Application of feed-forward and feedback control to a photolithography sequence

Describe the implementation of supervisory control of three photolithography machines: a spincoat and bake track, a stepper and a developer. The objective of the experiment was to improve the reproducibility of critical dimensions of photoresist patterns. The results showed that the supervisory controller is capable of bringing the lithography process back to its previous specifications, even after all three machines have been taken down for maintenance and repairs.<
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