A plasticity-based model of material removal in chemical-mechanical polishing (CMP)

It is well known that the chemical reaction between an oxide layer and a wa ter-based slurry produces a softer hydroxylated interface layer. During che mical-mechanical polishing (CMP), it is assumed that material removal occur s by the plastic deformation of this interface layer. In this paper, the be havior of the hydroxylated layer is modeled as a perfectly plastic material , and a mechanistic model for material removal rate (MRR) in CMP is develop ed. The deformation profile of the soft pad is approximated as the bending of a thin elastic beam. In addition to the dependence of MRR on pressure an d relative velocity, the proposed plasticity-based model is also capable of delineating the effects of pad and slurry properties. The plasticity-based model is utilized to explore the effects of various design parameters (e.g ., abrasive shape, size and concentration, and pad stiffness) on the MRR. M odel predictions are compared with existing experimental observations from glass polishing, lapping, and CMP.