Growth and characterization of aluminium nitride thin films for piezoelectric devices

The authors describe research on aluminium nitride (AlN) for use in thin-film microwave acoustic devices. The goal of the research here is to obtain high-quality material on Si, GaAs, and other substrates for subsequent device fabrication. Particular attention is given to research in film growth conducted in ultrahigh vacuum systems with a number of RF magnetron target configurations in order to provide an essentially water- and oxygen-free environment. In addition, commercial manufacturing feasibility studies are being conducted in an automated commercial magnetron sputtering system using 3-, 4-, and 6-in wafers. Measurements were made on fundamental-mode resonators and low-mode-number composite structures to determine the real or effective coupling coefficient of the material