High-performance FBAR humidity sensor based on the PI film as the multifunctional layer

For achieving the high-performance film bulk acoustic resonator (FBAR) humidity sensor with MEMS process reliability, we proposed a novel FBAR design based on the polyimide film (PI-FBAR). The PI film was employed to provide multifunction for the structural supporting and humidity sensing simultaneously, which was first used in the back-trench FBAR. Due to its flexible and low acoustic impedance characters, it can provide adequate structural...