Copper-silver alloy for advanced barrierless metallization

In this study we observed significantly improved properties, over a pure copper (Cu) film, for a copper-silver alloy film made with a pure copper film co-sputtered with a minute amount of either Ag N or Ag N on a barrierless Si substrate. In either case, no noticeable interaction between the filmand the Si substrate was found after annealing at 600°C for 1 h. The Cu(Ag ,N ) film was thermally stable after annealing at 400°C for 240 h. The film's resistivity was 2.2 μΩ cm after annealing at 600°C, while its leakage current was found to be lower than that of a pure Cu film by three orders of magnitude. The adhesion of the Cu(Ag ,N ) film to the Si substrate was approximately seven times that of a pure Cu film to a silicon substrate. Hence, a Cu film doped with Ag and N seems to be a better candidate for both barrierless metallization and the making of superior interconnects. © 2009 TMS.