Simulation analysis on the impact of furnace batch size increase in a deposition loop

In the dynamic environment of semiconductor manufacturing operations, a bottleneck could be created at the bake furnaces of the deposition loop as capacity expands. Upgrading of the bake furnaces by adding a lot-per-batch in the boat or purchasing a new furnace are two possible solutions to this problem. A simulation model was constructed to assist the decision making, with the behavior of the wet benches (upstream tools) and cluster tools (downstream tools) being modeled in detail. We concluded that a limited number of furnaces upgrade is sufficient to sustain the capacity expansion. But the bottleneck was shifted to an upstream tool, which required the backup tool to be activated to manage the queue. A loading policy that constrains batches to queue at maximum time before loading into the furnaces has to be implemented to balance the efficiency at the furnaces and their downstream tools, without compromising on the cycle time.