Patent ID: 7244313

Claim:
A plasma etch process for a workpiece having a low-dielectric constant thin film that is exposed during the etch process, said process comprising: forming a photoresist mask on a top surface of the workpiece, said mask including apertures defining hole locations to be etched; placing the workpiece in a plasma reactor chamber; performing an etch step by introducing into the chamber a polymerizing etch process gas of type comprising a fluorocarbon or fluoro-hydrocarbon species and coupling RF plasma source power and RF plasma bias power into the chamber to produce a plasma of: (a) etch species which etch holes in said workpiece in registration with the apertures in said photoresist mask, and (b) polymerizing species which accumulate as a polymer layer on the surface of said photoresist mask during said etch step; prior to removing the photoresist mask: (a) removing residue of the type including polymer material from chamber surfaces including a ceiling of said chamber, by coupling RF plasma source power into said chamber while coupling substantially no RF plasma bias power into said chamber, and introducing a hydrogen-containing gas into said chamber, until said residue is removed from the chamber surfaces; (b) removing said polymer layer from the surface of said photoresist mask, by coupling RF plasma bias power into said chamber while coupling substantially no RF plasma source power into said chamber, and introducing into the chamber a process gas comprising oxygen and carbon monoxide, until said polymer layer is removed from the surface of said photoresist mask; and stripping said photoresist off of said workpiece.