UNT Theses and Dissertations - 54 Matching Results

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Adherence/Diffusion Barrier Layers for Copper Metallization: Amorphous Carbon:Silicon Polymerized Films

Description: Semiconductor circuitry feature miniaturization continues in response to Moore 's Law pushing the limits of aluminum and forcing the transition to Cu due to its lower resistivity and electromigration. Copper diffuses into silicon dioxide under thermal and electrical stresses, requiring the use of barriers to inhibit diffusion, adding to the insulator thickness and delay time, or replacement of SiO2 with new insulator materials that can inhibit diffusion while enabling Cu wetting. This stu… more
Date: May 2004
Creator: Pritchett, Merry
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Chemistry, Detection, and Control of Metals during Silicon Processing

Description: This dissertation focuses on the chemistry, detection, and control of metals and metal contaminants during manufacturing of integrated circuits (ICs) on silicon wafers. Chapter 1 begins with an overview of IC manufacturing, including discussion of the common aqueous cleaning solutions, metallization processes, and analytical techniques that will be investigated in subsequent chapters. Chapter 2 covers initial investigations into the chemistry of the SC2 clean - a mixture of HCl, H2O2, and DI wa… more
Date: May 2005
Creator: Hurd, Trace Q.
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Computational Studies of Coordinatively Unsaturated Transition Metal Complexes

Description: In this research the validity of various computational techniques has been determined and applied the appropriate techniques to investigate and propose a good catalytic system for C-H bond activation and functionalization. Methane being least reactive and major component of natural gas, its activation and conversion to functionalized products is of great scientific and economic interest in pure and applied chemistry. Thus C-H activation followed by C-C/C-X functionalization became crux of the s… more
Date: December 2006
Creator: Vaddadi, Sridhar
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Computational Studies on Group 14 Elements (C, Si and Ge) in Organometallic and Biological Compounds.

Description: A series of computational studies were carried out on Group 14 (C, Si and Ge) elements in organometallic and biological compounds. Theoretical studies on classical and H-bridged A3H3+ (A=C, Si and Ge) as p ligands with different organometallic fragments at B3LYP and B3P86 level reveal a reverse charge transfer from ligand to metal in Si and Ge complexes whereas in C complexes there is a small charge transfer from metal to ligand. The H-bridged complexes are more stable than the complexes base… more
Date: May 2007
Creator: Yu, Liwen
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Cu Electrodeposition on Ru with a Chemisorbed Iodine Surface Layer.

Description: An iodine surface layer has been prepared on Ru(poly) and Ru(0001) electrodes by exposure to iodine vapor in UHV and polarizing in a 0.1 M HClO4/0.005 M KI solution, respectively. A saturation coverage of I on a Ru(poly) electrode passivates the Ru surface against significant hydroxide, chemisorbed oxygen or oxide formation during exposure to water vapor over an electrochemical cell in a UHV-electrochemistry transfer system. Immersion of I-Ru(poly) results in greater hydroxide and chemisorbed o… more
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Date: August 2005
Creator: Lei, Jipu
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Diffusion Barriers/Adhesion Promoters. Surface and Interfacial Studies of Copper and Copper-Aluminum Alloys

Description: The focus of this research is to study the interaction between copper and the diffusion barrier/adhesion promoter. The behavior of copper sputter-deposited onto sputter-cleaned tantalum nitride is investigated. The data show that copper growth on tantalum nitride proceeds with the formation of 3-D islands, indicating poor adhesion characteristics between copper and Ta0.4N. Post-annealing experiments indicate that copper will diffuse into Ta0.4N at 800 K. Although the data suggests that Ta0.4N i… more
Date: August 2000
Creator: Shepherd, Krupanand Solomon
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Diphosphine Ligand Activation Studies with Organotransition-Metal Compounds

Description: Thermolysis of CoRu(CO)7(m -PPh2) (1) in refluxing 1,2-dichloroethane in the presence of the diphosphine ligands 2,3-bis(diphenylphosphino)maleic anhydride (bma) and 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) furnishes the new mixed-metal complexes CoRu(CO)4(μ -P-P)(μ -PPh2) [where P-P = bma (3); bpcd (6)], along with trace amounts of the known complex CoRu(CO)6(PPh3)(μ -PPh2) (4). The requisite pentacarbonyl intermediates CoRu(CO)5(μ -P-P)(μ -PPh2) [where P-P = bma (2); bpcd (5)… more
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Date: December 2000
Creator: Wang, Jiancheng
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Electrochemical Synthesis and Characterization of Inorganic Materials from Aqueous Solutions

Description: The dissertation consists of the following three sections: 1. Hydroxyapatite (HA) coatings. In this work, we deposited HA precursor films from weak basic electrolytic solution (pH= 8-9) via an electrochemical approach; the deposits were changed into crystallite coatings of hydroxyapatite by sintering at specific temperatures (600-800 ºC). The formed coatings were mainly characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microsc… more
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Date: December 2006
Creator: Yuan, Qiuhua
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The evaluation, development, and application of the correlation consistent basis sets.

