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Electromigration (EM) remains a major reliability concern for on-chip Cu interconnects due to the continuing scaling and the introduction of new materials and processes. In Cu interconnects, the atomic diffusion along the Cu/SiCN cap interface dominates the mass transport and thus controls EM reliability. The EM lifetime degrades by half for each new generation due to the scaling of the critical void volume which induces the EM failure. To improve the EM performance, a metal cap such as CoWP was applied to the Cu surface to suppress the interfacial diffusion. By this approach, two orders of magnitude improvement in the EM lifetime was demonstrated. For Cu lines narrower than 90 nm, the Cu grain structure degraded from bamboo-like grains to polycrystalline grains due to the insufficient grain growth in the trench. Such a change in Cu grain structures can increase the mass transport through grain boundaries and thus degrade the EM performance. The objective of this study is to investigate the scaling effect on EM lifetime and Cu microstructure, and more importantly, the grain structure effect on EM behaviors of Cu interconnects with the CoWP cap compared to those with the SiCN cap only. This thesis is organized into three parts. In the first part, the effect of via scaling on EM reliability was studied by examining two types of specially designed test structures. The EM lifetime degraded with the via size scaling because the critical void size that causes the EM failure is the same with the via size. The line scaling effect on Cu grain structures were identified by examining Cu lines down to 60 nm in width using both plan-view and cross-sectional view transmission electron microscopy. In the second part, the effect of grain structure was investigated by examining the EM lifetime, statistics and failure modes for Cu interconnects with different caps. A more significant effect of the grain structure on EM characteristics was observed for the CoWP cap compared to the SiCN cap. For the CoWP cap, the grain structure not only affected the mass transport rate along the Cu line, but also impacted the flux divergence site distribution which determined the voiding location and the lifetime statistics. Finally, the effect of grain structure on EM characteristics of CoWP capped Cu interconnects was examined using a microstructure-based statistical model. In this model, the microstructure of Cu interconnects was simplified as cluster and bamboo grains connected in series. Based on the weakest-link approximation, it was shown that the EM lifetime and statistics could be adequately modeled by combining the measured cluster length distribution with the EM lifetime-cluster length correlation for each individual failure unit. / text

In copper chemical mechanical planarization (CMP), in situ detection of barrier to dielectric layer transition is typically done using an optical reflectance technique. The introduction of carbon doped oxides (CDOs) as low-dielectric constant (k) materials for dielectric layers has opened up the possibility of using spectroscopic techniques for detecting such transitions more efficiently. The vibrational frequencies of the bonds between C, H, O, and Si in these low-k materials may be readily detected by spectroscopic techniques such as Raman and infrared (IR) spectroscopies. Since CMP is carried out in aqueous media, IR spectroscopy is not very desirable due to strong absorption of water in the same region as C-H vibrations (2800 cm⁻¹ to 3300 cm⁻¹). In contrast, Raman spectroscopy shows minimal water interference and can be used to efficiently monitor the signal from CDO films even in aqueous environments that prevail under CMP conditions. The research reported in this dissertation concerns the use of Raman spectroscopy in detecting the transition from tantalum (Ta) barrier layer to CDO dielectric layer, insitu. Intensities of Raman peaks characteristic of Si-Si vibrations from silicon substrates and C-H vibrations from low-k materials were used for monitoring CDO thickness and detecting removal of Ta layer. An abrasion cell was integrated with a Raman spectrometer to demonstrate the feasibility of Raman monitoring in-situ. Additionally, an alternative method was investigated for monitoring transitions in highly fluorescent low-k materials where Raman can not be used. The fluorescence intensity was used to effectively monitor Ta to low-k transitions. As a secondary objective, the Raman technique was used to monitor the composition of polishing slurries, which in the case of copper CMP, have a rich chemistry, which may change during the course of polishing due to consumption and decomposition of certain constituents. Various aspects, such as small layer thickness (<50 μm), continuous flow of the slurry, and dynamics of the film removal process pose a great challenge to the monitoring of slurry components between the pad and the wafer. The slurry constituents such as oxidants and corrosion inhibitors have unique signatures that can be detected using spectroscopic techniques. In this study Raman spectroscopy was used to detect and quantify chemical species such as hydroxylamine, benzotriazole and hydrogen peroxide in-situ. A more detailed study pertaining to the protonation of hydroxylamine with respect to the pH was also performed. Finally, surface enhanced Raman spectroscopy (SERS) was also investigated to improve the detection of pyridine and benzotriazole at low concentrations (<100 ppm).

