To improve the performance of an automated material handling system (AMHS) in 300 mm semiconductor fabrication plants (FABs), an overhead-hoist-transport (OHT) vehicle dispatching problem was described for semiconduct...To improve the performance of an automated material handling system (AMHS) in 300 mm semiconductor fabrication plants (FABs), an overhead-hoist-transport (OHT) vehicle dispatching problem was described for semiconductor FABs. An original wafer lot dispatching policy was proposed. To minimize costs due to transportation logic, a dispatching rule based on an adapted Hungarian algorithm was presented, and six factors were considered. In addition to the recurring parameters, two original parameters of the vehicles utilization and wafer lot priority were considered to evaluate system performance. To obtain a balanced efficiency regarding the FAB output factors, simulation and sensitive analysis were used to find the best weight parameters of the cost matrix. In particular, a high rate of priority wafer lots (greater than 20%) and vehicles utilization (greater than 75%) are obtained without penalizing the efficiency of the FABs. The results indicate that the proposed dispatching policy is valid and practical.展开更多
Overhead-hoist-transporters (OHTs) have become the most appropriate tools to transport wafer lots between inter-bay and intra-bay in united layouts of automated material handling systems (AMHSs) in 300 mm semiconducto...Overhead-hoist-transporters (OHTs) have become the most appropriate tools to transport wafer lots between inter-bay and intra-bay in united layouts of automated material handling systems (AMHSs) in 300 mm semiconductor wafer fabrications. To obtain a conflict-free scheduling solution, an intelligent multi-agent-based control system framework was built to support the AMHSs. And corresponding algorithms and rules were proposed to implement cooperation among agents. On the basis of the mentioned above, a time-constraint-based heuristic scheduling algorithm was presented to support the routing decision agent in searching the conflict-free shortest path. In the construction of the algorithm, the conflicted intervals of the k-shortest-route were identified with the time window theory. The most available path was chosen with an objective of the minimum completion time. The back tracking method was combined to finish the routing scheduling. Finally, experiments of the proposed method were simulated. The results show that the multi-agent framework is suitable and the proposed scheduling algorithm is feasible and valid.展开更多
基金National Natural Science Foundations of China ( No. 71071115,No. 61273035)National High-Tech R&D Program for CIMS,China ( No. 2009AA043000)
文摘To improve the performance of an automated material handling system (AMHS) in 300 mm semiconductor fabrication plants (FABs), an overhead-hoist-transport (OHT) vehicle dispatching problem was described for semiconductor FABs. An original wafer lot dispatching policy was proposed. To minimize costs due to transportation logic, a dispatching rule based on an adapted Hungarian algorithm was presented, and six factors were considered. In addition to the recurring parameters, two original parameters of the vehicles utilization and wafer lot priority were considered to evaluate system performance. To obtain a balanced efficiency regarding the FAB output factors, simulation and sensitive analysis were used to find the best weight parameters of the cost matrix. In particular, a high rate of priority wafer lots (greater than 20%) and vehicles utilization (greater than 75%) are obtained without penalizing the efficiency of the FABs. The results indicate that the proposed dispatching policy is valid and practical.
基金National Natural Science Foundations of China(No. 61273035,No. 71071115)National High-Tech R&D Program for CIMS,China(No. 2009AA043000)
文摘Overhead-hoist-transporters (OHTs) have become the most appropriate tools to transport wafer lots between inter-bay and intra-bay in united layouts of automated material handling systems (AMHSs) in 300 mm semiconductor wafer fabrications. To obtain a conflict-free scheduling solution, an intelligent multi-agent-based control system framework was built to support the AMHSs. And corresponding algorithms and rules were proposed to implement cooperation among agents. On the basis of the mentioned above, a time-constraint-based heuristic scheduling algorithm was presented to support the routing decision agent in searching the conflict-free shortest path. In the construction of the algorithm, the conflicted intervals of the k-shortest-route were identified with the time window theory. The most available path was chosen with an objective of the minimum completion time. The back tracking method was combined to finish the routing scheduling. Finally, experiments of the proposed method were simulated. The results show that the multi-agent framework is suitable and the proposed scheduling algorithm is feasible and valid.
