- 學位論文
以模擬實驗方式探討晶圓廠之最佳經濟規模
The study of the economical scale of a semiconductor plant through simulations
摘要
由於晶圓製造特殊的製程回流(reentry)現象造成晶圓廠複雜的特性。近年來的新建晶圓廠，為了要避免機台飢餓和阻塞，造成晶圓廠規模越來越大。規模大的晶圓廠帶來了設備稼動率的提升，卻也使得物料搬運更加複雜化，而造成晶圓廠的生產效率不佳。改善物料搬運系統除了投資在設備部份外，系統的控制軟體更是需要大筆經費，而造成了物料搬運系統投資成本提高，使得大規模晶圓廠稼動率提升所到來的效益減少，因此晶圓廠規模要適當才最能符合經濟效益。 本研究目的為探討晶圓廠規模擴大後的整體經濟效益評估，藉由建構晶圓廠模型來觀察規模改變後的運作情形；大型晶圓廠帶來生產週期和在製品數量降低，同時也造成晶圓製造複雜度提升和各加工區之間更多的交互作用情形。晶圓廠規模倍增到六倍前，生產週期和在製品數量有明顯改善，六倍規模則顯現出相對較高的生產週期，規模倍增到了七倍，系統已無法穩態，由結果可判斷晶圓廠最佳規模，以及從物料搬運成本的角度出發，討論規模大小對搬運成本的影響，結果顯現規模過大時，會導致單位晶圓搬運成本的提高。 關鍵詞：晶圓廠規模、搬運成本、生產週期、產能、WIP、AMHS
並列摘要
The semiconductor manufacturing is complex due to the re-entry phenomenon. The semiconductor fab scales are larger and larger to avoid machine hungry and block penomena. Larger scale fabs bring up machine utilizations, meanwhile, they make the automated material handling system (AMHS) complicated. This results the poor performance of the AMHS. Semiconductor people invest a large amount of capital in the AMHS control & management system to prevent from the plant size effect. This reduces the benefit of the large fabs. Therefore, what is an optimal semiconductor fab scale needs to be discussed. The main purpose of this study intends to evaluate the benefit from the step-by-step enlarged semiconductor fab scales and find the optimal scale of the plant by simulations. The simulation results show the cycle times and WIPs decrease gradually as the fab scales increase before 6 times. The 6-time scaled fab has relatively high cycle times and WIPs, and the 7-time scaled fab system cannot be stable. This indicates an optimal fab size exists. Besides the system performance, an AMHS cost analyses would also be discussed in this study. The unit wafer material handling cost is increased when the fab size is too large. Keyword：semiconductor wafer fabrication, AMHS, cycle time, WIP, throughput, material handling cost