Simulation of CMP Process Based on Mixed Elastohydrodynamic Lubrication Model with Layered Elastic Theory

Abstract

A simulation framework based on the mixed elastohydrodynamic lubrication (mixed EHL) model has been used successfully to explain some phenomena observed in Chemical mechanical polishing (CMP) process. However, the pad deformation model adopted in various CMP simulation frameworks, such as Winkler elastic foundation model or elastic half-space model, can not correctly describe the deformation features of pad, especially at the wafer periphery. In this study, a layered elastic theory, which can calculate the pad deformation with similar accuracy but lower computational cost than 3D finite element method (FEM), is introduced into the mixed EHL, and it is significant to predict the contact pressure distribution more accurately than existing approaches. Further, the material removal rate can be predicted accurately, it is useful for the study of the mechanism of CMP and the optimization of the CMP processing parameters.