An open scheduling architecture for cluster tools

Cluster tools, which have several processing modules (PMs) and wafer transport module(s) (TM), are widely used for semiconductor manufacturing. They have diverse architectures and scheduling requirements. Each time the wafer recipe and scheduling requirement change, the scheduling rules should be properly designed and timely changed or tuned. To make such changes easy, we propose an open standard for specifying and exchanging the scheduling rules, which should be determined and changed depending on the tool architecture, the wafer recipe, and the scheduling requirements. It is to easily implement the scheduling rules into a real-time scheduler and to improve interoperability of the scheduling rules between the tools, tool vendors, and fabs. To do this, we propose the use of Petri net models for modeling and specifying the tool architecture, the wafer flow pattern or the recipe, the scheduling requirements, the tool behavior, and finally the scheduling rules. The scheduling rules are defined as a token routing rule in conflict places of the Petri net model. We propose XML(eXtensible Markup Language)-based file formats for specifying these, which all constitute an integrated scheduling information exchange format, called Scheduling Command File. Finally, we explain how to implement a scheduling command file within a cluster tool controller.