Patent ID: 8323877

Claim:
A method for fabricating a dual damascene opening, comprising: providing a substrate having at least one conductive region covered by a liner; forming a dielectric layer and a patterned metal hard mask layer on the liner in sequence, wherein the patterned metal hard mask layer has an opening exposing the dielectric layer; forming a tri-layer structure filling the opening on the patterned metal hard mask layer, wherein the tri-layer structure comprises an organic layer, a silicon-containing mask layer and a patterned photoresist layer stacked in a bottom-up manner; removing the silicon-containing mask layer using the patterned photoresist layer as a mask; using a reactive gas for conducting an etching step so as to remove the organic layer with the silicon-containing mask layer as a mask, wherein the reactive gas contains no oxygen species; removing the dielectric layer using the silicon-containing mask layer and the organic layer as a mask, so that a via hole exposing the liner is formed in the dielectric layer; removing the organic layer; and removing the dielectric layer using the patterned metal hard mask layer as a mask to form a trench in the dielectric layer, and removing the liner exposed by the via hole to expose the conductive region, wherein the trench is connected with the via hole.