AVS 45th International Symposium
    Plasma Science and Technology Division Thursday Sessions
       Session PS-ThA

Paper PS-ThA9
Investigation of the Gasphase of Expanding Ar/C@sub x@H@sub y@ Plasmas

Thursday, November 5, 1998, 4:40 pm, Room 318/319/320

Session: Diagnostics II
Presenter: K.G.Y. Letourneur, Eindhoven University of Technology, The Netherlands
Authors: A. de Graaf, Eindhoven University of Technology, The Netherlands
M.F.A.M. van Hest, Eindhoven University of Technology, The Netherlands
K.G.Y. Letourneur, Eindhoven University of Technology, The Netherlands
M.C.M. van de Sanden, Eindhoven University of Technology, The Netherlands
D.C. Schram, Eindhoven University of Technology, The Netherlands
Correspondent: Click to Email
An expanding argon plasma into which several C@sub x@H@sub y@ precursors are injected was used for the deposition of diamond-like carbon films. The argon plasma is created in a cascaded arc and expands into a low-pressure vessel, where precursor gases, such as CH@sub 4@, C@sub 2@H@sub 2@, C@sub 2@H@sub 4@ and C@sub 2@H@sub 6@ are injected into the beam. The gasphase of these plasmas was investigated by means of Fourier Transform Infrared (FTIR) absorption spectroscopy and Mass Spectrometry (MS). The consumption of the different precursor gases was derived from both FTIR and MS measurements for several arc currents, pressures and flows. The results from the two techniques are compared in order to eliminate the effect of temperature and to distinguish whether reaction products are formed in the background or in the plasma beam. By correlating the depletion measurements with the growth rate measured in situ by ellipsometry, information is obtained on the reactions taking place inside the plasma and during deposition. Assuming that only argon ions are contributing to the dissociation of the C@sub x@H@sub y@, the electron energy being too low (typically 0.2 eV in these plasmas), the ionization degree of the arc can be deduced as function of arc current and argon flow. The measurements also prove that other stable monomers are produced in the plasma phase, i.e. polymerization is taking place. The possible polymerization reactions, occurring either in the gasphase or at the reactor walls, will be discussed for the different precursor gases.