Global model of Ar, O[sub 2], Cl[sub 2], and Ar/O[sub 2] high-density plasma discharges

• Published in: Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vol. 13:2
• Main Authors: Lee, C., Lieberman, M.A.
• Format: Journal Article
• Language: English
• Published: United States 01-03-1995
• Subjects: 661300 - Other Aspects of Physical Science- (1992-); ARGON; CHLORINE; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ELECTRIC DISCHARGES; ELECTRON TEMPERATURE; ELEMENTS; FLUIDS; GASES; HALOGENS; MATHEMATICAL MODELS; NONMETALS; OXYGEN; PLASMA DENSITY; PRESSURE DEPENDENCE; RARE GASES; RECOMBINATION
• ISSN: 0734-2101; 1520-8559
• DOI: 10.1116/1.579366

We develop a global (volume averaged) model of high-density plasma discharges in molecular gases. For a specified discharge length and diameter, absorbed power, pressure, and feed gas composition, as well as the appropriate reaction rate coefficients and surface recombination constants, we solve the energy and particle balance equations to determine all species densities and the electron temperature. We use an expression for charged particle diffusive loss that is valid for low and high pressures and for electropositive and electronegative plasmas. We apply the model to Ar, O[sub 2], Cl[sub 2], and Ar/O[sub 2] discharges and compare with available experimental data. In Ar, we find that the ion density increases monotonically with increasing pressure, while for O[sub 2] and Cl[sub 2], the total positive ion density increases initially, then decreases as pressure is further increased. For a pure Cl[sub 2] discharge, we find that surface recombination processes are important in affecting the degree of dissociation and the negative-ion density of the system. For mixtures of Ar and O[sub 2], we find that at a fixed ratio of Ar to O[sub 2] flowrates, the dominant ionic species changes from Ar[sup +] to O[sup +] as pressure is increased. When a small amount of Ar is added to a pure O[sub 2] discharge, the overall positive-ion density increases, whereas the ratio of negative ion to electron density decreases.