Power Durability Evaluation of Higher-Order Mode Polarization-Inverted ScAlN Thin Film Resonators

A number of RF base stations are required for 5G communication compared with 4G because of their high frequency operation. One of the solutions to minimize the RF base stations is to replace the current large dielectric resonator filters with BAW filters. The power durability of 1 W is sufficient for smartphones. However, the power durability of tens of watts is required for RF base stations. High n-th order resonance operation is available for n-th polarization-inverted multilayers. n-Fold thick and n-fold large area (due to 50 Ω matching) in polarization-inverted multilayered resonator enables BAW devices to improve power durability. In this study, we fabricated polarization-inverted ScAlN 1-layer and 4-layer thin films solidly mounted resonator (SMR). The power durability of these devices was compared. The power durability of the 4-layered ScAlN film of 180 mW was 6-times higher than that of the 1-layered ScAlN film of 30 mW.