Design of a run-to-run controller based on discrete sliding-mode observer

Abstract

In this study, a run-to-run controller based on a discrete sliding-mode observer (DSMO) is presented for photolithography manufacturing processes. A second-order DSMO is introduced to estimate the process disturbances caused by tool aging and preventive maintenance. The proposed controller is constructed by applying DSMO estimation to the deadbeat control law and the stable region is discussed. Numerical simulations and an industrial case demonstrated the performance of the proposed algorithm. It is observed that the proposed controller has a superior performance over the exponentially weighted moving average (EWMA) and double EWMA (dEWMA) controller under the first-order integrated moving average disturbance with shift or drift. This superiority is maintained when the system contains a certain plant-model mismatch. Moreover, the tolerance of the proposed controller for metrology delay is better than that of the dEWMA controller.