Control of Galvanic Corrosion Behavior Between Tungsten and Titanium Nitride in CMP Application

Localized galvanic corrosion at the tungsten (W) and titanium nitride (TiN) interface causes fatal defects (e.g., corrosion and pitting issues) in chemical mechanical planarization (CMP) process. In this study, we control the corrosion potential difference between W and TiN via mixing of two corrosion inhibitors in order to decrease those defects. The roles of corrosion inhibitors in CMP slurry are analyzed by open circuit potential (OCP) measurements, linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Through these electrochemical approaches, we found that two mixed inhibitor system can decrease the galvanic potential and current density. CMP result with W/TiN patterned structure wafer shows that mixed inhibitor system prevents galvanic corrosion at the W/TiN interface during CMP, leading to decreasing the defects. We believe that the results investigated in this study will provide researchers with the importance of electrochemical approaches in W CMP.