Chemical Mechanical Planarization of Copper Damascene Structures

Abstract

We describe the chemical mechanical planarization (CMP) of copper damascene structures using an IC1400 pad and four different types of slurries. Two alumina‐based slurries and two silica‐based slurries were evaluated. After successful removal of the excess Cu, we examined the topography of the planarized structures using scanning electron microscopy. The effects of the CMP process on spacer erosion, Cu line recess, corrosion of submicrometer Cu lines, liner removal selectivity, and contamination of the patterned structures are presented. It was found that minimizing the etch rate (∼10 nm/min) of the slurry is required to achieve reproducible removal rates and unrecessed (etched) damascene structures. No dishing was observed with the utilized pad. We also show that corrosion is prone to occur in low Cu pattern density areas and that the removal of the liner material (tantalum) remains problematic because of its chemical inertness. © 2000 The Electrochemical Society. All rights reserved.