Comparison of Run-to-Run Control Methods in Semiconductor Manufacturing Processes

Run-to Run (RtR) control plays an important role in semiconductor manufacturing. In this paper, RtR control methods are generalized. The set-valued RtR controllers with ellipsoid approximation are compared with other RtR controllers by simulation according to the following criteria: A good RtR controller should be able to compensate for various disturbances, such as process drifts, process shifts (step disturbance) and model errors; moreover, it should be able to deal with limitations, bounds, cost requirement, multiple targets and time delays that are often encountered in real processes. Preliminary results show the good performance of the set-valued RtR controller. Furthermore, this paper shows that it is insufficient to use linear models to approximate nonlinear processes and it is necessary to develop nonlinear model based RtR controllers.