New methodology of dynamic lot dispatching: required turn rate

摘要

In a semiconductor manufacturing fab with production-to-order typeoperation, hundreds of devices and various processes are managed. Toprovide short cycle time and precise delivery to satisfy customers'expectation is always the major task. The difficulties encountered arecomplex process and product mix, unscheduled machines down time andequipment arrangement. How to dispatch lots effectively has become avery important topic in handling manufacturing. A dispatching algorithmnamed “Required Turn Rate (RTR)” is developed. According tothe level of current wafers in process (WIP), RTR algorithm revises thedue date for every lot to satisfy the demand from Master ProductionScheduling (MPS). Further to calculate the required turn rate of eachlot based on process flow to fulfill the delivery requirement. RTRalgorithm determines not only due date and production priority of eachlot, but also provides required turn rate for local dispatching.Therefore, local dispatching systems of each working area will dispatchthe lots by using required turn rate to maximize output and machinesutilization