Finite element analysis on von Mises stress distributions of Si DSP

In this paper, we describe a 2D axisymmetric quasi-static finite element model based on 300 mm wafer and double-side polishing (DSP) using a COMSOL Multiphysics software. Afterwards, the effects of Young's modulus and Poisson's ratio of polishing pad and the thickness ratio of upper and lower pads on the von Mises stress distribution are observed and chemical mechanical polishing (CMP) experiments are carried out to verify the above numerical calculations. The results show that a harder polishing pad results in a less edge roll-off, where a sharp variation in removal rate is observed near the edge of the wafer, but Poisson's ratio of pad has a less effect on the von Mises stress distribution on the wafer edge. A larger thickness ratio of upper and lower pads leads to a better wafer planarization.