Closed loop adaptive control of spectrum-producing step using ne

Details Closed loop adaptive control of spectrum-producing step using ne Closed loop adaptive control of spectrum-producing step using ne

1992-11-09

1998-11-24

Elmore, Reba I.

Boots, shoes, and leggings

216 59, 216 61, 1566431, G01R 2900

Patent

active

058416510

ABSTRACT:
Characteristics of the plasma in a plasma-based manufacturing process step are monitored directly and in real time by observing the spectrum which it produces. An artificial neural network analyzes the plasma spectrum and generates control signals to control one or more of the process input parameters in response to any deviation of the spectrum beyond a narrow range. In an embodiment, a plasma reaction chamber forms a plasma in response to input parameters such as gas flow, pressure and power. The chamber includes a window through which the electromagnetic spectrum produced by a plasma in the chamber, just above the subject surface, may be viewed. The spectrum is conducted to an optical spectrometer which measures the intensity of the incoming optical spectrum at different wavelengths. The output of optical spectrometer is provided to an analyzer which produces a plurality of error signals, each indicating whether a respective one of the input parameters to the chamber is to be increased or decreased. The microcontroller provides signals to control respective controls, but these lines are intercepted and first added to the error signals, before being provided to the controls for the chamber. The analyzer can include a neural network and an optional spectrum preprocessor to reduce background noise, as well as a comparator which compares the parameter values predicted by the neural network with a set of desired values provided by the microcontroller.

REFERENCES:
patent: 4226896 (1980-10-01), Coburn et al.
patent: 5014219 (1991-05-01), Savage
patent: 5107119 (1992-04-01), Kimura et al.
patent: 5160402 (1992-11-01), Cheng
patent: 5166525 (1992-11-01), Rodgers et al.
patent: 5212821 (1993-05-01), Gorin et al.
patent: 5214744 (1993-05-01), Schweizer
patent: 5458732 (1995-10-01), Butler et al.
patent: 5467883 (1995-11-01), Frye et al.
patent: 5486235 (1996-01-01), Ye et al.
Sze, S. M., "VLSI Technology", 2d. Ed., pp. 233-326 (1988).
C. D. Himmel et al., "A Comparison of Statistically-Based and Neural Network Models of Plasma Etch Behavior", IEEE/SEMI Int. Semiconductor Manufacturing Symposium, 124-129 (Jun. 15, 1992).
R. Shadmehr et al., "Principal Componet Analysis of Optical Emission Spectroscopy and Mass Spectromety: Application to Reactive Ion Etch Process Parameter Estimation Using Neural Networks", J. Electrochem. Soc., vol. 139, No. 3, 907-914 (Mar. 1992).
Fu-Chuang Chen, "Back-Propagation Neural Networks for Nonlinear Self-Teaching Adaptive Control", 1990 Apr. 30, 44-48.
Compton & Landon, "Parallel Detection Systems Offer Advantages Beyond the Obvious", Applications Review, published by Tracor Northern (1985).
Hirose, et al., "Back-Propagation Algorithm Which Varies the Number of Hidden Units", Neural Networks, vol. 4, pp. 61-66 (1991).
Jenkins, et al., "The Modeling of Plasma Etching Processes Using Response Surface Methodology", Solid State Technology Journal, vol. 29, No. 4, pp. 175-182 (1986).
Kaufmann, et al., "Introduction to Fuzzy Arithmetic", Van Nostrand Reinhold Company, pp. 8-15 (1985).
Lawrence, J., "Data Preparation for a Neural Network", AI Expert, pp. 34-41, Nov. 1991.
Lee, C. C., "Fuzzy Logic in Control Systems: Fuzzy Logic Controller--Parts I and II", IEEE Transactions on Systems, Man, and Cybernetics, vol. 20, No. 2, pp. 404-435, Mar./Apr. 1990.
Lippmann, R. P., "An Introduction to Computing with Neural Nets," IEEE ASSP Magazine, pp. 4-22, Apr. 1987.
Malchov, D. S., "Characterization of Plasma Processes with Optical Emission Spectroscopy", SPIE, Advanced Techniques for Integrated Circuit Processing, vol. 1392, pp. 498-505 (Oct. 4, 1990).
Rigler, et al., "Rescaling of Variables in Back Propagation Learning", Neural Networks, vol. 4, pp. 225-229 (1991).
Singer, P. H., "Diagnosing Plasmas and Detecting Endpoints", Semiconductor International, pp. 66-70, Aug. 1988.
Sun, et al., "Fuzzy Modeling Based on Generalized Neural Networks and Fuzzy Clustering Objective Functions", Proceedings of the 30th IEEE Conference on Decision and Control (1991).
Sze, S. M., "VLSI Technology", 2d. Ed., pp. 184-239, 262-269, 386-400 (1988).
Tracor Northern, "The Role of Photodiode Array Detectors in `Snap-Shot` Spectroscopy" (1985).
Weir, M. K., "A Method for Self-Determination of Adaptive Learning Rates in Back Propagation", Neural Networks, vol. 4, pp. 371-379 (1991).
Zadeh, L. A., "Fuzzy Logic", IEEE Computer, pp. 83-93 (1988).
Zadeh, L. A., "Fuzzy Sets", Information and Control, vol. 8, pp. 338-353 (1965).

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