Piezoelectric aluminum nitride films, 1.4 - 6.2 mm thick, have been grown on z-cut Al2O3 substrates by reactive radio frequency sputtering at 180 °C. The films were clear, uniform, stress-free and highly adhesive to the substrate. Surface acoustic wave (SAW) delay lines with harmonic modes operating at frequencies up to about 2.4 GHz were obtained just using conventional optical lithography at 7.5 ìm line width resolution. The phase velocity and the electromechanical coupling factor of SAWs propagating along zx-Al2O3 /AlN and zy-Al2O3/AlN structures were investigated and found in good agreement with the theoretical predictions. The AlN/Al2O3 first order temperature coefficient of frequency was estimated for different film thickness to wavelength ratio values and temperature compensated SAW delay line was obtained.
Gigahertz-band electroacoustic devices based on AlN thick films sputtered on Al2O3 at low temperature
Caliendo C
2003
Abstract
Piezoelectric aluminum nitride films, 1.4 - 6.2 mm thick, have been grown on z-cut Al2O3 substrates by reactive radio frequency sputtering at 180 °C. The films were clear, uniform, stress-free and highly adhesive to the substrate. Surface acoustic wave (SAW) delay lines with harmonic modes operating at frequencies up to about 2.4 GHz were obtained just using conventional optical lithography at 7.5 ìm line width resolution. The phase velocity and the electromechanical coupling factor of SAWs propagating along zx-Al2O3 /AlN and zy-Al2O3/AlN structures were investigated and found in good agreement with the theoretical predictions. The AlN/Al2O3 first order temperature coefficient of frequency was estimated for different film thickness to wavelength ratio values and temperature compensated SAW delay line was obtained.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
