Improving dispatch rules for cascading tools

Line balance and tool throughput are two important, yet conflicting goals. Especially for cascading tools supporting multiple layers in the line, there has to be a trade off between these two optimization criteria. Short cascades are optimal for line balancing, but this strategy leads to lower tool throughput. The size of the negative throughput impact is even stronger when tools require setup times for the switch from one cascade performing recipe A to another cascade performing recipe B. In the semiconductor industry, state-of-the-art dispatch rules are widely used as a tool to calculate optimal operational decisions. The paper presents an approach on how to combine the two criteria in a dispatch rule.