Abstract: A micro-acoustic wave device is proposed for application in ultrahigh frequency range. The device uses a thin film piezoelectric material stacked on a carrier substrate. Additionally, a material is embedded between carrier substrate and piezoelectric thin film that decouples the acoustic of these layers. With this approach it is possible to achieve very high Q factor even for longitudinal waves, which are required for high frequency applications.

Abstract: In at least one embodiment, the SAW device comprises a carrier substrate (1), a piezoelectric thin-film (2) on the carrier substrate, an interdigital electrode structure (3) on the piezoelectric thin-film and a layer stack (4) of waveguide layers. The layer stack is arranged between the carrier substrate and the piezoelectric thin-film. The layer stack comprises a first waveguide layer (41) and second waveguide layer (42), wherein a sound velocity in the first waveguide layer is at least 1.5 times as great as in the second waveguide layer. The device may comprise a temperature compensating layer (5) and a trap rich layer (6) between the layer stack and the carrier substrate.