Partial via hard mask open on low-k dual damascene etch with dual hard mask (dhm) approach

Abstract

A method for forming a dual damascene opening comprising the following steps. A structure having an exposed conductive structure formed therein is provided. An etch stop layer is formed over the structure and the exposed conductive structure. A dielectric layer is formed over the etch stop layer. A hard mask layer is formed over the dielectric layer. The hard mask layer is patterned to form a partially opened hard mask layer. The partially opened hard mask layer having a trench area and a via area. The partially opened hard mask layer within the via area is patterned to form a partial via opened hard mask layer. Simultaneously, the partial via opened hard mask layer within both the trench area and the via area are etched and removed, and the dielectric layer within the via area is partial etched to form a partially opened dielectric layer to: expose a portion of dielectric layer within the trench area; and form a partial via within the partially opened dielectric layer. The partially opened dielectric layer is etched: within the trench area to form a trench; and within the via area to form a final via exposing a portion of etch stop layer. The trench and the final via forming the dual damascene opening.