Discrete-time control system design for a Reactive Ion Etching (RIE) system

The problem of designing a robust controller to solve a tracking control problem for improving plasma characteristics in Reactive Ion Etching process is studied. The presented design methodology is based on the construction of a two-time scale motions of the closed-loop system. It has been shown that under discussed conditions the proposed dynamical controller induces a two time-scale separation of the fast and slow modes in the closed-loop system. Stability conditions imposed on the fast and slow motions can ensure that the full-order closed-loop system achieves the desired properties so that the out-put transient performances are insensitive to parameter variations and external disturbances. Simulation results on a multivariable auto regressive moving average model of a RIE process are presented to demonstrate the utility of the proposed algorithm.