Etching methods for reducing micro and macro scalloping on sidewalls of etched features of semiconductor devices

Abstract

Embodiments of the present disclosure relate to methods for patterning a material layer on a substrate. The method includes forming a hard mask layer on a material layer disposed on a substrate. The material layer includes a plurality of first layers and a plurality of second layers alternately formed over the substrate. The method further includes performing a first etch process to form features in the material layer through the hard mask layer by supplying a first etching gas; performing an oxidation process to oxidize a sidewall of the features by supplying an oxidation gas; and performing a second etch process to etch the sidewall of the features formed in the material layer by suppling a second etching gas.