A three-dimensional transient model to predict interfacial phenomena during chemical mechanical polishing using computational fluid dynamics

摘要

Interfacial phenomena between the wafer and the polishing pad during chemical mechanical polishing are an area of great interest as they affect post-chemical mechanical polishing wafer topographies. Traditionally, the Reynolds equation has been used to predict the fluid pressure between the wafer and the polishing pad. However, with computational fluid dynamics it is possible to predict the fluid pressure and obtain insight into the fluid motion at the leading edge and trailing edge of the wafer. Additionally, computational fluid dynamics allows for the added ability to increase the resolution of the fluid physics to the asperity scale. In this study, a model is developed to predict phenomena related to mixed lubrication chemical mechanical polishing using computational fluid dynamics. Contact mechanics between the wafer and the pad are resolved through a Winkler elastic foundation formulation. The wafer is mounted on a ball joint which allows free rotation to occur. Friction between the wafer and the polishing pad causes the wafer to assume a position which produces a sub-ambient pressure distribution similar to that obtained from experiments. The effects of different table speeds on the interfacial fluid pressure, as predicted by the computational fluid dynamics are presented.