Modeling of Copper CMP Using the Colloidal Behavior of an Alumina Slurry with Copper Nanoparticles

Abstract

The measured agglomerate size distributions of alumina abrasives in various slurry chemistries and at different pH values were used in a model to predict material removal rates (MRRs). The alumina agglomerate size and distribution were measured both with and without the presence of copper nanoparticles in the solution for each slurry chemistry studied. Although the agglomerate sizes were measured under quiescent conditions, it is determined that the agglomerated abrasive particles remain intact during chemical mechanical planarization (CMP), hence the measurements can be used in the CMP model. The model predictions using these measurements both with and without copper in solution were compared to experimental copper CMP data. The model was unable to predict the MRR when the slurry did not have any chemical additives because the dispersion was unstable and small fluctuations in the agglomerate size and distribution caused large changes in the predicted MRR. The model predictions were in excellent agreement with experimental MRR for a slurry with glycine in alkaline conditions. The model results from the size distribution measurements with copper in solution agreed slightly more with experiment than those without copper.