Effect Of Oxidizer On The Galvanic Behavior Of Cu/Ta Coupling During Chemical Mechanical Polishing

The effect of oxidizer addition, namely, H2O2, KIO3, and Fe(NO3)(3), on the galvanic behavior of the Cu/Ta coupling in 0.01 M Na2SO4 + 1 wt% Al2O3 base slurry was studied. Both open-circuit potentials of the uncoupled Cu and Ta as well as galvanic current of the Cu/Ta were measured in static and under chemical mechanical polishing conditions to analyze the roles of these additives. The results showed that Fe(NO3)(3) was more effective than H2O2 and KIO3 in promoting the passivation of Ta, which in turn caused the change of polarity between Cu and Ta. The effect of Cu/Ta area ratio on the galvanic behavior of the coupling was also investigated. The results showed that in Fe(NO3)(3)-containing slurry, Ta was the anode with a Cu/Ta area ratio of 5: 1 but became the cathode with an area ratio of 1:1. (C) 2006 The Electrochemical Society.