| abstract |
Chemical mechanical polishing, of a semiconductor wafer with a tungsten layer (38) on a dielectric layer (32), uses a single polishing pad (44) and a first slurry mixture (42) containing an oxidising agent to polish the tungsten and expose the dielectric layer. A second slurry mixture containing an oxide etchant is then used to polish the dielectric. Both slurry mixtures have a pH of 2-4. The first slurry includes water, Fe(NO3)3, Al2O3, H2O2, and may also contain KIO3. |