Innovative techniques in plasma modeling.

摘要

A reactor-scale simulation of an inductively coupled plasma (ICP) is developed and applied to systems of interest in semiconductor processing. The focus of this dissertation is the kinetics and transport of neutral species in ICPs and the collisional coupling between the charged and neutral species.; The simulation is used to study point of use plasma abatement (PPA) of perfluorinated compound (PFC) emission from plasma reactors. Simulation predictions are compared to experimental measurements of abatement and neutral temperature with semi-quantitative agreement. Neutral transport under PPA conditions is dominated by convection. The rate controlling step in PFC abatement is electron impact dissociation of the PFC. Simulation results are used to show that low pressure, high rf power, and high neutral temperature are the most effective conditions for PFC abatement.; Experimental measurements of the electron energy distribution function (EEDF) in an argon ICP are used to implement a non-Maxwellian EEDF in the model. With the non-Maxwellian EEDF, good agreement is obtained between experiment and model for electron density, electron temperature, and neutral argon metastable density. We show that metastable characteristics are controlled by a combination of electron kinetics, neutral heating, metastable diffusion, and metastable quenching at reactor surfaces.; Simulation results in an oxygen ICP are compared to experimental measurements. We show that the balance between gas phase O₂ dissociation and surface O recombination controls the plasma characteristics under the investigated conditions. Evidence is presented to suggest that the current description of oxygen kinetics in high density, low pressure plasmas is incomplete. Simulation predictions show that neutral transport is controlled by diffusion and fast gas phase and surface reactions. O(1D), O₂(a 1Δ) and O₂(b1Σ) metastables are important in dissociation, ionization and attachment kinetics, whereas the O(1S) metastable is not kinetically important.; Finally, we consider neutral transport in silicon etching using a chlorine-based ICP. Both the feedgas flow rate and the reactor inlet position significantly affect the redeposition of silicon on the wafer by changing the neutral flow patterns. Convective flow at the wafer helps remove etch products prior to exposure to the plasma, where electron impact chemistry converts etch products to depositing species. Deposition of silicon onto the wafer and chamber walls results from both neutral and ionic silicon-containing species in the plasma.