Use of malonic acid in chemical-mechanical polishing (CMP) of tungsten

The use of malonic acid as an additive in alumina slurries used for the chemical mechanical polishing (CMP) of tungsten has been explored for the reduction of particulate contamination. The principal objective of this work was to delineate conditions under which alumina contamination on polished surfaces could be reduced. The interaction between malonic acid and alumina particles has been investigated through electrokinetic and adsorption measurements. At suitable malonic acid concentrations and pH values, tungsten and alumina surfaces develop a negative zeta potential resulting in conditions conducive to reduced particulate contamination. Small scale polishing experiments have been carried out to relate electrokinetic result; to the level of particulate contamination after polishing.