Abstract
Because of the manufacturing process complexity in semiconductor manufacturing, dispatching has been an important factor to the overall fab productivity and equipment effectiveness. Although there are numerous dispatching methodologies, Most almost all of them are designed from the production perspective. A great majority of them are based on the optimization of production, cycle time, equipment utilization, bottleneck machines, etc. This study used target hit rate as the major performance good for dispatching with additional reference of production and cycle time per layer. The process time and transport time for a lot are more or less predictable. It is time waiting time that not only contribute majority of time a lot spent in a fab but also is the main target of influence by order releasing and dispatching method. This research proposed a waiting time allocation scheme to allocate available waiting time to each process based on historical data. The allocated waiting times for the lotsin the same process buffer are used for priority comparison as far as dispatching isconcerned. Simulation tests using data from Minifab and Arizona State University indicated that the proposed WTA method is better than some commonly used dispatching rules such as First In First Out (FIFO)、Global First In First Out (GFIFO) 、EDD (Earliest Due Date) 、CR (Critical Ratio) and Weight Turn Ratio(WTR) .