晶圓製造廠微影黃光區再加工策略之探討

Abstract

晶圓製造廠中加工過程會發生加工不良的情形，一旦發生不良品往往無法補救。但在微影黃光區中，如果加工不當可經重新再加工予以彌補，經過再加工補救之後可減少製造成本、材料成本的浪費。晶圓加工是以批量為單位進行，在處理微影黃光區再加工問題時必須考慮批量間關係。如何安排再加工批量使對其它等待加工批量影響最小是晶圓製造廠生產管理上一個重要主題。 本文中，一方面比較文獻所介紹的四種再加工策略，另方面針對文獻中策略的缺點，提出第五種再加工策略。文獻中的四種再加工策略分別為母批等待子批、母批不等子批而子批加工完成後形成獨立一批、子批累積達一定數量才成一批、子批加入下一個母批。以上方法會發生母批浪費時間等待子批、母批與子批分離的管理問題、子批浪費時間累積數量、及因子批數量太少使加工不經濟之缺點。本研究第五種策略係母批與子批在後續加工機台會合，減少文獻中各個再加工方案的缺點。經過模擬程式驗證以及統計檢定後可以證明本研究所提出的第五種再加工策略優於文獻介紹的方案，同時能實際應用於晶圓製造。

In the wafer fabrication factory, a fraction of the batch, or lot may require reworking because its members fail to conform to standards. It is usually unable to rework when a defective batch happened. In photolithography area, it is possible to deal with these defective batches. After defective batches reworked, the cost may be reduced. In batch manufacturing, it is important to deal with these batches when reworking happened. The issue of this study is to compare with the policies expressed in references and find another policy to deal with these nonconforming members. There are four policies to deal with defective batches in references. The first, the mother lot is held back while the child sub-lots are reworked. The second to the forth, the mother lot is allowed to proceed to the next operation, and the child lot be a new lot or cumulate to a quantity or join to the next mother lot. Some shortcomings are in above policies such as the management problems about mother lots and child lots and the economic to manufacture. This study introduces the fifth policy to avoid these shortcomings. In the fifth policy, mother lots and child lots are completed after reworking. Additionally, it is not necessary for mother lots to spend time waiting for child lot, and can follow the economic rules. From the simulation and statistic tests, the fifth policy is more suitable for the wafer fabrication factory when reworking happened.