Controlling the Removal Rate Selectivity of Ruthenium to Copper during CMP by Using Guanidine Carbonate and 1, 2, 4-Triazole

Abstract

The chemical mechanical polishing (CMP) of ruthenium (Ru) based barrier layer has been a key process in the manufacture of a novel copper (Cu) interconnect structure. The removal rate selectivity of Ru to Cu play a major role during Ru CMP as the technology scaling down to 14 nm. In this paper, the removal rate selectivity of Ru to Cu was studied by using guanidine carbonate (GC) as complexing agent and 1, 2, 4-triazole (TAZ) as inhibitor in hydrogen peroxide (H2O2) based slurry. The study results show that the removal rate selectivity of Ru to Cu can be controlled by adjusting the GC and TAZ contents, and the dishing and erosion of Cu patterned wafers can be corrected under the conditions with high removal rate selectivity of Ru to Cu. The influence mechanism of GC and TAZ on removal rates of Cu and Ru was investigated by electrochemistry, scanning electron microscope and X-Ray photoelectron spectroscopy. It is revealed that the soluble Cu-Guanidine (Cu-Gnd) and Ru-Guanidine (Ru-Gnd) complexes would be generated through the chemical reaction between Cu, Ru, and the complexes, which improves the removal rate of Cu and Ru. While TAZ can effectively reduce the Cu removal rate by protecting the Cu surface from corrosion. Furthermore, high removal selectivity and low surface roughness of Cu and Ru can be achieved simultaneously under the effect of GC and TAZ.