AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Numerical Modeling of a Low-Pressure Radio Frequency Argon-Silane Plasma in Which Silicon Particles Nucleate and Grow
PULKIT AGARWAL, Steven Girshick, University of Minnesota
Abstract Number: 96 Working Group: Synthesis of Functional Materials using Flames, Plasmas and other Aerosol Methods
Abstract Numerical simulations were conducted to predict the spatiotemporal evolution of a low-pressure radio frequency capacitively-coupled parallel-plate argon-silane plasma in which silicon nanoparticles nucleate and grow. The 1-D numerical model self-consistently couples the behavior of the plasma and of the aerosol. The plasma model includes population balance equations for electrons and ions, the electron energy equation under the assumption of a Maxwellian electron velocity distribution, Poisson’s equation for the electric field, and the chemical kinetics of small silicon hydrides created by plasma dissociation of silane. The aerosol general dynamic equation is solved using a sectional model for the distributions of particle size and charge. Particle charging by electron and ion attachment is modeled using orbital motion limited theory. Particle size- and charge-dependent coagulation is calculated, accounting for image potentials induced in interactions between charged and neutral particles. Particle transport effects considered include neutral gas drag, ion drag, the electrostatic force, Brownian diffusion and gravity. The silane chemistry model predicts the spatiotemporal profiles of the production rates of species believed to be most involved in particle nucleation and growth. These production rates, multiplied by suitable scaling factors, are used to predict nucleation and surface growth rates. Simulation results are presented for a case that corresponds to experiments in the literature, with RF frequency 13.56 MHz, applied voltage amplitude 55 V, pressure 17 Pa, electrode gap 4 cm, and gas velocity through the upper (showerhead) electrode of 26.3 cm/s.