US Patent 7857982 Methods of etching features into substrates

The invention includes methods of etching features into substrates. A plurality of hard mask layers is formed over material of a substrate to be etched. A feature pattern is formed in such layers. A feature is etched only partially into the substrate material using the hard mask layers with the feature pattern therein as a mask. After the partial etching, at least one of the hard mask layers is etched selectively relative to the substrate material and remaining of the hard mask layers. After etching at least one of the hard mask layers, the feature is further etched into the substrate material using at least an innermost of the hard mask layers as a mask. After the further etching, the innermost hard mask layer and any hard mask layers remaining thereover are removed from the substrate, and at least a portion of the feature is incorporated into an integrated circuit.