以看板系統構建晶圓製造廠之生產規劃與控制模式

Abstract

晶圓製造廠的生產管理上，在製品(WIP)存量之控制為一重要的課題，適 當的在製品存量將可使生產週期時間縮短，並減少存貨持有成本及晶片損 失。JIT生產方式中所使用的看板控制系統，能以看板 數量來控制系統 中之在製品存量，因此吾人在晶圓製造之特殊生產環境下，構建一合適的 看板控制模式，使系統產出在高水準之下達成控制在製品存量的目的。 吾人將看板控制模式的執 行階段定位在生產活動控制(PAC)上， 藉由看板的運作流程可使生產活 動控制的五個模組達到互相支援的作用。 在模式的構建上，以系統短期中（一 週）所辨識的瓶頸工作站作為看板控制點，在此工作站設立輸出、入暫存 區及看板匣，以作為看板流程的控制中心；並採用等候線理論作為發展看 板張數演算法的基礎。經由模擬實例來驗證結果，除證明了看板張數演算 法的合理性，亦發覺系統在此看板控制模式的運作下，產出量非常平穩且 能符合需求，並可控制系統之在製品最大存量以縮短生產週期時間。 The control of work-in-process (WIP) level is an important issue of the production management in a wafer fabrication factory. The reasonable level of WIP will reduce the production cycle time, inventory holding cost and the wafer lost. The kanban control system, proposed by Just-in-time(JIT) production method, can control the amount of WIP in the system through the limited number of kanban cards. Under the circumstance that the wafer fabrication has high throughput rate, a kanban control system is designed in this thesis to control the level of WIP. The execution of kanban control system belongs to the prodrction activity control (PAC) stage. The five modules of PAC can support each other through the use of kanban system. To run the kanban control system, the bottleneck workstation in a short time interval (one week) is identified first as the kanban control point. At this workstation, there are an input buffer, an output buffer and a kanban box to serve as the control center to control the flow of kanbans. Then, the queueing theory is applied to develop an algorithm for determining the apporiate number of kanban cards. The simulation results show that the proposed kanban control system has high performance. The throughput rate is high and stable to meet demand, and the WIP level of the system is controled within an acceptable level.