Method for forming trenches having different widths and the same depth

Abstract

A lithographic material stack including a photo-resist and an organic planarizing layer is combined with an etch process that generates etch residues over a wide region from sidewalls of etched regions. By selecting the etch chemistry that produces deposition of etch residues from the organic planarizing layer over a wide region, the etch residue generated at the sidewalls of the wide trench is deposited over the entire bottom surface of the wide trench. An etch residue portion remains at the bottom surface of the wide trench when the organic planarizing layer is etched through in the first trench region. The etch residue portion is employed in the next step of the etch process to retard the etch rate in the wide trench, thereby producing the same depth for all trenches in the material layer into which the pattern of the lithographic material stack is transferred.