Entwicklung von Al(1-x)Sc(x)N-basierten BAW-Komponenten für breitbandige Mobilfunkfilter

Description

BAW resonators meet the critical requirements necessary for mobile communication and offer highly selective filter applications. Nevertheless, wide bandwidth frequency bands pose a challenge for modern BAW technology. In this work, mirror-type BAW resonators comprising AlN with high Sc concentrations up to 35 at.- % and advanced BAW concepts were investigated. It was possible to develop an optimized process sequence with high Q and high-piezoelectric AlScN layers. In addition, the optimized thin film was integrated into BAW resonators and optimized with respect to improved bandwidth and high Q-factor using proper design methods. Finally, the optimized AlScN-based resonators were used to demonstrate the performance in purely acoustic BAW filters for critical frequencies up to 5 GHz. The improvement of the material and the compilation of a material data set also offered new possibilities to investigate advanced filter concepts like acoustically coupled resonators, a reconfigurable approach and the application of novel LC BAW hybrid filter topologies. In conclusion, the developed resonators and methods push the application of high-coupling AlScN for improved and advanced BAW technologies, which are capable of meeting the growing demands on wide bandwidth filter technologies.