Deadlock avoidance policy for dual-armed multi-cluster tools with multi-flow

Cluster tools are widely used for semiconductor manufacturing. Scheduling of multi-cluster tools has been received much attention. A cluster tool consists of several processing modules, transfer module with single or dual-armed handling robot and loadlock modules. The multi-cluster tool consists of two or three cluster tools which are connected with buffer module. In this paper, we present a deadlock-free scheduling for dual-armed multi-cluster tools with multi-flow. We develop a deadlock avoidance policy for dual-armed multi-cluster tools with dual path. A Petri net model is analyzed to derive a deadlock avoidance policy. The deadlock-freeness is confirmed by analyzing siphon of Petri net model. The deadlock-free scheduling method is proposed. The proposed method is applied to the scheduling problem of three-cluster tools with dual path. The computational results show that no deadlock occurs with the proposed deadlock avoidance policy.