The Garson Ni-Cu-PGE deposit is located on the South Range of the 1850 Ma Sudbury structure along the contact between the Sudbury Igneous Complex (SIC) and the underlying metasedimentary and metavolcanic rocks of the Paleoproterozoic Huronian Supergroup. It comprises four ore bodies that are hosted by E-W-trending shear zones that dip steeply to the south. The shear zones formed as south-directed D1 thrusts in response to flexural-slip during regional buckling of the SIC. They imbricated the ore zones, the SIC norite, the underlying Huronian rocks and they emplaced slivers of Huronian rocks and anatectic breccia into the overlying Main Mass norite. Coexisting garnet-amphibole pairs yielded syn-D1 amphibolite facies metamorphic temperatures ranging from ~550°C to 590°C. The shear zones were coeval with the moderately southdipping South Range and Thayer Lindsley shear zones, which formed to accommodate the strain in the hinge zone as the SIC tightened with progressive D1 shortening. The SE limb of the SIC was overturned together with the D1 thrusts, which were then reactivated as steeply south-dipping reverse shear zones during syn-D2 greenschist metamorphism. Syn-D2 metamorphic titanite yield a U-Pb age of ca. 1849 ± 6 Ma, suggesting that D1 and D2 are part of a single progressive deformation event that occurred immediately after crystallization of the SIC during the Penokean Orogeny. The ore bodies plunge steeply to the south parallel to the colinear L1 and L2 stretching mineral lineations. Ore types consist mainly of pyrrhotite-pentlandite-chalcopyrite breccia ores, but also include pyrrhotite-pentlandite-chalcopyrite disseminated sulfide mineralization in norite, and syn-D2 quartz-calcite-chalcopyrite-pyrrhotite-pentlandite iv veins. In the breccia ores, matrix sulfides surround silicate rock fragments that have a strong shape-preferred orientation defining a pervasive foliation. The fragments are highly stretched parallel to the mineral lineations in wall rocks, suggesting that the ore bodies are zones of high strain. Pyrrhotite and chalcopyrite occur in piercement structures, in boudin necks between fragments, in fractures in wall rocks and in fold hinges, suggesting that the sulfides were mobilized by ductile plastic flow. Despite evidence of high strain in the ore zones, the sulfide matrix in D1 and D2 breccia ores show little evidence of strain as they consist predominantly of polygonal pyrrhotite aggregates, suggesting that they recrystallized during, or immediately after D1 and D2. However, rare elongate pyrrhotite grains aligned parallel to S2 are locally preserved only in D2 breccia ores. Exsolution of pentlandite loops along grain boundaries of elongate pyrrhotite formed S2-parallel pentlandite-rich layers in D2 breccia ores, whereas the pentlandite loops are multi-oriented in D1 contact breccia as they were exsolved along grain boundaries polygonal pyrrhotite. Because exsolution of pentlandite post-date D1 and D2, and that individual pentlandite grains neither have a shape-preferred orientation nor show evidence for cataclastic flow, the sulfides reverted to, and were mobilized as a homogeneous metamorphic monosulfide solid solution (mss) during D1 and possibly D2. This is in agreement with predictions from phase equilibria as the average Garson composition plots within the mss field in Fe-Ni-S ternary diagram at temperatures above ~400°C. Disseminated and breccia ores at Garson have similar mantle-normalized multi-element chalcophile patterns as undeformed contact-type disseminated and massive ore, v respectively, at the well known Creighton mine in the South Range. This suggests that the Garson ores are magmatic in origin and that their compositions were not significantly altered by hydrothermal fluids and deformation. The lack of variations in Ni tenors between the disseminated and breccias ores suggest that the R-factor was not the process controlling metal tenors because the disseminated sulfides do not consistently have higher metal tenors than the breccia ore. The breccia ores are enriched in Rh-Ru-Ir and are depleted in Cu-Pd-Pt-Au, in contrast to footwall-type ore at the nearby Garson Ramp mine which is enriched in the same metals. When Ni100, Rh100, Ir100, Pt100 and Pd100 are plotted against Cu100, the breccia and footwall-type ore analyses plot along model mss fractionation and sulfide melt model curves, suggesting that these two ore types are related by mss fractionation. In summary, the Garson breccia ores are mss cumulates that settled quickly at the base of the SIC via a gravity filtration process, and were mobilized as a metamorphic mss by ductile plastic flow during D1 and D2. Despite minor local hydrothermal mobilization of some metals, the study confirms findings from other studies that highly deformed Ni-Cu- PGE deposits, such as the Garson deposit, can provide important information on the genesis of the deposits.

