Details

Autor(en) / Beteiligte

• Wu, Naiqi
• Chu, Chengbin
• Chu, Feng
• Zhou, Meng Chu

Titel

A Petri Net Method for Schedulability and Scheduling Problems in Single-Arm Cluster Tools With Wafer Residency Time Constraints

Ist Teil von

• IEEE transactions on semiconductor manufacturing, 2008-05, Vol.21 (2), p.224-237

Ort / Verlag

New York, NY: IEEE

Erscheinungsjahr

2008

Quelle

IEEE Electronic Library (IEL)

Beschreibungen/Notizen

• With wafer residency time constraints for some wafer fabrication processes, such as low pressure chemical-vapor deposition, the schedulability and scheduling problems are still open. This paper aims to solve both problems. A Petri net (PN) model is developed for the system. This model describes when the robot should wait and a robot wait is modeled as an event in an explicit way. Thus, to schedule a single-arm cluster tool with wafer residency time constraint is to decide how long a robot wait should be. Based on this model, for the first time, we present the necessary and sufficient conditions under which a single-arm cluster tool with residency time constraints is schedulable, which can be checked analytically. Meanwhile, a closed form scheduling algorithm is developed to find an optimal periodic schedule if it is schedulable. Also, a simple method is presented for the implementation of the periodic schedule for steady state, which is not seen in any previous work.