An apparatus and method for the ultraviolet (UV) treatment of carbon-containing low-k dielectric enables process-induced damage repair. A semiconductor substrate processing system may be configured to include degas and plasma pre-clean modules, UV process modules, copper diffusion barrier deposition modules and copper seed deposition modules such that the substrate is held under vacuum and is not exposed to ambient air after low k damage repair and before copper barrier layer deposition. Inventive methods provide for treatment of a damaged low-k dielectric on a semiconductor substrate with UV radiation to repair processing induced damage and barrier layer deposition prior breaking vacuum.