PROJECT TITLE :

Optimal Scheduling of Transient Cycles for Single-Armed Cluster Tools With Parallel Chambers

ABSTRACT:

Cluster tools have been extensively used for several semiconductor producing processes like lithograph, etching, deposition, and testing. Most previous studies on cluster tool scheduling have centered on steady cycles in which cluster tools repeat identical work cycles. However, the proportion of noncyclic transient operation cycles such as start-up cycles and shut-down cycles becomes larger because the ton size tends to be smaller. We tend to examine optimal transient scheduling for one-armed cluster tool, in which there are parallel chambers and a method chamber may be a bottleneck, while minimizing the makespan of a heap. To do this, we tend to 1st establish elementary properties of noncyclic transient cycles in a tool by analyzing resource workloads. We then propose a simple robot task sequence, a generalized backward sequence, which performs backward operations incrementally for start-up cycles and decrementally for close-down cycles. We tend to conjointly develop workload-based mostly conditions for that the generalized backward sequence has the minimum makespan for single-armed cluster tools with parallel chambers. Finally, we develop a linear programming model to seek out the minimum makespan of the generalized backward sequence for the cases in that the conditions are not met and show its effectiveness.