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Proceedings Paper

Real-time feedback control of reactive ion etching
Author(s): Michael E. Elta; J. P. Fournier; James S. Freudenberg; M. D. Giles; Jessy W. Grizzle; Pramod P. Khargonekar; Brian A. Rashap; Fred Lewis Terry Jr.; T. Vincent
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Paper Abstract

This paper explores the application of modern feedback control technology to the regulation of the reactive ion etching process. Currently, this process is run open-loop, except for the PID controller to regulate pressure. We investigate the utility of additional measurements for the purpose of feedback control to improve process performance and robustness. First, we compare a feedback controller that regulates Vbias and chamber pressure to one that regulates Vbias and fluorine. We show that the fluorine controller yields better control of etch rate; this result is to be expected since fluorine is more closely related to the chemical etching process than is pressure. Our second study compares various controllers that regulate Vbias and fluorine using the conductance throttle and applied RF power. We show that multivariable feedback controllers that can compensate for process coupling by coordinating control inputs have advantages over decentralized controllers consisting of two independent feedback loops.

Paper Details

Date Published: 15 February 1994
PDF: 14 pages
Proc. SPIE 2091, Microelectronic Processes, Sensors, and Controls, (15 February 1994); doi: 10.1117/12.167364
Show Author Affiliations
Michael E. Elta, Univ. of Michigan (United States)
J. P. Fournier, Univ. of Michigan (United States)
James S. Freudenberg, Univ. of Michigan (United States)
M. D. Giles, Univ. of Michigan (United States)
Jessy W. Grizzle, Univ. of Michigan (United States)
Pramod P. Khargonekar, Univ. of Michigan (United States)
Brian A. Rashap, Univ. of Michigan (United States)
Fred Lewis Terry Jr., Univ. of Michigan (United States)
T. Vincent, Univ. of Michigan (United States)

Published in SPIE Proceedings Vol. 2091:
Microelectronic Processes, Sensors, and Controls
Kiefer Elliott; James A. Bondur; James A. Bondur; Kiefer Elliott; John R. Hauser; John R. Hauser; Dim-Lee Kwong; Asit K. Ray, Editor(s)

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