Comparison of the structural properties and residual stress of AlN films deposited by dc magnetron sputtering and high power impulse magnetron sputtering at different working pressures

Abstract

Aluminium nitride (AlN) films were deposited by dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) on (100) oriented silicon (Si) substrates, in Ar–N2 gas mixture, at different working pressures. The films were characterized using X-ray diffraction (XRD), profilometer and transmission electron microscopy (TEM). The effect of the sputtering pressure on the structure, the residual stress and the deposition rate of AlN films deposited by the two processes (dcMS and HiPIMS) was investigated. It was found that the deposition rate is always lower in HiPIMS compared to dcMS. The AlN films are textured along (002) direction in both cases of dcMS and HiPIMS as it is indicated by XRD measurements, with residual stresses which are more important in the case of films deposited by HiMIPS. These residual stresses decrease with the sputtering pressure increase, especially in the case of the films deposited by HiPIMS. TEM analyses have shown a local epitaxial growth of AlN on the Si substrate which would favour thermal evacuation improvement of AlN as thermal interface material.