<P> The equilibrium behavior of the boundaries separating the a and y crystalline phases in the copper zinc alloy system is investigated by measuring the magnitude, the relative anisotropy and the temperature dependence of the interfacial energies. A model, consistent with the interfacial energetics, is proposed and supported by observations of misfit dislocations at the boundary. The migration kinetics of the y/β interface are determined for both dendritic and polyhedral morphologies and the atomic mechanisms of growth are inferred from the. internally faulted ordered y precipitates. </p> / Thesis / Doctor of Philosophy (PhD)

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Integrating nanometer-sized pores into low-k ILD films is one of the approaches to lower the RC signal delay and thus help sustain the continued scaling of microelectronic devices. While increasing porosity of porous dielectrics lowers the dielectric constant (k), it also creates many reliability and implementation issues. One of the problems is the little understood metal ion diffusion and drift in porous media. Here, we present a rigorous simulation method of Cu diffusion based on Master equation with elementary jump probabilities within the contiguous dielectric film, along the pore boundary, from the dielectric matrix to the pore boundary, and from the pore boundary to the matrix material. In view of the diffusional jump distance being as large as 2 nm, the nano-pores being on a similar length scale, and the film thickness being only a few tens of nanometers, the conventional diffusion equation in differential equation form is grossly inadequate and elementary jump frequencies are required for a proper description of the Cu diffusion in porous dielectric. The present atomistic approach allows a consistent implementation of Cu ion drift in electric field by lowering and raising of the diffusion barriers along the field direction. This will help understand the behavior of Cu interconnects under thermal or electric stress at an atomistic level. Another approach to lower the increasing RC delays is to bring memory and logic closer by integrating memory in the BEOL. Resistive RAM is one such memory is not transistor based and thus, does not require a silicon substrate. Thus, it offers the possibility of integration directly into the back-end reducing memory to logic distance from 1000s of µm to a 10s of nm. This 3D integration also allows for increased density as well. However, one barrier in the implementation of RRAM in the back end is the use of expensive as well as non-BEOL native material in conventional Cu/TaOx/Pt resistive devices. In this thesis, we present our research about functionality of RRAM with porous low-k dielectrics (which are a candidate for CMOS ILD), and through the similar elementary jump simulations, discuss the impact of porosity in dielectrics on the functionality of RRAM. Lastly, we present a cheaper replacement for Pt as the counter electrode in RRAM and show that it functions as good as Pt. This work addresses following three areas: 1. Modeling of diffusion in porous dielectrics through elementary jump based simulation. The model is based on random walk theory of elementary particle jumps. Initially, qualitative simulations are conducted without actual parameters. It is shown that Cu diffusion in porous dielectrics decreases quasi-linearly with porosity. Furthermore, it is shown that morphology of the pores may have a greater effect on diffusivity compared to porosity. The simulations are then calibrated with parameters, and the result is shown to yield a similar diffusivity times as actual process time. 2. Modeling of Cu ions drift in porous dielectrics under electric stress. First, the model is explained, and then qualitative simulation results are presented for porous dielectrics with varied porosities and morphologies. 3. Research to find a suitable replacement for Pt as the counter electrode in RRAM devices. The research methodology is discussed and a much cheaper Rh is selected as the potential replacement for Pt. Successful functionality of Rh based resistive devices is presented. / Master of Science / As electronic devices are being scaled for integrating more functions and higher computation, the internal delays are increasing, which may become a bottleneck in performance. To resolve this issue of internal delay, new materials are being proposed to replace the conventional materials to make the chip. One promising material like that are the porous dielectrics, to replace the conventional dielectrics used to manufacture electronic chips. The introduction of ‘air pores’ inside the dielectric used in chips may improve the delay, but it leads to several thermal and electrical reliability concerns. In this thesis, we argue that using differential equations to simulate effects on the nano-scale to explore such reliability issues is insufficient, and a simulation method based on individual atom/ion movement should be used to describe it. Here we provide a simulation model to explain the diffusivity of copper under thermal stress, as well as movement of Cu ions during electric stress in porous dielectrics, using our particle movement based simulation model, and prove that it delivers correct results. Secondly, the delay is especially significant for processor to memory communication. Thus, integrating memory close to processor is another method to reduce the delay. Resistive RAM (RRAM) is one such novel RAM technology that can be integrated close to processor. However due to usage of non-native as well as expensive materials, RRAM has not been commercially integrated close to processor. In this thesis, we also present a functioning RRAM using cheaper materials, as well as materials that are native to present electronics.

