Print Email Facebook Twitter Isotropic Atomic Layer Etching of ZnO Using Acetylacetone and O2 Plasma Title Isotropic Atomic Layer Etching of ZnO Using Acetylacetone and O2 Plasma Author Mameli, A. Verheijen, M.A. Mackus, A.J.M. Kessels, W.M.M. Roozeboom, F. Publication year 2018 Abstract Atomic layer etching (ALE) provides Ångström-level control over material removal and holds potential for addressing the challenges in nanomanufacturing faced by conventional etching techniques. Recent research has led to the development of two main classes of ALE: ion-driven plasma processes yielding anisotropic (or directional) etch profiles and thermally driven processes for isotropic material removal. In this work, we extend the possibilities to obtain isotropic etching by introducing a plasma-based ALE process for ZnO which is radical-driven and utilizes acetylacetone (Hacac) and O2 plasma as reactants. In situ spectroscopic ellipsometry measurements indicate self-limiting half-reactions with etch rates ranging from 0.5 to 1.3 Å/cycle at temperatures between 100 and 250 °C. The ALE process was demonstrated on planar and three-dimensional substrates consisting of a regular array of semiconductor nanowires (NWs) conformally covered using atomic layer deposition of ZnO. Transmission electron microsco\JVPstudies conducted on the ZnO-covered NWs before and after ALE proved the isotropic nature and the damage-free characteristics of the process. In situ infrared spectrosco\JVPmeasurements were used to elucidate the self-limiting nature of the ALE half-reactions and the reaction mechanism. During the Hacac etching reaction that is assumed to produce Zn(acac)2, carbonaceous species adsorbed on the ZnO surface are suggested as the cause of the self-limiting behavior. The subsequent O2 plasma step resets the surface for the next ALE cycle. High etch selectivities (80:1) over SiO2 and HfO2 were demonstrated. Preliminary results indicate that the etching process can be extended to other oxides such as Al2O3. Copyright © 2018 American Chemical Society. Subject atomic layer etchingisotropic removalnanowiresplasma etchingZnOAcetoneAluminaAluminum oxideAtomic layer depositionAtomsHafnium oxidesHigh resolution transmission electron microscopyII-VI semiconductorsInfrared spectroscopyMagnetic semiconductorsNanowiresPlasma etchingSilicaSpectroscopic ellipsometrySubstratesTransmission electron microscopyZinc oxideAtomic layer etchingCarbonaceous speciesIsotropic materialsIsotropic removalSemiconductor nanowireSitu infrared spectroscopySpectroscopic ellipsometry measurementsThree-dimensional substratesWide band gap semiconductors To reference this document use: http://resolver.tudelft.nl/uuid:d740d100-bc5d-4fa9-8882-dd742eb89bc3 TNO identifier 843690 Publisher American Chemical Society ISSN 1944-8244 Source ACS Applied Materials and Interfaces, 10 (44), 38588-38595 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.