Stress Relaxation in Reactively Sputter-Deposited TiOxNy Films

Abstract

Internal stress in TiOxNy films sputter-deposited on negatively biased silicon wafers in an Ar-N2-O2 gas mixture was measured by a substrate deflection method. X-ray diffraction (XRD), Auger electron spectroscopy (AES) and field emission scanning electron microscopy (FE-SEM) were also employed for studying structural features of the films. TiN films deposited under an oxygen-free condition have high compressive stress (7.8 GPa for bias 90 V), and the compressive stress in TiOxNy films decreases markedly with increasing oxygen concentration and becomes slightly tensile at an oxygen flow ratio of more than 1%. It is suggested that the relaxation of the compressive stress is due to the decrease in the lattice parameter caused by substituting nitrogen atoms with oxygen ones and the formation of an amorphous phase in the TiOxNy films.