<p> This dissertation presents a series of studies related to the study and control of slurry flow, process temperature, and aggressive diamonds in Chemical Mechanical Planarization (CMP). The purpose of these studies is to better understand the fundamentals of CMP and to explore solutions to some of CMP&rsquo;s greatest challenges. </p><p> Within-wafer removal rate non-uniformity (WIWRRNU) is a critical parameter to determine film thickness planarity on a wafer-scale level and it grossly impacts yield. Resolving this issue continues to be an area of intense focus in the industry. The first study in this dissertation shows the feasibility of adopting a new method to improve WIWRRNU during copper CMP that is solely based on intentional local temperature manipulation of the pad. A pad surface thermal management system is developed to locally change pad surface temperature. This system consists of one or more thermal transfer modules contacting the pad surface. In this study, the system is employed to adjust the &ldquo;center-fast&rdquo; copper removal rate profile to illustrate its effect during the process. Results shows that, when two thermal transfer modules are employed, local removal rates in the wafer center region decrease significantly while maintaining the removal rates near the wafer edge thereby significantly improving WIWRRNU. </p><p> Another contribution of this dissertation is the investigation of the effect of pad groove design on slurry injection scheme during interlayer dielectric CMP. A novel slurry injector with multiple slurry outlets is designed, which provides optional slurry injection schemes (i.e. one injection point scheme and multi-injection point scheme). These schemes are compared with the standard slurry application method on a concentrically grooved pad and an xy-groove pad, respectively. On the concentrically grooved pad, the one injection point scheme generates significantly higher oxide removal rates (ranging from 22 to 35 percent) compared to the standard slurry application method at different slurry flow rates. On the xy-groove pad, the one injection point scheme still results in higher removal rates (ranging from 3 to 9 percent), however, its removal rate enhancement is not as high as that of the concentrically grooved pad. In order to further improve slurry availability on the xy-groove pad, the multi-injection point scheme is tested. Results show that the multi-injection point scheme results in significantly higher removal rates (ranging from 17 to 20 percent) compared to the standard slurry application method. This work underscores the importance of optimum slurry injection schemes for accommodating particular groove designs. </p><p> The last contribution of this dissertation involves a study regarding aggressive diamond characterization and wear analysis during CMP. A 3M A3700 diamond disk is used to condition a Cabot Microelectronics Corporation (CMC) D100 pad for 30 hours. The top 20 aggressive diamonds for two perpendicular disk orientations are identified before the polishing, as well as after 15- and 30-hour polishing. The furrow surface area generated by these top 20 aggressive diamonds and their evolution are analyzed and compared. Results show that the original top 20 aggressive diamonds identified before polishing are subjected to wear after the first 15-hour polishing as the furrow surface area that they generate decreases dramatically (by 47%). As these original aggressive diamonds are worn, seven new aggressive diamonds are &ldquo;born&rdquo; and join the new top 20 list for both disk orientations. After the second 15-hour wafer polishing, the furrow surface area of these new top 20 aggressive diamonds do not change significantly. The furrow surface area created by all the active diamonds exhibits the same trend as the top 20 aggressive diamonds, confirming that most pad conditioning work is performed by these aggressive diamonds and that the disk loses its aggressiveness in the first 15 hours of polishing and then maintains its aggressiveness during the second 15 hours, albeit to a lesser extent.</p>

The kinetics and mechanism of the reduction of simulants of the iron-bearing lunar minerals olivine ((Fe,Mg)₂SiO₄), pyroxene ((Fe,Mg,Ca)SiO₃), and ilmenite (FeTiO₃) are investigated, extending previous work with ilmenite. Fayalite is reduced by H₂ at 1070 K to 1480 K. A layer of mixed silica glass and iron forms around an unreacted core. Reaction kinetics are influenced by permeation of hydrogen through this layer and a reaction step involving dissociated hydrogen. Reaction mechanisms are independent of Mg content. Augite, hypersthene and hedenbergite are reduced in H₂ at the same temperatures. The products are iron metal and lower iron silicates mixed throughout the mineral. Activation energy rises with calcium content. Ilmenite and fayalite are reduced with carbon deposited on partially reduced minerals via the CO disproportionation reaction. Reduction with carbon is rapid, showing the carbothermal reduction of lunar minerals is possible.

<p> Materials with apatite structure have attracted interest due to their versatile applications from medical diagnostics and drug delivery to energy and fuel cells. Apatites have flexible structures that can accommodate a range of elements and dopants (in terms of both size and charge) in two distinct crystallographic cation sites and consequently, exhibit fascinating defect chemistry. Recently, several different properties have been engineered into apatite structures by varying their doping schemes. However, advancement of these properties for various material applications needs a fundamental understanding of stability and sustainability of apatites under various conditions. A systematic thermodynamic study can provide insights to understanding structure - composition - property - stability relations as well as guidance to predict, prepare, and select optimized materials for specific desired applications. The lack of knowledge of thermodynamic stabilities in apatite systems with different dopants and doping levels was the motivation behind this study on apatite materials with various compositions and stoichiometry. For this study, a unique and powerful high temperature oxide melt solution calorimetry technique was used to obtain energetics of lanthanide silicate/germanate and calcium phosphate materials with non-doped and doped divalent and trivalent cations. Apatites with composition Ln9.33+x(TO4)6O2+3x/2 (Ln = lanthanide and T = Si and/or Ge), have been proposed as a new group of candidate materials for electrolytes at the intermediate temperature (~600 &ring;C) in solid oxide fuel cells (SOFCs). The enthalpies of formation of these materials from oxides were determined to investigate a relationship between the stability and the structural defects (cation vacancy and intestinal oxygen). For the lanthanide silicate group, we found that formation of vacancies and oxide interstitials destabilize the apatite structure and vacancy formation appears to be a dominate factor. Both lanthanide cation and tetrahedral anion sizes were found to affect the stability of this system. Substitution of La with Nd and Si with Ge separately in lanthanide silicate apatites shows that the structure becomes more stable with an increase in the lanthanide cation radius and a decrease in the tetrahedral-site cation radius. Another apatite system, calcium phosphate hydroxyapatite doped with lanthanides, has gathered attention for its luminescent properties and its potential as a drug carrier for the delivery of a variety of pharmaceutical molecules. The enthalpies of formation of calcium phosphate hydroxyapatite, Ca10-x-yLny(PO4)6-x(HPO4)x(OH)2-x-yOy.nH2O (Ln = lanthanides), was investigated using high temperature oxide melt solution calorimetry. Energetic results show that the enthalpies of formation become linearly less exothermic with increase in concentration as well as the size of the dopant lanthanide. The calorimetric studies have revealed the existence of distinctive energetic trends with defects formation and interactions in different doped apatite systems. These fundamental thermodynamic studies could help to understand the structure - property - stability relations in apatite-type materials. These results could guide processing, application and sustainability of apatite type materials in both the energy and biotechnology industry.</p>

