Abstract
In this study we consider the batch processing machine with limited waiting time constraints (i.e. if the lots don’t start processing during the period), it must be reworked or scrapped, to develop a prior control policy that includes deciding on when to start a process cycle and the priority of lots.The batch processing machine is capable of processing multiple lots simultaneously as a single batch, and often the maximum batch size (machine capacity) of batch processing is greater then the size of the arriving lots. However, the processing times of each batch are independent of batch size. Choosing start times for process cycles must balance waiting and the utility rate of the batch processing machine. The DJAH is one of strategies by given the availability of information on a few near future arrivals decides on when to schedule a job, but it doesn’t take account of the effect of time constraints.The first objective of the research is to propose a dispatching rule to accommodate batch processing with time constraints. By improving DJAH and analyzing the impact of time constraints on product environment, a dispatching rule, DJATC, is developed. There is amount of information need to know: future lots arrival time, batch size of future arrival and the number of lots which have been waited, to decide when to start a process cycle and the priority of lots. To demonstrate the effectiveness of the dispatching rule proposed in this research, a simulation model is constructed. The simulation result indicate the DJATC rule can effectively reduced average flowing time and reduced the number of wafer rework.Finally, since time constraints are installed by engineering to prevent native oxidation or contamination effect on wafer surface. We use the demonstrated simulation model and genetic algorithm to observe various time constraints which is influence on system performance, and give recommendations to improve it.