Material Removal Behavior of Nano-sized Cerium Hydroxide Abrasive Slurry for Chemical Mechanical Polishing

Microscratch induced by Chemical Mechanical Polishing (CMP) is a chronic problem to device yield-killing and its criticality becomes more important in sub-14nm device manufacturing. In order to mitigate scratching during CMP, minimizing abrasive particle size without sacrificing removal rate is the most important parameter. For this purpose, less than 5nm sized cerium hydroxide-based (nano-sized cerium hydroxide-based, NC) particle is utilized as oxide CMP slurry, which is much smaller than conventionally used calcined ceria slurry (100nm - 200nm in particle size). Although it shows more than 80% microscratch reduction obtained by NC slurry in poly CMP process, its polishing behavior is not well understood. In this study, tetraethyl orthosilicate (TEOS) oxide removal behavior with NC slurry is explored by a series of experiments involving tribological analysis. Based on experimental results, this study emphasizes surface reaction as a dominant parameter to determine removal rate rather than mechanical aspect of material removal.