Abstract
Abstract Chemical mechanical planarization of ruthenium (Ru) in a slurry formulation containing silica abrasive and hydrogen peroxide oxidizer was investigated. The removal rate and the etch rate increase with increase in oxidizer concentration due to increased oxide formation on Ru surface. The removal rate selectivity and the galvanic corrosion of Ru/Cu couple were also studied. In the presence of oxidizer, formation of RuO2, Ru(OH)3, Ru(OH)4, RuO4─ and RuO42─ takes place in alkaline pH. The removal mechanism of the metals was studied using electrochemical techniques in the presence of a supporting electrolyte i.e., sodium perchlorate (NaClO4) and varying concentration of H2O2 solution. The electrochemical characterization was carried out at natural pH varying the hydrogen peroxide concentration. The Icorr values calculated using the extrapolation of potentiodynamic polarization plots follow the similar trend as the CMP removal rate. The electrochemical impedance spectroscopy (EIS) results of Ru and Cu show decreased impedance values with increase in H2O2 concentration which matches well with the etch rate and CMP experiments. Kramer-Kronig Transformation (KKT) was used to check the stability, linearity and causality of the system.
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