Galvanic Corrosion Effect of Co Liner on ALD TaN Barrier

This paper describes strong galvanic corrosion effect of Co liner on atomic layer deposition (ALD) TaN barrier during Cu CMP. Compared to Co liner on physical vapor deposition (PVD) TaN, Co liner on ALD TaN was more easily corroded resulting in Cu void defects. We investigated characteristic differences between ALD and PVD TaN, and identified the root cause of Cu void formation is higher nitrogen content in ALD TaN film. We could minimize the galvanic corrosion and the resulting Cu voids by reinforcing plasma treatments after ALD TaN deposition.