In this paper, new methodologies for effective process excursion monitoring and defect source isolation are proposed. We introduce new defect classification scheme, in which relevant defect types that are likely to be caused by the same mechanism or source are grouped into a "defect family." We demonstrate that trending by the defect family drastically improves the excursion detection efficiency without suffering noise from irrelevant benign defects. Furthermore we have developed a methodology for identifying the source of the excursion using defect type Pareto. This is based on the fact that the signature of defect type Pareto leads to the defect source information and thus possibly indicates the origin of the problem. Thus both process control and excursion source identification can be achieved simultaneously by effective defect classification.

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