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

Abstract

Whenever the fabrication process consists of several steps and the dynamic modification of individual steps or step sequences of the process is allowed, multi-step feedback and feed-forward control can be utilized to improve the quality of the fabrication process. Feedback and feed-forward control have been identified as important features of the semiconductor manufacturing facility of the future, and research has been carried out on developing suitable control algorithms. However, the issue of providing generic enabling mechanisms for multi-step control has not been adequately addressed. To fill this gap, we have developed the Active Controller -a generic, adaptable and reusable software enabler for multi-step 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 multi-step control algorithms. The conditions of Active Controller rules are defined to check for scenarios in which multi-step control is needed. The Active Controller keeps track of relevant processing events and data, and when the conditions for multi-step control hold, executes appropriate actions to compensate for the errors in processing. We show that the Active Controller implementation, with its capability for the definition of complex rules over a history of processing events and ability to invoke user-provided analysis routines, provides for a generic and adaptable implementation that can be used to implement various algorithms for multi-step control. We also address the important issue of integrating the Active Controller with existing CIM environments and describe the Active Controller's interaction with CIM applications to highlight the fact that the Active Controller is not tied to a specific CIM implementation.

Modular Finite State Machines Implemented as Event-Condition-Action Systems

“…The condition can simply be evaluated as true or false, whereas the action can be an action toward the environment or internal to the database and can be the trigger of a new ECA rule, causing a chain of rules to fire. ECA rules have been used in many domains ranging from business workflow managers (Bae et al, 2004), manufacturing control (Chaudhry et al, 1998) or web applications (Papamarkos et al, 2003). The advantages of ECA rules lie primarily on the fact that they allow behavior to be specified and managed on a rule base (rather than being encoded in diverse applications), improving modularity, maintainability and thus reconfigurability.…”