Mehrfach konnte in der Literatur ein enger Zusammenhang zwischen der Stärke des Phantomschmerzes und der Reorganisation im somatosensorischen Kortex nachgewiesen werden. Sowohl topographische Veränderungen als auch Veränderungen in der Erregbarkeit zentraler Hirnstrukturen könnten pathologische Veränderungen in Zentren, die an der Schmerzverarbeitung beteiligt sind, reflektieren. Zahlreiche Befunde zur Reorganisation des motorischen Systems indizieren eine größere kortikale Repräsentation von Muskeln, die der Amputation benachbart sind (auf Kosten des deafferenzierten Areals), und höhere Erregbarkeit dieser Repräsentationen in der Hemisphäre kontralateral zur Amputation. Es ist naheliegend, daß aufgrund der engen anatomisch-funktionellen Verbindung des somatosensorischen und des motorischen Systems Patienten mit Phantomschmerz auch eine stärkere kortikale Reorganisation im Motorkortex aufweisen als Amputierte ohne Phantomschmerz. Im Mittelpunkt dieser Arbeit steht die Frage, inwieweit es zwischen der sensorimotorischen Reorganisation und dem Phantomschmerz einen Zusammenhang gibt. Des weiteren wurde untersucht, ob Patienten mit Phantomschmerz eine generelle, unspezifische Erhöhung der kortikalen Erregbarkeit aufweisen. Zur Klärung dieser Fragestellung wurden zwei Studien durchgeführt. In der ersten Untersuchung wurde an 10 unilateral Armamputierten mittels transkranieller Magnetstimulation (TMS) und der Überlagerung somatosensorischer Potentiale (SEPs) und Magnetresonanztomographie ein enger Zusammenhang zwischen der Stärke des Phantomschmerzes und der sensorimotorischen Reorganisation nachgewiesen. In der zweiten Untersuchung wurde ebenfalls an 10 unilateral Armamputierten mittels funktioneller Lokalisation bewegungsinduzierter kortikaler Potentiale (bikP) in einem steady-state-Paradigma eine signifikant größere Reorganisation des motorischen Kortex bei Patienten mit Phantomschmerz nachgewiesen. Ebenfalls konnte bei diesen Patienten eine signifikant erhöhte unspezifische kortikale Aktivierung in einem visuellen Oddball-Paradigma nachgewiesen werden. Die motorische Reorganisation war in beiden Untersuchungen ebenfalls eng assoziiert mit einem geringen Ausmaß an täglicher Prothesebenutzung. Die Bedeutung dieser Ergebnisse wird vor dem Hintergund des aktuellen Forschungsstandes diskutiert. / Several studies report a close relationship between the intensity of phantom limb pain in amputees and the amount of reorganization of the somatosensory cortex. Both topographic changes as well as changes of the excitability of central brain structures could reflect pathological alterations in brain structures that are involved in the processing of pain. Numerous findings on motor reorganization indicate larger cortical representations of muscles adjacent to the amputation (at the expense of the deafferented area) and increased excitability of these representations at the hemisphere contralateral to the amputation. Because of the close anatomical and functional connections between the somatosensory and motor system, it is likely that patients with phantom pain also show a higher amount of reorganization in the motor cortex than amputees without phantom pain. Therefore this thesis adresses the question if there is a relationship between sensorimotor reorganization and phantom limb pain. Furthermore, it was investigated if amputees with phantom limb pain also show rather nonspecific increases of cortical excitability. To answer these questions two studies were conducted. First, using transcranial magnetic stimulation (TMS) and neuroelectric source imaging of somatosensory evoked poetentials (SEPs), the sensorimotor reorganization was investigated in 10 upper limb amputees with unilateral amputations. This study revealed a close relationship between severe phantom pain and a high amount of sensorimotor reorganization. Second, using neuroelectric source imaging of steady-state movement-related cortical potentials (MRCPs), a similar relationship between sensorimotor reorganization and phantom pain was shown in 10 upper limb amputees with unilateral amputations. Additionally, using a visual oddball paradigm, it was found that phantom pain was also accompanied by rather nonspecific increases of cortical excitability. In both studies, motor reorganization was closely correlated with a lower amount of daily prosthesis use. The results of the two studies are discussed with reference to recent research on cortical reorganization subsequent to deafferentation.