Description: Employing correlation consistent basis sets coupled with electronic structure methods has enabled accurate predictions of chemical properties for second- and third-row main group and transition metal molecular species. For third-row (Ga-Kr) molecules, the performance of the correlation consistent basis sets (cc-pVnZ, n=D, T, Q, 5) for computing energetic (e.g., atomization energies, ionization energies, electron and proton affinities) and structural properties using the ab initio coupled clust… more
Date: December 2006
Creator: Yockel, Scott
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Fabrication and light scattering study of multi-responsive nanostructured hydrogels and water-soluble polymers.

Description: Monodispersed microgels composed of poly-acrylic acid (PAAc) and poly(N-isopropylacrylamide) (PNIPAM) interpenetrating networks were synthesized by 2-step method with first preparing PNIPAM microgel and then polymerizing acrylic acid that interpenetrates into the PNIPAM network. The semi-dilute aqueous solutions of the PNIPAM-PAAc IPN microgels exhibit an inverse thermo-reversible gelation. Furthermore, IPN microgels undergo the reversible volume phase transitions in response to both pH and tem… more
Date: December 2003
Creator: Xia, Xiaohu
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General Chemistry Topic Coverage (GCTC) comparison between community colleges and universities in the United States.

Description: This study is based on survey responses of 224 general chemistry instructors at United States (U.S.) community colleges and universities representing 46 states. The mean values of General Chemistry Topic Coverage (GCTC) score, developed by this researcher specifically for this dissertation study as a measure of course content, were statistically analyzed. The aim of this study is to answer five research questions: (a) Is there a difference in mean GCTC scores between U.S. community colleges and… more
Date: December 2006
Creator: El-Ashmawy, Amina Khalifa
Item Type: Refine your search to only Thesis or Dissertation
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Hydrogen terminated silicon surfaces: Development of sensors to detect metallic contaminants and stability studies under different environments

Description: Hydrogen terminated silicon surfaces have been utilized to develop sensors for semiconductor and environmental applications. The interaction of these surfaces with different environments has also been studied in detail. The sensor assembly relevant to the semiconductor industry utilizes a silicon-based sensor to detect trace levels of metallic contaminants in hydrofluoric acid. The sensor performance with respect to two non-contaminating reference electrode systems was evaluated. In the fi… more
Date: August 2002
Creator: Ponnuswamy, Thomas Anand
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Interaction of learning approach with concept integration and achievement in a large guided inquiry organic class.

Description: A study was conducted to investigate the relationship of students' concept integration and achievement with time spent within a topic and across related topics in a large first semester guided inquiry organic chemistry class. Achievement was based on evidence of algorithmic problem solving; and concept integration was based on demonstrated performance explaining, applying, and relating concepts to each other. Twelve individual assessments were made of both variables over three related topics - … more
Date: August 2009
Creator: Mewhinney, Christina
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Interfacial Electrochemistry and Surface Characterization: Hydrogen Terminated Silicon, Electrolessly Deposited Palladium & Platinum on Pyrolyzed Photoresist Films and Electrodeposited Copper on Iridium

Description: Hydrogen terminated silicon surfaces play an important role in the integrated circuit (IC) industry. Ultra-pure water is extensively used for the cleaning and surface preparation of silicon surfaces. This work studies the effects of ultra-pure water on hydrogen passivated silicon surfaces in a short time frame of 120 minutes using fourier transform infrared spectroscopy – attenuated total reflection techniques. Varying conditions of ultra-pure water are used. This includes dissolved oxygen poor… more
Date: December 2003
Creator: Chan, Raymond
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Interfacial Electrochemistry of Metal Nanoparticles Formation on Diamond and Copper Electroplating on Ruthenium Surface

Description: An extremely facile and novel method called spontaneous deposition, to deposit noble metal nanoparticles on a most stable form of carbon (C) i.e. diamond is presented. Nanometer sized particles of such metals as platinum (Pt), palladium (Pd), gold (Au), copper (Cu) and silver (Ag) could be deposited on boron-doped (B-doped) polycrystalline diamond films grown on silicon (Si) substrates, by simply immersing the diamond/Si sample in hydrofluoric acid (HF) solution containing ions of the correspon… more
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Date: May 2003
Creator: Arunagiri, Tiruchirapalli Natarajan
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Interfacial Studies of Bimetallic Corrosion in Copper/Ruthenium Systems and Silicon Surface Modification with Organic and Organometallic Chemistry

Description: To form Cu interconnects, dual-damascene techniques like chemical mechanical planarization (CMP) and post-CMP became inevitable for removing the "overburden" Cu and for planarizing the wafer surface. During the CMP processing, Cu interconnects and barrier metal layers experience different electrochemical interactions depending on the slurry composition, pH, and ohmic contact with adjacent metal layers that would set corrosion process. Ruthenium as a replacement of existing diffusion barrier lay… more
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Date: August 2006
Creator: Nalla, Praveen Reddy
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Investigation of Structure and Properties of Low Temperature Deposited Diamond-Like Carbon Films

