Embodiments of the invention are directed to an interconnect stack including a first dielectric layer, a first trench formed in the first dielectric layer, and a first liner deposited in the first trench, wherein the first liner defines a second trench. A first conductive material is in the second trench and deposited over the first dielectric layer and the first conductive material. A third trench extends through the second dielectric layer and is over the first conductive material. A bottom surface of the third trench includes at least a portion of the top surface of the first conductive material. A second liner is in the third trench, on sidewalls of the third trench, and also on the portion of the top surface of the first conductive material. The second liner functions as a cap region configured to counter electro-migration or surface migration of the first conductive material.