AlScN thin films sputtering optimization

Doping aluminium nitride with scandium is one of the recent techniques used to improve piezoelectric performance of thin films in the field of MEMS. Highly dependent on the sputtering parameters, the quality of these films is subject to complex optimization. In this project several depositions have been done in order to determine the best parameters for sputtering AlScN thin films. Residual stress, rocking curves have been measured, surface and cross sections of the film have been studied. It has been found that 20 sccm of Argon and 30 sccm of gas flow with a bias power setpoint of 3 W lead to the best results, enabling to reach a FWHM value of 1.69 degrees. Also a link between the bias voltage of the sputtering machine and the FWHM values has been made. Still, final depositions on high resistive and liftoff wafers lead to uneven results, highlighting the difficulties surrounding the sputtering technique and the volatility of its results.