Fabrication of AlN Films by RF Magnetron Sputtering for Surface Acoustic Wave Applications

Abstract

Highly c-axis oriented AlN films were successfully deposited on SiO 2 /Si and sapphire substrates by RF magnetron sputtering. The optimum deposition conditions are nitrogen gas ratio (N 2 /Ar + N 2 ) of 40%, RF power of 400 W, deposition pressure of 4 mTorr, and substrate temperature of 200 • C. The full width at half maximum intensity of AlN(002) peak of AlN films on SiO 2 /Si and sapphire substrates sputtered at the optimum deposition conditions were about 0.26 • and 0.2 • , respectively. The phase velocity of the fabricated SAW device with AlN/SiO 2 /Si and AlN/sapphire layered structure was estimated to be about 4996 and 5589 m/s, respectively.

Enhanced performance of AlN SAW devices with wave propagation along the 〈11−20〉 direction on c-plane sapphire substrate

“…To our knowledge, the insertion loss of two-port SAW-A resonator is only 8.71 dB, which is more lower than the published result [11,13,[18][19][20]. The excellent insertion loss can be attrabuted to the excellent crystalline quality of AlN film with a low AlN (0 0 2) FWHM value of 0.088° and suitable choice of acoustic wave propagation direction.…”