Chemical mechanical polishing of tantalum: oxidizer and pH effects

Chemical mechanical polishing of tantalum was carried out in alumina-dispersed deionized water, 5% H2O2as well as 0.25 M KIO3solution at pH ranging from 1 to 10. High polishing rates were observed in H2O2-containing slurry at low pH values, while KIO3slurry showed no appreciable effect of pH and the polishing rates were low. While tantalum pentoxide readily forms in either slurry, electrochemical observations indicate a higher dissolution rate of the oxide in H2O2slurry, particularly at low pH accounting for the greater polishing rate.