Title :
12E-5 Fabrication and Properties of High-Q AlN/SiO2 Composite TFBAR´s for above IC Oscillators
Author :
Artieda, A. ; Muralt, P.
Author_Institution :
Ceramics Lab., Lausanne
Abstract :
High-Q, bulk acoustic wave composite resonators based on a symmetric layer sequence of SiO2-AlN-SiO2 sandwiched between electrodes have been developed. Acoustic isolation was achieved by means of deep silicon etching to obtain membrane type TFBAR´s. Three different device versions were investigated. The SiO2 film thicknesses was varied (70 nm, 310 nm and 770 nm) while the piezoelectric A1N film had a constant thickness of 1.2 mum. The sputter deposited AlN film grown on the amorphous, sputter deposited SiO2 layer exhibited a d33,f of 4.0 pm/V. Experimental results of quality factors (Q) and coupling coefficients (kt 2) are in agreement with finite element calculations. A Q of 2000 is observed for the first harmonic of the 310 nm oxide devices. The most intense resonance of the 770 nm oxide device is the third harmonic reaching Q factors of 1450. The temperature drift reveals the impact of the SiO2 layers, which is more pronounced on the first harmonic.
Keywords :
Q-factor; acoustic resonators; aluminium compounds; composite materials; finite element analysis; harmonic generation; silicon; sputter deposition; Q factor; SiO2-AlN-SiO2; acoustic isolation; acoustic wave composite resonators; deep silicon etching; film thickness; finite element calculation; sputter deposition; third harmonic generation; Acoustic devices; Acoustic waves; Electrodes; Fabrication; Film bulk acoustic resonators; Oscillators; Piezoelectric films; Q factor; Silicon; Sputter etching;
Conference_Titel :
Ultrasonics Symposium, 2007. IEEE
Conference_Location :
New York, NY
Print_ISBN :
978-1-4244-1384-3
Electronic_ISBN :
1051-0117
DOI :
10.1109/ULTSYM.2007.294
