P1H-6 Picosecond Ultrasonics as a Helpful Technique for Introducing a New Electrode Material in BAW Technology: The Iridium Case

We present picosecond ultrasonic characterizations on e-beam evaporated Ir thin films and on AlN films deposited by pulsed DC reactive sputtering on Ir. Picosecond ultrasonics is an optical technique which uses ultrashort laser pulses to generate and detect very short acoustic pulses. We first investigate the properties of the Ir films by measuring samples of various thicknesses and deposition parameters. It permits to extract the longitudinal sound velocity, the acoustic impedance and the acoustic losses in the Ir electrode. Second, we focus on AlN on Ir films. We measure the thickness and the sound velocity of an AlN thin layer deposited on an Ir electrode. This work illustrates how useful the picosecond ultrasonic technique can be for introducing a new material in bulk acoustic wave technology.