INTERCONNECT STRUCTURE AND MANUFACTURING METHOD THEREOF

Interconnect structures are provided. An interconnect structure includes a substrate; a first dielectric layer on the substrate and including an opening for a first interconnect layer extending to the substrate; a first metal layer having a first portion in the opening and a second portion in contact with the first portion and on a portion of the first dielectric layer adjacent to the opening; a second dielectric layer on the first dielectric layer and on the first metal layer, the second dielectric layer including a trench for a second interconnect layer, the trench exposing the second portion of the first metal layer; and a second metal layer in the trench, wherein the second portion of the first metal layer forms a lower portion of the second interconnect layer.