Development of a Slurry Employing a Unique Silica Abrasive for the CMP of Cu Damascene Structures

Abstract

We describe the development and examine the performance of a slurry containing an organic acid salt, a silica abrasive obtained from the hydrolysis of ethyl silicate (TEOS), and a passivating agent for the chemical mechanical planarization (CMP) of Cu damascene structures. The study is performed on full (200 mm) wafers coated with blanket Cu films to examine removal rates and uniformity and on partial wafers to investigate the CMP of Cu damascene structures. The silica slurry shows moderately high removal rates, good uniformity values, low defectivity, and excellent ability to remove the Ta liner. It is demonstrated that despite the fairly low Cu to selectivity values, a severe erosion of the does not occur. Because of the effective removal of the liner material, long overpolishing times become unnecessary, thus, spacer erosion is avoided. Corrosion induced defects are prevented by the addition of a passivating agent. © 2001 The Electrochemical Society. All rights reserved.