X-Band Multi-Frequency 30% Compound SCALN Microacustic Resonators and Filters for 5G-Advanced and 6G Applications

SummaryThis paper reports on record-high resonance frequency-quality factor product (f s · Q) figure of merit 30% Sc-doped Aluminum Nitride (ScAlN) Cross-sectional Lamé Mode (CLM) microacustic resonators in the super high frequency (SHF) range, along with outstanding electromechanical coupling-quality factor products ($k_t^2 \cdot Q$). Moreover, for the first time above 5 GHz, ScAlN-based resonators have been arranged to produce first-order passband ladder filters, providing record-wide fractional bandwidth for the microacoustic technology in the same frequency range. The ScAlN piezoelectric material was deposited from a compound casted target on a 200 mm wafer, going into the direction of a foundry-standardized fabrication process for SHF resonators. This first-of-a-kind demonstration paves the way for the synthesis of high-performance commercial filters for communication in the 5G era and beyond, where SHF operation and wide carrier bandwidth are fundamental requirements.