Control of Rapid Thermal Processing: A System Theoretic Approach

Abstract Tight control of the wafer temperature is essential in Rapid Thermal Processing (RTP) of semiconductor wafers. Of the various techniques for controlling the temperature, model-based control has the greatest potential for attaining the best performance.An identification of a state-space model based on the subspace-fitting technique results in an experiment-based model. Subsequently, a Linear Quadratic Gaussian (LQG) controller is designed. To improve response, open loop control obtained by a convex optimization is incorporated into the feedback controller. The identification technique and the controller are validated with experimental results from an RTP system at Stanford University.