Robust high-gain control of nonlinear reactive sputter processes

A model-based control design method is developed for nonlinear reactive sputter processes that can be modelled by a nonlinear ordinary differential equation with linear input and stable and unstable equilibrium states. The controller shall robustly stabilize the unstable working points. Lyapunov's direct method is used to formulate stability conditions that respect possible uncertainties in the process model. It is shown that reactive sputter processes can be stabilized by robust high-gain control. The theoretical results are sustained by experiments for the validation of the developed control structure and to evaluate the agreement of the predicted closed-loop behavior with the measured behavior.