Patent ID: 8405223

Claim:
A multi-layer via structure, comprising: a metal layer; a first dielectric layer, covering the metal layer, and having a first open above the metal layer; a first via metal layer, formed in the first open and on the first dielectric layer, and comprising a first bottom, a first top portion formed on the first dielectric layer and a first inclined wall, and the first inclined wall comprises a first top edge joining to the first top portion and a first bottom edge joining to the first bottom, and the first bottom has a geometric center; a second dielectric layer, covering the first via metal layer, and having a second open above the first top portion and the first inclined wall of the first via metal layer; and a second via metal layer, formed in the second open and on the second dielectric layer, and comprising a second bottom, a second top portion formed on the second dielectric layer and a second inclined wall, and the second inclined wall comprises a second top edge joining to the second top portion and a second bottom edge joining to the second bottom, wherein the second bottom edge has a point closest to the geometric center, and a vertical projection of the point, which is vertical to the metal layer, falls on the first inclined wall.