運用負荷導向理念構建晶圓製造廠之細部生產排程模式

Abstract

由於半導體產業屬於資本技術密集產業,機器設備昂貴,導致生產成本奇 高,因此必須極大 化機器利用率,使產能充份利用.但機器利用率的提昇, 卻又往往引發產品生產週期時間過長,系統在製品水準失控,以及交貨期不 易控制等問題.因此,本文結合負荷導向製造管制(Load-Oriented Manufacturing Control)及工作負荷調節法(Workload Regulating)著重 規劃與控制各資源之工作負荷的理念,構建晶圓製造廠之細部生產排程模 式.此細部生產排程模式係在兼顧系統內瓶頸及非瓶頸產能負荷的情況下, 根據主生產排程所決定的計畫產出量,來設定瓶頸資源的負荷極限(Load Limit),使其以自我調節工作負荷的方式運作,期能 以最低的系統在製品 量來達成產品快速完工之目的.此外,系統是在瓶頸及所有限制資源的 工作負荷均受到控制的情況下進行投料,以防止限制資源成為暫時性瓶頸, 降低生產績效.模擬驗證結果顯示,本文所構建之細部生產排程模式不但可 達成主生產排程目標,亦能在使瓶頸資源產能最佳化利用的條件下,降低產 品生產週期時間與系統在製品水準.而且,透過上述投料模式的控制,確實 可以達致防止瓶頸資源漂移之效果. Currently, most of the semiconductor factories are facing the problems of high work-in-process (WIP) and long lead time, such that the desired due date cannotbe met. It is caused by over emphasis on increasing machine's utilization andsystem throughputs, without considering the load situation of work stations.Therefore, this thesis adopts both the concepts of load-oriented manufacturingcontrol (LOMC) and workload regulating (WR) to construct a feasible detailedcapacity plan and schedule to meet the master production schedule (MPS). Byusing the principle of load limit, the workload of bottlenecks and capacityconstraint resource (CCRs) is planned and controlled according to their planned output. Meanwhile, the capacity requirement planning of non-bottlenecks iscarried out to support the operations of bottlenecks. Meeting due date is theprimary objective, while reducing WIP and lead times are the secondaryobjectives. Then the workload regulating method is applied to control thematerial release time and WIP level. The simulation study indicates that thedetailed capacity plan and schedule enables the fab to meet the given due dateof MPS and to maintain an appropriate workstation utilization rates. Moreover, WIP and lead times are also reduced.