Model of Particle Growth in Silane Discharges

Published

August 1, 2000

Author(s)

Alan Gallagher

Abstract

The growth of silicon particles in the neutral plasma region of pure silane, rf capacitively coupled, steady-state discharges is calculated with a homogenous, plasma-chemistry model. Plasma conditions are typical of those used in hydrogenated amorphous silcon (a-Si:H) device production. SiH₃ and SiH₃- grow into particles by the step-by-step addition of silicon atoms, primarily due to reactions with SiH₃. Attrition of growing Si_xH_m^z radicals and ions with z charges, which are particles for large x, occurs by diffusion of neutral and positively charged radicals to the electrodes. Rate coefficients for electron, ion, radical, and silane collisions with the Si_xH_m^z for x=1-10⁵ are estimated form detailed considerations of the literature and relevant physics. Self-consistent anion, cation (n +), and electron (n_e) densities and charge fluxes are used, and charge neutrality is maintained. Typically n+ ln_e{identical with} 100, which causes a large fraction of neutral particles and thereby a major particle flux into the growing a-Si:H film. The density of visible particles (x>10⁴) varies many orders of magnitude with relatively minor changes in discharge power, pressure, and electrode gap. This parameter dependence agrees with experiment, and by adjusting collision parameters within a reasonable range the calculated particle densities can be brought into exact agreement with experiment. An additional result of the model, which has not yet been detected, is that Si_xH_m clusters with 3

Citation

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics)

Volume

62

Issue

No. 2

Pub Type

Journals

Keywords

growth of silicon particles, neutral plasma region of pure silane

Citation

Gallagher, A. (2000), Model of Particle Growth in Silane Discharges, Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) (Accessed May 18, 2024)