AVS 49th International Symposium
    Plasma Science Wednesday Sessions
       Session PS+TF-WeP

Paper PS+TF-WeP10
Two-dimensional Modeling of Charged Particles Transport in Capacitively Coupled Radio-frequency Discharges

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Plasma Etching & Deposition
Presenter: A. Salabas, Instituto Superior Técnico, Portugal
Authors: A. Salabas, Instituto Superior Técnico, Portugal
G. Gousset, Univ. Paris-Sud, France
L.L. Alves, Instituto Superior Técnico, Portugal
Correspondent: Click to Email
Plasma enhanced chemical vapour deposition is often employed to produce chemical active species, using capacitively coupled radio frequency (ccrf) glow discharges driven at 13.56 MHz. Predictions over film deposition rates necessarily pass through the description of charged particle transport in the discharge. The present work describes the transport phenomena in a ccrf reactor using a two dimensional fluid model. The description of charged particle transport is made by solving the continuity and momentum transfer equations for electrons and ions, coupled with Poisson and the electron mean energy equations.@footnote 1@ The physical model adopts the local mean energy approximation i.e. it computes the electron and energy transport parameters as well as the electron impact collision rates as functions of the electron mean energy. The model writes the electron and energy fluxes in the drift diffusion approximation, including the variation with position of the diffusion coefficient. Ion inertia terms are also considered by generalising the earlier concept of effective electric field.@footnote 2@ Adequate flux boundary conditions have been employed. The convergence criterion checks the main plasma parameters and assumes steady state solution when relative changes between two subsequent periods are less then 0.001. The model is solved for He, H@sub 2@ and SiH@sub 4@-H@sub 2@ discharges produced within a cylindrical ccrf reactor similar to GEC reference cell, for 68 mTorr - 3 Torr pressures and 100 V - 500 V applied rf voltages. Results concerning non-local phenomena, the influence of silane dilution and reactor geometry are pointed out. In general, comparisons with experimental data indicate that the model improves earlier reported results for some electrical benchmark parameters. @FootnoteText@ @footnote 1@ J. P. Boeuf and L. C. Pitchford Phys. Rev E 51 (2) (1995) 1376. @footnote 2@ J. D. P. Passchier and W. J. Goedhee J. Appl. Phys. 74 (6) (1993) 3744.