Patent ID: 9064812
Filing Date: 2015-06-23
Classification: H01J,H01L

Abstract:
1. A method of etching a substrate having a low aspect ratio feature and a high aspect ratio feature disposed in the substrate, comprising: (a) exposing the substrate to a first plasma formed from an inert gas; (b) subsequently exposing the substrate to a second plasma formed from a first process gas comprising an oxygen-containing gas to form an oxide layer on a bottom and sides of the low aspect ratio feature and on a bottom and sides of the high aspect ratio feature, wherein the oxide layer formed on the bottom of the low aspect ratio feature is thicker than the oxide layer formed on the bottom of the high aspect ratio feature; (c) etching the oxide layer from the bottom of the low aspect ratio feature and from the bottom of the high aspect ratio feature with a third plasma formed from a second process gas to expose the bottom of the high aspect ratio feature while the bottom of the low aspect ratio feature remains covered by the oxide layer; and (d) exposing the substrate to a fourth plasma formed from a third process gas comprising a halogen-containing gas to etch the bottom of the low aspect ratio feature and the bottom of the high aspect ratio feature.