In this article, we report the effect of nitrogen plasma, during and after deposition, on nitrogen incorporation into yttrium oxide dielectric films. Films are deposited using a yttrium β-diketonate precursor (Y(tmhd)3) introduced downstream from a O2 or N2 plasma. The precursor acted as a significant source of oxygen, and only small amounts of N (≪10 at. %) were incorporated in the films. Chemical bonding, concentration, and distribution of N in Y-oxide films after deposition and after high-temperature anneal were characterized using x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and Auger electron spectroscopy. CN is the primary form of nitrogen bonding in the as-deposited films, and IR results indicate the exchange of N with O to form CO bonds occurs during prolonged exposure to air. High-temperature annealing releases N from the surface of as-deposited films, and results in a film structure that is resistant to further N incorporation. Results suggest that yttrium oxynitride is likely inherently unstable, especially in contact with ambient moisture. © 2004 American Vacuum Society.