Design of experiment (DOE) method considering interaction effect of process parameters for optimization of copper chemical mechanical polishing (CMP) process

Chemical mechanical polishing (CMP) has been widely accepted for the metallization of copper interconnection in ultra-large scale integrated circuits (ULSIs) manufacturing. It is important to understand the effect of the process variables such as turntable speed, head speed, down force and back pressure on copper CMP. They are very important parameters that must be carefully formulated to achieve desired the removal rates and non-uniformity. Using a design of experiment (DOE) approach, this study was performed investigating the interaction effect between the various parameters as well as the main effect of the each parameter during copper CMP. A better understanding of the interaction behavior between the various parameters and the effect on removal rate, non-uniformity and ETC (edge to center) is achieved by using the statistical analysis techniques. In the experimental tests, the optimized parameters combination for copper CMP which were derived from the statistical analysis could be found for higher removal rate and lower non-uniformity through the above DOE results.