Concurrent processing makes the wafer fabrication process prone to deadlocks and completion node ambiguity.A Petri net model is established to describe the system operation process by taking for the single-arm cluster tools for fully parallel processing of two wafer types as the research object,and a control strategy is developed to avoid the system deadlock Based on the Petri net model,the temporal properties of the system is analyzed based on earliest starting strategy,and the action cycle sequence of robot is determined during the monitoring cycle for different scenarios of lot switching in a single production monitoring cycle.An adaptive scheduling algorithm is developed to obtain the production schedule,which can adaptively adjust the ratio of wafer output in each monitoring cycle by setting the type of wafers processed in the shared module,so that the desired production state is continuously approached by adjusting the ratio of wafer output in each monitoring cycle.The feasibility and effectiveness of the algorithm are verified by examples.
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