Title :
Piezoelectric materials for BAW resonators and filters
Author :
Löbl, H.P. ; Klee, M. ; Metzmacher, C. ; Brand, W. ; Milsom, R. ; Lok, P. ; van Straten, F.
Author_Institution :
Philips Res. Lab., Aachen, Germany
Abstract :
Thin film bulk acoustic wave (BAW) resonators and filters are appropriate for mobile communication systems operating at high frequencies between 0.5 and 10 GHz. c-axis orientated AlN films are used for medium bandwidth applications. Electromechanical coupling factors k t of 0.25±0.03, which are close to the bulk data, have been found in AlN thin films using optimum sputter conditions. The correlation between kt and AlN film orientation is discussed. Resonator Q values of approx. 450 are reported at 2.6 GHz and a Q of 250 was realized at 9.2 GHz. A physical model is shown to accurately predict the frequency responses of BAW resonators and band-pass filters. For wide bandwidth applications PbZrxTi1-xO3 (PZT) films are investigated. They exhibit large coupling coefficients
Keywords :
Q-factor; acoustic filters; acoustic resonators; aluminium compounds; band-pass filters; bulk acoustic wave devices; lead compounds; piezoelectric thin films; sputtered coatings; 0.5 to 10 GHz; AlN; AlN thin film; PZT; PZT thin film; PbZrO3TiO3; Q-factor; band-pass filter; bulk acoustic wave filter; bulk acoustic wave resonator; c-axis orientation; electromechanical coupling coefficient; frequency response; mobile communication system; piezoelectric material; sputter deposition; Acoustic waves; Bandwidth; Film bulk acoustic resonators; Frequency; Mobile communication; Piezoelectric films; Piezoelectric materials; Predictive models; Resonator filters; Sputtering;
Conference_Titel :
Ultrasonics Symposium, 2001 IEEE
Conference_Location :
Atlanta, GA
Print_ISBN :
0-7803-7177-1
DOI :
10.1109/ULTSYM.2001.991845
