Dynamic WIP control for semiconductor wafer fabrication

A Work in Process(WIP)controlling approach was proposed to cope with the complication of wafer fabrication,such as large number of equipments,long cycle time and reentering process flow.Firstly,through simulation experiment,each machine's constraint weight was defined by the sensitivity of the system's performance to the system key index.Then the target cycle time and WIP level was allocated into each process step according to the related machine's constraint weight and machining parameters.Finally,part was dynamically selected to be processed based on the difference between the target and actual WIP level and the upstream/downstream information.A simulation experiment was presented to illustrate the feasibility and effectiveness of this method.