ACOUSTIC WAVE RESONATOR USING MULTILAYER TRANSDUCTION MATERIALS WITH LOW/ZERO COUPLING BORDER REGION

• Main Authors: Schaefer, Michael, Rothemund, Ralph, Koohi, Milad Zolfagharloo, Tag, Andreas, Sadhu, Jyothi Swaroop
• Format: Patent
• Language: English
• Published: 13.07.2023
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS

The present disclosure relates to a Bulk Acoustic Wave (BAW) resonator, which includes a bottom electrode, a top electrode structure, and a multilayer transduction structure sandwiched therebetween. Herein, the multilayer transduction structure is composed of multiple transduction layers, at least one of which is formed of a ferroelectric material with a box-shape polarization-electric field curve. Each transduction layer includes a transduction border (BO) portion positioned at a periphery of a corresponding transduction layer and a transduction central portion surrounded by the transduction BO portion. A combination of all transduction BO portions forms a transduction BO section of the multilayer transduction structure, and a combination of all transduction central portions forms a transduction central section of the multilayer transduction structure. An electromechanical coupling coefficient of the transduction BO section is less than an electromechanical coupling coefficient of the transduction central section.