process. The optimum goal is a developing of the high quality and reliable AlN-driven cantilevers for use in MEMS/MOEMS.