Modification of Electrokinetic Behavior of CeO2 Abrasive Particles in Chemical Mechanical Polishing for Shallow Trench Isolation

Published

December 1, 2001

Author(s)

J P. Kim, J G. Yeo, U Paik, Y S. Jung, Jinkyoo Park, Vincent A. Hackley

Abstract

Ceria (CeO₂) slurry stability and oxide-to nitride selectivity in the shallow trench isolation chemical mechanical polishing (STI CMP) process were manipulated with the modification of ceria surface potentials. The electrophoretic mobility of CeO₂ particles is strongly dependent on suspension pH as well as ionizable acrylic polymer. With modification of surface potentials, the isoelectric point (pH_iep) of ceria shifted toward acidic pH values, resulting in an increasing negative surface potential at pH values between 5 and 7. This surface modification resulted in an increase of oxide removal rate due to mutually repulsive electrostatic forces between modified CeO₂ abrasive particle and SiO₂ film. When modified ceria particles are dispersed at a pH near the pH_iep of silicon nitride, where the surface potential of silicon nitride is minimal, the removal rate of nitride is sharply reduced and thus oxide-to-nitride selectivity is improved by a factor of roughly 1:50.

Citation

Journal of the Korean Physical Society

Volume

39

Issue

Suppl. S

Pub Type

Journals

Keywords

abrasive particles, ceria, chemo mechanical polishing, electrokinetics, passivation

Citation

Kim, J. , Yeo, J. , Paik, U. , Jung, Y. , Park, J. and Hackley, V. (2001), Modification of Electrokinetic Behavior of CeO₂ Abrasive Particles in Chemical Mechanical Polishing for Shallow Trench Isolation, Journal of the Korean Physical Society (Accessed March 13, 2025)