Poly(ethyleneimine) as a Passivating Agent for Ta Chemical Mechanical Planarization

Abstract

We report poly(ethyleneimine) (PEI) as a possible passivating agent for Ta during chemical mechanical planarization (CMP). Studies by electrochemical impedance spectroscopy in a model CMP slurry suggest that PEI forms a polymer film atop a Ta electrode, and voltammetry studies of Ta in 2.5 M HF suggest that PEI films suppress the formation of Ta oxide. Because Ta oxide is mechanically hard, suppressing Ta oxide growth may allow reduced downforce or higher removal rates. These observations are consistent with an increase of approximately 3 times in the Ta removal rate in a model CMP slurry upon addition of 3000 ppm PEI.