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PLUG: A FORTRAN program for the analysis of PLUG flow reactors with gas-phase and surface chemistry

Description: This manual describes the structure and usage of the computer program PLUG, which simulates the behavior of plug flow chemical reactors. More specifically, the code is designed to model the non-dispersive one-dimensional flow of a chemically reacting ideal gas mixture in a conduit of essentially arbitrary geometry. The code makes use of the CHEMKIN and SURFACE CHEMKIN software packages to handle gas-phase and heterogeneous kinetics as well as thermodynamic properties. In addition, the standard implicit code DASSL is used to solve the set of differential/algebraic equations describing the reactor. These equations are briefly discussed here, after which the procedures for running PLUG are described in some detail. Input and output files for a sample problem involving chemical vapor deposition are given.
Date: January 1, 1996
Creator: Larson, R.S.
Partner: UNT Libraries Government Documents Department

A reaction mechanism for titanium nitride CVD from TiCl{sub 4} and NH{sub 3}

Description: A gas-phase and surface reaction mechanism for the CVD of TiN from TiCl{sub 4} and NH{sub 3} is proposed. The only gas-phase process is complex formation, which can compete with deposition. The surface mechanism postulates the stepwise elimination of Cl and H atoms from TiCl{sub 4} and NH{sub 3}, respectively, to form solid TiN and gaseous HCl. The mechanism also accounts for the change in oxidation state of Ti by allowing for liberation of N{sub 2}. Provided that the surface composition is at steady state, the stoichiometry of the overall reaction is reproduced exactly. In addition, the global kinetic law predicted by the mechanism is successfully fit to new deposition data from a rotating disk reactor and is shown to be consistent with literature results.
Date: December 1995
Creator: Larson, R. S. & Allendorf, M. D.
Partner: UNT Libraries Government Documents Department

A Fully Coupled Computational Model of the Silylation Process

Description: This report documents the development of a new finite element model of the positive tone silylation process. Model development makes use of pre-existing Sandia technology used to describe coupled thermal-mechanical behavior in deforming metals. Material properties and constitutive models were obtained from the literature. The model is two-dimensional and transient and focuses on the part of the lithography process in which crosslinked and uncrosslinked resist is exposed to a gaseous silylation agent. The model accounts for the combined effects of mass transport (diffusion of silylation agent and reaction product), chemical reaction resulting in the uptake of silicon and material swelling, the generation of stresses, and the resulting material motion. The influence of stress on diffusion and reaction rates is also included.
Date: February 1, 1999
Creator: Evans, G. H.; Larson, R. S.; Prantil, V. C. & Winters, W. S.
Partner: UNT Libraries Government Documents Department

Results from modeling and simulation of chemical downstream etch systems

Description: This report summarizes modeling work performed at Sandia in support of Chemical Downstream Etch (CDE) benchmark and tool development programs under a Cooperative Research and Development Agreement (CRADA) with SEMATECH. The Chemical Downstream Etch (CDE) Modeling Project supports SEMATECH Joint Development Projects (JDPs) with Matrix Integrated Systems, Applied Materials, and Astex Corporation in the development of new CDE reactors for wafer cleaning and stripping processes. These dry-etch reactors replace wet-etch steps in microelectronics fabrication, enabling compatibility with other process steps and reducing the use of hazardous chemicals. Models were developed at Sandia to simulate the gas flow, chemistry and transport in CDE reactors. These models address the essential components of the CDE system: a microwave source, a transport tube, a showerhead/gas inlet, and a downstream etch chamber. The models have been used in tandem to determine the evolution of reactive species throughout the system, and to make recommendations for process and tool optimization. A significant part of this task has been in the assembly of a reasonable set of chemical rate constants and species data necessary for successful use of the models. Often the kinetic parameters were uncertain or unknown. For this reason, a significant effort was placed on model validation to obtain industry confidence in the model predictions. Data for model validation were obtained from the Sandia Molecular Beam Mass Spectrometry (MBMS) experiments, from the literature, from the CDE Benchmark Project (also part of the Sandia/SEMATECH CRADA), and from the JDP partners. The validated models were used to evaluate process behavior as a function of microwave-source operating parameters, transport-tube geometry, system pressure, and downstream chamber geometry. In addition, quantitative correlations were developed between CDE tool performance and operation set points.
Date: May 1, 1996
Creator: Meeks, E.; Vosen, S.R.; Shon, J.W.; Larson, R.S.; Fox, C.A. & Buchenauer
Partner: UNT Libraries Government Documents Department

Modeling high-density-plasma deposition of SiO{sub 2} in SiH{sub 4}/O{sub 2}/Ar

Description: The authors have compiled sets of gas-phase and surface reactions for use in modeling plasma-enhanced chemical vapor deposition of silicon dioxide from silane, oxygen and argon gas mixtures in high-density-plasma reactors. They have applied the reaction mechanisms to modeling three different kinds of high-density plasma deposition chambers, and tested them by comparing model predictions to a variety of experimental measurements. The model simulates a well mixed reactor by solving global conservation equations averaged across the reactor volume. The gas-phase reaction mechanism builds from fundamental electron-impact cross section data available in the literature, and also includes neutral-molecule, ion-ion, and ion-molecule reaction paths. The surface reaction mechanism is based on insight from attenuated total-reflection Fourier-transform infrared spectroscopy experiments. This mechanism describes the adsorption of radical species on an oxide surface, ion-enhanced reactions leading to species desorption from the surface layer, radical abstractions competing for surface sites, and direct energy-dependent ion sputtering of the oxide material. Experimental measurements of total ion densities, relative radical densities as functions of plasma operating conditions, and net deposition-rate have been compared to model predictions to test and modify the chemical kinetics mechanisms. Results show good quantitative agreement between model predictions and experimental measurements.
Date: March 1, 1997
Creator: Meeks, E.; Larson, R.S.; Ho, P.; Apblett, C.; Han, S.M.; Edelberg, E. et al.
Partner: UNT Libraries Government Documents Department