The preparation of ScAlN(002) alloy thin films deposited on Si(100) substrates by DC reactive magnetron sputtering

Abstract

Scandium aluminum nitride (ScAlN) alloy thin films were deposited on (100) silicon substrates by DC reactive magnetron sputtering method using a scandium aluminum alloy (Sc_0.06Al_0.94) target. The influences of N₂/Ar-flow ratio, substrate temperature, sputtering power and sputtering pressure on the film’s crystal orientation and surface morphology were investigated systematically. The c-axis preferred orientation degree changes obviously, firstly increasing to the maximum and then decreasing, with increasing each of the sputtering parameters. Meanwhile, the surface morphology of ScAlN films performs a similar variation. Then, the relationship between the crystal orientation and piezoelectric response is determined. Finally, it is demonstrated that highly c-axis oriented ScAlN thin films, with FWHM value of the rocking curve of 2.9°, RMS roughness of 2.612 nm and piezoelectric constant d₃₃ of 8.9 pC/N, can be obtained with a N₂/Ar-flow ratio of 3.3:7, a substrate temperature of 650 °C, a sputtering power of 130 W and a sputtering pressure of 0.5 Pa.