Design and fabrication of integrated film bulk acoustic resonator and filter on silicon nitride membrane

Abstract

AbstractIn this paper, fully integrated film bulk acoustic resonators (FBARs) and filter have been designed, fabricated, and characterized by using silicon bulk micromachining technology. The fabricated resonator is comprised of aluminum nitride (AlN) piezoelectric material sandwiched by two molybdenum (Mo) electrodes on top of silicon nitride thin membrane. The developed AlN piezoelectric film has 1.9° of FWHM (full width half maximum) of rocking curve and approximately 70 Mpa in tensile stress on top of the Mo electrode. The fabricated FBAR has a quality factor of 1530 in size of 200 × 200 μm2, insertion loss of −0.45 dB, and return loss of −28 dB, respectively. The fabricated FBAR ladder type filter is comprised of 7 resonators with 3 resonators in series and 4 resonators in parallel. It has insertion loss of −3.2 dB and ripple of 0.4 dB in pass band, absolute attenuation of 40 and 50 dB at 1.6–1.875 GHz and 2.110–2.170 GHz, respectively. The size of the fabricated FBAR filter is 1.2 mm × 1.4 mm before packaging and 3 mm × 3 mm after packaging, respectively. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2230–2233, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21905