A chemical mechanical polishing model based on the viscous flow of the amorphous layer

Based on the theoretical analysis of the molecular dynamics simulation of sliding contact between a single micro-particle and a smooth flat surface, a new dominant mechanism of viscous flow of the amorphous layer on wafer surface for the material removal in chemical mechanical polishing (CMP) process is proposed. Furthermore, a new mathematical model characterizing the material removal rate in CMP process is developed by using micro-contact mechanics and particle size distribution theory on the basis of this mechanism. Particularly, a new important parameter k, representing the ability to remove the amorphous layer from wafer surface by a single particle, is firstly put forward and integrated in the model. The model not only incorporates the mechanical effects of the slurry particles and chemical role of the slurry, but also includes the influences of other important factors on CMP process such as wafer material properties, pad surface profiles and operating variables. The model has also been verified by the experiments shows good agreement with those experimental data in the same CMP conditions. This research will provide a new platform for further investigation in CMP mechanism of material removal.