Metal carbides have attracted much attention over the past several years due to their unique qualities. The purpose of this research is to develop a cermet that demonstrates desired properties of nano-size titanium carbide (TiC) and copper-nickel (Cu-Ni) metals. In this study stoichiometric, nano-size TiC was synthesized through a patented carbothermal synthesis process (U.S. Patent No.: 5,417,952). The resulting TiC was sintered with varying copper (12.5-37.5wt %) and nickel (12.5-25wt %) contents. Hardness, fracture toughness, and microscopy studies were performed. Average hardness ranging between 325-1292 HV were found, with copper content showing a strongly negative correlation with hardness. Fracture toughness values were found to be between 4.85-14.36 Mpa*m^.5; TiC content had a nearly linear, negative correlation with fracture toughness. Samples with high copper to nickel ratios showed poor homogeneity and wetting.

Made available in DSpace on 2018-08-01T22:29:41Z (GMT). No. of bitstreams: 1 tese_8254_Dissertação Everson Souza -mestrado.pdf: 28342943 bytes, checksum: 624a7fea535603211d8475809590baa3 (MD5) Previous issue date: 2014-09-30 / Neste trabalho, a estabilidade energética, propriedades eletrônicas e estruturais de camadas de grafeno adsorvidas em superfície Cu(111) foram examinadas através de cálculos de primeiros princípios baseados na teoria do funcional da densidade (DFT). Nós examinamos a adsorção em superfície Cu(111) de (i) monocamada de grafeno sem defeitos (G) e bicamada de grafeno sem defeitos (BLG), (ii) bicamada de grafeno com defeito substitucional de átomo de Co. Em (i) foram consideradas três diferentes possíveis configurações para formação das interfaces. A partir de nossos resultados foi encontrado que a formação das interfaces G/Cu(111) e BLG/Cu(111) são processos exotérmicos, com energia de adsorção de 35,3 meV/Å2 e 39,2 meV/Å2 para as configurações mais estáveis, respectivamente. Além disso, nós encontramos para bicamada de grafeno em Cu(111) uma distância de equilíbrio entre o metal e a camada de grafeno interfacial de 2,89 Å, idêntico ao valor para monocamada. Assim, estes resultados indicam que a adsorção de G e BLG em Cu(111) é guiada por uma adsorção física. Além disso, a formação das interfaces G/Cu(111) e BLG/Cu(111) dá origem a flutuações de densidade de carga e a monocamada e bicamada de grafeno em Cu(111) são n-dopadas. Conforme verificado por análise de Bader, existe uma transferência de carga da superfície de cobre para G e para BLG de 0,0062 e/Å2 e 0,0058 e/Å2, respectivamente. Em (ii) estudou-se inicialmente defeitos substitucionais de átomos de Co na camada superior da BLG em dois sítios atômicos diferentes (sistemas BLG-Co&#945; e BLG-Co&#946;), sem a presença do substrato de metal. Neste caso, nossos resultados tem indicado que existe um momento magnético total não-nulo nos sistemas BLG-Co&#945; e BLG-Co&#946;. Em seguida, considerando a adsorção do sistema BLG-Co&#946; na superfície Cu(111), nós encontramos que a formação da interface BLG-Co&#946;/Cu(111) é um processo exotérmico, com energia de adsorção de 40,1 meV/Å2. Apesar de não existir ligação química na interface grafeno-metal ou aumento significativo da energia de adsorção, o momento magnético total do sistema BLG-Co&#946; é extinto quando adsorvido no substrato de cobre, devido principalmente à transferência de carga do Cu(111) para BLG-Co&#946; .

In this work a reversible transition between CeO2/Cu(111) and Ce2O3/Cu(111) was studied by metalic ceria evaporation and oxygen exposition. Prepared layers were characterised by XPS, ISS (and its angle resolved modification), LEED and XPD combined with computer modelling using EDAC code. Four reconstructi- on were identified within the transition - ( √ 7 × √ 7)R19.1◦ , ( √ 3 × √ 3)R30◦ , 3 × 3 and 4 × 4 - for which structural models were suggested. Prepared layers of Ce2O3/Cu(111) exhibiting the 4×4 reconstruction were identified as a cubic pha- se of Ce2O3 by the combination of all methods. The photoelectron spectroscopy study of the chemical state of layers revealed that reduction proceedes from the surface and oxidation is realised by oxygen diffusion into the volume.

