An approach to run-to-run control for rapid thermal processing

This paper introduces a new approach to run-to-run (RtR) control for semiconductor manufacturing processes. It is based on a technique developed for batch-to-batch operating profile modification for batch chemical processes. It is particularly appropriate for rapid thermal processing (RTP) reactors, where the recipe includes a function of time and the optimization requires the use of dynamic models. Our technique modifies the profile between runs directly, without requiring re-modeling or the adaptation of model parameters. This is accomplished by combining the existing model with process measurement information and obtaining a direction of improvement by utilizing the similarity between iterations in numerical optimization and runs in RtR control. The example that is used to illustrate the method is motivated by an overheating problem that was observed experimentally and reported in the literature. A very simple set of model and plant equations are used to emulate the model-plant mismatch.