Improvement of oxide chemical mechanical polishing performance by increasing Ce3+/Ce4+ ratio in ceria slurry via hydrogen reduction.

Ceria-based abrasive is widely used in the oxide chemical mechanical polishing (CMP) process due to its high polishing performance. Ce3+ ions on the surface of ceria form a Ce–O–Si chemical bond with surface of the SiO 2 wafer, significantly affecting the material removal rate (MRR). In this study, the ceria surface was reduced by contact with hydrogen gas in a high temperature isothermal environment. Hydrogen gas forms surface hydroxyls on the ceria. Then, the generated hydroxyls form H 2 O and oxygen vacancies occur through the desorption of the H 2 O. The color of ceria changed to blue due to a change of the crystal structure by the reduction reaction. The reducing ability of hydrogen gas increased as the reduction temperature increased and the Ce3+ ion concentration increased by 12.7% under isothermal conditions at 1000 °C. The MRR of reduced ceria was improved by up to 37.7% compared to the original ceria. [Display omitted] • The ceria particles were reduced by hydrogen gas in a high temperature environment. • Oxygen vacancy was formed through hydrogen adsorption and H 2 O desorption processes. • Ce3+ ion concentration increased as the reduction temperature increases. • The oxide removal rate was significantly affected by Ce3+ ion concentration. [ABSTRACT FROM AUTHOR]