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Metal Oxide Cluster Chemistries for Next Generation Nanomanufacturing Public Deposited

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  • Metal oxide clusters are promising inorganic photoresists in next generation nanomanufacturing because of their potential for high-resolution and low line-edge roughness patterning, and exceptional sensitivity to extreme ultraviolet (EUV) radiation. In EUV patterning, absorption of EUV radiation leads to electron emission that serve as a primary species for driving radiation sensitive chemistries. Hafnium oxide peroxide hydroxide sulfate (HafSOx), butyltin oxide hydroxide (BuSnOOH), and a synthesized, sodium templated, β-Keggin cluster (β-NaSn13) were studied in an effort to understand the differences and similarities in thermal and radiation mechanisms that occur during patterning. A combination of surface sensitive techniques serves to elucidate mechanisms in thin film photoresists. In particular, we have developed desorption methods, temperature programmed desorption (TPD) and electron stimulated desorption (ESD), as useful real-time, in-situ techniques to monitor photoresist chemistries. In all of the photoresists low energy electrons, with energies anticipated for photo- and Auger electrons during EUV patterning, were able to drive radiation chemistries. Desorption and film composition techniques, Raman spectroscopy or x-ray photoelectron spectroscopy (XPS), were used to relate the desorption chemistry to the resulting film chemistry. In the case of HafSOx, advanced studies of the changing precursor chemistry combined with x-ray total scattering data provided further insight into the cluster chemistry. Differences in the thermally induced loss of the contrast-controlling ligands illustrates the superiority of the organotin thermal stability compared to HafSOx. Using the β-NaSn13 as a model system, we demonstrated that the presence of an oxygen ambient provides a route to increasing the butyl ligand loss rate and photoresist sensitivity. The presence of O2 during patterning affects the solubility transition, photochemistry, and ESD cross sections. XPS indicates that only a very small percentage of the butyl ligands need to be removed to form the insoluble product. This finding raises questions that could be answered with studies of individual clusters and cluster-cluster interactions. To that end, we also present research regarding the creation of graphene-enhanced TiO2 catalysts via the reactive deposition of TiO2 nanoclusters onto defective graphene. This research demonstrated defects in graphene as a strong adsorption site for the anchoring of the metal oxide nanoclusters. We propose this as an exciting avenue for isolating clusters, or small-diameter agglomerations of clusters, for in-situ STM studies for a range of metal oxide cluster chemistries.
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  • Ongoing Research
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  • 2018-06-01 to 2020-07-02



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