Optimization and scaling limit forecast of nitrided gate oxide using an equivalent nitride/oxide (N/O) stack model

A semi-empirical model was developed to calculate the equivalent oxide thickness (EOT) and leakage current of nitrided gate oxide by hypothetically dividing the nitrided oxide into a nitride/oxide (N/O) stack. The calculations agree well with the experimental data (R² > 0.99) for various nitrided oxides with EOT ranging from 12 to 23 Å. A model-based strategy for the optimization of nitrided oxide is presented and demonstrated by a nitrided oxide sample which meets both the EOT and leakage current requirements of ITRS 65-nm low standby power (LSTP) technology and shows no electron mobility degradation. The model forecasts that a nitrogen concentration of 20% approximately the maximum from Oxide nitridation processes - satisfies the ITRS requirements for production until Year 2007. The production afterwards will require alternative dielectrics such as N/O stack or high-k materials for greater leakage current reductions.