A Wafer-Scale Material Removal Rate Model for Chemical Mechanical Planarization

In this work, a new wafer-scale material removal rate (MRR) model is proposed to investigate the underlying removal mechanism of wafer surface in the chemical mechanical planarization (CMP) process. Based on the governing equation of the plate theory, chemical reaction kinetics and wear theory, an analytical CMP model has been constructed to capture the influence of mechanical abrasion and chemical reactions on the removal rate with high efficiency. The effect of the elastic modulus of the pad, platen rotational speed, polishing temperature and reactant concentrations on the removal mechanism is investigated in detail to elucidate the intrinsic removal behavior. It is found that the material removal rate is sensitive to the elastic modulus of pad, temperature distribution, and chelator concentration, more sensitive to the oxidizer concentration, and most sensitive to the platen rotational speed. The magnitude of the removal rate can be adjusted significantly by properly selecting a good configuration of these influencing factors. The model predictions of the MRR profiles are consistent with the published experimental data at different polishing conditions. Therefore, the present CMP model can give insights into the wear mechanism of polishing process and may be utilized as a simulation tool for further optimization of removal rate and surface uniform control.