Active Controller: utilizing active databases for implementing multistep control of semiconductor manufacturing

Whenever the fabrication process consists of several steps and the dynamic modification of individual steps or step sequences of the process is allowed, multistep feedback and feed-forward control can be utilized to improve the quality of the fabrication process. In this paper, we describe the Active Controller-an adaptable and portable software enabler for multistep control in manufacturing facilities. The Active Controller utilizes a recently emerging technology, called active databases, to define and automatically execute powerful and expressive rules for implementing multistep control algorithms. The conditions of Active Controller rules are defined to check for scenarios in which multistep control is needed. The Active Controller keeps track of relevant processing events and data, and when the conditions for multistep control hold, executes appropriate actions to compensate for the errors in processing. We show that the Active Controller, with its capability for the definition of complex rules over a history of processing events and its ability to invoke user-provided analysis routines, provides for a portable and adaptable system that can be used to implement different algorithms for multistep control.