Selection of an oxidant for copper chemical mechanical polishing: Copper-iodate system

Diagnostic criteria were developed to elucidate the reduction mechanism of an oxidant on a copper (Cu) surface at the corrosion potential. The corrosion potential of Cu tu was measured for various pH and iodate (IO₃^–) concentrations using the rotating disk electrode technique. According to the measured corrosion potentials, IO₃^– was an effective CMP oxidant only below pH Application of the diagnostic criteria on the Cu – IO₃^– system showed that the reduction of IO₃^– on Cu was under the mixed kinetic and diffusion control at the corrosion potentia l below pH 3. Above pH 3, however, the anodic process dominated over the cathodic process.