A semiconductor device, having a composite barrier layer, comprising the following. A substrate has a dielectric layer formed thereover and having an opening within the dielectric layer. The opening exposes a first portion of the substrate. A composite barrier layer lines the opening. The composite barrier layer comprises: a dielectric flash layer within the opening and lining the opening wherein the dielectric flash layer does not cover the first exposed portion of the substrate; an aluminum layer over the dielectric flash layer and over the first exposed portion of the substrate; and a barrier metal layer over the aluminum layer. Wherein the dielectric flash layer, the aluminum layer and the barrier metal layer comprise the composite barrier layer. A planarized metal plug is within the barrier metal layer lined opening.