Patent ID: 6177337
Filing Date: 2001-01-23
Classification: H01L

Abstract:
A method for forming a metal-containing structure over a dielectric structure on a semiconductor substrate, said method comprising:(a) providing a semiconductor substrate having a dielectric layer, a lower electrically conductive barrier layer, an electrically conductive metal layer, an upper electrically conductive barrier layer, and a patterned mask layer, wherein said lower barrier layer overlies said dielectric layer, said electrically conductive metal layer overlies said lower barrier layer, said upper barrier layer overlies said electrically conductive metal layer and said patterned mask layer overlies said upper barrier layer such that portions of said upper barrier layer are exposed,(b) treating the substrate as follows:(i) contacting the exposed portions of said upper barrier layer under reactive ion etching conditions with a first gas mixture at a first pressure whereby a portion of said upper barrier layer is etched to expose portions of said electrically conductive metal layer, said first gas mixture consisting essentially of Cl.sub.2 and at least one high molecular weight halogen compound having a molecular weight greater than about 90,(ii) contacting said exposed portions of said electrically conductive metal layer under reactive ion etching conditions with a second gas mixture at a second pressure whereby the bulk of said electrically conductive mete layer thickness is anisotropically etched while avoiding exposure of said lower barrier layer, said second gas mixture having a different composition from said first gas mixture, said second gas mixture consisting essentially of Cl.sub.2 and at least one low molecular weight halogen compound having a molecular weight less than about 70,(iii) contacting remaining exposed portions of said electrically conductive metal layer from step (ii) under reactive ion etching conditions with a third gas mixture at a third pressure whereby said remaining exposed portions of said electrically conductive metal layer are anisotropically etched to expose portions of said lower barrier layer, said third gas mixture having a different composition from said first and second gas mixtures, and(iv) contacting said exposed portions of said lower barrier layer under reactive ion etching conditions with a fourth gas mixture at a fourth pressure to reveal portions of said underlying dielectric layer, said fourth gas mixture having a different composition from said second and third gas mixtures, and(c) removing said mask layer to reveal said metal-containing structure which structure includes remaining portions of said electrically conductive metal layer and said barrier layers.