Plasma modeling and simulation are used to understand the influence of plasma reactor operating conditions on the energy distribution of electrons and ions, and in turn the interaction of these species with the wafer surface. Of interest are “particle” simulations (Particle-in-Cell, Monte Carlo) of the electron energy distribution function (EEDF) in the plasma, and the ion energy distribution function (IEDF) on the wafer surface. The “inverse” problem, that of specifying the operating conditions to achieve a desired EEDF and/or IEDF, is particularly challenging. Modeling and simulation are complemented with experimental measurements with emphasis on real-time, non-intrusive, spatially-resolved spectroscopic diagnostics, as well as electron and ion energy (also angular) distribution measurements.

Figure 1. Ion energy distributions on the wafer surface: comparison of measurements (left) with particle-in-cell simulations (right) under identical conditions (S. K. Nam, D. J. Economou, and V. M. Donnelly,Plasma Sources Sci. Technol., 16, 90-96, 2007).

Figure 2. Measured (using Trace Rare Gases Optical Emission Spectroscopy or TRG-OES) electron energy distribution functions (EEDF) in a parallel plate dual-frequency, capacitively-coupled CF4-O2 plasma reactor (Z. Chen, V. M. Donnelly, D. J. Economou, L. Chen, M. Funk, and R. Sundararajan, J. Vac. Sci. Technol. A., 27, 1159, 2009).

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