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 Degree Discipline: Analytical Chemistry
 Collection: UNT Theses and Dissertations
Adherence/Diffusion Barrier Layers for Copper Metallization: Amorphous Carbon:Silicon Polymerized Films

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

Date: May 2004
Creator: Pritchett, Merry
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 study proposes modified amorphous silicon carbon hydrogen (a-Si:C:H) films as possible diffusion barriers and replacements for SiO2 between metal levels, interlevel dielectric (ILD), or between metal lines (IMD), based upon the diffusion inhibition of previous a-Si:C:H species expected lower dielectric constants, acceptable thermal conductivity. Vinyltrimethylsilane (VTMS) precursor was condensed on a titanium substrate at 90 K and bombarded with electron beams to induce crosslinking and form polymerized a-Si:C:H films. Modifications of the films with hydroxyl and nitrogen was accomplished by dosing the condensed VTMS with water or ammonia before electron bombardment producing a-Si:C:H/OH and a-Si:C:H/N and a-Si:C:H/OH/N polymerized films in expectation of developing films that would inhibit copper diffusion and promote Cu adherence, wetting, on the film surface. X-ray Photoelectron Spectroscopy was used to characterize Cu metallization of ...
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Analysis of PAH and PCB Emissions from the Combustion of dRDF and the Nondestructive Analysis of Stamp Adhesives

Analysis of PAH and PCB Emissions from the Combustion of dRDF and the Nondestructive Analysis of Stamp Adhesives

Date: May 1989
Creator: Poslusny, Matthew
Description: This work includes two unrelated areas of research. The first portion of this work involved combusting densified refuse derived fuel (dRDF) with coal and studying the effect that Ca(0H)2 binder had on reducing polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) emissions. The second area of work was directed at developing nondestructive infrared techniques in order to aid in the analysis of postage stamp adhesives. With Americans generating 150-200 million tons a year of Municipal Solid Waste (MSW) and disposing of nearly ninety percent of it in landfills, it is easy to understand why American landfills are approaching capacity. One alternative to landfilling is to process the MSW into RDF. There are technical and environmental problems associated with RDF. This work provides some answers concerning the amount of PAH and PCB emissions generated via the combustion of RDF with coal. It was found that the Ca(OH)2 binder greatly reduced both the PAH and the PCB emissions. In fact, PAH emissions at the ten-percent level were reduced more by using the binder than by the pollution control equipment. If the Ca(0H)2 binder can reduce not only PAH and PCB emissions, but also other noxious emissions, such as acid gases or dioxin, ...
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The Analysis of PCDD and PCDF Emissions from the Cofiring of Densified Refuse Derived Fuel and Coal

The Analysis of PCDD and PCDF Emissions from the Cofiring of Densified Refuse Derived Fuel and Coal

Date: August 1990
Creator: Moore, Paul, 1962-
Description: The United States leads the world in per capita production of Municipal Solid Waste (MSW), generating approximately 200 million tons per year. By 2000 A.D. the US EPA predicts a 20% rise in these numbers. Currently the major strategies of MSW disposal are (i) landfill and (ii) incineration. The amount of landfill space in the US is on a rapid decline. There are -10,000 landfill sites in the country, of which only 65-70% are still in use. The Office of Technology Assessment (OTA) predicts an 80% landfill closure rate in the next 20 years. The development of a viable energy resource from MSW, in the form of densified Refuse Derived Fuel (dRDF), provides solutions to the problems of MSW generation and fossil fuel depletions. Every 2 tons of MSW yields approximately 1 ton of dRDF. Each ton of dRDF has an energy equivalent of more than two barrels of oil. At current production rates the US is "throwing away" over 200,000,000 barrels of oil a year. In order to be considered a truly viable product dRDF must be extensively studied; in terms of it's cost of production, it's combustion properties, and it's potential for environmental pollution. In 1987 a research ...
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Calcium Silicates: Glass Content and Hydration Behavior

