In advanced interconnection technologies, Atomic Layer Chemical Vapour Deposition (ALCVD(TM)) is a promising technique to deposit very conformal thin barriers on low-k dielectrics. To enhance the ALCVD growth, we have modified Si-O-C and alpha-SiC:H dielectric films by O-2-based plasma treatments. This paper discusses the effect of the plasma on the growth of ALCVD TiN and the modifications induced at the surface and in the bulk of the dielectrics. The O-2-based plasma enriches the dielectric surface with the OH group, improving the quality of the TiN films. Further optimisation of the surface treatments is needed to prevent undesired modification of the dielectric bulk. (C) 2002 Elsevier Science B.V. All rights reserved.