The goal of this work is to design and fabricate inertial sensors based on c-axis oriented AlN polycrystalline thin films. AlN is a post-CMOS compatible piezoelectric material widely used for acoustic resonators, such Bulk Acoustic Wave (BAW) and Lamb Wave Resonators (LWR). In this work we develop the design techniques necessary to obtain inertial sensors with AlN thin film technology. Being able to use AlN as structural material for both acoustic wave resonator and sensing elements is key to achieve the three level integration of RF-MEMS components, sensing elements and CMOS in the same chip. Using AlN as integration platform is particularly suitable for large consumer emerging markets where production costs are the major factor that determine a product success. As this work shows analytically and experimentally, there are some fundamental constraints that limit the ultimate sensitivity of piezoelectric sensors based on resonating beam structures. Although the limitations of the structures here considered cannot achieve tactical grade sensitivities, this research proves that it is possible to achieve performances close to those required by large consumer electronics. This work proves that AlN based platforms can be an valuable opportunity for future developments in IMU and in general for MEMS integrated solutions.
Project end date: 02/01/12