Effect of substrate temperature and bias voltage on the crystallite orientation in RF magnetron sputtered AlN thin films

Abstract The crystal orientation and residual stress of AlN thin films were investigated using X-ray diffraction and substrate curvature method. The AlN films were deposited on Si(100) by RF magnetron sputtering in a mixed plasma of argon and nitrogen under various substrate negative bias Vs (up to − 100 V) and deposition temperature Ts up to 800 °C. The results show that lower temperature and moderate bias favor the formation of (002) plane parallel to the substrate surface. On the contrary, strong biasing beyond − 75 V and deposition temperature higher than 400 °C lead to the growth of (100) plane. At the same time nanoindentation hardness and compressive stress measured by substrate curvature method showed significant enhancement with substrate bias and temperature. The biased samples develop compressive stress while unbiased samples exhibit tensile or compressive stress depending on plasma power and temperature. The relationships between deposition conditions and crystallographic orientation of the films are discussed in terms of surface energy minimization and ion bombardment effects.