An opening is formed through a dielectric material layer to physically expose a top surface of a conductive material portion in, or over, a substrate. A metallic nitride liner is formed on a sidewall of the opening and on the top surface of the conductive material portion. A metallic adhesion layer including an alloy of copper and at least one transition metal that is not copper is formed on an inner sidewall of the metallic nitride liner. A copper fill material portion may be formed on an inner sidewall of the metallic adhesion layer. The metallic adhesion layer is thermally stable, and remains free of holes during subsequent thermal processes, which may include reflow of the copper fill material portion. An additional copper fill material portion may be optionally deposited after a reflow process.