Electrical characteristics of ultrathin oxynitride gate dielectric prepared by rapid thermal oxidation of Si in N2O

This letter presents a unique process to grow high quality ultrathin (∼60 A) gate dielectrics using N2O (nitrous oxide) gas. Compared with conventional rapid thermally grown oxide in the O2, the new oxynitride dielectrics show very large charge‐to‐breakdown (at +50 mA/cm2, 850 C/cm2 for oxynitride compared to 95 C/cm2 for the control thermal oxide) and less charge trapping under constant current stress. Significantly reduced interface state generation was also observed under constant current stress and x‐ray radiation. A secondary‐ion mass spectroscopy depth profile indicates a nitrogen‐rich layer at the Si/SiO2 interface, which can explain the improved integrity of oxynitride dielectric.