The continuously increasing demand for innovation in the miniaturization of microelectronics has driven the need for ever more precise fabrication strategies for device packaging, especially for printed circuit boards (PCBs). Subtractive copper etching is a fundamental step in the fabrication process, requiring very precise control of etch rate and etch factor. Changes in the etching chemical equilibrium have significant effects on etching behavior, and CuCl2 / HCl etching baths are typically monitored with several parameters including oxidation-reduction potential, conductivity, and specific gravity. However, the etch rate and etch factor can be difficult to control even under strict engineering controls of those monitoring parameters. The mechanism of acidic cupric chloride etching, regeneration and recovery is complex, and the current monitoring strategies can have difficulty controlling the interlocking chemical equilibria. A complimentary tool, thin-film UV-Vis spectroscopy, can be utilized to improve the current monitoring strategies, as UV-Vis is capable of identifying and predicting etching behavior that the current standard methodologies have difficulty predicting. Furthermore, as a chemically-sensitive probe, UV-Vis can investigate the complex changes to the chemical equilibrium and speciation of the etch bath, and can contribute overall to significant improvements in the control of the copper etching system in order to meet the demands of next-level design strategies.

A plethora of novel scientific phenomena and practical applications, such as solid-state molecular solar cells and other optoelectronic devices for energy harvesting and lighting technologies, have catalyzed us to synthesize novel compounds with tunable properties. Synthetic routes, single crystal structures, and spectral and materials properties are described. Reactions of Ag(I) and Cu(I) precursors with various types of ligands -- including the azolates, diimines, and diiphosphines -- lead to the corresponding complexes in high yield. Varying the metal ions, ligands, synthetic methods, solvents, and/or stoichiometric ratio can change the properties including the molecular geometry or packing structure, reactivity, photophysical and photochemical properties, semiconducting behavior, and/or porosity of the functional coordination polymers obtained. For solar cells purposes, the absorption energy can be extended from the ultraviolet (UV) region, through the entire visible (Vis) region, onto a significant portion of the near-infrared (NIR) portion of the solar spectrum with high absorption coefficients due to the infinite conjugation of Cu(I) with diimine ligands. Twenty-eight crystal structures were obtained by conventional crystal growth methods from organic solvents, whereas their bulk product syntheses also included "green chemistry" approaches that precluded the use of hazardous organic solvents. The resulting products are characterized by powder x-ray diffraction (PXRD), Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), UV/Vis/NIR absorption/diffuse reflectance/photoluminescence spectroscopies, and thermogravimetric analysis (TGA). Regarding the scientific phenomena investigated, the highlighting work in this dissertation is the discovery of novel bonding/photophysical/optoelectronic properties of the following materials: a black absorber with absorption from 200- 900 nm, a very stable compound with a bright green luminescence obtained by a solventless reaction, and a novel coordination polymer showing uncommon interaction of Ag(I) with three different types of diimine ligands simultaneously.

