Scheduling a Single-arm Robotic Cluster Tool with a Condition-based Cleaning Operation

As wafer circuit widths shrink down, stringent quality control is required during wafer fabrication processes. Therefore, a cleaning operation that removes chemical residuals inside a processing chamber is recently demanded in wafer fabs. To make a trade-off between quality and productivity, a condition-based chamber cleaning in practice is introduced to execute a cleaning operation with a known state of a chamber. Aiming to schedule a time-constrained single-arm cluster tool with a condition-based chamber cleaning operation, we present the necessary and sufficient conditions to check the schedulability of such a cluster tool. Efficient scheduling algorithms for a feasible schedule are derived. An example is given to show the application of the proposed approach.