BULK ACOUSTIC WAVE RESONATORS HAVING LOW ATOMIC WEIGHT METAL ELECTRODES

• Main Authors: Bradley, Paul, Larson, III, John D
• Format: Patent
• Language: English
• Published: 24.10.2019
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS

A BAW resonator comprises: a substrate comprising an acoustic reflector; a first electrode disposed over the acoustic reflector, and comprising a first electrode layer comprising a comparatively high acoustic impedance material, and a second electrode layer comprising a comparatively low acoustic impedance; a piezoelectric layer disposed over the second electrode layer; and a second electrode disposed over the piezoelectric layer, and comprising a third electrode layer comprising the low acoustic impedance, and a fourth electrode layer comprising the comparatively high acoustic impedance material and being disposed directly on the piezoelectric layer. A total thickness of an acoustic stack of the BAW resonator is approximately λ/2, where λ is a wavelength corresponding to a thickness extensional resonance frequency of the BAW resonator.