Die vorliegende Arbeit untergliedert sich in drei aufeinander aufbauende Themenkomplexe. Der erste Komplex umfasst Untersuchungen zum Nachweis und zur Quantifizierung von Beugungsanteilen in der ioneninduzierten Elektronenemission (IILEED). Dazu wurden bei der streifenden Streuung schneller He und H -Ionen an Cu(001) energiedispersive zweidimensionale Winkelverteilungen emittierter Elektronen aufgenommen. Es konnten reflexartige Intensitäten in der ioneninduzierten Elektronenemission nachgewiesen werden, deren Raumwinkeländerungen in Abhängigkeit von Anregungsrichtung und Detektionsenergie mittels einer modifizierten Ewaldkonstruktion quantitativ nachvollziehbar sind. Die beobachteten Beugungsstrukturen geben Aufschluss über den ursächlichen elektronischen Anregungsprozess an der Oberfläche. Im zweiten Teil wird die ioneninduzierten Elektronenemission beim Wachstum ultradünner 3d-Übergangsmetallfilme (Co, Fe, Mn) auf Cu(001) untersucht. Die streng zum jeweiligen Wachstumsstadium korrelierten Änderungen der Energiespektren und Anzahlverteilungen emittierter Elektronen (SEE-Oszillationen), sind hauptsächlich auf binäre Stossprozesse der Projektile mit Stufenkanten zurückzuführen. Die SEE-Oszillationen können zur in-situ Wachstumsanalyse und Bedeckungsbestimmung ultradünner Filme herangezogen werden. Im dritten Abschnitt wird eine neue Messmethode zur Analyse komplex rekonstruierter Oberflächenstrukturen vorgestellt. Die Methode der „Ionenstrahltriangulation“ (IST) basiert auf der relativen Änderung der Anzahlverteilung emittierter Elektronen bei azimutaler Drehung der Probenoberfläche. Bestimmt werden die azimutale Richtung und die relative Breite von Oberflächenkanälen in der obersten atomaren Lage. Die Registrierung der pro Streuprozess emittierten Elektronenanzahl eröffnet erstmalig eine quantitative Simulation von IST-Messkurven. Auf dieser Grundlage können mittels IST die lateralen Atompositionen langreichweitig geordneter Oberflächenstrukturen auf mehrere hundertstel Angström genau festgelegt werden. Das hohe strukturanalytische Potential dieser Messmethode demonstrieren IST-Untersuchungen an den Strukturphasen der Systeme Mn/Cu(001) und Fe/Cu(001). / H+ and He+ ions with an energy of 25 keV are scattered under a grazing angle of incidence from a clean and flat Cu(001) surface. For specific azimuthal orientations of the crystal surface with respect to low index directions in the surface plane we observe the ion induced emission of electrons with a conventional LEED (low energy electron diffraction) setup. By operating the instrument in an energy dispersive mode we find intensity distributions of emitted electrons which can unequivocally be ascribed to diffraction effects at the target surface. From this ion induced LEED-reflexes (IILEED) we get important information about the electron excitation- and emission effects during the scattering process. In the second part of this work we investigate the correlation between thin-film growth (Co, Fe, Mn on Cu(001)) and electron emission in the regime of grazing ion scattering. The “rough” surface of uncompleted layers increase the probability of binary collisions of incident ions with individual atoms at the surface. The energy spectras and the number distribution of emitted electrons are substantially influenced by these “violent” collisions and allow us to monitor growth of thin films via simple measurements of target current or from energy spectra of emitted electrons. The method provides excellent signals and is also applicable in the regime of poor layer growth. By making use of ion beam triangulation (IBT), direct information on the atomic structure of thin films and substrate surfaces is obtained. We discuss in the third part of this work a new variant of this method based on the detection of the number of emitted electrons. The data are analyzed via computer simulations using classical mechanics which provides a quantitative analysis with respect to projectile trajectories. This new detection scheme allows the determination of the in-plane structure of reconstructed thin films and surfaces with high precision. The impressed potential of this method is demonstrated by quantitative analysis of the structural phases of Fe and Mn on Cu(001).