In Situ Investigation of Slurry Flow Fields during CMP

Abstract

The objective of this work is to obtain in situ slurry fluid flow data during the chemical mechanical planarization (CMP) process. Slurry flow affects the material removal processes, the creation of defects, and consumable use during CMP, and therefore impacts the cost and quality of polishing. Wafer-scale flow visualization using seeded slurry was accomplished for a variable applied load (0.3–2.5psi downforce), wafer rotation speed (0 and 33rpm), slurry injection locations, and various pad types (flat, XY grooved, and AC grooved). In situ pad conditioning was employed in all experiments. The data indicated complex slurry flow fields on the pad surface in the wafer vicinity, which are influenced by slurry injection point, pad grooving, downforce, and wafer/conditioner rotation. Injection location and pad type were shown to have the strongest impact on the variation in the fluid flow fields obtained.