Deadlock-free scheduling method for track systems in semiconductor fabrication

This paper addresses a deadlock-free scheduling method for track systems in semiconductor fabrication. A track system is clustered equipment performing the photolithography process in semiconductor fabrication. Trends toward high automation and flexibility in the track systems accelerate the necessity of the intelligent scheduler that can guarantee reliability and optimize productivity of the track systems. We propose an efficient deadlock-free scheduling method that can avoid deadlock inherent to track systems and optimize the productivity. We employ two procedures for the deadlock-free scheduling. First, we define the potential deadlock set and deadlock-safe set to apply the deadlock avoidance policy efficiently. After introducing the potential deadlock set and the deadlock-safe set we propose a deadlock avoidance policy using an online Gantt chart, which can generate optimal or near-optimal schedules without deadlock. The proposed deadlock-free scheduling method is shown to be efficient in handling deadlock inherent to the track systems through simulation