Simulations-based and solver-based optimization approaches for batch processes in semiconductor manufacturing

Scheduling is one of the key factors for semiconductor fabrication productivity. Objectives like lot cycle time and throughput must be optimized to push the technological development and secure the existence on the rapid growing global market. But especially in the frontend the manufacturing process is dominated by cluster-tools and reentrance flows which makes a production planning and optimization very hard. The workflow here is mostly controlled only by dispatch rules. To get a further improvement in manufacturing planning strategies, there is an increasing request of exact or simulation-based solution methods for specified work centers or bottleneck machine groups. One example of this is the semiconductor oven process. Here, complex batch processes with a lot of restrictions have to be scheduled. A reduction of cycle time in this section by optimized manufacturing strategies has a great influence on all global optimization objectives. Two approaches are investigated in this paper.