Adhesion and removal of alumina slurry particles on wafer surfaces in CuCMP

Abstract

The adhesion force and removal of alumina particles on Cu, Ta, TEOS, SILK (TM), Aurora and FSG wafer surfaces were experimentally and theoretically investigated in slurry solutions of different pHs. These wafer surfaces showed negative zeta potentials in the investigated pH ranges with exception of FSG and Ta. However, the zeta potentials of FSG surface drastically decreased with increasing pH. The lowest adhesion force and smallest number of alumina particles were measured between alumina particle and FSG surface in a slurry solution of pH 11. Alkaline slurry was much more desirable in controlling the level of particle contamination during Cu CMP. The pH of the slurry and zeta potentials of the surfaces played important roles in controlling the interaction force.