Enhanced tungsten chemical mechanical polishing using stable alumina slurries

The chemical mechanical polishing of tungsten using stabilized alumina slur ries has been investigated. To stabilize the alumina slurries in the presen ce of high concentration of an oxidizer [K3Fe(CN)(6)] at acidic pH, a combi nation of anionic (sodium dodecyl sulfate, SDS) and nonionic (polysorbate 8 0, Tween 80) surfactants were added. Static electrochemical measurements we re carried out to compare the slurries with and without the surfactant. Che mical mechanical polishing experiments showed that the removal rate of tung sten decreases in the presence of a stable slurry. These experiments have a lso shown that the local roughness of the polished surface can be reduced s ignificantly using a stable slurry. Finally, the adhesion of alumina partic les on tungsten and silica surfaces has been reduced by more than an order of magnitude due to the presence of the surfactant. (C) 1999 The Electroche mical Society. S1099-0062(98)05-060-3. All rights reserved.