New Particle Metrology for CMP Slurries

A new particle sizing and counting method based on the coupling of flow field-flow fractionation (FFF) with dual-sensor, single particle optical sensing (SPOS) detection is reported. The integration of FFF and SPOS systems was accomplished by means of a dilution interface that preserved the resolution of FFF-separated particles. Analysis of a model mixture of polystyrene latex standards of different diameters established that the FFF-SPOS system can resolve particles into discrete peaks for subsequent particle counting. Application of this method for the analysis of a colloidal silica standard demonstrated its use for materials commonly employed as CMP abrasives. Further development and refinement of the technique will enable compositional and structural analyses of heterogeneous large particle populations constituting commercial CMP slurries