在12吋晶圓製造廠內，生產績效的衡量項目除了常見有生產良率(yield rate)、生產週期(cycle time)、半成品存貨(WIP)及機台產能利用率(utilization)等指標之外，另一個最直接影響機台產能的指標則為“機台閒置時間(idle time)”的比重，簡單而言就是機台在該時間是無材料可生產，空機等待著材料被指派且經由自動化搬運系統(AMHS)搬送來執行生產的時間。

以財務及生產成本的控管概念之下，價格昂貴的機台其閒置時間(idle time)越長表示機台處於空機不生產狀況越嚴重，此情況是不利生產績效及公司利潤極大化之目標，同時機台也需面臨折舊攤提的成本問題。

本研究論文將以改善機台閒置時間(idle time)為主題，提供三個改善方案，其中以“機台晶圓暫存器(Near Tool Material Buffer)”為主要改善方案。本論文除了詳細說明相關的背景、改善方式、效益比較之外，也以財務成本面的分析和比較，來說明機台晶圓暫存器(Near Tool Material Buffer)為何是最合適的方案，同時也可作為12吋晶圓廠機台效能及營運績效提升的應用之參考。

For a 12-inch wafer fabrication plant, common indicators used to evaluate production performance include yield rate, production cycle (cycle time), work in process (WIP), and equipment capacity utilization rate (utilization). Another key influential factor is “equipment idle time (idle time)”, when there are not sufficient materials for production and the idle equipment is waiting for materials to be assigned by the system and delivered by the AMHS for production.
From the financial aspect, based on the concept of production cost control, for expensive equipment, longer the idle time would be more unfavorable for the goals of production performance and company profit maximization. And there is also the issues of depreciation and amortization of the equipment to be taken into consideration.
This study aims to resolve the equipment idle time issue and provides three solutions to reduce idle time. The main solution is the “Near-Tool Material Buffer” (NTB) solution. This study not only illustrates the related background, methods of improvement, and efficiency comparisons in details, but also explains why the “Near-Tool Material Buffer” solution is the most suitable solution based on the analyses and comparisons from the financial perspective of costs. These findings can also be used as references for improving efficiency of equipment and operating performance of 12-inch wafer fabrication plants.

1.張原銘，晶圓廠之自動化物料搬運系統模擬研究－以黃光區與爐管區為例，國立清華大學工業工程與工程管理學系碩士論文，2003
2.Nadoli, G. and Pillai, D, “Simulation in Automation Material Handling Systems Design for Semiconductor Manufacturing”, Proceeding of the 1994 Winter Simulation Conference, pp.892-899,1994.
3.Weiss, M., “300mm Fab Automation Technology Options and Selection Criteria”,1997 IEEE/SEMI Advanced Semiconductor Manufacturing Conference Workshop, pp373-379,1997.
4.劉宏鈞，“晶圓廠機台之可組態邏輯程式”，國立清華大學工業工程與工程管理所碩士論文，2002
5.莊達人，VLSI製造技術，高立出版社，1999