Modeling and diagnostics of the structure of rf glow discharges in Ar at 13.56 MHz

Abstract

The structure of rf glow discharges in Ar at 13.56 MHz is described, making use of a relaxation continuum model. The model includes consideration of the relaxation kinetics for the momentum and energy of charged particles. The discharge structure and plasma property are modeled using molecular quantities (i.e. , collision cross sections, radiative lifetimes, etc.) and macroscopic transport quantities for charged particles. Spatiotemporal distributions for the field and the net production rate and density of particles are studied in detail in the bulk plasma as well as the ion sheath under periodic steady-state conditions. In particular, the temporal profiles including phase shift and nonlinear variation with respect to the applied-voltage wave form are discussed. Each type of excited atom shows a different spatiotemporal density distribution due to different loss mechanisms, although the production profiles are similar. That is, Ar( ps) is controlled by a radiative decay and quenching in collisions with Ar( So), while Ar( Po & ) is controlled by diffusion. The validity of the relaxation continuum model is investigated by the observation of external electric properties and the measurement of spatiotemporally resolved optical emission from the rf glow. Quantitative comparison of the results from theory and experiment supports the validity of the relaxation continuum model. The relaxation continuum model is simple and physically reasonable.PACS number(s): 52.80. Hc, 52.25.Fi, 52.70.Kz

Charged Particle Transport in Harmonically Varying Electric Fields: Foundations and Phenomenology

“…results which follow directly from (25), (26), (32) and the relationships (34). The distinction between two sets of transport coefficients vanishes when either R=0 or when the reactive cross sections are not energy selective [13,38].…”

“…This set of equations is sufficient to determine``flux'' transport coefficients [38] w, D | | and D = for specified field frequency and cross sections.``Bulk'' transport coefficients [38] (B) W, (B) D | | and (B) D = , as given by (34), require a second order density gradient expansion (c.f. (31)) and are dealt with in [42].…”

“…The R.C.T. model [33,34] and associated effective electric field are also briefly discussed as an example of an empirical model which follows as an approximation from our more general theory.…”

Frequency Variation of the Mean Energy of rf Electron Swarms

“…The theory, at its lowest level, is similar in spirit to the 'relaxation continuum' model of Makabe et al (1992), but the origin and definition of the collisional relaxation times is more precise. In essence, momentum-transfer theory provides a scheme for systematic approximation of collision terms in moment equations generated by integrating Boltzmann's equation for each charged species with 1, mv,~mv2, ... over all particle velocities v. In the lowest approximation, momentum-transfer theory consists in employing collision terms of the same mathematical form as for the Maxwell (constant collision frequency) model, but with cross sections evaluated according to actual energy dependencies.…”

On formation of thin SiO2/a-Si:H interface when biased oxidized semiconductor surface interacts with plasma or liquid solution

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