CMP pressure control based on dual-modes controller

Chemical Mechanical Polishing (CMP) is the most effective wafer global planarization technology. The quality of polishing not only depends on slurry, but also depends on the precise control of polishing pressure. This paper presents a bang-bang+ dual-modes gain-variable PID controller which is used as the core control strategy to overcome the phenomena of long adjustment time, large overshooting and so on. The strategy has the advantages of the robustness, fast dynamic response of the bang-bang controller and the high steady-state accuracy of the gain-variable PID controller. Experiment results show that the dual-modes controller is feasible, practical and correct.