Tribo-Electrochemical Performance of Copper ECMP in Mixed Phosphate Electrolyte
A mixed phosphate slurry is screened out first in terms of inhibition efficiency of the inhibitor by electrochemical static-corrosion test of copper for different concentrations of H3PO4 and BTA. Then ECMP experiments are carried out on a modified pin-on-disk type tribo-electrochemical tester for the candidate slurry under the potential range of applied voltage, with the anodic current and friction coefficient recorded and MRR measured. It is found that copper ECMP can achieve good surface quality with a high MRR under 0.75 V anodic potential in slurry of 10%KH2PO4 + 5%H3PO4+0.03M BTA. Down force is found to have little effect on MRR in the mixed slurry, this pressure-independent characteristics may help reduce the pattern effect during patterned wafer polishing.
W. J. Zhai and Y. Z. Yang, "Tribo-Electrochemical Performance of Copper ECMP in Mixed Phosphate Electrolyte", Advanced Materials Research, Vols. 314-316, pp. 2565-2568, 2011