Effect of Copper CMP Slurry Chemistry on the Rate of Agglomeration of Alumina Particles

The rate of agglomeration was measured for alumina particles with and without the copper in KNO3 at various pH values. For solutions without copper, agglomeration was greatest at pH of 7.5, near the isoelectric point of 6.5, at a rate of 82 nm/min, following a reaction-limited mechanism. Solutions with a pH away from the isoelectric point underwent reversible agglomeration, reaching a small agglomerate size at steady-state. The addition of copper did not affect agglomeration at pH 4. However, an increase in the agglomeration rates at pH 7.5 and 10 was observed with copper in the solutions, following a diffusion-limited mechanism