Two-Dimensional Fluid Simulation and Langmuir Probe Measurement of a Planar Inductively Coupled Oxygen Plasma

Abstract

A two-dimensional (2D) self-consistent axisymmetric fluid simulation of an inductively coupled discharge of electronegative oxygen plasma with a one-turn antenna placed on the top of the dielectric roof is presented. The model equations include continuity equations, the Poisson equation, and an electron energy balance equation. For a planar inductive discharge, the electric field component Eθ (r, z) is calculated, assuming axisymmetric geometry. Considering a deep penetration of the induced rf field, the power deposition profile is formulated and used as the electron heating term in the electron energy balance equation. The 2D distributions of charged particle densities, electric potential, electron temperature, and ionization rate are calculated and compared with experiments. The effect of neutral gas pressure on plasma characteristics is investigated. As a result, for a relatively low pressure (5 mTorr) case, the ionization rate and charged particle densities are uniform in the radial direction, and for a medium pressure (20 mTorr) case, the ionization rate and the negative ion density are sharply maximized in the axial and radial directions. The results of the simulation agree reasonably well with the results of the spatially averaged global model and experimental results.