AVS 53rd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS-ThP

Paper PS-ThP6
Predicting Ion Energy Distribution Function for Multi-Frequency Capacitive Discharges

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: High Pressure Discharges and Novel Diagnostics & Sources Poster Session
Presenter: A. Wu, University of California, Berkeley
Authors: A. Wu, University of California, Berkeley
M.A. Lieberman, University of California, Berkeley
J.P. Verboncoeur, University of California, Berkeley
A.J. Lichtenberg, University of California, Berkeley
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In single and multiple frequency capacitive discharges used for semiconductor processing, the ion energy distribution function (IEDF) is important for determining the effects of ions at the wafer. The ability to predict the IEDF from the applied discharge voltages is greatly desired. We present particle-in-cell simulations for different frequencies and voltages to determine the IEDF, and we develop a theoretical model to predict the IEDF for any number of frequency drives, as long as the voltage across the sheath is known. In the model, we use a frequency filtered version of the voltage applied to the wafer to determine the ion response function. The filter function shape depends mainly on the ratio of the ion transit time across the sheath to the various applied frequencies, and is implemented in the model using Fourier transform techniques. We are exploring the use of a filter function given by Benoit-Cattin (1968)@footnote 1@ to determine the ion response, in order to predict the IEDF. A further refinement can be used for the regime where the driving frequency is approximately the same as the ion transit time. @FootnoteText@@footnote 1@P. Benoit-Cattin and L. C. Bernard, "Anomalies of the Energy of Positive Ions Extracted from High-Frequency Ion Sources. A Theoretical Study," J. Appl. Phys. 39, 5723 (1968).