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       Session PS-WeA

Paper PS-WeA4
Controlling the Ion Flux and Energy Distributions in LAPPS@footnote 1@

Wednesday, October 31, 2001, 3:00 pm, Room 104

Session: Plasma Surface Interactions II
Presenter: S.G. Walton, Naval Research Laboratory
Authors: S.G. Walton, Naval Research Laboratory
D. Leonhardt, Naval Research Laboratory
D.D. Blackwell, Naval Research Laboratory
D.P. Murphy, Naval Research Laboratory
R.F. Fernsler, Naval Research Laboratory
R.A. Meger, Naval Research Laboratory
Correspondent: Click to Email
In situ mass and energy resolved measurements of ion fluxes to a conducting electrode surface in NRL's Large Area Plasma Processing System (LAPPS) are presented. In LAPPS, a high-energy electron beam is used to ionize a background gas, producing a plasma over the volume of the beam. The beam is generated by a linear hollow cathode and magnetically collimated which allows for the production of uniform plasmas over areas up to 1 m@super 2@ or more. Electron beams are efficient at producing high-density plasmas (10@super 10@-10@super 12@ cm@super -3@) at low temperatures (Te < 1.0 eV) and are decoupled from the reactor geometry. Hence, control over the flux and incident ion energy at independently located and biased electrodes is possible and advantageous in dry processing applications. Temporally resolved ion flux and energy distributions at an electrode surface are reported for pulsed discharges in noble and molecular gases. The flux, sampled through a small orifice located in the center of the electrode, is analyzed via an energy selector in series with a mass spectrometer. Measurements are presented for a grounded and RF-biased electrode as a function of operating pressure, source-electrode separation, and the applied bias. In argon for example, the incident Ar@super +@ energy is pressure dependent and found to scale with the applied RF bias. In molecular gases, the magnitude and composition of the flux is dependent upon the source-electrode separation and found to vary in time, particularly in the afterglow. The results are discussed in terms of processing applications. Additional details concerning LAPPS are presented by co-authors at this conference.@footnote 2@ @FootnoteText@ @footnote 1@ Work supported by the Office of Naval Research @footnote 2@ See presentation by D. Leonhardt and D.D. Blackwell. @footnote *@S.G. Walton: SFA, Inc.; D.D. Blackwell: NRC Postdoctoral Research Associate