Aspect ratio dependent etch (ARDE) lag reduction process by selective oxidation with inert gas sputtering

摘要

Embodiments of methods for etching a substrate include exposing the substrate to a first plasma formed from an inert gas; exposing the substrate to a second plasma formed from an oxygen-containing gas to form an oxide layer on a bottom and sides of a low aspect ratio feature and a high aspect ratio feature, wherein the oxide layer on the bottom of the low aspect ratio feature is thicker than on the bottom of the high aspect ratio feature; etching the oxide layer from the bottom of the low and high aspect ratio features with a third plasma to expose the bottom of the high aspect ratio feature while the bottom of the low aspect ratio feature remains covered; and exposing the substrate to a fourth plasma formed from a halogen-containing gas to etch the bottom of the low aspect ratio feature and the high aspect ratio feature.