CONTROL OF MMST RTP - REPEATABILITY, UNIFORMITY, AND INTEGRATION FOR FLEXIBLE MANUFACTURING

A real-time multivariable strategy is used to control the uniformity a nd repeatability of wafer temperature in rapid thermal processing (RTP ) semiconductor device manufacturing equipment. This strategy is based on a physical model of the process where the model parameters are est imated using an experimental design procedure. The Internal Model Cont rol (IMC) law design methodology is used to automatically compute the lamp powers to a multizone array of concentric heating zones to achiev e wafer temperature uniformity. Control actions are made in response t o real-time feedback information provided by temperature sensing, via pyrometry, at multiple points across the wafer. Several modules, inclu ding model-scheduling and anti-overshoot, are coordinated with IMC to achieve temperature control specifications. The control strategy, orig inally developed for prototype equipment at Stanford University, is an alyzed via the customization, integration, and performance on eight RT P reactors at Texas Instruments conducting thirteen different thermal fabrication operations of two sub-half-micron CMOS process technologie s used in the the Microelectronics Manufacturing Science and Technolog y (MMST) program.