Sol-gel derived bulk acoustic wave devices for cellular communication applications

Abstract

This paper reports recent advances obtained with bulk acoustic wave resonators fabricated using sol-gel thin €ilm transducers. Acoustic resonances in the uhflower microwave region have been observed with unloaded Q values of the order of 800-1000. The resonator characteristics were found to be improved with poling. The relative permittivity of the films were observed to decrease with frequency, an effect we believe is due to relaxation associated with domain switching. On-wafer input impedance measurements were carried out using Cascade Microtech high frequency probes in conjunction with an HP85 1OC Network Analyzer. The effects of parasitics at high frequencies were minimized using an on-wafer calibration scheme which was verified using impedance standards supplied by the probe manufacturer and also with verification elements realized on the sol-gel films themselves.

Fabrication of a 3.5-GHz Solidly Mounted Resonator by Using an AlScN Piezoelectric Thin Film

“…There are many types of filters; among them, the acoustic wave filter is of the most concern. The acoustic wave filters can be divided into surface acoustic wave (SAW) filters [1] and bulk acoustic wave (BAW) filters [2,3]. Compared with surface acoustic wave filters, bulk acoustic wave filters can more easily achieve a high frequency range (>2 GHz), and have a smaller volume, excellent device characteristics, higher power endurance and wider application frequency range, among other advantages, which make the bulk acoustic wave filters highly valued in future mobile communication applications.…”