Low temperature nitridation of silicon oxide layers by nitrogen plasma generated by electron impact is investigated using x-ray photoelectron spectroscopy (XPS) and synchrotron radiation ultraviolet photoelectron spectroscopy and it is found that a large amount of nitrogen can be incorporated in the layers. The valence band structure of the oxide surface nitrided at 25 °C is similar to that ofSi3N4,while that nitrided at 700 °C resembles the mixture of silicon oxide and silicon oxynitride. Measurements of XPS depth profiles show that the nitrogen concentration is high near the surface and the oxide/Si interface. ©1997 American Institute of Physics.