Chemical Mechanical Planarization of TaN Wafers Using Oxalic and Tartaric Acid Based Slurries

This work demonstrates that silica-based slurries (pH 3–8) using oxalic or tartaric acid as a complexing agent can be used for efficient, low pressure chemical mechanical polishing of tantalum nitride (diffusion barrier) in the fabrication of semiconductor devices. Depending on their pH and their oxidizer content, these slurries support satisfactory polish rates of TaN up to at a down pressure of 2 psi. Optical profilometry of wafers processed with these slurries shows very good postpolish surfaces. The possible mechanisms for chemically promoted material removal in these slurry systems are discussed.