Structural and Piezoelectric Properties of DC-Sputtered AlN Films Deposited on Different Si-Based Substrates

We study the DC magnetron sputtering deposition of AlN on different substrates: (100) resistive Si, Si3N4 on Si and SiO2 on Si. The growth conditions of such films have been analysed to obtain the best structural and piezoelectric properties on each substrate. We show that, while AlN follows a columnar growth from the early stage of deposition on Si, the non-crystalline nature of Si3N4 and SiO2 induces an amorphous early growth stage on such substrates. Despite this structural difference, high performances have been obtained by AlN delay lines realised on both Si3N4/Si and pure resistive Si, providing further flexibility in the development of Si-based technological applications.