Method of etching organic antireflection coating (ARC) layers

Abstract

A two-step method of etching an organic coating layer, in particular, an organic antireflection coating (ARC) layer, is disclosed. During the main etch step, the organic coating layer is etched using a plasma generated from a first source gas which includes a fluorocarbon and a non-carbon-containing, halogen-comprising gas. Etching is performed using a first substrate bias power. During the overetch step, residual organic coating material remaining after the main etch step is removed by exposing the substrate to a plasma generated from a second source gas which includes a chlorine-containing gas and an oxygen-containing gas, and which does not include a polymer-forming gas. The overetch step is performed using a second substrate bias power which is less than the first substrate bias power. The first source gas and first substrate bias power provide a higher etch rate in dense feature areas than in isolated feature areas during the main etch step, whereas the second source gas and second substrate bias power provide a higher etch rate in isolated feature areas than in dense feature areas during the overetch step, resulting in an overall balancing effect.

Dependencies are inferred from the claim text.