應用柔性演算法搜尋晶圓廠現場控制策略

Abstract

半導體業是台灣最重要也是未來具成長性的產業之一，晶圓製造更是其製程之關鍵所在。一般來說，晶圓的製造程序，通常需要200~300道的製程步驟才能完成。由於晶圓製造之繁複與再回流特性（reentrant），使其生產控制十分複雜。因此有許多文獻針對此領域進行研究，包括投料、排程、派工等現場控制策略均是學者研究之重心所在。然而，過去相關研究多僅單獨探討上述主題，較缺乏整合之研究，研究成果僅能達到局部最適化；另外晶圓廠製程再加工情形也多予忽略，當生產系統發生不良需進行再加工時，相關研究所建構之生產控制策略可能喪失其適用性。因此本研究將考量再加工因素，並結合投料、派工等進行整合性研究，利用柔性演算法（遺傳演算法、模擬退火法和禁忌收尋法）搭配模擬工具，進行生產控制策略整合性之探討，使能快速搜尋出最適生產控制策略組合（投料策略、派工策略和再加工策略），在考量不同績效指標（如在製品、流程時間、遲延、遲延比率、延遲成本和產出量）的前提下，尋找全面性最適合之生產控制策略組合，使晶圓製造廠的生產控制能達到全面最適化的理想。由結果顯示，本研究在合理的時間內，根據不同的績效指標搜尋出最適生產控制策略組合。最後，本研究根據研究結果提出一模擬-搜尋（Simulation-Search）程序以供管理者參考，利用本程序管理者可快速搜尋生產系統內之最適生產控制策略組合。

The semiconductor manufacturing industry is one of the most important industries in Taiwan. Wafer fabrication is an essential process in semiconductor manufacturing. However, controlling the production system on the shop floor is extremely difficult owing to the complicated manufacturing process and reentrant characteristics. Hence, selecting a suitable shop floor control (SFC) strategy for wafer fabrication is very important. Included in this research are decision problems for order review/release, dispatching and rework strategies. Unlike previous research, which these three SFC strategies are dealt with separately, this paper will consider these three SFC strategies simultaneously. The proposed combination simulation and soft computing approaches (genetic algorithm, simulated annealing and tabu search) are presented for SFC strategies in wafer fabrication. The objective is to seek the near global optimum solution for the combination of SFC strategies for a specific performance indicator, such as WIP, flow time, tardiness, tardy rate, delay cost and throughput within the reasonable computational time. From the results, the proposed methodology is found to perform well for combinations of SFC strategies using different performance indicators in wafer fabrication. Considerable computational time is saved in this research. The results indicate that a concept of simulation-search procedure should be applied in order to solve the decision-making problem for SFC multiple control strategies quickly in a production system.