Metal–Organic Chemical Vapor Deposition-Grown AlScN for Microelectromechanical-Based Acoustic Filter Applications

Abstract

AlScN films are produced in a commercial metal–organic chemical vapor deposition (MOCVD) system modified to low-vapor-pressure Sc metal–organic precursors. Growth conditions are optimized for surface morphology, film stress, and piezoelectric coefficient across a range of compositions. Epitaxial structures are designed to eliminate internal tensile stresses that develop during the film growth as well as prevent surface adatom interactions unique to the MOCVD process. From these films, wide-bandwidth resonators and filters are manufactured using a novel microelectromechanical-based bulk acoustic wave (BAW) transfer process. When tested on-wafer, resonators exhibit a (Formula presented.) of 10.5%, and a (Formula presented.) value of 1400. Ladder-type RF filters using these resonators are fabricated at 6.2 GHz and show improved performance over filters fabricated using physical vapor deposition-deposited AlScN.