@article{lee_broughton_hsain_song_edgington_horgan_dowden_bednar_lee_parsons_et al._2022, title={The influence of crystallographic texture on structural and electrical properties in ferroelectric Hf0.5Zr0.5O2}, volume={132}, ISSN={["1089-7550"]}, url={https://doi.org/10.1063/5.0128038}, DOI={10.1063/5.0128038}, abstractNote={Ferroelectric (Hf,Zr)O2 thin films have attracted increased interest from the ferroelectrics community and the semiconductor industry due to their ability to exhibit ferroelectricity at nanoscale dimensions. The properties and performance of the ferroelectric (Hf,Zr)O2 films generally depend on various factors such as surface energy (e.g., through grain size or thickness), defects (e.g., through dopants, oxygen vacancies, or impurities), electrodes, interface quality, and preferred crystallographic orientation (also known as crystallographic texture or simply texture) of grains and/or domains. Although some factors affecting properties and performance have been studied extensively, the effects of texture on the material properties are still not understood. Here, the influence of texture of the bottom electrode and Hf0.5Zr0.5O2 (HZO) films on properties and performance is reported. The uniqueness of this work is the use of a consistent deposition process known as Sequential, No-Atmosphere Processing (SNAP) that produces films with different preferred orientations yet minimal other differences. The results shown in this study provide both new insight on the importance of the bottom electrode texture and new fundamental processing-structure–property relationships for the HZO films.}, number={24}, journal={JOURNAL OF APPLIED PHYSICS}, author={Lee, Younghwan and Broughton, Rachel A. and Hsain, H. Alex and Song, Seung Keun and Edgington, Patrick G. and Horgan, Madison D. and Dowden, Amy and Bednar, Amanda and Lee, Dong Hyun and Parsons, Gregory N. and et al.}, year={2022}, month={Dec} }
 @article{song_kim_margavio_parsons_2021, title={Multimaterial Self-Aligned Nanopatterning by Simultaneous Adjacent Thin Film Deposition and Etching}, volume={15}, ISSN={["1936-086X"]}, url={https://doi.org/10.1021/acsnano.1c04086}, DOI={10.1021/acsnano.1c04086}, abstractNote={Printed component sizes in electronic circuits are approaching 10 nm, but inherent variability in feature alignment during photolithography poses a fundamental barrier for continued device scaling. Deposition-based self-aligned patterning is being introduced, but nuclei defects remain an overarching problem. This work introduces low-temperature chemically self-aligned film growth via simultaneous thin film deposition and etching in adjacent regions on a nanopatterned surface. During deposition, nucleation defects are avoided in nongrowth regions because deposition reactants are locally consumed via sacrificial etching. For a range of materials and process conditions, thermodynamic modeling confirms that deposition and etching are both energetically favorable. We demonstrate nanoscale patterning of tungsten at 220 °C with simultaneous etching of TiO2. Area selective deposition (ASD) of the sacrificial TiO2 layer produces an orthogonal sequence for self-aligned patterning of two materials on one starting pattern, i.e., TiO2 ASD on SiO2 followed by W ASD on Si-H. Experiments also show capacity for self-aligned dielectric patterning via favorable deposition of AlF3 on Al2O3 at 240 °C with simultaneous atomic layer etching of sacrificial ZnO. Simultaneous deposition and etching provides opportunities for low-temperature bottom-up self-aligned patterning for electronic and other nanoscale systems.}, number={7}, journal={ACS NANO}, publisher={American Chemical Society (ACS)}, author={Song, Seung Keun and Kim, Jung-Sik and Margavio, Hannah R. M. and Parsons, Gregory N.}, year={2021}, month={Jul}, pages={12276–12285} }