Description: Electrodeposition is a novel method for fabrication of diamond-like carbon (DLC) films on metal substrates. In this work, DLC was electrochemically deposited on different substrates based on an anodic oxidation cyclization of acetylene in liquid ammonia. Successfully anodic deposition was carried out for DLC onto nickel substrate at temperatures below -40°C. Comparative studies were performed on a series of different carbon sources (acetylene, sodium acetylide, and a mixture of acetylene and… more
Date: August 2004
Creator: Pingsuthiwong, Charoendee
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Investigations of Thermochemistry and the Kinetics of H Atom Radical Reactions

Description: The thermochemistry of several species, and the kinetics of various H atom radical reactions relevant to atmospheric and combustion chemistry were investigated using ab initio theoretical techniques and the flash photolysis / resonance fluorescence technique. Using ab initio quantum mechanical calculations up to the G3 level of theory, the C-H bond strengths of several alkanes were calculated. The bond strengths were calculated using two working reactions. From the results, it is apparent that … more
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Date: December 2002
Creator: Peebles, Lynda Renee
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Kinetic studies and computational modeling of atomic chlorine reactions in the gas phase.

Description: The gas phase reactions of atomic chlorine with hydrogen sulfide, ammonia, benzene, and ethylene are investigated using the laser flash photolysis / resonance fluorescence experimental technique. In addition, the kinetics of the reverse processes for the latter two elementary reactions are also studied experimentally. The absolute rate constants for these processes are measured over a wide range of conditions, and the results offer new accurate information about the reactivity and thermochemi… more
Date: August 2009
Creator: Alecu, Ionut M.
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Kinetic Studies of Hydroxyl and Hydrogen Atom Reactions

Description: Gas phase kinetics of the reactions involving hydroxyl radical and hydrogen atom were studied using experimental and ab initio theoretical techniques. The rate constant for the H + H2S reaction has been measured from 298 to 598 K by the laser photolysis/resonance fluorescence (LP-RF) technique. The transition state theory (TST) analysis coupled with the measurements support the suggestion that the reaction shows significant curvature in the Arrhenius plot. The LP-RF technique was also used to… more
Date: May 2002
Creator: Hu, Xiaohua
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Layered Double Hydroxides as Anion- and Cation-Exchanging Materials

Description: Layered double hydroxides (LDH) have been principally known as anion-exchanging, clay-like materials for several decades, and continues to be the main driving force for current and future research. The chemical interactions of LDH, with transition metallocyanides, have been a popular topic of investigation for many years, partly due to the use of powder x-ray diffraction and infrared spectroscopy as the main characterization tools. Each transition metallocyanide has a characteristic infrared st… more
Date: May 2007
Creator: Richardson, Mickey Charles
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Layered Double Hydroxides: Morphology, Interlayer Anion, and the Origins of Life

Description: The preparation of layered double hydroxides via co-precipitation of a divalent/trivalent metal solution against a base results in 1 mm LDH particles with a disorganized metal lattice. Research was performed to address these morphological issues using techniques such as Ostwald ripening and precipitation via aluminate. Another interesting issue in layered double hydroxide materials is the uptake and orientation of anions into the interlayer. Questions about iron cyanide interlayer anions have b… more
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Date: December 2002
Creator: Halcom-Yarberry, Faith Marie
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Mechanisms of Methoxide Ion Substitution and Acid- Catalyzed Z/E Isomerization of N-Methoxyimines

Description: The second order rate constants for nucleophilic substitution by methoxide of (Z)- and (E)-O-methylbenzohydroximoyl fluorides [C6H4C(F)=NOCH3] with various substituents on the phenyl ring [p-OCH3 (1h, 2h), p-CH3 (1g, 2g), p-Cl (1f, 2f), p-H (1e, 2e), (3,5)-bis-CF3 (1i, 2i)] in 90:10 DMSO:MeOH have been measured. A Hammett plot of these rate constants vs σ values gave positive ρ values of 2.95 (Z isomer) and 3.29 (E isomer). Comparison of these rates with methoxide substitution rates for Ometh… more
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Date: December 2001
Creator: Dolliver, Debra D.
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Metal-Aluminum Oxide Interactions: Effects of Surface Hydroxylation and High Electric Field

Description: Metal and oxide interactions are of broad scientific and technological interest in areas such as heterogeneous catalysis, microelectronics, composite materials, and corrosion. In the real world, such interactions are often complicated by the presence of interfacial impurities and/or high electric fields that may change the thermodynamic and kinetic behaviors of the metal/oxide interfaces. This research includes: (1) the surface hydroxylation effects on the aluminum oxide interactions with coppe… more
Date: December 2001
Creator: Niu, Chengyu
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