半導體是台灣兩兆雙星的重要產業之一，隨著市場需求和技術進步，已進入12吋晶圓世代和奈米技術，資本支出動輒數十億美元，機台投資日益昂貴，生產力提昇愈趨重要。
進入12吋晶圓廠世代，工廠自動化程度已進入到無人化境界，機台操作由人工改成全自動化，晶圓搬運也因為晶圓良率(Yield rate)提昇及勞工職業傷害的考慮由人工搬運進步到由自動搬運系統(AMHS)取代，自動搬運系統傳送效率會直接影響機台產出，本篇論文藉由機台傳送模式(Pattern)及搬運量計算找出AMHS傳送瓶頸在晶圓倉儲(Stocker)，運用軌道緩衝區(OHB,over-head buffer)設計，改變機台傳送模式，減少晶圓倉儲負荷，並使用等候理論(Queuing theory)分析改善成果，進而達到提高機台生產力之目的。

Semiconductor is key industry and one of two trillion and twin star industries development plan in Taiwan. It had upgraded to generation of 300mm wafer and nano-technology by customer demand and technology roadmap. The capital investment required over billions USD for single fabrication. The improvement of tool productivity will be key topic due to the increasing capital investment.
The factory had reached stage of fully automation with few operators in 300mm wafer fabrication. The tool operation became automation mode and manual material handling was replaced by Automatic material handling system (AMHS) because of higher wafer yield rate and labor occupation injury issue. Therefore. The tool productivity will be impacted by AMHS operation efficiency. To improve the tool productivity. The AMHS system bottleneck will be identified as wafer stocker by AMHS transportation pattern and volume estimation in this paper. The improvement method for high utilization of wafer stocker was to apply over-head buffer (OHB) to change transportation pattern. Moreover. The benefit of OHB application will be verified with queuing theory to ensure tool productivity was improved as well.

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