Simulation based comparison of semiconductor AMHS alternatives: continuous flow vs. overhead monorail

Automation is an essential component in today´s semiconductor manufacturing. As factories migrate to 300 mm technology, automated handling becomes increasingly important for variety of ergonomic, safety, and yield considerations. Traditional semiconductor AMHS systems, such as the Overhead Monorail Vehicles (OMV) or Overhead Hoist, can be overly expensive. Cost projections for a 300 mm inter/intrabay AMHS installation are in the range of $50 M-$100 M. As an alternative, a lower cost alternative AMHS, called Continuous Flow Transport has been proposed. The CFT system is similar to what has historically been identified as a conveyor based movement system. The CFT system provides cost savings at reduced flexibility and longer delivery time. This study compares the CFT to Overhead Monorail transport, determining a cumulative delivery time distribution. As expected, the CFT system requires a longer average delivery time interval than OMV, but may provide total savings through reduced transport variability