Evaluation of chemical mechanical planarization slurry dispersion using a combined scanning mobility particle sizer-optical particle sizer system

Abstract

A combined scanning mobility particle sizer-optical particle sizer (SMPS-OPS) system was evaluated for measuring the dispersion of a chemical mechanical planarization (CMP) slurry. The dilution rate of one particle per droplet was confirmed to minimize agglomeration. The SMPS and OPS measurements showed similar particle size distributions of 400 nm polystyrene latex particles. The particle size distributions of settled ceria and silica slurries were measured using the SMPS-OPS system. The settled commercial ceria slurry showed a decrease in the number concentration in the top layer. In the bottom layer, increases in the concentration of active particles and in the number of large particles were observed. This indicates that large particles were formed during settling of the slurry. In the silica slurry, there was a change in concentration with depth and little change in number of large particles with settling time. The SMPS-OPS system was able to analyze CMP slurries across a wide range of particle diameters for both active and large particles. Therefore, this system can be helpful for analysis of CMP slurry size.