An ultra-thin, high reliability oxide-nitride-oxide (ONO) gate dielectric was formed using low pressure oxidation and chemical vapor deposition. A sub-0.25 m device with high performance was fabricated whose gate dielectric reliability was studied using both Fowler-Nordheim tunneling stress and hot carrier aging. The results from both techniques demonstrate that the device lifetime is longer than 100 years. Auger spectroscopy shows that there is about 9 atomic % nitrogen at the SiO 2 /Si interface. However, no transconductance degradation is observed.