Modeling, scheduling, and dispatching in the dynamic environment of semiconductor manufacturing at FASL, Japan

At Fujitsu AMD Semiconductor Limited (FASL), the original scheduling and dispatching process was time consuming and inadequate to understand the effects on equipment utilization and cycle times caused by sudden changes in product mix or volume. The re-prioritizing of products due to dynamic changes in equipment status was difficult to achieve. As with any semiconductor manufacturing facility, the flow of materials through the factory was nonlinear. This meant that linear mathematical models could not predict the behavior of the flow accurately, and that initial metrics of the factory were not sufficient to predict status in the future. Furthermore, stochastic components inherent to process flows, such as equipment failures, yields, dynamic queues and reentrant flow compounded complexity. Consequently, FASL implemented MS/X OnTime from TYECIN Systems because of its modeling, scheduling, and dispatching capabilities. To update the simulation-based scheduler with actual WIP and equipment status, the scheduler was interfaced to the MES. The coupled systems provided an almost real-time dispatching capability. As a result of implementation, planners were able to model, schedule, and dispatch all products with 95% accuracy, generate dispatch lists by operator, and perform what-if analyses of changing factory conditions. Manual operations were also reduced to a minimum