Chemical mechanical planarization of copper damascene structures

We describe the chemical mechanical planarization (CMP) of copper damascene structures using an ICI400 pad and four different types of slurries. Two a lumina-based slurries and two silica-based slurries were evaluated. After s uccessful removal of the excess Cu, we examined the topography of the plana rized structures using scanning electron microscopy. The effects of the CMP process on spacer erosion, Cu line recess, corrosion of submicrometer Cu l ines, liner removal selectivity, and contamination of the patterned structu res are presented. It was found that minimizing the etch rate (similar to 1 0 nm/min) of the slurry is required to achieve reproducible removal rates a nd unrecessed (etched) damascene structures. No dishing was observed with t he utilized pad. We also show that corrosion is prone to occur in low Cu pa ttern density areas and that the removal of the liner material (tantalum) r emains problematic because of its chemical inertness. (C) 2000 The Electroc hemical Society. S0013-4651(99)06-096-6. All rights reserved.