A mm-Wave Trilayer AlN/ScAlN/AlN Higher Order Mode FBAR
Suhyun Nam, Wenhao Peng, Ping Wang, Ding Wang, Zetian Mi, Amir Mortazawi
Abstract
Modern wireless communication systems are increasingly complex with greater functionality and impose new challenges on the radio frequency (RF) front-end design. One of the major challenges involves filtering beyond the sub-6-GHz regime with increased fractional bandwidth (FBW). To the best of our knowledge, this work presents the first demonstration of a film bulk acoustic wave resonator (FBAR) with a composite ferroelectric/piezoelectric transduction layer (consisting of AlN–Sc0.3Al0.7N–AlN) that is capable of selectively operating at higher order resonant modes without compromising <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k_{t}^{2}$ </tex-math></inline-formula> for applications in the millimeter wave (mm-Wave) spectrum. The resonator exhibits a fundamental mode at GHz with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k_{t}^{2}$ </tex-math></inline-formula> of 5.2% but can switch to a higher order response at 31 GHz by reversing the polarization direction in the ScAlN layer ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k_{t}^{2}$ </tex-math></inline-formula> of 5.5%).