Application of run by run controller to the chemical-mechanical planarization process. II

The chemical-mechanical planarization (CMP) process has demonstrated planarization capabilities beyond other current technologies, and is considered a strategically important process for next generation multilevel metal interconnect devices. The Run by Run (RbR) controller is applied to CMP. The application of the RbR controller is to reduce the drifts and shifts in the average removal rate and nonuniformity in the CMP process. The RbR controller is a model-based process control system which combines the advantages of both statistical process control (SPC) and feedback control to provide accuracy and flexibility that cannot be achieved by using either method alone. In characterizing the CMP process for the models, there are a transition effect and a memory effect. In this paper, we report further experiments and the results of process modeling. Included in the process models are the pad age effect and the pad rebound effect, which we have characterized to increase the accuracy and effectiveness of the process models. The predicted average removal rate including all these effects matches the process data very well over hundreds of wafers, with only 5 adjustable parameters