An interconnect structure is disclosed. In one embodiment, the interconnect structure includes: a substrate including a first liner layer and a first metal layer thereover; a dielectric barrier layer over the first metal layer and the substrate; an inter-level dielectric layer over the dielectric barrier layer; a via extending between the inter-level dielectric layer, the dielectric barrier layer, and the first metal layer, the via including a second liner layer and a second metal layer thereover; and a diffusion barrier layer located between the second liner layer and the first metal layer, wherein a portion of the diffusion barrier layer is located under the dielectric barrier layer.