Material Removal Mechanisms of Oxide and Nitride CMP with Ceria and Silica-Based Slurries - Analysis of Slurry Particles Pre- and Post-Dielectric CMP

摘要

The effect of CMP process parameters (pressure and pad hardness) on the ceria and silica abrasive particle-size distribution (PSD), morphology, and surface composition when polishing oxide and nitride surfaces was investigated in detail. The PSD was observed to shift post-CMP, with ceria and silica exhibiting a decrease and increase, respectively, in the number of particles towards the tail end of the distribution. The shift in ceria PSD was observed to increase as pad hardness increased. An increase in polish pressure and work surface hardness resulted in an equivalent shift in the PSD when polished on a soft pad. The inclusion of an additive reduced the oxide removal rate, and the abrasive particles exhibited the presence of a thin organic coating on the surface. The difference in material removal mechanisms and selectivity when polishing oxide and nitride with ceria and silica-based slurries was also investigated in detail.