Copper based interconnects with low dielectric constant layers are currently used to increase interconnect densities and reduce interconnect time delays in integrated circuits. The technology used to develop copper interconnects involves Chemical Mechanical Planarization (CMP) of copper films deposited on low-k layers (silica or silica based films), which is carried out using slurries containing abrasive particles. One issue using such a structure is copper contamination over dielectric layers (SiO2 film), if not reduced, this contamination will cause current leakage. In this study, the conditions conducive to copper contamination onto SiO2 films during Cu-CMP process were studied, and a post-CMP cleaning technique was discussed based on experimental results. It was found that the adsorption of copper onto a silica surface is kinetically fast (< 0.5 minute). The amount of copper absorbed is pH and concentration dependent and affected by presence of H2O2, complexing agents, and copper corrosion inhibitor Benzotrazole. Based on de-sorption results, DI water alone was unable to reduce adsorbed copper to an acceptable level, especially for adsorption that takes place at a higher pH condition. The addition of complex agent, citric acid, proved effective in suppressing copper adsorption onto oxide silica during polishing or post-CMP cleaning by forming stable copper-CA complexes. Surface Complexation Modeling was used to simulate copper adsorption isotherms and predict the copper contamination levels on SiO2 surfaces.Another issue with the application of copper CMP is its environmental impact. CMP is a costly process due to its huge consumption of pure water and slurry. Additionally, Cu-CMP processing generates a waste stream containing certain amounts of copper and abrasive slurry particles. In this study, the separation technique electrocoagulation was investigated to remove both copper and abrasive slurry particles simultaneously. For effluent containing ~40 ppm dissolved copper, it was found that ~90% dissolved copper was removed from the waste streams through electroplating and in-situ chemical precipitation. The amount of copper removed through plating is impacted by membrane surface charge, type/amount of complexing agents, and solid content in the slurry suspension. The slurry particles can be removed ~90% within 2 hours of EC through multiple mechanisms.

The self-assembly of magnesium aluminate spinel as a result of dewetting an overlaid thin film of (chiefly) gold was investigated. Thin films of gold were deposited on single-crystalline spinel substrates and were heat-treated to dewet gold film which led to self-assembly of intricate structures consisting of faceted spherical particles atop of frustums. The current work was conducted in continuation of previous studies which reported formation of such intricate structures. The most recent studies had evidently overruled a pure gold self-assembly scenario as was pointed out in preliminary investigations. It was in fact proven that these structures consist of three distinct parts: (i) a single or polycrystalline gold faceted sphere, (ii) quasi-phase interfacial bilayer, and (iii) a crystalline MgAl2O4 necking structure spontaneously risen from spinel substrate. In the current work, samples were produced through different film deposition methods of sputter, thermal evaporation, and e-beam evaporation coating which underwent thermal annealing to induce dewetting of gold film and subsequent self-assembly of intricate structures. Several characterization methods such as electron microscopy, X-ray energy dispersive spectroscopy, electron energy loss spectroscopy, and atom probe tomography were utilized to survey the different features of the intricate structures with focus on chemical analysis of the gold-spinel interface. The results rejected the previous findings about formation of interface complexion at the boundary of gold-spinel. It was found out that gold-spinel interface is in fact an ordinary metal-oxide boundary with sharp atomic distinction and no inter-diffusion or formation of interfacial complexion. It was further discovered that dewetting pure gold thin films does not result in formation of spinel self-assembly and existence of elemental impurities of copper (Cu) in the initial film is vital in development of such structures. Finally, it was concluded that chemical composition of metallic overlayer and the heat treatment parameters most fundamentally influence formation and physical characteristics of those self-assembled structures. / Thesis / Master of Applied Science (MASc)

BC Hydro’s Water Use Planning (WUP) process is one of the world’s most comprehensive hydroelectric dam operational reviews and has served as a model to revise hydropower operating plans with the participation of an inclusive range of stakeholders, rights holders, and the use of up-to-date scientific information, that meets social and environmental goals alongside economic targets. In 2000, BC Hydro initiated a WUP process in the Jordan River watershed. This watershed hosts a wide diversity of water users, including active resource industry stakeholders (mining, forestry, and hydropower), Indigenous rights holders, and rural community citizens; which is representative of watersheds in British Columbia with established WUPs. BC Hydro finalized the Jordan River WUP in 2003, which focuses on establishing critical freshwater flows for fish habitat and achieving specific recreational values of the local community. However, numerous other issues still remain that were beyond the scope of the WUP process, including water quality concerns that were continually brought up by citizens during the consultative process of the WUP. In addition to these concerns, biological monitoring following the implementation of the WUP suggests that contamination from an inactive copper mine has affected and altered sensitive water quality parameters for a healthy Pacific salmon habitat in Jordan River. Yet, there has not been an extensive water quality study conducted that examines the spatial or seasonal water quality extents of the mining contamination in Jordan River, specifically copper. Consequently, fourteen years after the creation of the WUP, local advocates are still struggling to have their concerns heard by the entity responsible for freshwater flow, BC Hydro, alongside federal and provincial government agencies. Advocates are calling for the creation of a watershed-based group as a mechanism for having greater influence in water planning and governance processes. This study explores the research question: if and how has the WUP process contributed to creating watershed governance capacity? This social science thesis project employs a mixed-methods approach using both quantitative and qualitative data. The study includes a document review of relevant water governance literature and focuses on examining the freshwater quality of the Jordan River. Water quality samples were collected over a five-week period from five sites on the Jordan River beginning in September and concluding in October of 2015 during the most sensitive periods of salmon spawning activity in the lower reaches of the Jordan River. Spatial and seasonal water quality trends were identified, and analysis concluded that copper is the primary contaminate affecting the productivity of a healthy salmon habitat in the Jordan River. Acid mine drainage (AMD) processes were identified throughout the water quality data and are strongly influenced by the proximity of existing mine waste piles sourced from an abandoned copper mine, and unnatural anthropogenic flows from the three BC Hydro dams present in the Jordan River system. The final stage of the research project focuses on assessing the adaptive capacity in the watershed to address the issues of concern outlined in the WUP. There is a current movement to create watershed organizations that are formally supported through new legislation in British Columbia, but questions remain about the capacities of these watershed communities to sustain such a formal institution and if these watershed communities are ready to successfully implement a local watershed governance model. The Gupta et al. (2010) six adaptive capacity dimensions provide a logical framework to explore if these capacities are present such that it could be expected that local watershed organizations would be effective as society adapts to more watershed-based governance approaches. Thirteen semi-structured interviews were conducted from October 2016 to February 2017. Interviews and observational data focused on the WUP process and prospective and current members of the Jordan Watershed Round Table (JWRT). The research evaluated whether these six adaptive capacity dimensions are present in watershed communities that have been subjected to water management processes, specifically the WUP program. Overall, the research concluded that the WUP has contributed to some adaptive capacity for watershed governance in the Jordan River, specifically on building the adaptive capacity dimensions: variety, learning capacity, room for autonomous change, leadership, and resources within the JWRT. / Graduate