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Proceedings Paper

Ion velocity distributions in electron cyclotron resonance plasmas
Author(s): Richard A. Gottscho; Toshiki Nakano; Nader Sadeghi; Dennis J. Trevor; Rod W. Boswell
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Paper Abstract

For applications in ultra-large scale integration, low pressure, high density plasmas are being developed for etching and deposition of thin films. To control critical parameters such as the flux and energy distribution of ions impacting surfaces, it is necessary to understand how these parameters are influenced by physical and electromagnetic design. In this work, we report measurements of ion velocity distributions in Ar/He and Cl2/He electron cyclotron resonance plasmas. Using Doppler-shifted laser-induced fluorescence spectroscopy, we measure metastable Ar and Cl ion velocity distributions parallel and perpendicular to the magnetic field as a function of magnetic field amplitude, pressure, and microwave power. We also examine the effects of the wafer platen on the distribution functions by repeating the measurements after removing the platen. We find nearly isotropic ion velocity distributions when the source is operated as a magnetic mirror and the He partial pressure is low; higher He pressures tend to cool the parallel velocity distribution. Downstream, we consistently observe bimodal ion velocity distributions: the fast component, created in the source, follows magnetic flux lines into the reactor; the slow component, created mostly where the plasma expands from the source into the reaction chamber, is more isotropic. The relative amplitudes of these two components, the average ion energy, and the ion energy distribution are easily controlled by changing pressure and magnetic field.

Paper Details

Date Published: 1 January 1992
PDF: 6 pages
Proc. SPIE 1594, Process Module Metrology, Control and Clustering, (1 January 1992); doi: 10.1117/12.56650
Show Author Affiliations
Richard A. Gottscho, AT&T Bell Labs. (United States)
Toshiki Nakano, National Defense Academy (Japan)
Nader Sadeghi, Univ. Joseph Fourier and CNRS (France)
Dennis J. Trevor, AT&T Bell Labs. (United States)
Rod W. Boswell, Australian National Univ. (Australia)

Published in SPIE Proceedings Vol. 1594:
Process Module Metrology, Control and Clustering
Cecil J. Davis; Irving P. Herman; Terry R. Turner, Editor(s)

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