Repulsive effect between abrasives during CMP process

According to Paul et al.´s model [1], behavior of CMP slurry abrasives during polishing was modeled as an adsorption/desorption reaction on sites of polishing pad. The model showed a saturation relationship between removal rate and abrasive concentration. In this study, we extended this concept to include repulsive force between abrasives since it might result in reduction of effective sites on the pad and reduce removal rate. A kinetic mechanism is developed to illustrate this repulsive effect between abrasives. Our experimental results show higher charged abrasive makes removal rate lower at high concentration. Abrasive size also influences the static electric flux on particle surface. Smaller size abrasive will cause more significant repulsive effect than larger one.