Effects of Abrasive Morphology and Surfactant Concentration on Polishing Rate of Ceria Slurry

Abstract

To reveal the mechanism behind the high oxide-to-nitride removal selectivity of ceria slurry in shallow trench isolation (STI) chemical mechanical polishing (CMP), we examined the effects of the abrasive morphology and the concentration of surfactant added to control the selectivity. A slurry with small abrasives showed a more drastic drop in the oxide removal rate as the surfactant concentration increased, compared to a slurry with large abrasives. For the nitride removal rate, however, both slurries showed the same trend. These results can be qualitatively explained from the movement of abrasives though the layer of surfactant adsorbed on the film surface.