Trade-offs in temperature control of fast-ramp RTP systems

Trade-offs in temperature control of fast-ramp rapid thermal processing (RTP) systems from an open-loop optimal input point of view are investigated. Exact tracking of fast ramps with rates such as 250/spl deg/C/sec is usually not possible if other constraints, like actuator saturation and/or limited temperature overshoot, have to be met. A recently developed trajectory redesign technique allows to trade-off exact tracking versus other limitations in an optimal way. Application of this technique to a model of a generic RTP system exemplifies the possibilities and limitations of fast-ramping temperature control.