Development and optimization of slurry for RuCMP

Abstract

In this study, Ruthenium (Ru) chemical mechanical planarization (CMP) slurry was studied and developed to apply it for the formation of Ru bottom electrode in DRAM capacitor. An acidic chemical was chosen as both oxidant and etchant. The effects of the chemical on polishing and etching behavior were investigated as functions of chemical concentration and pHs. The static etch rate of Ru increased with an increase in chosen chemical concentration. Also, thin Ru oxide was generated in chemical solution. The. highest etching and removal rate were obtained in slurry of pH 6. However, Ru over etching was generated due to the high etch rate of Ru, and then good planarity was not obtained. In slurry of pH 6, the plarnarity and isolation of each capacitor was acquired successfully because Ru over etching was prevented due to low etch rate of Ru,.