Diploma thesis on Corrosion and Strenght Properties of Al – Cu Alloys. The thesis deals about aluminum, copper and alloys of these metals. It describes the production and processes, composition and it´s utilization. Furthermore, the thesis focuses on corrosion and rust prevention. The text concludes with the metodology of tensile tests which were used in the practical part of the thesis. The practical part of the thesis consists of description of operations before measurement, the measurement and subsequent evaluation

Das Cu-Cu-Bonden ist eine vielversprechende lötfreie Fine-Pitch-Verbindungstechnologie für die 2,5D- und 3D-Systemintegration. Diese Bondtechnologie wurde in den letzten Jahren intensiv untersucht und wird derzeit für miniaturisierte mikroelektronische Produkte eingesetzt. Allerdings, stellt das Cu‑Cu-Bonden zum einen sehr hohe Anforderungen an die Oberflächenplanarität und -reinheit, und zum anderen sollten die Bondpartner frei von Oxiden sein. Oxidiertes Cu erfordert erhöhte Bondparameter, um die Oxidschicht zu durchbrechen und zuverlässige Cu-Cu-Verbindungen zu erzielen. Diese Bondbedingungen sind für viele sensible Bauelemente nicht geeignet. Aus diesem Grund sollten alternative Technologien mit einer einfachen Technik zum Schutz von Cu vor Oxidation gefunden werden. In dieser Arbeit werden selbstorganisierte Monolagen (SAMs) für den Cu-Oxidationsschutz und die Verbesserung der Cu-Cu-Thermokompression- (TC) und Ultraschall- (US) Flip-Chip-Bondtechnologien untersucht. Die Experimente werden an Si-Chips mit galvanisch aufgebrachten Cu-Microbumps und Cu-Schichten durchgeführt. Die Arbeit beinhaltet die umfassende Charakterisierung der SAM für den Cu-Schutz, die Bewertung der technologischen Parameter für das TC- und US-Flip-Chip-Bonden sowie die Charakterisierung der Cu-Cu-Bondqualität (Scherfestigkeitstests, Bruchflächen- und Mikrostrukturanalysen). Eine Lagerung bei tiefen Temperaturen (bei ‑18 °C und ‑40 °C) bestätigte die langanhaltende Schutzwirkung der kurzkettigen SAMs für das galvanisch abgeschiedene Cu ohne chemisch-mechanische Politur. Der Einfluss der Tieftemperaturlagerung an Luft und der thermischen SAM-Desorption in einer Inertgasatmosphäre auf die TC-Verbindungsqualität wird im Detail analysiert. Die Idee, mit Hilfe der US-Leistung SAM mechanisch zu entfernen und gleichzeitig das US-Flip-Chip-Bonden zu starten, wurde in der Literatur bisher nicht systematisch untersucht. Die Methode ermöglicht kurze Bondzeiten, niedrige Bondtemperaturen und das Bonden an Umgebungsluft. Sowohl beim TC- als auch beim US-Flip-Chip-Bonden zeigt es sich, dass die Scherfestigkeit bei den Proben mit SAM-Passivierung um ca. 30 % höher ist als bei unbeschichteten Proben. Das Vorhandensein von Si- und Ti-Bruchflächen nach den Scherfestigkeitstests ist für die Proben mit der SAM-Passivierung typisch, was auf eine höhere Festigkeit solcher Verbindungen im Vergleich zu ungeschützten Proben schließen lässt. Die Transmissionselektronenmikroskopie (TEM) zeigt keine SAM-Spuren im zentralen Bereich der Cu-Cu-Grenzfläche nach dem US-Flip-Chip-Bonden. Die Ergebnisse dieser Arbeit zeigen die Verbesserung der Bondqualität durch den Einsatz von SAM zum Schutz des Cu vor Oxidation im Vergleich zum üblicherweise angewandten Cu-Vorätzen. Das gefundene technologische Prozessfenster für das US-Flip-Chip-Bonden an Luft bietet eine hohe Bondqualität bei 90 °C und 150 °C, bei 180 MPa, bei einer Bonddauer von 1 s an. Die in dieser Arbeit gewonnenen Erkenntnisse sind ein wichtiger Beitrag zum Verständnis des SAM-Einflusses auf Chips mit galvanischen Cu-Microbumps, bzw. Cu-Schichten, und zur weiteren Anwendung der Cu-Cu-Fine-Pitch-Bondtechnologie in der Mikroelektronik. / Cu-Cu bonding is one of the most promising fine-pitch interconnect technologies with solder elimination for 2.5D and 3D system integration. This bonding technology has been intensively investigated in the last years and is currently in application for miniaturized microelectronics products. However, Cu-Cu bonding has very high demands on the sur-face planarity and purity, and the bonding partners should be oxide-free. Oxidized Cu requires