Study of polishing characteristics of monodisperse ceria abrasive in chemical mechanical planarization

In this study, the monodisperse abrasive deposition (MDAD) system was developed to investigate the polishing mechanism of ceria abrasives for the chemical mechanical planarization of a wafer. Using the MDAD system, groups of ceria particles with a specific size were collected from slurry with various particle size distributions, and each group was deposited on a blanket silicon wafer to study the size effect of the ceria particle on polishing results. The effects of the ceria particle size on surface roughness, contact area ratio, and subsurface damages on the surface and subsurface crystallographic structure were investigated using atomic force microscopy, transmission electron microscopy, and a surface inspection system. A similar set of experiments was performed with types of ceria abrasive particles with the same diameter but different morphologies to investigate the effect of the ceria abrasive geometry on polishing results. In addition, the effect of the ceria particle size on the pattern loading was investigated by polishing the shallow trench isolation and high aspect ratio patterned wafers.