Investigation of the kinetics of tungsten chemical mechanical polishing inpotassium iodate-based slurries - I. Role of alumina and potassium iodate

We investigated aspects of the kinetics of tungsten chemical mechanical pol ishing (CMP) in iodate-based slurries. Specifically, we performed experimen ts in which we measured the tungsten polish rate and process temperature as a function of alumina concentration, potassium iodate concentration, plate n temperature, polish pressure, polish rotation rate, and pad type. We foun d that the polish rate data fit a multiterm regression model better than th e empirical Preston equation. Polish rate was found to vary with all of me factors investigated. Process temperature varied with all of the factors ex cept potassium iodate concentration. These results, in combination with an energy balance on the entire process, indicate the change in temperature du e to alumina concentration is mostly due to energy input from increased sha ft work. This implies that the chemical and physical interactions between t he alumina and tungsten surfaces are complex and play an important role in the mechanism of tungsten removal during CMP. (C) 1999 The Electrochemical Society. S0013-4651(98)04-096-8. All rights reserved.