| Summary: | 博士 === 中華大學 === 科技管理學系(所) === 97 === Wafers yield will drop off when the wafers stay in the clean room increased. To ensure final product yield, engineers have to set up queue time limits for particular operations during fabrications, which is named “Time Constraints (TC).” TC issues will increase the difficulty in production management, which is a new challenge of wafer fabrications. In such situation, an effective overall solution is necessary to conquer this dilemma.
The major objective of this study is to propose capacity planning and shop floor control models in wafer fabrications under time constraint issues. In capacity planning model, the GI/G/m queuing network was applied to determine the required capacity to achieve the yield target. Moreover, because of the difference between various operations, proposed model was adjusted to address individual environments further.
The concept of (S,s) policy was introduced in the shop floor control rules for two individual type of time constraints issue. By proposed rules, the WIP can be protected from over queue time by the upper bond of inventory, and the machine will avoid starvation by lower bond of it.
By the results of this study, the wafer fabrications are getting effective and reasonable approaches to solve the problem of time constraints.
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