 @article{limbu_adhikari_song_chitara_tang_parsons_yan_2021, title={Toward understanding the phase-selective growth mechanism of films and geometrically-shaped flakes of 2D MoTe2}, volume={11}, ISSN={["2046-2069"]}, DOI={10.1039/d1ra07787b}, abstractNote={This study investigates the phase-controlled growth of flakes and films of 2D MoTe2 by atmospheric-pressure chemical vapor deposition and presents a thorough understanding on the growth mechanism.}, number={61}, journal={RSC ADVANCES}, author={Limbu, Tej B. and Adhikari, Bikram and Song, Seung Keun and Chitara, Basant and Tang, Yongan and Parsons, Gregory N. and Yan, Fei}, year={2021}, month={Dec}, pages={38839–38848} }
 @article{saare_song_kim_parsons_2020, title={Effect of reactant dosing on selectivity during area-selective deposition of TiO2 via integrated atomic layer deposition and atomic layer etching}, volume={128}, ISSN={["1089-7550"]}, url={https://doi.org/10.1063/5.0013552}, DOI={10.1063/5.0013552}, abstractNote={A key hallmark of atomic layer deposition (ALD) is that it proceeds via self-limiting reactions. For a good ALD process, long reactant exposure times beyond that required for saturation on planar substrates can be useful, for example, to achieve conformal growth on high aspect ratio nanoscale trenches, while maintaining consistent deposition across large-area surfaces. Area-selective deposition (ASD) is becoming an enabling process for nanoscale pattern modification on advanced nanoelectronic devices. Herein, we demonstrate that during area-selective ALD, achieved by direct coupling of ALD and thermal atomic layer etching (ALE), excess reactant exposure can have a substantially detrimental influence on the extent of selectivity. As an example system, we study ASD of TiO2 on hydroxylated SiO2 (Si–OH) vs hydrogen-terminated (100) Si (Si–H) using TiCl4/H2O for ALD and WF6/BCl3 for ALE. Using in situ spectroscopic ellipsometry and ex situ x-ray photoelectron spectroscopy, we show that unwanted nucleation can be minimized by limiting the water exposure during the ALD steps. Longer exposures markedly increased the rate of nucleation and growth on the desired non-growth region, thereby degrading selectivity. Specifically, transmission electron microscopy analysis demonstrated that near-saturated H2O doses enabled 32.7 nm thick TiO2 patterns at selectivity threshold S > 0.9 on patterned Si/SiO2 substrates. The correlation between selectivity and reactant exposure serves to increase fundamental insights into the effects of sub-saturated self-limiting surface reactions on the quality and effectiveness of ASD processes and methods.}, number={10}, journal={JOURNAL OF APPLIED PHYSICS}, author={Saare, Holger and Song, Seung Keun and Kim, Jung-Sik and Parsons, Gregory N.}, year={2020}, month={Sep} }
 @article{song_saare_parsons_2019, title={Integrated Isothermal Atomic Layer Deposition/Atomic Layer Etching Supercycles for Area-Selective Deposition of TiO2}, volume={31}, ISSN={["1520-5002"]}, url={https://doi.org/10.1021/acs.chemmater.9b01143}, DOI={10.1021/acs.chemmater.9b01143}, abstractNote={New approaches for area-selective deposition (ASD) are becoming critical for advanced semiconductor patterning. Atomic layer deposition (ALD) and atomic layer etching (ALE), that is, “inverse ALD”, are considered important for ASD, but to date, direct integration of ALD and ALE for ASD has not been reported. This work demonstrates that self-limiting thermally driven ALE, using WF6 and BCl3, can be directly coupled with self-limiting thermal ALD, using TiCl4 and H2O, in a single isothermal reactor at temperature 0.9, nearly a 10× improvement over previous reports of inherent TiO2 ASD. After ALD/ALE (=30/5) 14 supercycles at 170 °C, X-ray photoelectron spectroscopy da...}, number={13}, journal={CHEMISTRY OF MATERIALS}, publisher={American Chemical Society (ACS)}, author={Song, Seung Keun and Saare, Holger and Parsons, Gregory N.}, year={2019}, month={Jul}, pages={4793–4804} }