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ItemCharacterization of Commercial Dielectric Zaristo-700 as a Redistribution Layer Material for Advanced Packaging(Georgia Institute of Technology, 2023-12-06) Madelone, Sophia MarieThis body of work, in detail, outlines the fundamental steps taken to characterize a material for novel use in RDL build-up layers for advanced packaging. The material (Zaristo-700) discussed in this thesis was only used in RF applications, and now we are exploring its use in the wiring layers. In the PRC, research into thin films, spin-on films, and many other dielectrics have been published before. It is essential to understand that this work is necessary to establish a “library” or catalog of information on all the materials we use to provide the correct material, depending on the goals of future projects. The material and electrical properties of Zaristo-700 are characterized through JEDEC adhesion testing (Peel test), leakage current measurements on ITO glass slides before and after Highly Accelerated Stress Testing (HAST) treatment, a series of dose tests to document the most optimized pitch-scalability at 8.0 m L/S, and lastly Shadow-Moire warpage studies of one layer and three-layer RDL samples. Leakage current measurements taken before and after HAST stayed at or below 2.0 nA. As we will explore, the CTE and adhesion of Zaristo-700 are excellent and contribute to making a great material for the RDL wiring layers. Taiyo Ink. has stated that this version of the dielectric film accounts for issues such as stability in how long it can sit, delamination during or after curing, delamination during fabrication processes, and so on. Whereas some of the dielectric films of other companies still have these problems. This research is working towards answering the unknowns about this dielectric and how well it will function as a future RDL build-up material through characterization and analysis of its properties. These results are a positive indication for use as an RDL dielectric in advanced packaging.
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ItemAtomic Layer Deposition As A Method Of Fine Tuning The Surface Chemistry Of Oxide Materials(Georgia Institute of Technology, 2023-12-05) Yom, TypherAtomic layer deposition (ALD) is a vapor-phase synthesis method in which a material is deposited onto a surface with precise atomic thickness. Through ALD, ultra-thin monolayers of oxide materials can be deposited onto powders, creating mixed oxide surfaces with tunable surface chemistries, enabling their usefulness towards catalytic processes in the petrochemical and fine chemical industries. ALD holds an advantage over typical solution-phase methods of creating mixed oxide materials due to the latter’s difficulty in controlling the surface composition, making analysis difficult. However, if we can better understand the interactions of the surface in solution, it can be used to design more effective catalysts. One way to observe this is by studying the zeta potential of the surface, which is directly correlated with surface charge and is a product of these acid-base interactions at the interface. Each material can be identified using the isoelectric point, which is the point at which the zeta potential/net surface charge is zero. For mixed metal oxides, their isoelectric points were calculated in the literature to be the summation of each individual component’s isoelectric point multiplied by its surface coverage. However, this calculation assumes that the components do not interact with each other when mixed. In order to investigate this discrepancy, we used ALD to deposit thin layers of titanium oxide onto silicon oxide powders. If we were to assume the equation used in the literature, we can assume that one single monolayer over the surface would be sufficient to convert the isoelectric point from that of silicon oxide to that of titanium oxide. However, our results have indicated that the isoelectric point did not reach that of titanium oxide until multiple monolayers were deposited, indicating that a different model/equation must be utilized to better elucidate the surface behavior. Additionally, during these studies of the isoelectric point, we have formulated an equation that can correlate the thickness of ALD-deposited films with the material’s relative atomic percent. This equation was created by assuming that the shape of the particle + film retains its shape, and therefore its volume formula, allowing it to work for ultra-thin films, but not for much thicker films. Finally, this thesis highlights the importance of being mindful of the precursor used for powder ALD: precursors like TiCl4 can create byproducts like HCl from the reactor walls and the powder itself. These byproducts can then adsorb onto the powder surface, which can block film growth or affect the pH of the resulting solution when the powder is dispersed in water. Extra measures, such as a double dose or a post-process washing step, were implemented, and should be used when performing powder ALD.
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ItemStability Studies of ALD Films and Infiltrated Hybrid Materials(Georgia Institute of Technology, 2022-12-19) Fairach, Selma RaquelAluminum oxide (alumina) thin films deposited through atomic layer deposition (ALD) are of great interest in chemical barrier and corrosion protection applications. However, the stability of ALD alumina in aqueous solutions is still not fully understood. Due to its metastable amorphous phase, the hydration and degradation behavior of ALD alumina films behaves differently from its crystalline Al2O3 counterpart. A full understanding of why these films hydrate and/or dissolve requires the exploration of different deposition conditions and ion content in solutions used. This thesis will discuss efforts to further elucidate the hydration and dissolution behavior of ALD alumina films. For this study, alumina thin films were ALD deposited onto silicon substrate at 150 °C using trimethylaluminum (TMA) and H2O. These films were then studied in Type 1 DI water and different concentrations of NaCl solutions at room temperature. Films were gently dried using a nitrogen gun and thickness was measured using a Cauchy ellipsometry model. After 15 days of immersion in Type 1 DI water, significant thickness growth is observed at twice (27 days) and 2.5 times (33 days) the normalized thickness. Similar hydration is not observed in salt-containing aqueous solutions nor upon exposure to air. This thesis will discuss the possible effects of CO2 dissolution and carbonate formation as well as ionic species on the hydration and dissolution processes of these alumina films. Similar stability applications are observed in the infiltration of hybrid organic-inorganic electronic devices through vapor phase infiltration (VPI). Spiro-OMeTAD is one of the most-studied hole transport layer (HTL) materials in perovskite solar cells, but it is known to degrade quickly due to thermal effects as well as gold diffusion into the layer. This thesis will discuss how infiltration on TiCl4 and H2O into Spiro-OMeTAD layers can change the thermal properties and prevent early degradation. Upon infiltration of TiOx, the formation of crystals observed on Spiro-OMeTAD layers decrease, and at 10 hours of infiltration, the glass transition temperature of the film is found to decrease almost 15 °C. Similar behavior is not found in samples that are thermally controlled, indicating that this behavior is not an annealing effect. This thesis will discuss all the different thermal stability results with varying infiltration times and precursors used.