Patent ID: 7857982

Claim:
A method of etching a feature into a substrate, comprising: forming a plurality of hard mask layers over material of a substrate to be etched, one of the plurality being an innermost of the hard mask layers; forming a feature pattern in the plurality of hard mask layers; etching a feature only partially into the substrate material using the plurality of hard mask layers with the feature pattern therein as a mask, such partial etching forming a residue within the feature pattern laterally over sidewalls of the innermost hard mask layer; after the partial etching, etching at least one of the hard mask layers selectively relative to the substrate material and remaining of the hard mask layers, the etching of the at least one of the hard mask layers etching said residue from the substrate; after the etching of at least one of the hard mask layers, further etching the feature into the substrate material using a mask comprising the innermost hard mask layer; and after the further etching, removing the mask comprising the innermost hard mask layer from the substrate and incorporating at least a portion of the feature into an integrated circuit.