Experimental Verification of CMP Process Analysis

The present study performs an experimental verification of an analytical model of the Chemical Mechanical Polishing (CMP) process, focusing on friction force and the distribution of the material removal rate. A coupled Fluid-Structure analytical model, which can predict the friction force and the distribution of the material removal rate, is developed. Oxide CMP experiments are conducted using a fabricated CMP system, and measured friction force and distribution of the material removal rate are compared with the analytical results. As a result, it is confirmed that the wafer´s rotational speed affects the friction force and the distribution of the material removal rate. Additionally, the results determined by the developed analytical model agree with the measurements. The magnitude of the friction force under a condition in which the wafer does not rotate becomes smaller than when the wafer rotates at the same speed as the polishing pad. The direction of the friction force inclines against the rotational center of the polishing pad. The material removal rate when the wafer does not rotate is high around the edge of the wafer as compared with that at other areas. In particular, it becomes high around the leading edge and the area where the rotational radius of the polishing pad is large. These specific characteristics of the friction force and the distribution of the material removal rate are explained using the analytical results.