Output Disturbance Observer Structure Applied to Run-to-Run Control for Semiconductor Manufacturing

Abstract

Among the run-to-run (RtR) controllers, the EWMA controller, the double EWMA controller, and the predictor corrector controller are widely adopted in the semiconductor industry. This paper presents a unified framework for these controllers, which is called the output disturbance observer (ODOB) structure. The advantages of applying the ODOB structure are that the process output will be forced to the process target and the actual plant to the nominal plant while the process disturbance and the measurement noise are rejected. The relations of the tuned parameters of the above-mentioned controllers and the ODOB controller are discussed. Furthermore, based on the unified framework, the RtR controller with model mismatch and metrology delay can be analyzed systematically. In this paper, we analyze the robust stable conditions for the ODOB controller taking the model mismatch and metrology delay into consideration and provide a method to tune the controller.