Patent ID: 7067235

Claim:
A method for etching an opening using a bi-layer photoresist to improve an etching resolution and reduce particulate contamination comprising the steps of: providing an unpatterned non-silicon containing photoresist layer over a substrate to form a first resist layer; providing a silicon containing photoresist layer on the first resist layer to form a second resist layer thinner than the first resist layer; exposing the second resist layer to form a second resist layer pattern revealing first resist layer portions; dry developing said first resist layer portions according to the second resist layer pattern to reveal the substrate according to a first plasma etching process consisting essentially of nitrogen, oxygen, and argon to form an etching mask; plasma etching according to a second plasma etching process an opening into the substrate according to the etching mask; and, then carrying out an in-situ ashing process to remove remaining overlying resist layers selected from the group consisting of the first and second resist layers.