ScxAl1-xN piezoelectric film grown at room temperature

In order to overcome the shortcomings of AlN piezoelectric thin films such as low piezoelectric coefficient and low electromechanical coupling coefficientrealize, ScxAl1-xN thin films with CMOS process compatibility were prepared by pulsed DC reactive magnetron sputtering. High performance ScxAl1-xN piezoelectric thin films were prepared at room temperature by optimizing process parameters including power, gas flow ratio, substrate temperature, seed layers and so on. The phase separation phenomenon was investigated through XRD, TEM, and XPS. We found that the phase separation is related to the appearance of rocksalt ScN and led to the degeneration of film properties. The existence of ScN phase is a key factor affecting the performance of ScxAl1-xN. The results show that the piezoelectric constant d(33) of ScAlN film achieved 27.5 pC/N and the full width at half maximum (FWHM) of the rocking curve is 1.9 degrees in room temperature when the content of Sc reaches 35%.