A concurrent-engineering approach is applied to the development of an axisymmetric rapidthermal-processing (RTP) reactor and its associated temperature controller. Using a detailed finiteelement thermal model as a surrogate for actual hardware, we have developed and tested a multi-input multi-output (MIMO) controller. Closed-loop simulations are performed by linking the control algorithm with the finite-element code. Simulations show that good temperature uniformity is maintained on the wafer during both steady and transient conditions. A numerical study shows the effect of ramp rate, feedback gain, sensor placement, and wafer-emissivity patterns on system performance.