Chemical Mechanical Polishing of Mo Using H2O2as Oxidizer in Colloidal Silica Based Slurries

Chemical mechanical polishing (CMP) of molybdenum (Mo) using H2O2 based slurry with colloidal silica as abrasives has been systematically investigated. Effects of pH values, abrasives and additive of the slurry on CMP of Mo were investigated respectively. Results show that by adding ammonium sulfate (AS) in the alkaline H2O2 based slurry, both static etch rate (SER) and removal rate (RR) of Mo became much greater than without adding AS because of formation of a highly soluble (NH4)2MoO4. It is found that colloidal silica abrasive particles could adsorb on the Mo surface and have inhibitory effect on corrosion and polishing of Mo, and the higher concentration of colloidal silica particles, the lower SER and RR. AS addition in the slurry would enhance this phenomenon. Raman measurement results show that, silicomolybdic acid could form on the Mo surface in the slurry because of reaction between Moly oxide and silica particles, which causes the adsorption and inhibition of Mo etching and polishing.