A displacement-deposited Ag layer was investigated as an oxidation barrier in damascene Cu structure for high performance
interconnection. A 40 nm thick bright and continuous Ag film was formed at the surface of electrodeposited Cu by immersing the
copper film into the silver displacement solution. The Ag film at Cu surface significantly blocked oxygen diffusion into the Cu film
and retarded oxidation. More importantly, an elevated barrier performance for oxygen diffusion through elimination and stuffing
of grain boundaries of Cu was observed upon annealing in a 400°C N2 atmosphere. Outward Cu diffusion through Ag layer
controlled Cu oxidation when the surface was passivated with Ag layer
