Growth and characterization of c-axis inclined AlN films for shear wave devices

This paper reports on the growth and the characterization of c-axis inclined AlN thin films synthesized at low temperature. These films are of significant interest for shear wave generation in the shear mode resonators that operate as a liquid sensor. AlN films were deposited on 3 inch (1 0 0) silicon wafers using an RF-magnetron sputtering planar system. A SiO2 buffer layer was used to promote the c-axis inclination. This c-axis inclination of AlN thin films was investigated using scanning electronic microscopy and x-ray diffraction in θ/2θ, χ and rocking curve scan modes. These analyses showed up to 10° of c-axis inclination in our planar charging system at low temperature. An AlN film thickness variation of about ±5% was recorded. In this study, we only presented the effect of the pressure on the c-axis inclination of AlN films. A discussion about the effect of this parameter and the role of the SiO2 buffer layer is reported. A shear mode acoustic wave device based on the deposited c-axis inclined AlN film was constructed and showed a phase velocity of 5832 m s−1. This value of shear velocity is discussed.