PROJECT TITLE :

Feedback Control of Cluster Tools for Regulating Wafer Delays

ABSTRACT:

Robotized cluster tools for semiconductor producing have strict time constraints such that a wafer processed at a processing chamber ought to be unloaded inside a specified cut-off date. Otherwise, it's a heavy quality problem due to residual gases and heat among the chamber. Even though there have been studies on identifying a possible tool operation schedule over such time constraints on wafer delays, such a schedule is subject to timing disruptions or time variation, and therefore might violate the time constraints. During this study, we propose a a lot of sturdy method of regulating wafer delays against timing disruptions to not exceed a specified limit. We have a tendency to initial model the discrete-event behavior of a tool by a timed event graph. We tend to then develop a feedback controller for single-armed and twin-armed cluster tools that may satisfy the time constraints by regulating wafer delays. To try and do this, we have a tendency to develop a feedback controller for the timed event graph by analyzing the timing behavior in a very linear system model based mostly on the max-and algebra. The feedback controller postpones an occasion or firing of a transition, i.e., loading a wafer into a chamber, until a properly determined time elapses once an associated preceding event happens. Finally, we tend to gift examples of feedback control and show that the feedback control is sort of sturdy even under persistent time variation.