Development of novel process for Ru CMP using ceric ammonium nitrate (CAN)-containing nitric acid

In the present study, electrochemical and surface analytical techniques were employed to study the mechanism of chemical mechanical planarisation (CMP) process for highly inert noble ruthenium (Ru) film in ceric ammonium nitrate (CAN) additivescontaining acidic slurry. The steady-state polarisation curves with surface abrasion exhibited increment in the corrosion potential and cathodic current, suggesting that the partially exposed bare Ru acts as a cathodic site for CAN reduction on Ru2O3- covered Ru film as validated by X-ray photoelectron spectroscopy (XPS). Based upon the combined results of open-circuit potential (OCP) and anodic current transients, with scanning electron microscopy (SEM), we may assert that the mechanical removal of Ru2O3 enhances the local formation rate of RuO2 or RuO4 film, resulting in a loss of Ru by successive galvanic corrosion at the anodic sites. Using CAN-containing acidic slurry, Ru CMP process for manufacturing a bottom electrode for capacitors in DRAM device was satisfactorily accomplished as validated by SEM and atomic force microscopy (AFM). # 2004 Elsevier B.V. All rights reserved