Effects of interstitial oxygen defects at HfOxNy/Si interface on electrical characteristics of MOS devices

Effects of the defects at high-n dielectric/Si interface on the electrical characteristics of MOS devices are important issues. To study these issues, a low defect (denuded zone) at Si surface was formed by a high-temperature annealing in hydrogen atmosphere in this paper. Our results reveal that HfOxNy demonstrates significant improvement on the electrical properties of MOS devices due to its low amount of the interstitial oxygen [O-i] and the crystal-originated particles defects as well as small surface roughness at HfOxNy/Si interface. The current-conduction mechanism of the HfOxNy film at the low- and high-electrical field and high-temperature (T > 100 degrees C) is dominated by Schottky emission and Frenkel-Poole (FP) emission, respectively. The trap energy level involved in FP conduction was estimated to be around 0.5 eV Reduced gate leakage current, stress-induced leakage current and defect generation rate, attributable to the reduction of defects at HfOxNy/Si interface, were observed for devices with denuded zone. The variable rise and fall time bipolar-pulse-induced current technique was used to determine the energy distribution of interface trap density (D-it). The results exhibit that relatively low Dit can be attributed to the reduction of defects at Si surface. By using denuded zone at the Si surface, HfOxNy. has demonstrated significant improvement on electrical properties as compared to SiOxNy.