Browsing by Author "Mattson, Eric C."
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Item Chemical Modification Mechanisms in Hybrid Hafnium Oxo-Methacrylate Nanocluster Photoresists for Extreme Ultraviolet Patterning(American Chemical Society) Mattson, Eric C.; Cabrera, Yasiel; Rupich, Sara M.; Wang, Yuxuan; Oyekan, Kolade A.; Mustard, T. J.; Halls, M. D.; Bechtel, H. A.; Martin, M. C.; Chabal, Yves J.; Mattson, Eric C.; Cabrera, Yasiel; Rupich, Sara M.; Wang, Yuxuan; Oyekan, Kolade A.; Chabal, Yves J.The potential implementation of extreme ultraviolet (EUV) lithography into next generation device processing is bringing urgency to identify resist materials that optimize EUV lithographic performance. Inorganic/organic hybrid nanoparticles or clusters constitute a promising new class of materials, with high EUV sensitivity from the core and tunable chemistry through the coordinating ligands. Development of a thorough mechanistic understanding of the solubility switching reactions in these materials is an essential first step toward their implementation in patterning applications but remains challenging due to the complexity of their structures, limitations in EUV sources, and lack of rigorous in situ characterization. Here, we report a mechanistic investigation of the solubility switching reactions in hybrid clusters comprising a small HfOx core capped with a methacrylic acid ligand shell (HfMAA). We show that EUV-induced reactions can be studied by performing in situ infrared (IR) spectroscopy of electron-irradiated films using a variable energy electron gun. Combining additional ex situ metrology, we track the chemical evolution of the material at each stage of a typical resist processing sequence. For instance, we find that a cross-linking reaction initiated by decarboxylation of the methacrylate ligands under electron irradiation constitutes the main solubility switching mechanism, although there are also chemical changes imparted by a typical post application bake (PAB) step alone. Lastly, synchrotron-based IR microspectroscopy measurements of EUV-irradiated HfMAA films enable a comparison of reactions induced by EUV vs electron beam irradiation of the same resist material, yielding important insight into the use of electron beam irradiation as an experimental model for EUV exposure.Item Cobalt and Iron Segregation and Nitride Formation from Nitrogen Plasma Treatment of CoFeB Surfaces(American Institute of Physics Inc) Mattson, Eric C.; Michalak, D. J.; Veyan, Jean Francois; Chabal, Yves J.; 0000-0002-3743-5521 (Veyan, JF); 0000-0002-6435-0347 (Chabal, YJ); Mattson, Eric C.; Veyan, Jean Francois; Chabal, Yves J.Cobalt-iron-boron (CoFeB) thin films are the industry standard for ferromagnetic layers in magnetic tunnel junction devices and are closely related to the relevant surfaces of CoFe-based catalysts. Identifying and understanding the composition of their surfaces under relevant processing conditions is therefore critical. Here we report fundamental studies on the interaction of nitrogen plasma with CoFeB surfaces using infrared spectroscopy, x-ray photoemission spectroscopy, and low energy ion scattering. We find that, upon exposure to nitrogen plasma, clean CoFeB surfaces spontaneously reorganize to form an overlayer comprised of Fe2N3 and BN, with the Co atoms moved well below the surface through a chemically driven process. Subsequent annealing to 400 °C removes nitrogen, resulting in a Fe-rich termination of the surface region. © 2016 Author(s).Item Role of Excess Ligand and Effect of Thermal Treatment in Hybrid Inorganic-Organic EUV Resists(SPIE) Mattson, Eric C.; Rupich, S. M.; Cabrera, Y.; Chabal, Yves J.; Mattson, Eric C.; Chabal, Yves J.The chemical structure and thermal reactivity of recently discovered inorganic-organic hybrid resist materials are characterized using a combination of in situ and ex situ infrared (IR) spectroscopy and X-ray photoemission spectroscopy (XPS). The materials are comprised of a small HfOx core capped with methacrylic acid ligands that form a combined hybrid cluster, HfMAA. The observed IR modes are consistent with the calculated modes predicted from the previously determined X-ray crystal structure of the HfMAA-12 cluster, but also contain extrinsic hydroxyl groups. We find that the water content of the films is dependent on the concentration of excess ligand added to the solution. The effect of environment used during post-application baking (PAB) is studied and correlated to changes in solubility of the films. In doing so, we find that hydroxylation of the clusters results in formation of additional Hf-O-Hf linkages upon heating, which in turn impacts the solubility of the films.Item Thermal Atomic Layer Etching of Silica and Alumina Thin Films Using Trimethylaluminum with Hydrogen Fluoride or Fluoroform(American Chemical Society) Rahman, Razwanur; Mattson, Eric C.; Klesko, Joseph P.; Dangerfield, Aaron; Rivillon-Amy, S.; Smith, D. C.; Hausmann, D.; Chabal, Yves J.; 0000 0000 4239 3958 (Chabal, YJ); 0000-0002-8109-4787 (Rahman, R); 0000-0002-0755-2583 (Mattson, EC); 0000-0003-3989-8009 (Klesko, JP); 0000-0002-6435-0347 (Chabal, YJ); Rahman, Razwanur; Mattson, Eric C.; Klesko, Joseph P.; Dangerfield, Aaron; Chabal, Yves J.Thermal atomic layer etching (ALE) is an emerging technique that involves the sequential removal of monolayers of a film by alternating self-limiting reactions, some of which generate volatile products. Although traditional ALE processes rely on the use of plasma, several thermal ALE processes have recently been developed using hydrogen fluoride (HF) with precursors such as trimethylaluminum (TMA) or tin acetylacetonate. While HF is currently the most effective reagent for ALE, its potential hazards and corrosive nature have motivated searches for alternative chemicals. Herein, we investigate the feasibility of using fluoroform (CHF₃) with TMA for the thermal ALE of SiO₂ and Al₂O₃ surfaces and compare it to the established TMA/HF process. A fundamental mechanistic understanding is derived by combining in situ Fourier transform infrared spectroscopy, ex situ X-ray photoemission spectroscopy, ex situ low-energy ion scattering, and ex situ spectroscopic ellipsometry. Specifically, we determine the role of TMA, the dependence of the etch rate on precursor gas pressure, and the formation of a residual fluoride layer. Although CHF₃ reacts with TMA-treated oxide surfaces, etching is hindered by the concurrent deposition of a fluorine-containing layer, which makes it unfavorable for etching. Moreover, since fluorine contamination can be deleterious to device performance and its presence in thin films is an inherent problem for established ALE processes using HF, we present a novel method to remove the residual fluorine accumulated during the ALE process by exposure to water vapor. XPS analysis herein reveals that an Al₂O₃ film etched using TMA/HF at 325 °C contains 25.4 at. % fluorine in the surface region. In situ exposure of this film to water vapor at 325 °C results in 90% removal of the fluorine. This simple approach for fluorine removal can easily be applied to ALE-treated films to mitigate contamination and retain surface stoichiometry. ©2018 American Chemical Society.