Thin-Film Bulk Acoustic Wave Resonator Floating Above CMOS Substrate

A thin-film bulk acoustic wave resonator (FBAR) having a floating, 3-D structure above a CMOS substrate is presented. The integration of the FBAR to the CMOS substrate is performed with independence of FBAR or CMOS fabrication technologies. Wafer-level transfer is carried out to obtain a suspended FBAR above CMOS substrates of different technologies, whose resonant frequency is found in the 2.4 GHz band. The electrical interconnection between the FBAR and CMOS is provided by at least two conducting posts, which at the same time offer mechanical support to the resonator's structure. Experimental characterization results and Q-factor comparison with conventional FBAR technologies are discussed.