Numerical analysis of the kinetics of chemical reactions in an argon-silane plasma of the glow discharge

A. A. Lyakhov ; V. I. Strunin

Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mehanika, no. 50 (2017), pp. 79-89

Résumé

The chemical kinetics of neutral components in an argon-silane plasma of the glow discharge is considered. The modeling of plasma chemical composition is implemented in $\mathrm{2D}$-cylinder geometry based on numerical solution of the set of coupled diffusion equations. The model includes $20$ neutral species and about $60$ chemical reactions. The coefficients of electron collision rate are computed using numerical solution of two-term approximation of the Boltzmann equation for electrons. The electron density is set as an input parameter with the value of $10^8$ cm$^{-3}$. A contribution of the principal chemical reactions on the entire source and sink of different components is discussed. In modeling of the chemical kinetics of film-forming radicals, the role of higher silane radicals Si$_n$H$_x$ ($n\geqslant3$) is not significant up to $10^{-2}$ s. Consequently, if the residence time of feed gas in the reaction chamber is of about milliseconds, the effect of such components and chemical reactions, which produce them, can be neglected in the simulation of silane plasma. Calculation results obtained using the model with the quantity of components reduced to $14$ give almost the same values for silane radical densities. In modeling of plasma chemistry system, an analysis of contribution of the reactions can be used as a tool for reducing preliminary set of species and reactions to the minimal set, which is sufficient for the computations in a certain time interval.

Détail

Keywords: silane plasma, transport processes in a chemical-active plasma
Mots-clés : amorphous silicon.