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Thermal atomic layer etching: Mechanism, materials and prospects
摘要： In the semiconductors and related industries, the fabrication of nanostructures and nanopatterns has become progressive demand for achieving near-atomic accuracy and selectivity in etching different materials, particularly in ultra-thin gate dielectrics and ultra-thin channels used in field-effect transistors and other nanodevices below 10 nm scale. Atomic layer etching (ALE) is a novel technique for removing thin layers of material using sequential and self-limiting reactions. Different from most ALE processes using plasma-enhanced or other energetic particles-enhanced surface reactions, thermal ALE realizes isotropic atomic-level etch control based on sequential thermal-drive reaction steps that are self-terminating and self-saturating. Thermal ALE can be viewed as the reverse of atomic layer deposition (ALD), both of which define the atomic layer removal and growth steps required for advanced semiconductor fabrication. In this review, we focus on the concept and basic characteristics of the thermal ALE in comparison with ALD. Several typical thermal ALE mechanisms including fluorination and ligand-exchange, conversion-etch, oxidation and fluorination reactions are intensively introduced. The pros and cons of thermal ALE, plasma ALE, and traditional plasma etching are compared. Some representative materials and their typical thermal ALE processes are summarized. Finally, the outlook and challenges of thermal ALE are addressed.
关键词： Thermal atomic layer etching,Reaction mechanism,Atomic-scale precision,Atomic layer deposition,Self-limiting
更新于2025-09-23 15:22:29
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European Microscopy Congress 2016: Proceedings || Insight on the fine structure of semiconductor nanowires down to single atom detection: correlation to their physical properties
摘要： Nanotechnology allows modifying the structure of nanoobjects down to the atomic scale. Low dimensional quantum structures can be embedded in a nanowire system in order to modify its properties at will. Electronic and optoelectronic devices benefit from the new advances in growth methodologies, with a fine control of the elemental species locally deposited. In the present work, we will present how an accurate knowledge on the atomic positions, down to single atom detection, may help to deeply understand the improved properties of our complex nanowire heterostructures. We will show how from scanning transmission electron microscopy (STEM), it is possible to obtain precise 3D atomic models that can be used as input for the simulation of its physical properties. Finally, these theoretical properties will be cross-correlated to the experimental measurements obtained locally on our nanowire systems. Some of the presented works will include: the effect of the isotope distribution on the phononic behavior of nanowires, the measurement of the internal electric fields in quantum structures and the influence of doping on the compensation of the polarization field, or the influence of polarity and the atomic arrangement on the photonic and electronic properties of single heterostructured nanowires.
关键词： polarity,physical properties,atomic scale,non-planar nanostructures,Semiconductor Nanowires
更新于2025-09-10 09:29:36
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Atomic-scale structure characteristics of antiferroelectric silver niobate
摘要： Antiferroelectric materials are a kind of functional material, which are widely used in electrostatic energy storage, energy conversion devices, and magnetoelectric coupling devices. As a typical lead-free antiferroelectric material, silver niobate has attracted much attention in recent years due to its excellent performance in energy storage. In this work, using the spherical aberration corrected electron microscopy technique, atomic-resolution images of pure silver niobate were obtained, which revealed typical microscopic physical characteristics of such complex antiferroelectric oxides: in such materials, all cations deviate from the average positions of the main lattice, and the displacement of each kind of cation varies periodically in two opposite directions, resulting in periodic wavy (1–10)c atomic planes, and the period of cation displacement is 15.6 A? . At the same time, the 90(cid:2) antiferroelectric domain boundary and the antiphase domain wall defects are further revealed and analyzed.
关键词： electron microscopy,antiferroelectric,atomic-scale structure,domain boundary,silver niobate
更新于2025-09-04 15:30:14