Application of tungsten slurry for copper-chemical mechanical polishing

We investigated the effects of oxidizer additive on the performance of copper-chemical mechanical polishing (Cu-CMP) process using commercial tungsten (W) slurry. In order to compare the removal rate (RR) and within-wafer non-uniformity (WIWNU%) as a function of oxidizer additive contents, we used Al2O3-based tungsten slurry and copper blanket wafers deposited by dc sputtering method. As an experimental result, the CMP removal rates and particle size distribution, and the microstructures of surface layer as a function of oxidizer contents were greatly influenced by the slurry chemical composition of oxidizer additives. The difference in removal rate and roughness of copper surface are believed to cause by modification in the mechanical behavior of Al2O3 abrasive particles in tungsten slurry.