Patent ID: 7611986

Claim:
A method for patterning a dual damascene structure, the method comprising the steps of: depositing a dielectric layer on a substrate; depositing a capping layer on the dielectric layer; etching a first hole in the capping layer and the dielectric layer; depositing a gap filling material such that the first hole is completely filled; removing a part of the gap filling material such that the gap filling material is level with the capping layer; depositing a metal hardmask layer on the capping layer; depositing at least one imaging material on the metal hardmask layer; forming at least one first pattern in the imaging material; transferring the first pattern to the metal hardmask layer; removing the imaging material; removing all remaining gap filling material; and thereafter etching a second hole over the first hole using an oxygen-free plasma containing fluorocarbon compound as an etchant, whereby a dual damascene structure is patterned.