Effects of CMP Slurry Chemistry on the Zeta Potential of Alumina Abrasives

Abstract

The colloidal behavior of alumina in typical copper chemical mechanical planarization (CMP) solutions was investigated through the measurement of zeta potential and particle cluster size distribution. The effects of various common additives on zeta potential for alumina slurries used in copper CMP were studied. Addition of 1mM to 0.1M glycine stabilized the zeta potential for alumina for a large pH range. Although slurry pH has the largest effect on zeta potential and particle cluster size distribution, sodium dodecyl sulfate caused alumina to maintain a small aggregate size (∼200nm) while ethylenediaminetetraacetic acid caused alumina to agglomerate (∼1.2-2μm) over the entire pH range investigated.