A single damascene interconnect structure which includes a first layer of a first dielectric material having a first filled opening that has a sidewall layer which includes a compound of a metal, O, and Si such that the metal is Mn, Ti and Al, and with Cu filling the first filled opening. The compound is in direct contact with the first dielectric material. Also included is a second layer that includes a second dielectric material having a second filled opening that has a barrier layer of a refractory material with Cu filling the second filled opening. The first layer is adjacent to the second layer and the first filled opening is aligned with the second filled opening so that one of the first and second filled openings is a via and the other of the first and second filled openings is a trench.