One embodiment is a semiconductor device including: at least one patterned dielectric layer having at least one opening therein, said at least one opening having sidewalls and bottom; at least one barrier layer disposed over the sidewalls and bottom; a first metallic layer disposed over the at least one barrier layer; a second metallic layer disposed over the first metallic layer; and a metallic filling layer disposed over the second metallic layer; wherein: the first metallic layer is continuous over the sidewalls and bottom, has a thickness in a range from about 10 Å to no more than 40 Å over a sidewall of the at least one opening; and the second metallic layer, and the metallic filling layer are selected from a group consisting of Cu, Ag, and alloys containing one or more of these metals.