Characterization of electroless plated CoWB barrier films

Electroless deposited CoWB films were studied as a capping material for copper interconnect applications. Selective deposition of CoWB was carried out on electroplated copper after a CMP process. AES and SIMS profiles showed uniform distribution of the elemental components throughout the film. SIMS depth profiles indicated that CoWB films above 250 A thick could function as copper diffusion barriers after annealing at 400°C. XRD analysis showed that the plated film is polycrystalline in nature. Leakage current and resistance changes of CoWB plated copper lines depend on the copper pre-clean process used.