Importance

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Abstract

A wafer cluster tool comprising a series of processes has a scheduler which synchronizes all events in the system. Events in the cluster tool are scheduled to occur at regular, periodic intervals, thereby improving throughput and quality. The scheduler also eliminates conflicts for transportation resources between modules in the cluster tool. Wafers are loaded into the cluster tool at a regular interval, referred to as a sending period. All events in the system are synchronized with the sending period, and all event timings are normalized in terms of the sending period. The conflicts are resolved by selectively adding delays in modules which can tolerate them without degrading throughput or performance in the system; modules that cannot tolerate delays are exempted. The periodicity of the scheduled cluster tool enables the identification of wafers in the cluster tool. The identification of the order in which a wafer was loaded also identifies a module path followed by the wafer.

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First Claim