A major capability that a semiconductor automation framework has to provide is the control of the fabrication process as a wafer undergoes a variety of fabrication steps. This requirement is due to the fact that the processes often drift and shift with time due to a variety of factors. The requirement from the automation system, thus, is not only to specify and enact the process but also to make provisions for continuous tuning of this process. In addition, the lack of precise models for many semiconductor processes means that it is often difficult to interpret precise results of a process into precise actions to be taken to improve processing.

To provide a framework for monitoring and control of a semiconductor manufacturing process over multiple processing steps, we have developed a software controller, the Active Controller (AC). This controller is built utilizing active database technology. Multi-step control is facilitated through the use of Event-Condition-Action (ECA) rules of the database. In a simplified form, these rules are utilized for multi-step control as follows: execution of a process step at an equipment or a composition of many such process steps constitutes the (composite) event for the AC rules. The conditions of these rules are the scenarios in which multi-step control can be used to improve the processing of the product. These conditions can be defined in terms of relevant process parameters. Firing of the rules causes appropriate actions to be taken to compensate for the error in processing. A prototype of the AC has been developed by IMPACT using the ODE active database management system (DBMS) from AT&T.

People Involved

Graduate Student Research Assistant:
Nauman Chaudhry

Advisors:
Dr. James Moyne
Prof Elke Rundensteiner

Project Description

Active Object-Oriented DBMS for Discrete Control

Publications

Visit our Publications Archive to download more detailed documention of our research into inter-process control, as well as other control and automation research of the Integrated Manufacturing Process Automation and Control Technologies group.

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