Patent ID: 7253115

Claim:
A method of forming dual damascene structures in a dielectric stack covered by a BARC material, the method comprising: introducing a first process gas into a process zone in which the dielectric stack is located, the first process gas including a fluorocarbon gas, and wherein the dielectric stack does not comprise a middle stop layer; maintaining a plasma of the first process gas in the process zone to remove a first portion of the BARC over the dielectric stack thereby exposing a second portion of the BARC; introducing a second process gas into the process zone, the second process gas including oxygen and nitrogen; continuously maintaining a plasma of the second process gas in the process zone to remove the second portion of the BARC over the dielectric stack; introducing a third process gas into the process zone, the third process gas including a fluorocarbon gas; maintaining a plasma of the third process gas to etch a hard mask layer disposed in the dielectric stack; introducing a fourth process gas into the process zone, the fourth process gas including oxygen and nitrogen; and maintaining a plasma of the fourth process gas to etch portions of the BARC material not covering the hard mask layer.