Calcium Silicates: Glass Content and Hydration Behavior

Date: August 1987
Creator: Zgambo, Thomas P. (Thomas Patrick)
Description: Pure, MgO doped and B2C3 doped monocalcium, dicalcium, and tricalcium silicates were prepared with different glass contents. Characterization of the anhydrous materials was carried out using optical microscopy, infrared absorption spectroscopy, and X-ray powder diffraction. The hydration of these compounds was studied as a function of the glass contents. The hydration studies were conducted at 25°C. Water/solid ratios of 0.5, 1, 10, and 16 were used for the various experiments. The hydration behavior was monitored through calorimetry, conductometry, pH measurements, morphological developments by scanning electron microscopy, phase development by X-ray powder diffraction, and percent combined water by thermogravimetry. A highly sensitive ten cell pseudo-adiabatic microcalorimeter was designed and constructed for early hydration studies. Conductometry was found to be of great utility in monitoring the hydration of monocalcium silicate and the borate doped dicalcium silicates.
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Chemistry, Detection, and Control of Metals during Silicon Processing

Chemistry, Detection, and Control of Metals during Silicon Processing

Date: May 2005
Creator: Hurd, Trace Q.
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 water - especially on the behavior of H2O2 in this solution and the impact of HCl concentration on metal removal from particle addition to silicon oxide surfaces. Chapter 3 includes a more generalized investigation of the chemistry of metal ions in solution and how they react with the silicon oxide surfaces they are brought into contact with, concluding with illumination of the fundamental chemical principles that govern their behavior. Chapter 4 shows how metal contaminants behave on silicon wafers when subjected to the high temperature (≥ 800 °C) thermal cycles that are encountered in IC manufacturing. It demonstrates that knowledge of some fundamental thermodynamic properties of the metals allow accurate prediction of what will happen to a metal during these processes. Chapter 5 covers a very different but ...
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Copper Electrodeposition on Iridium, Ruthenium and Its Conductive Oxide Substrate

Copper Electrodeposition on Iridium, Ruthenium and Its Conductive Oxide Substrate

Date: December 2003
Creator: Huang, Long
Description: The aim of this thesis was to investigate the physical and electrochemical properties of sub monolayer and monolayer of copper deposition on the polycrystalline iridium, ruthenium and its conductive oxide. The electrochemical methods cyclic voltammetry (CV) and chronocoulometry were used to study the under potential deposition. The electrochemical methods to oxidize the ruthenium metal are presented, and the electrochemical properties of the oxide ruthenium are studied. The full range of CV is presented in this thesis, and the distances between the stripping bulk peak and stripping UPD peak in various concentration of CuSO4 on iridium, ruthenium and its conductive oxide are shown, which yields thermodynamic data on relative difference of bonding strength between Cu-Ru/Ir atoms and Cu-Cu atoms. The monolayer of UPD on ruthenium is about 0.5mL, and on oxidized ruthenium is around 0.9mL to 1.0mL. The conductive oxide ruthenium presents the similar properties of ruthenium metal. The pH effect of stripping bulk peak and stripping UPD peak of copper deposition on ruthenium and oxide ruthenium was investigated. The stripping UPD peak and stripping bulk peak disappeared after the pH ≥ 3 on oxidized ruthenium electrode, and a new peak appeared, which means the condition of pH is very important. ...
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Cu Electrodeposition on Ru with a Chemisorbed Iodine Surface Layer.

Cu Electrodeposition on Ru with a Chemisorbed Iodine Surface Layer.

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Date: August 2005
Creator: Lei, Jipu
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 oxygen formation than water vapor exposure, but an inhibition of surface oxide formation relative that of the unmodified Ru(poly) surface is still observed. Studies with combined electrochemical and XPS techniques show that the iodine surface adlayer remained on top of the surface after cycles of overpotential electrodeposition/dissolution of copper on both Ru(poly) and Ru(0001) electrodes. These results indicate the potential bifunctionality of iodine layer to both passivate the Ru surface in the microelectronic processing and to act as a surfactant for copper electrodeposition. The electrodeposition of Cu on Ru(0001) or polycrystalline Ru was studied using XPS with combined ultrahigh vacuum/electrochemistry methodology (UHV-EC) in 0.1 M HClO4 with Cu(ClO4)2 concentrations ranging from 0.005 M to 0.0005 M, and on polycrystalline Ru in a 0.05M H2SO4/0.005 M CuSO4/0.001 ...
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Determination of Solute Descriptors for Illicit Drugs Using Gas Chromatographic Retention Data and Abraham Solvation Model

