Disclosed is a multi-layer via structure, comprising a metal layer, a first via metal layer formed on a first open of a first dielectric layer and a second via metal layer formed on a second open of a second dielectric layer. The first and second via metal layers comprise first and second bottoms, first and second top portions, first and second inclined walls, respectively. The first and second inclined walls comprise first and second top edges, first and second bottom edges respectively. The second top edge has a point closest to a geometric center of the first bottom. A vertical projection of the point falls on the first inclined wall. Alternatively, a point of the second bottom edge, which is closest to the geometric center, has a vertical projection. The vertical projection is vertical to the metal layer and falls on the first inclined wall.