Ultrathin dielectrics, oxides and oxynitrides were grown using microwave afterglow oxygen and N2O plasma at low temperature. N2O plasma annealing and pretreatment improved the breakdown properties of O2 plasma oxides. From secondary ion mass spectroscopy (SIMS) analysis, nitrogen was found to be incorporated into oxides effectively by this low-temperature method. Nitrogen content was highest at the oxide surface and decreased toward the oxide/Si interface. This indicates a nitridation mechanism different from the conventional N2O gas annealing or oxidation processes. The relationships among interface state densities, tunneling current and nitrogen profiles were also investigated by C-V and I-V measurements.

Microwave afterglow plasma oxidation at a low temperature (600 °C ) and rapid thermal annealing (RTA) were combined to grow high quality ultra-thin dielectrics. This new approach has a low thermal budget. The mid-gap interface state density of oxides pretreated in N 2 0 plasma was decreased to about 5 X 1010 cm-2 eV-1 after rapid thermal annealing at 950 °C. It was found that RTA is very effective for relieving the oxide stress and reducing the interface state density. Nitrogen incorporated in oxides by the N 2 0 plasma pretreatment of the Si surface helped to reduce the interface state density. Microstructures of ultra-thin oxide grown by microwave afterglow oxidation with or without RTA were revealed by extended-X-ray-absorption-finestructure (EXAFS) and X-ray photoelectron spectroscopy (XPS) analysis.