The use of upstream and downstream information in scheduling semiconductor batch operations

This paper presents a control strategy that exploits and uses both upsueam and downstream information on the current and expected states of a semiconductor manufacturin-e facilit.v (.F AB) to make intelli-ee nt batch size decisions. Throug-h simulation, this strategy is compared with current methods that consider only uvstream information, as well as with aa-e neral threshold. oli.cv T. he resultsconfirm that significant improvements in cycle rime can be realized by exploiting upstream information. Some additional improvement can be gained at low to moderate traffic intensities by looking downstre&. However, as iaffic intensity increases, use of downstream information can actually lead to longer delays, indicating that the scheduling of the batch machine may he more important than the scheduling of the serial machine in congested systems.