An interconnection structure includes a first dielectric layer, a bottom conductive feature present in the first dielectric layer, a second dielectric layer present on the first dielectric layer, an aluminum-containing etch stop layer present between the first dielectric layer and the second dielectric layer, an upper conductive via present at least in the second dielectric layer and electrically connected to the bottom conductive feature, and at least one aluminum-containing fragment present at least at a bottom corner of the upper conductive via.