Optimal buffer space configuration and scheduling for single-arm multi-cluster tools

摘要

A method for scheduling single-arm multi-cluster tools is provided. The present invention studies the scheduling problem of a single-arm multi-cluster tool with a linear topology and process-bound bottleneck individual tool. Its objective is to find a one-wafer cyclic schedule such that the lower bound of cycle time is reached by optimally configuring spaces in buffering modules that link individual cluster tools. A Petri net model is developed to describe the dynamic behavior of the system by extending resource-oriented Petri nets such that a schedule can be parameterized by robots' waiting time. Based on this model, conditions are presented under which a one-wafer cyclic schedule with lower bound of cycle time can be found. With the derived conditions, an algorithm is presented to find such a schedule and optimally configure the buffer spaces.

主权项

1. A computer implemented method for scheduling single-arm multi-cluster tools with optimal buffer space configuration, comprising:
obtaining, by a processor, a wafer processing time, a robot wafer loading and unloading time, and a robot moving time; calculating, by a processor, a shortest time for completing a wafer based on the wafer processing time, the robot wafer loading and unloading time, and the robot moving time; calculating, by a processor, a robot cycle time based on the robot wafer loading and unloading time, and the robot moving time; determining, by a processor, a fundamental period based on selecting a maximum value among the shortest time for completing the wafer and the robot cycling time; determining, by a processor, a type of cluster tool by:
if the fundamental period is a value of the shortest time for completing the wafer, the type of cluster tool is process-bound;otherwise the type of cluster tool is a transport-bound; determining, by a processor, the multi-cluster tools to be process-bound, or transport-bound based on the type of cluster tool having a maximum value of the fundamental period; determining, by a processor, a lower bound of cycle time based on the maximum value of the fundamental period; determining, by a processor, an algorithm for scheduling and buffer space configuration based on a petri net model; and calculating, by a processor, a robot waiting time based on the algorithm; calculating, by a processor, a wafer sojourn time based on the algorithm and the lower bound of cycle time; determining, by a processor, a buffer space for buffer module based on the wafer sojourn time and the robot waiting time; and obtaining, by a processor, a schedule based on the buffer space for buffer module and the lower bound of cycle time.