We report the properties of paramagnetic defects in SiCN films which are used as copper diffusion barriers. Electron spin resonance (ESR) signals with a g value of 2.003 and the Delta H-PP of 1.1 - 1.2 mT were observed for as-grown and UV-illuminated SiCN films. These characteristics of the observed ESR signals are very similar to those of the K-0 center in N-rich silicon nitrides. We also show that a substantial increase in the leakage current occurs by exposing the SiCN films to UV illumination. We suggest that the paramagnetic defects generated by the UV illumination are responsible for this current increase. (C) 2008 Elsevier B.V. All rights reserved.