Al0.8Sc0.2N film-based BAW filters using transfer process for Wi-Fi6 applications

Abstract

With the emergence of fifth-generation communication systems, filters with bandwidth (BW) >5% and center frequency >4 GHz are in urgent need. This work presents film bulk acoustic resonators (FBARs) and bulk acoustic wave (BAW) filters based on Al0.8Sc0.2N films. To obtain a better quality AlScN film, we deposited AlScN by physical vaper deposition method on metal-organic chemical vapor deposition developed AlN seed, which was deposited directly on a Si (111) substrate. Using film transfer technology combined with adopting different FBAR structures, filter topology circuits, and external circuits, a BAW filter with a minimum insertion loss of 1.819 dB, a center frequency of 5.56 GHz, a −3 dB BW of 599 MHz, and an out-of-band suppression of at least 35 dB is fabricated and presented in this work.