The effects of common slurry additives on the colloidal behavior of alumina suspensions used for copper chemical mechanical planarization (CMP) were investigated. The alumina suspensions were characterized by zeta potential and agglomerate size distribution measurements with various chemical additives. To simulate the slurry during copper CMP, the effect of the addition of similar to 100 nm diameter copper particles was studied. The presence of 0.12 mM copper caused a decrease in agglomeration for pH values less than 6.5 and an increase in agglomeration ranging from 200-1000 nm for pH values greater than 7 in aqueous solutions. Addition of glycine caused the formation of a soluble Cu-glycine complex that decreased agglomeration at pH values less than 4. The addition of 0.1 wt % H2O2 did not affect the effective alumina agglomerate size without copper, but with copper in the solution the majority of the alumina agglomerated to similar to 2 mu m for all pH values. However, increasing H2O2 concentration to 2.0 wt % decreased the agglomerate size by 100-400 nm. The pH of the slurry had the largest effect on the zeta potential and agglomerate size distributions. (c) 2006 The Electrochemical Society.