Dispatching of overhead hoist vehicles in a fab intrabay using a multimission-oriented controller

The semiconductor manufacturing system has become one of the most important manufacturing systems in recent years. Intrabay automation for wafer transport is in high demand in a 300? mm foundry fab. The control of the transport system plays an important roles in manufacturing efficiency and the satisfaction of production strategy. In general, efficiency is the most important issue that has appeared in most research of automated transport systems. However, how to dynamically adjust the transport policy to meet the production strategy and to increase the transport efficiency as well seems to be more crucial to modern semiconductor manufacturing systems. In this paper, a fuzzy-logic-based multimission-oriented overhead vehicle dispatcher is developed. The vehicle dispatching rule is assigned in real-time according to the statistics of the manufacturing performance. In this manner, the dispatching rules can be adjusted according to possible high-risk lots so that most of the production strategies can be satisfied. If all of the lots meet the prescribed production strategies, then the nearest-job-first rule can be used to offer higher transport efficiency. In addition, the proposed vehicle dispatcher is also capable of deadlock-free operation, collision avoidance, and blockage prevention. Finally, this paper uses AutoMod simulation software to construct and evaluate the manufacturing models. By evaluating the simulation results, the proposed intelligent multimission-oriented vehicle dispatcher performs better performance than the others, and all of the production strategies are satisfied.