Patent ID: 7294580

Claim:
A method for etching a feature in a low-k dielectric layer through a photoresist etch mask over a substrate, comprising: placing a low-k dielectric layer over a substrate; placing a patterned photoresist mask over the low-k dielectric layer; etching at least one feature into the low-k dielectric layer; and performing a gas-modulated cyclic stripping process for more than three cycles for stripping a single photoresist mask, wherein each cycle comprises: performing a protective layer forming phase using a first gas, wherein the protective layer forming phase is performed in about 0.005 to 10 seconds for each cycle, comprising; providing the first gas; and forming a plasma from the first gas, wherein a protective layer is formed on sidewalls of the at least one feature and a thickness of the protective layer is increased, wherein the protective layer is a layer of deposited material that is relatively inert to etching reactions with respect to the photoresist mask; and performing a stripping phase for stripping the photoresist mask using a second gas, where the first gas is different than the second gas, wherein the etching phase is performed in about 0.005 to 10 seconds for each cycle, comprising: providing the second gas; and forming a plasma from the second gas, wherein the thickness of the protective layer is decreased and some of the photoresist mask is stripped.