Patent ID: 7718543

Claim:
A method for removing a BARC layer from a feature formed in a dual damascene structure, comprising: providing a substrate having a feature filled with a BARC layer in an etching chamber, wherein the feature includes a trench connected to a via defined in a dielectric bulk insulating layer, wherein the BARC layer is an organic material filled within the via; supplying a first gas mixture comprising NH 3 gas into the chamber to etch a first portion of the BARC layer filling in the feature while providing sidewall protection of the dielectric bulk insulating layer; and supplying a second gas mixture comprising O 2 gas into the etching chamber to etch the remaining portion of the BARC layer disposed in the feature, wherein a process time for etching the portion of the BARC layer in the presence of the first gas mixture relative to a process time for etching the remaining portion of the BARC layer has a ratio of between about 1:1 and about 4:1.