Chemical mechanical polishing of tungsten: Effect of tungstate ion on the electrochemical behavior of tungsten

The effect of tungstate ion on the electrochemical behavior of tungsten has been investigated using direct current potentiodynamic polarization. As th e concentration of tungstate ion increases, the anodic current increases an d shifts to less noble potentials. This unexpected result is attributed to the solubilization (via polymerization) of tungstate ions generated via W d issolution, by the tungstate species previously introduced into solution. W ith the iodate ion as a model oxidizer, the dissolution current was found t o increase in the presence of added tungstate ions. This suggests that tung state ions can facilitate the metal dissolution during tungsten chemical me chanical polishing. (C) 1999 The Electrochemical Society. S1099-0062(98)06- 079-9. All rights reserved.