Chemical Mechanical Planarization of Tungsten with Hard Abrasives

The impact of abrasive characteristics such as abrasive type, size, and crystallographic phase on the chemical mechanical planarization of tungsten and oxide films was investigated. The removal rates increased linearly with particle size, whereas the defectivity decreased as the particle size became smaller. Reducing the alpha alumina particle size to 120 nm showed a good combination of high removal rate and low oxide defectivity. The best oxide defectivities were achieved with transition alumina and silicon carbide. However, the transition alumina polished tungsten at a low rate compared to the other abrasives tested. The silicon carbide abrasive polished tungsten at a slightly lower rate than alpha alumina. In addition, silicon carbide planarized SiO2 at a significant rate and therefore was not as selective to oxide as the alumina abrasives. To achieve high metal removal rates, high metal/oxide selectivity, and good defectivity, the finer alpha alumina (120 nm) performed the best in this study. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3358135] All rights reserved.