快速評估12吋晶圓廠AMHS的模擬方法

Abstract

12吋晶圓廠由於晶舟重量上升導致自動化物料搬運系統（AMHS）的設計與運作變的相當重要。過去研究往往使用模擬來評估AMHS的績效，然而兩個問題油然而生。第一，模擬系統針對於（layout）的改變上並不夠人性化，略作改變就得大幅變更模型。第二，包含機台與搬運行為的模擬程式由於系統複雜度高和物件數多，在模擬上相當耗時。 本研究希望改善這兩個問題來增進程式的使用彈性與效率。在解決第一個問題上，利用AutoCAD結合e-Mplant，僅需利用AutoCAD繪出設施規劃則模擬系統即可自動產生來增加模型彈性。若layout略作修改也僅須針對AutoCAD略作修正再重新讀入模擬系統。第二，將每個加工中心間的搬運行為模擬成不同的運輸時間分配，則模擬系統利用不同的運輸時間分配來取代模擬AMHS部分的模型來降低系統複雜度和物件數，實驗結果指出在實際晶圓廠模型中，與考量機台與搬運的模擬系統的績效指標差異不大但可節省約94%的模擬時間。

In a semiconductor fab that manufactures 12” wafers, the weight of a wafer cassette increases substantially. The design and operation of the AMHS (automatic material handling system) thus becomes more important than ever. Prior research often uses discrete-event simulation to justify the effectiveness of an AMHS in a 12” fab. Yet, two efficiency problems would arise in such simulations. First, a modified AMHS layout may need substantial human intervention to modify the existing simulation problem. Second, it takes lengthy computation time to run a simulation program that attempts to comprehensively model both machine operations and material handling. This research aims to solve the two efficiency problems. To solve the first problem, we develop and implement a CAD-simulation interface methodology, by which a simulation program for a manually modified CAD layout can be automatically generated. To resolve the second efficiency problem, we attempt to model the material handling times between tool groups by probabilistic time distributions. The simulation model is then simplified by considering only the material-handling time distributions and ignores the exact simulation of AMHS. Experiments indicate that the simplified simulation methodology would yield results, compatible to that obtained by a comprehensive simulation model.