AVS 46th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoP

Paper PS-MoP15
Comparison of Plasma Density Measurements in ICP and Helicon Discharges using Langmuir probe, Plasma Oscillation Probe and Interferometry Techniques

Monday, October 25, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: J.D. Evans, University of California, Los Angeles
Authors: W. Zawalski, Hiden Analytical Ltd.
J.D. Evans, University of California, Los Angeles
Correspondent: Click to Email
A comparison study of the application of various probe theories, including the so-called orbital motion limited@footnote 1@ and ABR@footnote 2@ theories, in the interpretation of Langmuir probe I-V characteristics is performed. Experimental data for the comparison is obtained in both an inductively coupled plasma (ICP) and a low-field helicon plasma source (HPS), over a wide range of parameters of interest to the plasma processing community.@footnote 3@ Measurements of N@sub e@ and N@sub i@ from the Hiden Electrostatic Plasma Probe (ESP) characteristics and ESPion software are compared to "known" values of N@sub e@ obtained via microwave interferometry and the plasma oscillation probe (POP) technique,@footnote 4,5@ in regimes including those where the probe theories yield different results. Closely spaced multiple peaks in the spectra of the POP are observed in some cases at higher RF input powers, possibly due to RF modulation of the source plasma density, leading to experimental uncertainty in N@sub e@ values thus obtained. Broadband low frequency electrostatic emissions and substantial peak broadening are observed when the beam-plasma instability excited by the probe is overdriven into the nonlinear regime. Other considerations for the applicability of the POP method will also be discussed. @FootnoteText@ @footnote 1@ J.G. Laframboise, Univ. Toronto Inst. Aerospace Studies Rept. 100 (1966). @footnote 2@ J.E. Allen, R.L.F. Boyd, and P. Reynolds, Proc. Phys. Soc. B 70, 297 (1957). @footnote 3@ N@sub p@ ~ 10@super 1@@super 0@-10@super 1@@super 2@ cm@super -@@super 3@, T@sub e@ ~ 2-4 eV, P@sub r@@sub f@ ~ 1 kW, P@sub o@ ~ 1-10 mTorr. @footnote 4@ T. Shirakawa and H. Sugai, Japan. J. Appl. Phys. 32, 5129 (1993). @footnote 5@ A. Schwabedissen et al., Plasma Sources Sci. Technol. 7, 119 (1998).