Application of feed-forward control to a lithography stepper

Leang, S.; Spanos, Costas J.

doi:10.1109/ismss.1992.197641

Cited by 10 publications

(3 citation statements)

References 8 publications

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“…Feed-forward control was not activated in this experiment, because its effect has already been previously demonstrated in [12]. Its activation would also not have favored either controller over the other, since both controllers use feed-forward control in the same fashion.…”

Section: Resultsmentioning

confidence: 99%

“…The sensitivity of the alarm depends on the number of output parameters p, and the constants κ and η (equ. (12), (13), and (15)), which can be adjusted for the desired probability α of stopping erroneously a good process. Equivalently, we can adjust the average run length (ARL) between false alarms when the process is in control, also called on-target ARL.…”

Section: Alarms For Feedback Controlmentioning

confidence: 99%

“…Although the statistical techniques used in our controller are not novel [8], the manner they are used for process control is new, and results in improved capability of the entire process sequence. The control algorithms presented in this paper also have the additional advantage that they offer multivariate control and complex adaptation of non-linear models, without introducing extraneous variance in the process [9] [10] [11] [12] [13].…”

Section: Introductionmentioning

confidence: 99%

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A control system for photolithographic sequences

Leang

Thomson

et al. 1996

IEEE Trans. Semicond. Manufact.

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The goal of our control system is to improve the reliability, accuracy, and economy of operation of a sequence of interrelated processes. We achieve this task by using well known, rigorous statistical techniques to continuously monitor process parameters, detect out-of-control equipment, and then optimally adjust relevant machine inputs to bring the process back on target. We have implemented the supervisory control system on the photolithography sequence in the Berkeley Microfabrication Laboratory, where it has been conclusively proven that the supervisory control system increases significantly the capability of the entire process. The supervisory control algorithms, consisting of feedback and feed-forward control, multivariate, model-based statistical process control (SPC), and automated specification management algorithms, are independent of machine and/or process, and can be applied to any semiconductor manufacturing sequence.

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Section: Resultsmentioning

confidence: 99%

Section: Alarms For Feedback Controlmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A control system for photolithographic sequences

Leang

Thomson

et al. 1996

IEEE Trans. Semicond. Manufact.

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Designing response surface model-based run-by-run controllers: a worst case approach

Baras

Patel

1996

IEEE Trans. Comp., Packag., Manufact. Technol. C

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Abstract-This paper presents a framework for carrying out run-by-run (RbR) control via a deterministic worst-case approach. In particular the RbR controller developed tries to minimize the worst-case performance of the plant. This yields a methodology for handling uncertainty. A consequence of using the deterministic approach is that we no longer need any assumptions on the statistics of the noise. Rather, what we require is that the noise be bounded. Thus, we can also deal with nonGaussian and correlated noise. We provide results comparing the performance of the controller to a recursive least squares ( U S ) based controller.Index Terms-Run-by-run control, deterministic approach, bounded noise, worst-case design, ellipsoidal algorithms, response surface models.

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

Chaudhry

Moyne²,

Rundensteiner

1998

IEEE Trans. Comp., Packag., Manufact. Technol. C

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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.

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Application of feed-forward control to a lithography stepper

Cited by 10 publications

References 8 publications

A control system for photolithographic sequences

A control system for photolithographic sequences

Designing response surface model-based run-by-run controllers: a worst case approach

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

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