Scandium doped aluminium nitride (ScAlN) gained much attention during last years, since its piezoelectric response is much enlarged as compared to pure AlN films. Above 30% Sc the films are of high interest for piezoMEMS sensing and actuation, ultrasound generation, as well as energy harvesting applications. In this work, piezo-performance uniformity maps are presented for 20% and 33% Sc containing films, sputter deposited on 200-mm wafers. Furthermore, we employ a new method to determine the electro-mechanical coupling k t 2 . Coupling results for various Sc/(Sc+Al) concentration (0, 6, 20, 26, 33%) are shown. In addition, the dielectric constant ε r and dielectric loss tanδ, and the transversal and the longitudinal piezoelectric coefficients, e 31,f and d 33,f , were measured. The wafers show a high with-in-wafer uniformity (1s uniformity < 2% for Sc 20 Al 80 N and < 1% for Sc 33 Al 67 N). The highest coupling k t 2 = 21.2% was achieved for a 33% Sc film. The presented Al–Sc property–uniformity maps provide a good foundation for ScAlN based MEMS device design and manufacturing.
|Conference||2019 IEEE International Ultrasonics Symposium, IUS 2019|
|Period||6/10/19 → 9/10/19|