Investigation of Cu/TaN and Co/TaN Barrier-Seed Oxidation by Acidic and Alkaline Copper Electroplating Chemistry for Damascene Applications

The effect of plating chemistry on standard damascene integration has been investigated to assess their effect on the interface quality of the final barrier/seed/fill integration. Dipping Co/TaN/SiO2 and Cu/TaN/SiO2 substrates wafers in acidic copper plating chemistry and ligand-based alkaline copper plating chemistry (aveni solution) shows that only the latter maintain the integrity of the substrate while the former degrades the seed (Co or Cu) and the barrier (TaN). We demonstrate that this degradation is extremely fast in the case of a cobalt seed thus only an alkaline ligand-based chemistry is compatible with a direct copper plating on cobalt seed approach. These results are critical because of the ever-going trend of decreasing semiconductors features size that requires the thinning down and removal of disposable metal layers while still maintaining the quality of the interfaces and the integrity of the whole integration.