Determination of Solute Descriptors for Illicit Drugs Using Gas Chromatographic Retention Data and Abraham Solvation Model

Date: August 2015
Creator: Mitheo, Yannick K.
Description: In this experiment, more than one hundred volatile organic compounds were analyzed with the gas chromatograph. Six capillary columns ZB wax plus, ZB 35, TR1MS, TR5, TG5MS and TG1301MS with different polarities have been used for separation of compounds and illicit drugs. The Abraham solvation model has five solute descriptors. The solute descriptors are E, S, A, B, L (or V). Based on the six stationary phases, six equations were constructed as a training set for each of the six columns. The six equations served to calculate the solute descriptors for a set of illicit drugs. Drugs studied are nicotine (S= 0.870, A= 0.000, B= 1.073), oxycodone(S= 2.564. A= 0.286, B= 1.706), methamphetamine (S= 0.297, A= 1.570, B= 1.009), heroin (S=2.224, A= 0.000, B= 2.136) and ketamine (S= 1.005, A= 0.000, B= 1.126). The solute property of Abraham solvation model is represented as a logarithm of retention time, thus the logarithm of experimental and calculated retention times is compared.
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Electrochemical Synthesis and Characterization of Inorganic Materials from Aqueous Solutions

Electrochemical Synthesis and Characterization of Inorganic Materials from Aqueous Solutions

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Date: December 2006
Creator: Yuan, Qiuhua
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 microscopy (SEM). XRD patterns show well-defined peaks of HA when sintered under vacuum conditions. FTIR measurements indicate the existence of hydroxyl groups, which were confirmed by the characteristic intensity of the stretching and bending bands at ~3575 and ~630 cm-1, respectively. The SEM shows an adhesive, crack free morphology for the double-layer coating surface of the samples sintered in a vacuum furnace. 2. Silver/polymer/clay nanocomposites. Silver nanoparticles were prepared in layered clay mineral (montmorillonite)/polymer (PVP: poly (vinyl pyrrolidone)) suspension by an electrochemical approach. The silver particles formed in the bulk suspension were stabilized by the PVP and partially exfoliated clay platelets, which acted as protective colloids to prevent coagulation of silver nanoparticles together. The synthesized silver nanoparticles/montmorillonite/PVP composite was characterized and identified by XRD, SEM, and TEM (transmission electron microscopy) measurements. 3. Ce-doped lead ...
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Electrodeposition of adherent copper film on unmodified tungsten.

Electrodeposition of adherent copper film on unmodified tungsten.

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Date: May 2004
Creator: Wang, Chen
Description: Adherent Cu films were electrodeposited onto polycrystalline W foils from purged solutions of 0.05 M CuSO4 in H2SO4 supporting electrolyte and 0.025 M CuCO3∙Cu(OH)2 in 0.32 M H3BO3 and corresponding HBF4 supporting electrolyte, both at pH = 1. Films were deposited under constant potential conditions at voltages between -0.6 V and -0.2 V vs Ag/AgCl. All films produced by pulses of 10 s duration were visible to the eye, copper colored, and survived a crude test called "the Scotch tape test", which stick the scotch tape on the sample, then peel off the tape and see if the copper film peels off or not. Characterization by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray photon spectroscopy (XPS) confirmed the presence of metallic Cu, with apparent dendritic growth. No sulfur impurity was observable by XPS or EDX. Kinetics measurements indicate that the Cu nucleation process in the sulfuric bath is slower than in the borate bath. In both baths, nucleation kinetics do not correspond to either instantaneous or progressive nucleation. Films deposited from 0.05 M CuSO4/H2SO4 solution at pH > 1 at -0.2 V exhibited poor adhesion and decreased Cu reduction current. In both borate and sulfate baths, small ...
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