Super High-Frequency Scandium Aluminum Nitride Crystalline Film Bulk Acoustic Resonators Mingyo Park Jialin Wang Rytis Dargis Department of Electrical and Computer Department of Electrical and Computer IQE Plc Engineering Engineering Greensboro, NC, USA Georgia Institute of Technology Georgia Institute of Technology
[email protected] Atlanta, GA, USA Atlanta, GA, USA
[email protected] [email protected] Azadeh Ansari Andrew Clark Department of Electrical and Computer IQE Plc Engineering Greensboro, NC, USA Georgia Institute of Technology
[email protected] Atlanta, Ga, USA
[email protected] Abstract—This work presents promising results of overtone thickness resonance modes of film bulk acoustic resonators Ti/Au TiScAlN/Au Mo cREO Si (FBARs) operating at Ku band, traditionally perceived Top Electrode unachievable by acoustic devices. We take advantage of the epitaxial growth of the bottom metal electrode, as well as the Epi-Sc0.12Al0.88N piezoelectric layer to improve thin-film crystal quality and hence Piezo-layer Bottom Contact quality factor (Q). This work is the first demonstration of a multi- EpBottomi-Mo Electrode GHz FBAR realized on single-crystalline Sc0.12Al0.88N/Mo stack. Buffer Layer cREO Keywords—5G mobile communication, Films bulk acoustic (a) (a) (b) (b) resonators, Acoustic filters, Single crystalline, Scandium aluminum nitride, Epitaxial molybdenum, Molecular beam Fig.1. (a) SEM imag of the fabricated Sc0.12Al0.88N apodized FBAR. (b) epitaxy. Resonant stack with a total stack tickness of ~550 nm. I. INTRODUCTION the crystallinity of the metal layer for the bottom electrodes Emerging next-generation wireless communication devices plays an important role in supporting the formation of a well- call for high-performance filters that operate at 3-30 GHz oriented piezoelectric layer with surface uniformity [7].