A petri-net-based scheduling strategy for dual-arm cluster tools with wafer revisiting

Naiqi Wu, Mengchu Zhou, Feng Chu, Chengbin Chu

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


There are wafer fabrication processes in cluster tools that require wafer revisiting. The adoption of a swap strategy for such tools forms a 3-wafer cyclic (3-WC) period with three wafers completed in each period. It has been shown that, by such a scheduling strategy, the minimal cycle time cannot be reached for some cases. This raises a question of whether there is a scheduling method such that the performance can be improved. To answer this question, a dual-arm cluster tool with wafer revisiting is modeled by a Petri net. Based on the model, the dynamical behavior of the process is analyzed. Then, a 2-wafer cyclic (2-WC) scheduling strategy is revealed for the first time. Cycle time analysis is conducted for the proposed strategy to evaluate its performance. It shows that, for some cases, the performance obtained by a 2-WC schedule is better than that obtained by any existing 3-WC ones. Thus, they can be used to complement each other in scheduling dual-arm cluster tools with wafer revisiting. Illustrative examples are given.

Original languageEnglish (US)
Pages (from-to)1182-1194
Number of pages13
JournalIEEE Transactions on Systems, Man, and Cybernetics Part A:Systems and Humans
Issue number5
StatePublished - 2013

All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Software
  • Information Systems
  • Human-Computer Interaction
  • Computer Science Applications
  • Electrical and Electronic Engineering


  • Cluster tool
  • Petri nets (PNs)
  • Scheduling
  • Semiconductor manufacturing


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