Hybrid BAW/SAW AlN and AlScN thin film resonator

High Quality Factor Hybrid SAW/BAW Resonators

“…Additionally, many works focused on delay lines. Thus, so far, no work on hybrid SAW/BAW resonators has reported an experimental quality factor [2][3][4]. In this work, we introduce an optimized fabrication process allowing to define transducers with a periodicity down to 1 µm and thicknesses up to 2 µm, and demonstrate that clean and sharp resonances can indeed be achieved at the theoretically expected frequencies.…”

“…The evaluated electromechanical coupling factors reach up to 2 % for both modes. Future work will aim at further improving performances in terms of electromechanical coupling and quality factors by increasing the transducers aspect ratios and replacing AlN by AlScN as suggested in [2,5].…”

Film bulk acoustic resonators (FBARs) as biosensors: A review

“…AlN has high acoustic velocity and is biocompatible with high chemical inertness, particularly suitable for biosensor applications, but its piezoelectric constant and coupling coefficient are not as good as those of ZnO. To this end, a new type of piezoelectric material AlScN doped with scandium up to 40% has been developed, which showed much improved effective electromechanical coupling coefficient by 300 400% (Akiyama et al 2009;Wang et al 2014b) and has been used to fabricate FBARs with coupling coefficient of the device up to 3.8% achieved (Pashchenko et al 2016). Additionally, the thickness of piezoelectric films can be optimised depending on the electrode materials has been reported (Choi et al 2014).…”

Scandium-Doped Aluminum Nitride for Acoustic Wave Resonators, Filters, and Ferroelectric Memory Applications

“…Tuning these sputter parameters allows one to optimize the film microstructure and morphology as well as the stress to meet device design requirements. , Additionally, the typical growth temperature of sputter deposition is below 400 °C, satisfying the requirement of the CMOS process. Moreover, the performance of AlScN-based thin film acoustic wave devices has been extensively evaluated. − For example, Wang et al reported that Al 0.88 Sc 0.12 N-based laterally coupled alternating thickness (LCAT) mode resonators operate at above 3 GHz with an enhanced effective coupling coefficient ( k eff 2 ) of 12.1%, showing that a higher bandwidth can be achieved by using AlScN . More recently, Fichtner et al reported the ferroelectric properties of AlScN in 2019 .…”