Communication—Reduction of Friction Force between Ceria and SiO2 for Low Dishing in STI CMP

Abstract

We investigated the effect of friction force between ceria abrasive and SiO2 film on dishing in STI CMP. The control of adsorption amount of poly acrylic acid (PAA) on ceria surface led to the reduction of the friction force during CMP. The reduced friction force by a thick surface layer on ceria resulted in the decrease of the dishing in STI structure during over-polishing process. In the patterned wafer, the dishing decreased from 976 to 594 Å/min at 37.5% pattern density (Si3N4/SiO2 = 30/50 μm) as a maximum adsorption amount increased from 0.49 to 0.64 mg/m2.