A series of investigations have been conducted into the properties of N2O silicon oxynitride gate dielectrics, and the various methods of their growth. One of the principle advantages of these oxides is their resistance to interface state generation. This is linked to the presense of nitrogen near the substrate interface, where it is triply bonded to silicon. It is also demonstrated that during N2O-based furnace growth, the total concentration of NOx species varies strongly with the flow rate of N2O. This has been correlated to the temperature profile of the furnace, which can be affected by the exothermic decomposition of N2O. This property has been exploited to controllably adjust the rate of nitrogen incorporation by up to a factor of three. Although nitrogen incorporation during furnace processing is generally stable, it is shown that atomic oxygen is capable of removing previously incorporated nitrogen. Sources of atomic oxygen include the decomposition of N2O during RTP treatment, N2O processing in a high flow rate furnace, or from ozone annealing.