Materials for bulk acoustic wave (BAW) resonators and filters

Shear mode coupling and properties dispersion in 8GHz range AlN thin film bulk acoustic wave (BAW) resonator

“…5) should correspond to a range of c-planes tilt of ∼ 4.5-8.0°. It must be noticed that recent work from the authors demonstrated that the observed tilt in AlN grains does not correspond to the actual tilt of the cplanes [10], as previously observed by Löbl et al [11].…”

Two-step reactive sputtering of piezoelectric AlN thin films

“…Piezoelectric aluminum nitride (AlN) thin films have received a lot of attention for applications to high-frequency (GHz) acoustic wave devices, especially thin film bulk acoustic resonator (FBAR), for the last two decades [1][2][3][4][5][6][7][8][9]. The simplest configuration of such an FBAR is an AlN thin film sandwiched between two metal electrodes.…”

Synthesis of c-Axis Inclined AlN Films in an Off-Center System for Shear Wave Devices

“…posed that, in the case of the following direction of the impinging source material with a small angle, the (002) plane was almost always perpendicular to the normal of the surface, and the column inclination was due to the shadowing effect. 18 Martin suggested a second growth mechanism, according to which the (002) planes always grew in a direction perpendicular to the substrate in order to minimize the surface energy and the inclined columns were a result of the oblique incidence. 19 In our case, the grains are quasivertical (inclination of 0°to 2°) to the film surface at a low pressure of 0.5 Pa.…”