摘要
Effects of the defects at high-K 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 HfO <sub>x</sub> N <sub>y</sub> demonstrates significant improvement on the electrical properties of MOS devices due to its low amount of the interstitial oxygen [O <sub>i</sub> ] and the crystal-originated particles defects as well as small surface roughness at HfO <sub>x</sub> N <sub>y</sub> /Si interface. The current-conduction mechanism of the HfO <sub>x</sub> N <sub>y</sub> film at the low- and high-electrical field and high-temperature (T > 100°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 HfO <sub>x</sub> N <sub>y</sub> /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 <sub>it</sub> ). The results exhibit that relatively low D <sub>it</sub> can be attributed to the reduction of defects at Si surface. By using denuded zone at the Si surface, HfO <sub>x</sub> N <sub>y</sub> has demonstrated significant improvement on electrical properties as compared to SiO <sub>x</sub> N <sub>y</sub> . © 2005 IEEE.