Y Super fine cerium hydroxide abrasives for-SiO2 film chemical mechanical planarization performing scratch free

Abstract

Face-centered-cubic crystallized super-fine (= 2 nm in size) wet-ceria-abrasives are synthesized using a novel wet precipitation process that comprises a Ce4+ precursor, C3H4N2 catalyst, and NaOH titrant for a synthesized termination process at temperature of at temperature of 25 degrees C. This process overcomes the limitations of chemical-mechanical-planarization (CMP)-induced scratches from conventional dry ceria abrasives with irregular surfaces or wet ceria abrasives with crystalline facets in nanoscale semiconductor devices. The chemical composition of super-fine wet ceria abrasives depends on the synthesis termination pH, that is, Ce(OH)(4) abrasives at a pH of 4.0-5.0 and a mixture of -CeO2 and Ce(OH)(4) abrasives at a pH of 5.5- 6.5. The Ce(OH)(4) abrasives demonstrate better abrasive stability in the SiO2-film CMP slurry than the CeO2 abrasives and produce a minimum abrasive zeta potential (similar to 12 mV) and a minimum secondary abrasive size (similar to 130 nm) at the synthesis termination pH of 5.0. Additionally, the abrasive stability of the SiO2-film CMP slurry that includes super-fine wet ceria abrasives is notably sensitive to the CMP slurry pH; the best abrasive stability (i.e., a minimum secondary abrasive size of similar to 130 nm) is observed at a specific pH (6.0). As a result, a maximum SiO2 film polishing rate (similar to 524 nm/ min) is achieved at pH 6.0, and the surface is free of stick-and-slip type scratches.