晶圓製造廠動態在製品水準控制之研究

Abstract

目前國內的晶圓體製造業，可以說是台灣最具競爭力之產業，而為維 持這種競爭的優勢，業者莫不致力於半導體的生產管理，使其在達成產出 目標之際，亦能降低在製品水準與其變異，進而控制生產週期時間，提高 交期滿意度與產出量。 本論文的主要目的，是從主生產排程、細部生 產排程到現場生產活動控制系統，針對實體在製品水準，將固定在製品法 與雙界法修正而提出四種不同的控制模式與評估方法。其與一般的生產活 動控制（投料/派工），最大的不同點是在於考量暫存區容量的限制與當 機時產能重新規劃，並利用在製品水準生產流程控制圖（WIPPFC）與在製 品控制能力指標（ ），來評估不同方法之迴圈在製品水準的控制績效， 以達成動態在製品水準之控制。 吾人所發展的實體在製品控制模式， 經模擬驗證知，修正雙界法雖然其控制的程序較為煩雜，必需控制每個層 級之在製品量與產出量，但具有穩定產出及平準化層級在製品量之優點。 而在製品控制法只有當機時才對每一層級調整在製品量，因此對於系統之 在製品量有降低之成效，但對系統之產出成效並不顯著。最後CONWIP/ FIFO及CONWIP/SPT兩組，其中SPT可使暫存區利用率降低，此外兩組皆未 控制每一層級之產出量及在製品量，因此其對系統之產出量與在製品量之 控制成效不彰。 透過在製品的管理與在製品生產流程控制評估，能 有效的控制及評估在製品數量與分佈，並使在製品的變動能迅速預知，做 合理的判斷，達到提昇生產績效的效果。 The wafer fabrication industry in Taiwan has the most competitive advantage. To keep the competitive superiority, each firm devotes to production planning and control. The goals of production planning and control include reducing WIP level and production cycle time, increasing due date performance and throughput. The objective of this research is to study the effect of four modified models on the actual WIP distribution. Buffer management and machine breakdown are taken into consideration in our study. The four modified models are CONWIP/ FIFO, CONWIP/SPT, CONWIP/replying the Machine-Breakdown and modified TB+. We apply the idea of Taguchi method to design WIP Production Flow Control（WIPPFC）chart and WIP Control Capability Index（Cwip） for evaluating the performance of these models on the WIP level. The modified TB+ is more complicated due to the control of the throughput and WIP of each layer. However , the results of simulation show it has advantages of stabilizing the throughput and leveling the WIP of each layer. CONWIP/replying the Machine-Breakdown adjusts the WIP level when the machines break down. The simulation results show that it can lower down the WIP level but does not have significant effect on increasing the throughput. The other two methods, CONWIP/FIFO and CONWIP/SPT, just control the system throughput and the system WIP level; they do not control the throughput and WIP of each layer. However, CONWIP/SPT can lower down the maximum utilization rate of the buffer before each workstation . Through this research, modified TB+ method with WIP management and WIP production flow control is found to be useful and efficient in controlling the variation and distribution of WIP and in increase the system performance.