Many novel gate oxidation processes have been developed to meet the ongoing quest for thinner and higher-quality gate dielectric layers. Among these processes, fluorination and nitridation methods have emerged as promising techniques for ultra-large scale integrated circuit (ULSI) technology. Reported data in the literature is presented to show the advantages of these two processes. There are various ways to fabricate fluorinated and oxynitrided SiO 2 films. In this work, fluorination is done by shallow F-ion implantation through polysilicon gate, followed by thermal diffusion into the underlying gate oxide. Oxynitridation is done by a heat treatment in N 2 O gas. The samples are fabricated as lot-splits of the Mitel 1.5 om process.  As background, the mechanisms of generation of oxide trapped charges during hot carrier injection stress are discussed. In this light, the quality of fluorinated and oxynitrided gate-oxides are discussed, in comparison with control oxides. The dissertation also discusses methods used to characterize the electrical properties of oxides. According to the framework of DiMaria et al , gate voltage changes during Fowler-Nordheim stress are sensitive only to trapped charges located outside a tunneling distance from the cathode interface. The dissertation discusses how DiMaria's framework can be applied to obtain information about trapped-charge generated in the bulk oxide and trapped charges generated at or near the SiO 2 interfaces outside or within a tunneling distance from the cathode interface. This technique will be used to do electrical characterization on gate oxides treated by fluorination or oxynitridation.  In this work, oxynitrides show convincingly better performance than the fluorinated and the conventional thermally-grown oxides under positive gate bias Fowler-Nordheim tunnelling injection stress. However, under negative gate bias Fowler-Nordheim tunnelling injection stress, only the lower-temperature oxynitrides show advantages, not the higher-temperature oxynitrides. Channel hot electron injection stress also confirms the feasibility of incorporating oxynitridation into sub-micrometer processes. The application of the developed electrical characterization technique helps to reveal the complex behaviors of charge components induced in gate oxides under Fowler-Nordheim stress.