Dynamic scheduling in a cluster tool for semiconductor manufacturing

Cluster tools play an important role in the semiconductor fabrication industry. Optimization of an individual cluster tool maximizes productivity of mass fabrication. Optimizing the scheduler results in increased throughput. The cluster tool is a real-time, dynamic environment in which different parts interact. That is why it is necessary to have a dynamic scheduler that makes its decisions online and within an acceptable computation time in the presence of unexpected sporadic events. Our contribution is to develop and implement a scheduler for a cluster tool. Attributes of the scheduler are predictive, periodic and dynamic to satisfy real-time characteristics of the cluster tool. The major characteristic of the scheduler is that it is optimized to produce high throughput and low complexity, i.e. time to schedule as overhead. First steady-state and transient-state of the cluster tool are analyzed. Then different scheduling algorithms are experimented with and compared. As the results of experiments demonstrate, throughput is optimized in steady-state and transient-state of the scheduler with low overhead.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat