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Browsing by Author "Hsiung, Y"

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    A tool planning approach considering cycle time constraints and demand uncertainty
    (2005-09-01)
    Wu, MC
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    Hsiung, Y
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    Hsu, HM
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    工業工程與管理學系
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    Department of Industrial Engineering and Management
    The tool planning problem is to determine how many tools should be allocated to each tool group to meet some objectives. Recent studies aim to solve the problem for the cases of uncertain demand. Yet, most of them do not involve cycle time constraints. Cycle time, a key performance index in particular in semiconductor foundry, should not be ignored. The uncertain demand is modeled as a collection of scenarios. Each scenario, with an occurrence probability, represents the aggregate demand volume under a given product mix ratio. A genetic algorithm embedded with a queuing analysis is developed to solve the problem. Experiments indicate that the proposed solution outperforms that obtained by considering only a particular scenario.
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    Tool planning in the scenario of multiple existing semiconductor fabs
    (2005-11-01)
    Wu, MC
    ;
    Hsiung, Y
    ;
    Hsu, HM
    ;
    工業工程與管理學系
    ;
    Department of Industrial Engineering and Management
    The tool planning problem involves determining how many tools should be allocated to each tool group to achieve a set of objectives. Most previous studies assume that a demand mix has been given for a new factory to be planned. However, when a semiconductor company has several existing fabs, the demand mix for the new fab is not explicitly known, and needs to be allocated from the demand mix of the whole company. This paper presents an integrated approach to determine the optimal demand mix and associated tool plan for the new fab that can minimize the tool cost of the new fab while each fab (new or existing) is requested to meet a predefined target in its mean cycle time. Simulation experiments indicate that the proposed solution is better than that obtained by a heuristic method used in industry. The saving in tool cost for a typical tool planning problem can be over US$ 70 million.