Gel particle systems were studied as a means to separate macromolecules such as proteins and DNA. A mathematical model for diffusive - convective transport was developed in order to study the separation of two different components. The model used a one dimensional approximation for a gel particle in a packed column. The electrophoretic transport of a single solute species across a one dimensional three layered system was analyzed using the geometrical structure of the spectrum of the operator. The structure of the spectrum allows a complete characterization of all the eigenvalues of the system in terms of the various parameters including the distribution coefficients, electrical field, electrophoretic mobility, and diffusion coefficient. The separation of two components was parametrically studied by varying the relative ratio of Peclet numbers in the gel packed column. / A second aspect of protein separation examined in this project is adsorption effects in gel particle systems. An analysis using a Laplace transform was performed to investigate the separation behavior of gel chromatography. The ionic strength effects on adsorption were analyzed using the thermodynamic model extended from the work of Horvath (1976). / The adsorption of large DNA was found to be strongly influenced by ionic strength and gel surface area. Some experimental factors affecting DNA separation were discussed. / Source: Dissertation Abstracts International, Volume: 54-02, Section: B, page: 0972. / Major Professor: Bruce R. Locke. / Thesis (Ph.D.)--The Florida State University, 1993.

Solvent diffusion from spheres in theoretical and real continuous-flow systems is examined. A general model of a continuous-flow solvent removal process is developed. Solvent diffusion from spheres at constant mass-transfer Fourier number Fo$\sb{\rm M}$ in a single continuous-flow stirred tank (CFST) and in a series of CFST is simulated. The degree of solvent removal from the spheres is characterized by a transfer efficiency $\xi$. A series of transfer efficiency curves demonstrate the effect of Fo$\sb{\rm M}$, convective conditions in the system and the spheres residence time distribution on $\xi$. / A pilot-plant process designed to remove ethyl acetate from nitrocellulose spheres in a series of continuous-flow stirred evaporators (CFSE) is studied. Experimental values of $\xi$ are defined from pilot-plant data. The relationship between experimental $\xi$ and Fo$\sb{\rm M}$ is compared to that predicted from transfer efficiency curves. A model of the pilot-plant process is developed. The model incorporates the solution of the mass transport equation with a concentration-dependent diffusivity describing diffusion from a shrinking sphere into the material balance and thermodynamic equations describing the steady-state behavior of a CFSE. The model demonstrates that the transfer efficiency curves can be useful in the design of continuous processes for solvent removal from spheres. / Source: Dissertation Abstracts International, Volume: 51-12, Section: B, page: 6003. / Major Professor: Thomas R. Hanley. / Thesis (Ph.D.)--The Florida State University, 1990.

A new experimental technique was developed to measure volumetric mass transfer coefficients in agitated gas-liquid systems utilizing the second-order reaction between ozone and indigo disulfonate. Under the proper operating conditions the reaction can be considered instantaneous relative to the mass transfer rate. Instantaneous reactions have not been used previously for gas-liquid mass transfer studies. / The experimental system was operated semi-batch with continuous gassing of a liquid batch. The reaction vessel was of traditional design for these studies, consisting of a cylindrical, baffled tank with a height equal to the diameter. An ozonated air stream was dispersed by a standard disc turbine. The ozone dissolves into the liquid phase and reacts with the indigo. The rate of gas absorption was followed by monitoring the depletion of the indigo reagent. Liquid samples were continuously withdrawn from the reactor through a flow-cell and analyzed for their absorbance at 610 nanometers. An advantage of the technique is that the analysis is simple and highly accurate. / Additionally, a model was developed to analyze the unsteady-state absorption data. The model uses penetration theory to calculate a value for the mass transfer coefficient assuming either the gas is completely backmixed or in plug flow. / The mass transfer coefficient data were correlated as a function of power input and gassing rate. This is the traditional method of representing data and there is a great deal of variation in the values reported. The derived correlation matches the literature reasonably well, although the data do show a greater dependence on the gassing rate than most reported correlations. / As a model system, the instantaneous reaction technique holds promise for agitated absorption studies. A wide-range of systems could be modeled without affecting the instantaneous nature of the reaction by using additives to match the physical properties desired. The technique offers advantages over other popular chemical methods with its low ionic strengths and its use of penetration theory to describe the interfacial hydrodynamics. / Source: Dissertation Abstracts International, Volume: 51-11, Section: B, page: 5466. / Major Professor: Thomas R. Hanley. / Thesis (Ph.D.)--The Florida State University, 1990.

No description available.

No description available.

No description available.

No description available.