elevated bonding parameters in order to break through the oxide layer and achieve reliable Cu-Cu interconnects. Those bonding conditions are undesirable for many devices (e.g. due to the temperature/pressure sensitivity). Therefore, alternative technologies with a simple technique for Cu protection from oxidation are required. Self-assembled monolayers (SAMs) are proposed for the Cu protection and the improvement of the Cu-Cu thermocompression (TC) and ultrasonic (US) flip-chip bonding technologies in this thesis. The experiments were carried out on Si dies with electroplated Cu microbumps and Cu layers. The thesis comprises the comprehensive characterization of the SAM for Cu protection, evaluation of technological parameters for TC and US flip-chip bonding as well as characterization of the Cu-Cu bonding quality (shear strength tests, fracture surface and microstructure analyses). The storage at low temperatures (at ‑18 °C and ‑40 °C) confirmed the prolonged protective effect of the short-chain SAMs for the electroplated Cu without chemical-mechanical polishing. The influence of the low-temperature storage in air and the thermal SAM desorption in an inert gas atmosphere on the TC bonding quality was analyzed in detail. The approach of using US power to mechanically remove SAM and simultaneously start the US flip-chip bonding has not been systematically investigated before. The method provides the benefit of short bonding time, low bonding temperature and bonding in ambient air. Both the TC and US flip-chip bonding results featured the shear strength that is approximately 30 % higher for the samples with SAM passivation in comparison to the uncoated samples. The presence of Si and Ti fracture surfaces after the shear strength tests is typical for the samples with the SAM passivation, which suggests a higher strength of such interconnects in comparison to the uncoated samples. The transmission electron microscopy (TEM) indicated no SAM traces at the central region of the Cu-Cu bonding interface after the US flip-chip bonding. The results of this thesis show the improvement of the bonding quality caused by the application of SAM for Cu protection from oxidation in comparison to the commonly applied Cu pre-treatments. The found technological process window for the US flip-chip bonding in air offers high bonding quality at 90 °C and 150 °C, at 180 MPa, for the bonding duration of 1 s. The knowledge gained in this thesis is an important contribution to the understanding of the SAM performance on chips with electroplated Cu microbumps/layers and further application of the Cu-Cu fine-pitch bonding technology for microelectronic devices.

Yes / To develop potential next-generation metal anticancer agents, we designed and synthesised five Cu(II) 2-pyridine-thiosemicarbazone complexes by modifying the hydrogen atom at the N-4 position of ligands, and then investigated their structure-activity relationships and anticancer mechanisms. Modification of the N-4 position with different groups caused significant differences in cellular uptake and produced superior antitumor activity. Cu complexes arrested the cell cycle at S phase, leading to down-regulation of levels of cyclin and cyclin-dependent kinases and up-regulation of expression of cyclin-dependent kinase inhibitors. Cu complexes exerted chemotherapeutic effects via activating p53 and inducing production of reactive oxygen species to regulate expression of the B-cell lymphoma-2 family of proteins, causing a change in the mitochondrial membrane potential and release of cytochrome c to form a dimer with apoptosis protease activating factor-1, resulting in activation of caspase-9/3 to induce apoptosis. In addition, Cu complexes inhibited telomerase by down-regulating the c-myc regulator gene and expression of the human telomerase reverse transcriptase. / Natural ScienceFoundation of China (31460232, 21431001, 21561017, 21462004),the Natural Science Foundation of Guangxi (2017GXNSFEA198002,AD17129007), IRT_16R15, Guangxi“Bagui”scholar program to HBSun, and High-Level Innovation Team and Distinguished Scholarprogram of Guangxi universities to F Yang.