Abstract: PhD Dissertation: MOCVD of WNx Dissertation Discovery Company and University of Florida are dedicated to making scholarly works more discoverable and accessible throughout the world. This dissertation, "Chemical Vapor Deposition of Thin Films for Diffusion Barrier Applications" by Omar James Bchir, was obtained from University of Florida and is being sold with permission from the author. A digital copy of this work may also be found in the university's institutional repository, IR@UF. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation.

This book provides an overview of chemical vapor deposition (CVD) methods and recent advances in developing novel materials for application in various fields. CVD has now evolved into the most widely used technique for growth of thin films in electronics industry. Several books on CVD methods have emerged in the past, and thus the scope of this book goes beyond providing fundamentals of the CVD process. Some of the chapters included highlight current limitations in the CVD methods and offer alternatives in developing coatings through overcoming these limitations.

CVD thin film deposition from 3a, b, 4, and 5 highlights the importance of precursor selection and deposition parameters (e.g., coreactant selection, deposition temperature) on the film properties and diffusion barrier performance. Detailed film characterization and preliminary diffusion barrier testing revealed that films deposited with 3a, b and NH3 exhibited the most promise for diffusion barrier applications. To aid the precursor screening process and help understand the mechanism of precursor fragmentation prior to the growth studies, quantum mechanical (QM) calculations using density functional theory were carried out. Statistical mechanics along with QM calculations were employed to determine the energy barrier of potential reaction pathways which would lead to the deposition of WNxCy thin film. QM calculations for fragmentation of precursor 5 showed that the first step of precursor fragmentation was dissociation of the CH3CN ligand, followed by removal of the Cl ligands by either sigma-bond metathesis or reductive elimination.

A comprehensive overview of chemical vapor deposition (CVD), an extremely versatile process for manufacturing coatings, powders, fibers, and monolithic components.

Thin titanium dioxide films were produced by metalorganic chemical vapor deposition on sapphire(0001) in an ultrahigh vacuum (UHV) chamber. A method was developed for producing controlled submonolayer depositions from titanium isopropoxide precursor. Film thickness ranged from 0.1 to 2.7 nm. In situ X-ray photoelectron spectroscopy (XPS) was used to determine film stoichiometry with increasing thickness. The effect of isothermal annealing on desorption was evaluated. Photoelectron peak shapes and positions from the initial monolayers were analyzed for evidence of interface reaction. Deposition from titanium isopropoxide is divided into two regimes: depositions below and above the pyrolysis temperature. This temperature was determined to be 300 deg C. Controlled submonolayers of titanium oxide were produced by cycles of dosing with titanium isopropoxide vapor below and annealing above 300 deg C. Precursor adsorption below the pyrolysis temperature was observed to saturate after 15 minutes of dosing. The quantity absorbed was shown to have an upper limit of one monolayer. The stoichiometry of thin films grown by the cycling method were determined to be TiO2. Titanium dioxide film stoichiometry was unaffected by isothermal annealing at 700 deg C. Annealing produced a decrease in film thickness. This was explained as due to desorption. Desorption ceased at approximately 2.5 to 3 monolayers, suggesting bonding of the initial monolayers of film to sapphire is stronger than to itself. Evidence of sapphire reduction at the interface by the depositions was not observed. The XPS O is peak shifted with increased film thickness. The shifts were consistent with oxygen in sapphire and titanium dioxide having different O is photoelectron peak positions. Simulations showed the total shifts for thin films ranging in thickness of 0.1 to 2.7 nm to be -0.99 to -1.23 eV. Thick films were produced for comparison.