US Patent 9859218 Selective surface modification of interconnect structures

Semiconductor structures including copper interconnect structures and methods include selective surface modification of copper by providing a CuxTiyNz alloy in the surface. The methods generally include forming a titanium nitride layer on an exposed copper surface followed by annealing to form the CuxTiyNz alloy in the exposed copper surface. Subsequently, the titanium layer is removed by a selective wet etching.